V ■rsa^jVSJ^ii-'^seiE' >=7:s _~g;Ty rrj^^^^^'t^ssiijirr: : j.-jKif^s!i£ti3a32T;a-sa3t'i:JEiX/ai£L \.*"A ■/ Columbia ^nitiers;itP(i,o-tt\ ^tJjool of Bental anb (J^ral ^wrgerp ' i^i3 M'i^.i^™ - i^SS^T^ M JBmSl 0-^ gd* 1 1 -:| m ^^^^^^^^^^ B 1 -s- 1 m ^^ ^fe^l^M M ; I ^ mJlgy ;i 8 fe'^^if^ffi rf ^ it iS^ 1 1 M Ea^^^g-S^g ^g^^ 1 lli S |!^^ 1 W !^ ;M ^^^^^^B i S!^^^ 1 EfiSatW li^S ',-j- aa^.xin,,^^^ ^^Mffi .m^ S^S'i^^ -i iB iiSsi ^ 1 1111 ■iSi 1 [E^^ t& 5 iS' if W' ••^^ ijf'jj m ■"■•^^ irnigw 1 Wl H - "4 P S^l5M«SiSagx*Sfr"S5Hs^, £>, calcified dentine ; £>C, non-calcified dentine: £>M, dentine in the process of formation from medullar)- corpuscles; O, odontoblasts in multiple rows, with spindle-shaped elements wedged in between the broad odontoblasts ; 71/, medullary corpuscles produced from odonto- blasts ; such corpuscles also attached to the distal ends of the odontoblasts. Magnified 800 diameters. 12 DENTAL PATHOLOGY AND PRACTICE. A beautiful illustration of this process may be seen in the developing- tooth of a pig's fetus, ten centimeters long. (See Fig. 4.) Here we Fig. 6. Tooth of a Human Fetus, Six Months. D, D, calcified and stratified dentine; DC, DC, non-calcified dentine, the border of the cal- cified dentine being marked by globular formations ; O, odontoblasts splitting into medullary corpuscles toward the dentine, and showing rows of such corpuscles at the distal ends ; M, medullary corpuscles ready for transformation into basis-substance of dentine ; P, P, myxoma- tous tissue of papilla. Magnified 400 diameters. ODONTOBLASTS AND DEVELOPING DENTINE. 1 3 see several rows of odontoblasts, bordering the non-calcified portion of the basis-substance of the dentine. At that portion in which un- changed odontoblasts stand against the dentine, others, likewise fully developed, are attached to the uppermost row. This we may consider to be in a condition of comparative rest. At that portion, on the contrary, in which the odontoblasts are replaced by medullary cor- puscles toward the dentine, without a distinct boundary-line between the two, we see rows of medullary corpuscles attached to the inner ends of the odontoblasts, whereby the transverse diameter of the odontoblastic layer is noticeably broadened. In the former instance, the layer of odontoblasts is fairly well marked toward the papillary tissue ; in the latter instance it is indistinct, the odontoblasts blending with the papillary tissue. High powers of the microscope illustrate still better this claim. (See Fig. 5.) With these it becomes evident that the dentinal fibers, originally attached to and connected with the odontoblasts, are placed between the medullary corpuscles as soon as the former are converted into the latter. Wherever we find rows of medullary corpuscles at the inner ends of the odontoblasts, delicate fibrillae are seen coursing between their rows or groups. Since, according to the views which I hold, the myxomatous basis- substance of the papillary tissue is supplied with living matter, the same as are the so-called cells, there is no difficulty in explaining the origin of new protoplasmic bodies from the previous myxomatous basis- substance, for the purpose of supplying continuous additions to the odontoblasts. The facts just described are well illustrated in the developing teeth of a human fetus from six to seven months old. (See Fig. 6.) The cusp of the dentine shows stratification, although no odonto- blasts are seen at the summit of the papilla. At the sides of the cusps, odontoblasts appear, broken up into finely granular medullary cor- puscles toward the non-calcified basis-substance of the dentine, and augmented in their bulk by rows of glistening, almost homogeneous, medullary corpuscles, toward the papillary tissue. Occasionally we meet with a basis-substance of dentine not yet calcified, and still exhibiting its composition of medullary corpuscles. (See Fig. 7.) Upon studying this specimen, all doubts as to the origin of the basis-substance of the dentine must vanish. All previous attempts at explaining how the odontoblasts are converted into dentine must prove futile in the face of such a specimen. Although admitting that such a plain example is seen only exceptionally, this specimen seemed to be so instructive and so convincing that the illustration with a very high power was made. With the facts advanced, a hitherto mooted question seems to have found solution. 14 DENTAL PATHOLOGY AND PRACTICE. As to the question why dentine in all its stages of development appears to be a continuous mass, and but exceptionally interrupted Fig. 7. Tooth of Human F^tus, Seven Months. D,D, dentine calcified ; DC, non-calcified basis-substance of dentine, close above the caoil- lary b.ood-vessels, broadened and visibly n.ade up of medullary corpuscles ; C, cap Hary b ood- vessel m transverse and longitudinal section ; M, M, medullary corpuscles eady fo nfi'trltron Tdln. h,"? r":/^""' '^^' ™^dullary corpuscles arranged in rows for the format on of odontoblasts. Magnified 800 diameters. uimaiion 01 GROWTH OF ENAMEL. I5 by marks of stratification, the explanation is that the odontoblasts themselves are continuous. ^Not that the original odontoblasts are preserved and augmented from the periphery toward the center ; but that so much of an odontoblast as is converted into dentine at its peripheral portion, is made good by the addition of medullary cor- puscles at the central end or portion, from the tissue of the papilla, both the protoplasmic bodies and the basis-substance. CHAPTER III. GROWTH OF ENAMEL. Many acute and conscientious observers have exhausted their talent in attempting to reveal the mysteries surrounding the development of the dental tissues. For all such honest attempts we should be most grateful, for they serve as stepping-stones enabling us to reach a height which renders the history of the development of these organs fairly intelligible. Our modern researches have conclusively settled the fact that the laws governing the formation of dental tissues are the same as those controlling all other tissues of the animal body. The stumbling-block has always been the method of development of enamel. For many years histologists have agreed that enamel is originally an epithelial formation, and consequently to be considered as a dermal or tegumentary appendage, as Todd and Bowman, in their celebrated cyclopedia (1848-49), termed it. Still, the result of metamorphosis of the epithelia was known to be the stellate reticulum, which closely resembles myxomatous connective tissue. All observers heretofore have shrunk, on merely theoretical grounds, from the idea that epithelium could ever give rise to connective tissue. The idea that it must, under all circumstances, produce epithelial derivations exclusively has apparently served as an insurmountable obstacle to the full understanding of the development of enamel. How could brilliant thinkers be satisfied that a single row of cells, supposedly epithelial in nature, would give rise to a heavy layer of enamel, such as exists on the crowns of temporary teeth at the time of eruption ? What is the function of the stellate reticulum, — a rather heavy layer of tissue, so notable for its beautiful structure ? Is there any satisfaction in the idea that this enamel-organ should serve merely for the nutrition of the enamel, or, as others have it, for pro- tection, in the shape of a soft gelatinous cushion, against injuries to * Abbott, Dental Cosmos, 1889. l6 DENTAL PATHOLOGY AND PRACTICE. the enamel from without ? It sounded almost like a revelation when G. Hertz, in 1866, had the courage to assert and maintain that the stellate reticulum contributes directly to the formation of the enamel through a new formation of cells. The mistaken conception that the sum total of what we term odontoblasts was to be considered as a membrane known as the " membrana eboris," and the sum total of what we call ameloblasts as a membrane termed " membrana adaman- tina," wrought havoc in the minds of many histologists. The secretion theory was one of the outgrowths of this membrane theory. A few good men, I am sorry to say, still cling to it. A. Kolliker, in his "Handbook of Histology of Man" (1852), speaks of development of enamel in the following terms : ' ' The de- velopment of the dental substances has always been considered a very difficult topic. The relations are the simplest in the enamel, and not the slightest doubt prevails that the enamel-cells, by a complete calcification, become transformed into enamel-fibers (enamel-rods). As soon as a small portion of the cells, without any preliminary deposition of lime particles, begins to ossify, we recognize a small lamella of enamel over the somewhat larger dentine-cap, which has also recently originated. The deposition of lime proceeds in the cells from within outward till they are at last transformed into enamel-fibers and simultaneously transgress on new cells, by which means the layer of enamel is broadened. While this is going on the enamel-membrane has not disappeared at the place where the ossifi- cation started. On the contrary, we find this membrane always of the same breadth so long as the deposition of the enamel lasts, which proves that the ossified portion of the membrane is con- tinuously being replaced by an additional mass. Apparently this is done, not by the production of new cells, but by a continuous out- growth of the original ones. The enamel-organ (stellate reticulum) is certainly of great importance in the building up of enamel, and owing to its richness in albumen and a gelatinous mass in its meshes is, so to speak, a pantry from which the enamel-membrane derives the material for its growth, being at some distance from the blood- vessels. In fact, we see this spongy tissue losing in its bulk during the development of enamel, and finally disappearing when the forma- tion of enamel is completed." I will here add that to Kolliker the enamel-membrane means a layer of epithelia. He describes the enamel-organ as being made up of anastomosing star-shaped cells, or a reticular connective tissue, which contains in its meshes a large amount of albumen and a liquid rich in mucus. The same author, in his work on the " History of Development of Man and the Higher Animals," in 1879, claims that the stellate reticulum of the enamel-organ is identical in appearance GROWTH OF ENAMEL. I7 with connective tissue, but is really nothing but a peculiarly trans- formed epithelium. KoUiker, therefore, in 1852, held the opinion which those who believe with me consider to-day the correct one, but which years afterward he very materially modified, almost to the point of entire abandonment. This author was the first to announce that the theory of exclusiveness is not tenable, in the pro- cess of development, from the three original embryonal layers, the "ectoderm," the "mesoderm," and the "entoderm," or, using Balfour's terminology, the "epiblast," the "mesoblast," and the ' ' hypoblast ; ' ' and yet he narrows his views to an almost incredible degree, in the chapter upon development of enamel. John Tomes, in his "Dental Physiology and Surgery" (London, 1848 ; Philadelphia, 1853), gives wonderfully accurate drawings of what he calls enamel-pulp, or columnar tissue, now known as amelo- blasts. On page 102 he explains the development of enamel-rods or fibers in the following words : ' ' The cells being formed in lines, eventually become confluent ; the points of union being sometimes transverse, and at other times oblique. At this stage the earthy elements are received, and the lines of union between the component cells of the fibers become less distinct, and are eventually lost, leaving a continuous fiber. The nuclei, from the first very small, are alto- _gether lost in the formation of the fibers, or exist as very fine tubes passing through the length of each." On page 104. we read : "To the best of my belief the transverse striae are due to the alternate dilatation and contraction of the fibers, — each dilatation corresponding to the center of a formative cell, and each contraction to the junction of two cells. ' ' Ifrom these quotations it becomes evident that John Tomes was a most careful observer. Even at that early date, with the limited pow;ers of his microscope, he conceived the full truth when he stated ' ' that each enamel-rod is the result of a juxtaposition of formative cells, between which are left the striae." He considers the formative cells as the recipients of the calcareous matter in exactly the same way that we see it to-day. F. Waldeyer, in his " Handbook of Histology," edited by Strieker (Leipzig, 1869), page 347, describes the formation of enamel in the following manner : ' ' The formation of enamel is done exclusively by the enamel-epithelium, since the enamel-prisms are the result of a direct calcification of its long cylindrical cells. The boundary of petrifaction on the cells is by no means linear, but extends downward to an irregular depth, — a fact which likewise is not in favor of the view that a secretion of the enamel-cells is being calcified. After treatment of young enamel with dilute acids, the enamel-prisms swell slightly and resume entirely the forms of the previous cylindrical 3 l8 DENTAL PATHOLOGY AND PRACTICE. cells. The disappearance of the nuclei, in the process of the calcifi- cation of the cells, is of so common occurrence that their absence in the enamel cannot cause any wonder. Enamel, therefore, is to be considered as the petrified dental epithelium." This author explains the formation of the stellate reticulum by a transformation of the epithelia, and considers its gelatin of a merely mechanical importance, to keep an open space for the growing tooth. John and Charles S. Tomes, in their ' ' System of Dental Surgery' ' (London, 1873), page 253, say, "The conclusions respecting the development of enamel which are most in accordance with appear- ances observed are these : The columns of the enamel-organ (enamel-cells, internal epithelium of the enamel-organ) are subserv- ient to the development of the enamel-prisms into which they by calcification become actually converted. This conversion goes on in the following method : The proximal end of the cell undergoes some chemical change preparatory to calcification, and is subse- quently calcified ; but this calcification does not go on uniformly throughout its whole thickness, but proceeds from its periphery toward its interior, the central portion of the cell thus being calcified later than the external portion, which lies at the same level. At the same time that calcification is proceeding inward, in each individual cell, it has united the contiguous cells to each other. The calcifica- tion of the central portions of the enamel-fibers does not keep pace with that of their exteriors, nor even in fully completed enamel does it attain to precisely the same characters. In the progress of calcifi- cation the nuclei of the enamel-cells disappear, and it is probable, as is believed by Waldeyer, that the internal epithelium of the enamel is reunited by the cells of the stratum intermedium as it becomes itself used up by advancing calcification, converting it into enamel-fibers." These authors give credit to Kolliker as the originator of the idea that the enamel-cells do not undergo direct conversion into enamel- fibers, but that the enamel is, as it were, shot out from their ends ; that is, it is a secretion from them, not a deposition of lime-salts into their own substance. Our quotations from Kolliker' s original Ger- man work, issued in Leipzig in 1852, plainly show that at that time he believed fully in the conversion theory. Since the Tomeses quote from the fifth German edition of Kolliker's Histology, issued in 1867, it is obvious that he had changed his views, much, in my judgment, to his own disadvantage. The views taken in a series of papers upon the history of develop- ment of the enamel by C. Heitzmann and C. F. W. Bodecker, — " Contributions to the History of Development of the Teeth" {Inde- pendent Practitio7ier, vols, viii, ix, 1887-S8), — are in harmony with my own observations, and furnish the foundation for what I have to GROWTH OF ENAMEL. 19 add, in the way of a more comprehensive explanation of the process of building enamel, than has heretofore been advanced. This I pro- pose to give in as few words as I conveniently can and make myself clearly understood. Fig. 8. BE Tooth of Human Fetus, Six Months. /'.papilla; ZJi, non-calcified dentine ; i?2, calcified dentine ; £•, enamel ; /I, rowof ameloblasts ; M, medullary corpuscles at the peripheral portion of ameloblasts ; G, globular corpuscles from which ameloblasts develop ; EE, buds of external epithelium ; F, follicle, made up of fibrous connective tissue. Magnified 100 diameters. Fig. 8 gives an illustration of these views. The figure, it must be emphasized, is not diagrammatic, but copied with the utmost care 20 DENTAL PATHOLOGY AND PRACTICE. from one of Bodecker's specimens of a human fetus six months old, the period at which enamel begins to appear. The different layers, it will be observed, appear to be separated from one another. This is usually the case in even the most carefully prepared speci- mens, owing to slight mechanical injury in cutting, and shrinkage of the soft parts ; the relations, however, are absolutely correct in this drawing. After the epithelial peg has grown into the depth of connective tissue of the oral mucosa, in the twelfth week of embryonal devel- opment, the distal end of this peg becomes club-shaped, and then appears the first trace of medullary tissue, which two weeks later plainly shows the stellate reticulum. The club at this period assumes a cup shape, whose concave surface is lined by the internal epithe- lium, while the outer surface is made up of the so-called external epithelium, which is in uninterrupted continuity with the internal epithelium at the most prominent border of the cup. If we examine the lower edge of the cup of the enamel-organ at about the six- teenth week of embryonal life, we observe a peculiar change in the columnar bodies of the internal epithelium, which consists in the appearance of highly glistening globular bodies, in a more or less row-like arrangement, replacing the previous columnar epithelia. These bodies are either solid or slightly vacuoled, and are forma- tions of living matter such as we are accustomed to look upon as medullary, embryonal, or indifferent corpuscles in their earliest stage of appearance. Obviously these glistening globules have originated from the reticulum of living matter of the columnar epithelia themselves. This conclusion is justified from the fact that we can trace, step by step, the growth of these glistening granules up to the formation of the glistening lumps which we have termed medullary corpuscles. The more the cup of the enamel-organ is enlarged, the more conspicuous becomes the transmutation of the previous internal epithelium into glistening lumps ; so much so that toward the end of the fifth month of fetal life the original columnar epithelium at the concave portion of the cup has entirely disappeared. In its stead, other bodies closely resembling columnar epithelia, now known as ameloblasts, or enamel-formers, begin to show, first at the deeper portion of the cup. From this description it seems evident that all previous observers — with due respect to their judgment — have been in error in the assumption that the columnar epithelia of the internal wall of the cup were identical with the ameloblasts. All of them have over- looked the intermediate stage of the glistening medullary lumps. In Fig. 8 these lumps are marked G. They are traceable down to the neck of the papilla, therefore to the point of recurvation of the GROWTH OF ENAMEL. 21 previous internal into the previous external epithelium. The lumps, I wish to repeat, are extremely glossy, with a high degree of refrac- tion. They are arranged, at first irregularly, in a layer of consider- able breadth, higher up in rows, and by their coalescence and pro- longation give rise to small columns, the ameloblasts. These are seen up to the end of the fifth month of fetal development at the deepest concavity of the cup and its lateral walls down to varying depths, and closely attached to the now forming dentinal cap. The odontoblasts grow smaller toward the thin extremity of the dentinal cap, and below its end they appear as blunt and short columns, while, close above, the ameloblasts make their appearance, being traceable all around the outer periphery of the dentinal cap. In the sixth month of fetal life, as is well known, the enamel-cap begins to show ; first at the summit of the dentinal cap, where it gains its greatest breadth, gradually becoming thinner toward the sloping sides, and, as a whole, a trifle thinner and shorter than the dentinal cap. If we now examine the ameloblasts close above the already-formed enamel, we will observe finely granular bodies, arranged in a row, between the enamel and ameloblasts. These are best seen in speci- mens where the hardening and cutting procedures have not caused a detachment of the soft tissues from the hard, — i.e., the enamel-organ from the calcified enamel. It is seldom that this is accomplished ; but a few of such perfect specimens are in Bodecker's collection, which by his kind permission I have used for my studies and these drawings. Even though a slight detachment has occurred, the enamel-organ still remains intact, and the finely granular corpuscles at the proximal ends of the ameloblasts remain visible. What are these finely granular bodies ? The last-named authors claim that they are medullary corpuscles, holding small and indis- tinct or no nuclei, and only a very small amount of living matter, which accounts for their finely granular appearance with low powers of the microscope. They further claim that these corpuscles, or the liquids contained in their reticulum, become solidified into basis-sub- stance, and immediately infiltrated with lime-salts. They claim also that the enamel-rods are built up by rows of such calcified or "petrified" medullary corpuscles, the successive arrangement of which into rows causes the more or less regular appearance of the transverse striae of Retzius, whereas between the rows longitudinal interstices will remain, filled, perhaps, with a small amount of cement- substance, differing in its chemical constitution from the basis-sub- stance of the rods proper, and in its interior holding extremely delicate fibrillae (Bodecker's enamel-fibers), which branch into the transverse striae. Being: satisfied that the views of these gentlemen 22 DENTAL PATHOLOGY AND PRACTICE. are correct, I will simply add a new feature, to make those views more symmetrical, — and, as it occurs to me, it is a feature of consid- erable importance : viz, the changes that take place in the amelo- blasts during the process of the formation of enamel. (Fig. 9,) Fig. 9. First-Formed Enamel of Human Fetus, Six Months. D, dentine; E, enamel toward the dentine, made up of irregular calcified fields, toward the periphery of prisms with transverse interruptions ; M, medullary corpuscles finely granular, from which the enamel-prisms are formed ; A, ameloblasts, toward the enamel breaking up into medullary corpuscles, toward the periphery rebuilt by such corpuscles ; ^i, irregular amelo- blasts torn from their connection with enamel: F, fibrous connective tissue, changing to medullary tissue. Magnified 800 diameters. The ameloblasts, as just stated, split up into rows of finely granu- lar medullary corpuscles, and consequently are reduced considerably in their size. In fact, it is difficult to find full-sized ameloblasts at the summit of the enamel-cap, where the production of enamel is most active, the same as it is impossible to find full-sized odonto- blasts at the summit of the papilla, where the formation of dentine GROWTH OF ENAMEL. 23 is most active. The mutilated ameloblasts in this situation still exhibit nuclei, although their forms are odd, — mostly cut or broken, with offshoots running upward and laterally toward the stratum intermedium. At the same time peculiar glistening, homogeneous lumps and irregular wedge-shaped nucleated bodies appear between the offshoots of the ameloblasts ; not as regular, however, as the original medullary corpuscles were, from which the ameloblasts originally developed. All these indifferent bodies must have arisen from the living material stored up in the stratum intermedium, close above the row of ameloblasts. By their occasional row-like arrange- ment I am led to the conclusion that they serve for a restitution or rebtiilding of the ameloblasts (which at their proximal ends have split up into enamel-formers), and thus serve to establish a continuity of the ameloblasts, and, in turn, of the enamel-rods, throughout the entire thickness of the enamel. In Chapter II I have endeavored to show that odontoblasts, being split up at their distal ends into medullary corpuscles, enter directly into the formation of the basis- substance of dentine, at the same time being superadded to at their proximal ends by medullary corpuscles derived from the living matter of the papilla. Thus the continuity of the odontoblasts and dentine is established, stratification of the dentine being the exception. I now assert a similar procedure for the ameloblasts, in a reverse direc- tion, owing to the centrifugal direction of enamel growth. The amelo- blasts being broken up at their proximal ends into medullary corpuscles^ which are directly transformed into btocks of enam.el-rods , are super- added to at their distal or peripheral ends by medullary corpuscles derived fro7n the stratum ifitermedium. Normal enamel is non-strati- fied ; its rods or prisms run a wavy course, as a rule uninterruptedly, from near the dentine to the cuticular (Nasmyth's) membrane. In Chapter VI stratified enamel is described as rather an anom- alous occurrence, it being as a rule connected with pigmentation of its rods. The study of this condition enabled me to show the manner in which enamel is formed, — first in crown layers around and upon the cusps, and much later in lateral or neck layers at the sides of the crowns. This fact again proves that the most active formation of enamel always takes place at the summit of the crowns or upon the cusps ; while the lateral layers are formations of a much later date, and are much thinner. Neither the structure nor the development of this tissue is to me explicable on the basis of the cell theory, which suggests that each cell is an individual, and only exceptionally in connection with its neighbor. To me a cell is a lump of protoplasm, in which the living matter is stored up in different shapes. The glistening globules of small size, having arisen from the protoplasm of the original columnar 24 DENTAL PATHOLOGY AND PRACTICE. epithelia of the enamel-organ, represent a juvenile condition of living matter in its most compact aggregation. The medullary corpuscles, sprung from the ameloblasts, show only a delicate reticulum of living matter, being ready for immediate trans- formation into basis-substance and for calcification. Between these extreme stages stand the ameloblasts, with their vesicular nuclei, and a markedly heavy reticulum of living matter in their interior. The indifferent corpuscles, serving to supply additions to the ameloblasts, exhibit all the intermediate stages between small, globular, glossy, and compact globules up to distinctly nucleated protoplasmic lumps. Whatever the size and shape of such lumps may be, they are invari- ably connected with one another by means of delicate offshoots, which Fig. io. Ameloblasts beginning the Formation of Enamel ; from Human Fetus, Six Months. D, border of newly-formed dentine ; E, first trace of forming enamel ; A, row of ameloblasts ; Jl/i, medullary corpuscles for restitution of ameloblasts ; M", medullary corpuscles just previous to their infiltration with lime- salts ; F, fibrous connective tissue, the so-Called intermediate layer. Magnified looo diameters. vary greatly in thickness and in^their course. Each ameloblast sends offshoots toward the dentine in great numbers, known as Tomes pro- cesses. They also run upward toward the intermediate layer, and laterally for the immediate union of neighboring ameloblasts. (See Fig. ID.) Broad and clumsy offshoots, such as are depicted by Tomes and Waldeyer, are seen only upon torn and teased ameloblasts. So long as these bodies are in situ the offshoots are always delicate, and visible with higher powers of the microscope only, — i.e., from 800 to 1000 di- ameters. Through the splitting up of the ameloblasts in a longitudinal direction, delicate wedge-shaped pieces are seen to arise between GROWTH OF ENAMEL. 25 funnel-shaped or square bodies. By the coalescence of the lateral offshoots in a longitudinal direction, delicate fibrillae originate between the ameloblasts, known as Bodecker's enamel-fibers. While the formation of a tissue is going on, it seems probable, from the great variety of forms of the protoplasmic bodies, that there is not for a moment rest either in the growth or in the new formation of living matter. Thus the proximal ends of the ameloblasts are metamorphosed, through the intermediate stage of medullary cor- puscles, into the calcified basis-substance of the enamel-rods. The distal ends exhibit the stages through which the living matter passed before the original ameloblasts were formed. Still the question Fig. II. Ameloblasts at Rest; from Developing Tooth of Human Fetus, Six Months. ^, row of ameloblasts; /, /, intermediate layer; M, myxomatous reticulum; P, papilla; S, so-called structureless membrane. Magnified 1000 diameters. remains an open one, whether or not ameloblasts are an absolute necessity for the production of enamel after the formation of the rods has once begun. The rows of globular bodies as seen in Fig. lo, M"", strongly favor a negative answer to this query. Nothing but a trans- mutation of solid globular lumps of living matter into delicately retic- ulated medullary corpuscles seems to be required for the building up of the minute blocks of enamel-rods, without the intermediate stage of ameloblasts. We must admit, however, that, for symmetry of construction, the part played by these bodies seems essential. Although varying greatly in size, even in the same tooth, ameloblasts are to be considered as merely provisional formations, and by no means stable or unchangeable. This conclusion is the same as that we reached in regard to the significance of odontoblasts. 26 DENTAL PATHOLOGY AND PRACTICE. Full development of ameloblasts into oblong or conical bodies, each containing one or two nuclei, sharply bordered by a delicate cuticular formation toward the papilla, and distinctly marked by the intermediate layer toward the enamel-organ, is seen only in the condition of temporary rest, where the formation of enamel has not as yet started. (See Fig. ii.) As soon as the first trace of enamel is seen the ameloblasts lose their regularity by being split up toward the dentine, and are superadded to from the intermediate layer. The first enamel to appear is made up of irregular angular and glistening lumps, varying greatly in size. (See Figs, g and lo.) The first blocks of enamel-rods show compact edges and comparatively thin and translucent centers, in which traces of the nuclei of the medullary corpuscles even are to be seen. This shows plainly the correctness of the assertion of Tomes, that "the enamel-rods are calcified from the periphery toward the center." The irregularity toward the first-formed calcified blocks also accounts for the fact that fissures and breaks are of such common occurrence in specimens of enamel, either ground or cut, at the border toward the dentine, as demonstrated in the chapter on the anomalies of enamel, such anomalies being most common in this situation. We now return to the enamel-organ, of which it is known that it begins to show at the end of the third month of intra-uterine life, by the appearance of medullary corpuscles between the internal and external epithelium. From the fourth month to the seventh or eighth, the beautiful stellate reticulum known as the enamel-organ comes to view. , Although Huxley and Kolliker stated in 1850-52 that this is connective tissue, all the later writers, including Kolliker himself, insist that it is a peculiarly modified epithelium. I contend that this reticulum is true myxomatous tissue, and the stratum inter- medium true fibrous connective tissue. The first microscopist to describe and illustrate the intermediate layer was John Tomes, in 1848, in his work before quoted, though the credit for this is usually given to Hannover, whose work appeared in 1856. As to the significance of the enamel-organ, I must take decided exception to the views of most modern writers, viz, that it serves as a kind of protecting cushion, or to preserve an open space for the tooth to grow into. In my opinion the view first announced by Hertz in 1866, that "the enamel-organ is stored-up material for the benefit of the growing enamel itself," the same as is the intermediate layer, is the correct idea. The reasons for this are given by Heitz- mann and Bodecker in their paper quoted above. One fact will strike every observer, viz, that the enamel is seldom, if ever, perfectly symmetrical in the growing tooth, one side being GROWTH OF ENAMEL. 27 broader, to the extent of five or six times, than the other ; some- times it is found only on one side of the developing tooth, while on the other nothing but delicate fibrous connective tissue is seen. From these facts we must conclude that the myxomatous form of this organ is by no means a characteristic or an absolute necessity. How are we to explain the scantiness of this organ at the summit of the crown, where the enamel at its full development has the great- est thickness ? Can the original enamel-organ, even if ever so broad, Fig. 12. Developing Tooth of Sheep's Fetus, 10 Centimeters Long. D, dentine in longitudinal and transverse sections; A, row of ameloblasts at rest; A^, ameloblasts broken up into medullary tissue, preceding the formation of enamel ; /, /, inter- mediate layer; il/, 71/, myxomatous enamel-organ ; C, capillary blood-vessels. Magnified 1000 diameters. suffice for the production of all the enamel ? Is not the enamel coat of a temporary tooth five, nay, ten times as broad, as the original enamel-organ ? All this points strongly toward the fact that the budding external epithelium, and even the primary epithehal peg, must furnish material for the building of enamel, no matter what the intermediate or subsequent changes of this tissue may be. I have studied the development of enamel in pigs and sheep, and have found the relations similar to those in human beings. (See Fig. 12.) In the sheep's fetus, ten centimeters long, the form-changes 28 DENTAL PATHOLOGY AND PRACTICE. of the ameloblasts are especially pronounced, since shortly before the appearance of the enamel a splitting into medullary corpuscles takes place for the production of enamel-rods, and at the same time new medullary corpuscles show themselves at their distal ends, evidently produced at the expense of the intermediate layer. CHAPTER IV. TEETH OF THE LOWER JAW AT BIRTH. » The object aimed at in this chapter is to show that the temporary teeth, so far as their crowns are concerned, are in aij advanced stage of development at the time of birth, and consequently not subject to the imperfections caused by any of the diseases of childhood. This accounts for the generally perfect or nearly perfect condition in which we usually find them ; while the crowns of the permanent set, being less advanced in their development, that is, being perfected after birth, are in consequence subject to the effects of all local dis- turbances of the mucous membrane. It will be remembered that Heitzmann and Bodecker, in their ' ' Contributions to the History of the Development of Teeth, ' ' brought their researches up to the ninth month of fetal life. I have extended their studies up to the time of birth, in order to ascertain at this period the progress of development of the temporary, as well as of the permanent teeth, during the last month of fetal life. The re- sults are here presented. Two lower jaws of apparently well-developed new-born babes were excised soon after death, stripped of their soft tissues, and placed for preservation in alcohol. Afterward they were placed in a half of one per cent, solution of chromic acid, for the purpose of decalcifying the hard tissues, while preserving the soft structures. I call attention especially to this method since it has proven, in my hands, to be the safest for the preservation of the teeth. Previous descriptions of de- veloping teeth have been questioned in Germany on the ground that the preservation of the tissues was not thoroughly provided for. After repeated renewals of the chromic acid solution, the jaws were sup- posed to have become soft enough to be cut with a razor ; but it was found that the central portions, after they had been cut up into blocks, were still hard, and had to be again immersed in the chromic acid solution, for the completion of the decalcification. The blocks had been obtained from the right half of each of the jaws, and were cut radially in order to secure antero-posterior vertical sections. The * Abbott. Proceedings of the World's Columbian Dental Congress, 1893. TEETH OF THE LOWER JAW AT BIRTH. 29 blocks were imbedded in celloidin, sliced into thin sections, and each section numbered with the utmost care, in order to keep the succession of the teeth unbroken. Thus the sections could be examined and those selected for mounting which contained teeth or exhibited fea- tures belonging to the process of the development of teeth. The sum total of the sections thus obtained was one hundred and twenty- five. Out of these, again, only those were selected for study and drawing which showed the teeth in greatest perfection, the most cen- tral sections being selected for drawing. Before entering into a description of the teeth, I wish to say that one of the jaw-bones, under the microscope, was found to be slightly rachitic, as was proven by some scanty islands of hyaline cartilage found in the bone-tissue, though the baby was to all appearances normal. Previous observations have established the fact that con- genital rachitis is first shown under the microscope by a retardation of development of bone-tissue in the lower jaw, before any abnor- mal symptoms appear to the naked eye either on the skull or shaft bones. It is evident that in this case the rachitic process has caused a slight delay in the formation of dentine and enamel. This asser- tion is clearly established by a comparison with the sections ob- tained from the second jaw, in which there was not the slightest symptom of rachitis. The best specimens, however, and most of the drawings, were obtained from the first jaw, the slight deficiency in the deposition of lime-salts enabling me to obtain nearly perfect sections, whereas nearly all of the sections of the second jaw were torn and very imperfect. Another difficulty arose. As before stated, all the sections were made in an antero-posterior vertical direction. Some of the tempo- rary, and most of the permanent front teeth, are, as is well known, irregular or devious while within the jaw, so much so that the direc- tion of the sections does not always fully comply with the expression; consequently some of the drawings may not correspond to the great- est height or designed diameter of the tooth illustrated. The first tooth met with was, of course, the central incisor. (See Fig. 13.) The papilla of this tooth exhibited a bluntly ovoid shape, with a somewhat broader top, and tapering slightly to the lower end. As a matter of course, the entire papilla, at this stage, is destined for the production of the crown of the tooth only, no trace of the future root yet being present. The papilla is composed ^of a myxo- fibrous connective tissue, throughout its main bulk, and is scantily supplied with capillary blood- vessels. The periphery of the papilla shows a row of odontoblasts at the labial aspect only, and even here not complete, since the lowest third of the papilla lacks in this respect. Here, and on one-half of 30 DENTAL PATHOLOGY AND PRACTICE. the summit, as well as along the entire lingual aspect, the surface of the papilla exhibits a myxomatous medullary tissue, without any ad- mixture of delicate bundles of fibrous connective tissue, with which the remainder of the papilla is abundantly supplied. The summit of the papilla is covered with a dentine and enamel cap, the former slightly exceeding the latter in diameter. The dentine-cap is farther advanced in development on the labial than on the lingual aspect ; Fig. 13. Central Temporary Incisor. E, enamel-cap ; /?, dentine-cap ; IE, inner epiihelium, ameloblasts ; M, medullary layer, from which enamel forms; EO, enamel-organ; OE, outer epithelium broken up; P, papilla; O, TOW of odontoblasts ; R, recurvation of inner into outer epithelium. Magnified 50 diameters. it exhibits a non-calcified portion nearest the papilla, which has assumed a deep stain from the carmine ; the calcified portion remain- ing unstained. The border line between the two is marked by the well-known globular deposit of lime-salts. The enamel-cap, of a greenish-brown color (due to the chromic acid), stops short of the dentine-cap, and is, at its peripheral portion, made up of regularly developed prisms. TEETH OF THE LOWER JAW AT BIRTH. 31 The inner epithelium, from which the ameloblasts arise, produces a perfect row all around the papilla, with the exception of the apex. The place of recurvation to the outer epithelium, which latter is con- siderably broken up at this stage of development, is noticeably deeper on the labial than on the lingual aspect. The space between the inner epithelium and the already formed tooth is produced by a detachment of the former from the latter, showing plainly a layer of Fig. 14. Permanent Central Incisor. E, enamel-cap ; D, dentine-cap ; IE, inner epithelium ; EO, enamel-organ ; OE, outer epitlielium ; P, papilla ; R, recurvation of inner into outer epithelium ; O, medullary tissue forming odontoblasts. Magnified 50 diameters. protoplasmic bodies, into which the ameloblasts have retrogressed before becoming infiltrated with lime-salts. Since this feature is pro- nounced in all the teeth of the jaws under consideration, the specimens are of great value in assisting, at least, in settling the still mooted ques- tion as to the mode of development of enamel. I propose to dwell more fully upon this topic, after the description of the cuspid tooth. The permanent central incisor (see Fig. 14) is a formation with a 32 DENTAL PATHOLOGY AND PRACTICE. considerably broader papilla, but with a less developed enamel and dentine cap, than the corresponding temporary tooth. The papilla is made up exclusively of medullary tissue, supplied scantily with blood-vessels, none of which could be seen in the specimen from which the illustration was taken. Fig. 15. Temporary Lateral Incisor. E, enamel-cap ; D, dentine-cap ; IE, inner epithelium; ameloblasts ; M, medullary layer, from which enamel forms ; EO, enamel-organ ; OE, outer epithelium broken up ; P, papilla ; C, O, rows of odontoblasts ; R, recurvation of inner into outer epithelium. Magnified 50 diam- eters. Both the inner and the outer epithelium were plainly visible. The enamel-organ is much less advanced in the formation of myxomatous tissue, especially at the point of recurvation of the epithelia, than in the temporary tooth. The temporary lateral incisor (see Fig. 15) has a papilla much TEETH OF THE LOWER JAW AT BIRTH. 33 longer than that of the central ; at the same time it is of a more cylindrical form, but otherwise of identical structure in all respects. On the top of the papilla we notice a rounding labial aspect, and a sharply pronounced angle at the lingual portion. We observe a row of odontoblasts only at the central portion of the labial surface, at the summit, and along the upper two-thirds of the lingual aspect, while the remainder of the surface is occupied by a medullary tissue, destitute of fibrous elements, the same as in the central incisor. The dentine-cap is considerably broader than that of the central in- cisor, and extends farther down upon the labial surface. It of course forms a decided angle at the lingual portion of the top of the tooth. The border line between the non-calcified and calcified portions of the dentine is more conspicuous in this tooth through the presence of globular deposits of lime-salts, than in the central incisor. The enamel is of about the breadth of that of the central, and follows strictly in its general contour, the dentine-cap. A pronounced feature in this tooth is the medullary tissue occupying the space between the row of ameloblasts and the surface of the tooth. The myxomatous enamel-organ in both temporary incisors does not show a well-de- veloped reticulum, but in its stead is a finely-granular protoplasmic mass, obviously a stage of development in the progressive formation of the myxomatous reticulum. The permanent lateral incisor (see Fig. i6) has an oblong papilla, notable for the abrupt stopping of the enamel and dentine caps at the lingual aspect, and also for the precipitous lingual portion of its upper one-half The blood-vessels traversing the medullary tissue of the papilla are comparatively few in number. A fully-developed row of odontoblasts is to be seen only at the lingual and posterior cutting-edge, the remainder of the cutting-edge being mostly desti- tute of these bodies. The other portions of the papillary surface show only rows of medullary corpuscles tending toward the formation of odontoblasts. A conspicuous feature in this specimen is the dif- ference between the points of recurvation of the epithelia, embracing at the labial aspect quite a portion of the bottom of the papilla ; while at the lingual, it barely reaches down one-half its length. The temporary cuspid (see Fig. 17) has a papilla which, it will be observed, is somewhat triangular in shape, with a sharply-pointed apex, apd irregularly rounded at the base ; with the lingual portion extending down slightly beyond the labial. The structure of the papilla does not materially differ from that of the incisors, the number of capillaries also being about the same. A row of odontoblasts is observable, but only at the lower portions of the surface of the tooth on the labial and lingual aspects. The summit is occupied by a well- pronounced myxomatous tissue, the remainder of the surface by a 4 34 DENTAL PATHOLOGY AND PRACTICE. medullary formation. The dentine-cap is very broad, and sharply pointed at its summit. It extends far down along the surfaces of the papilla, more so anteriorly than posteriorly. The non-calcified por- tion is decidedly narrower, and the globular boundary line less pro- nounced, than in the incisors. The enamel-cap is likewise very broad, stopping short of the dentine-cap, and is regularly developed in every respect. Fig. i6. Permanent Lateral Incisor. E, enamel-cap; D, dentine-cap; IE, inner epithelium; EO, enamel-organ; R, recurvation of inner into outer epithelium ; O, rows of odontoblasts ; /*, papilla. Magnified 50 diameters. The sections obtained from the cuspid were so perfect that they could be and were advantageously utilized to assist in settling certain mooted questions as to the development of dentine and enamel. In the first place, the odontoblasts, since their discovery, have been considered by the majority of histologists as the dentine-formers proper. TEETH OF THE LOWER JAW AT BIRTH. 35 It was Heitzmann and Bodecker, in their above-quoted paper, who first denied the direct transformation of the odontoblasts into den- tine, but claimed that they are first broken up into medullary cor- puscles at the distal ends, which become infiltrated, first, with a glue- yielding basis-substance, and afterward with lime-salts, and that the offshoots of the original odontoblasts, being the dentinal fibrillae, Fig. ty. Temporary Cuspid. .£, enamel-cap ; Z), dentine-cap ; /I/, myxomatous tissue ; P, papilla ; O, row of odontoblasts. Magnified 50 diameters. pass between the calcified medullary corpuscles in their respective canaliculi. Every odontoblast sends off" one or more fibrillae. This fact has apparently made it impossible for s'ome observers to clearly understand the formation of the basis-substance. So great, indeed, has been the difficulty that some observers have resorted to the supposition of specific fiber-cells for the production of these fibrillae,. 36 DENTAL PATHOLOGY AND PRACTICE. the odontoblasts proper, according to their view, producing only the basis-substance. This view was met at the time it was announced by a demonstra- tion showing that the "fiber-cells" were wedge-shaped odontoblasts, most numerous where the odontoblasts are arranged around a sharp Fig. i8. ieofi/^lRD e-o ■ rw_ Summit of Papilla of Temporary Cuspid. C, calcified dentine; N, non-calcified dentine, with globular deposits of lime-salts at the border between calcified and non-calcified dentine ; /^.flattened out indifferent or medullary tissue; jl/, myxomatous tissue; /*, myxo-fibrous tissue of papilla with capillary blood-vessels. Magnified 800 diameters. curve, especially at the summit of the papilla. In the pig's fetus, for instance, the summit of the papilla is occupied almost exclu- sively by these narrow and wedge-shaped odontoblasts. The diffi- culty is, however, easily overcome by the demonstration of the presence of medullary corpuscles at the periphery of the papilla, directly beneath the already -formed dentine. In my specimens, espe- TEETH OF THE LOWER JAW AT BIRTH. 37 cially the cuspid, one is struck by the scantiness of the rows of odontoblasts and the presence of medullary elements in their stead, one row of odontoblasts being visible on a portion of the labial, another on a portion of the lingual surfaces only. Not infrequently the odontoblasts are arranged at acute angles to the dentinal canal- iculi. (See Fig. 17.) This feature may possibly be attributable to the 0. I. A. M. Lateral Portion of Temporary Cuspid. O, enamel-ors:an ; /.intermediate layer; A, row of ameloblasts ; M, medullary tissue; E, enamel; C, calcified dentine ; A^, non-calcified dentine ; /'.papilla. Magnified 800 diameters. hardening process and the subsequent disfigurement by shrinkage, although good reasons may be adduced to the contrary, as the speci- mens are so perfect in all other respects. The greater part of the area of the surface of the papilla is occupied by a medullary tissue, which is claimed to be the dentine-builder proper. In our cuspid, the summit is occupied by a myxomatous tissue, approaching in 38 DENTAL PATHOLOGY AND PRACTICE. gracefulness almost that of the enamel-organ. (See Fig. 1 8. ) Between this myxomatous tissue and the border of the non-calcified dentine clusters of indifferent or medullary corpuscles are seen, arranged longitudinally along the surface of the papilla, therefore not as yet adapted for the formation of dentine. Beneath the myxomatous tissue we find vascularized myxo-fibrous tissue, constituting the main bulk of the papilla. Professor Ebner, of Vienna, in the " German Hand-Book of Den- tistry," 1 89 1, by J. Schefif, Jr., claims that the characterization of medullary corpuscles as the dentine-formers shows the interpretation of poorly-preserved specimens. In view of this assertion, I will draw the gentleman's attention to these illustrations, taken from per- fect specimens, and ask him how he accounts for the absence of odontoblasts where they should be and the presence of medullary tissue in their stead. Obviously, there is a series of tissue-changes preceding the appearance of dentine, and one of the links in the chain is the odontoblast. At the lateral portion of the cuspid, evidence is to be found by which the question of the formation of enamel may possibly be set- tled. (See Fig. 19.) Between the fully-developed enamel and the row of ameloblasts at that point there is a broad layer of medullary tissue, considerably broader, indeed, than in any other specimen of developing human teeth I have ever before seen. Ebner takes issue with the view ' ' that the ameloblasts are not direct enamel-formers , but only transient formations ^ origi?iating from a coalescerice of medullary co7'puscles and breaking up again into such corpuscles before the appearance of enamel-tissued Can he or any one else explain, may I ask, the composition of enamel-prisms, of square or many-sided blocklets (the forms admitted by all observers), except by the con- struction of each enamel-rod, by a succession of medullary cor- puscles becoming infiltrated with lime-salts ? It is unnecessary for me to state here that I seriously object to the assertion of Ebner or any one else that the specimens from which the conclusions he combats were or are imperfect. The greatest care having been taken in their preparation, I can vouch for their per- fection. With equal propriety, I might ask the learned professor why it is that his specimens were so imperfect as to not show the fibers between the enamel- prisms, or the medullary tissue between the ameloblasts proper and the formed enamel. The permanent cuspid (see Fig. 20) has a papilla considerably broader than that of the temporary, so much so that it could be illus- trated entirely only with a power of twenty-five diameters. The labial aspect is far more bulky than the lingual ; the former being precipitous, the latter more gently tapering. It is composed ot TEETH OF THE LOWER JAW AT BIRTH. 39 medullary tissue, without the slightest admixture of the myxo-fibrous or fibrous connective variety, and is at the same time poorly supplied with blood-vessels. Both dentine and enamel- caps are as yet nar- row, terminating upon the labial side abruptly, an apparent stricture presenting at their termination, beyond which the papilla bulges con- siderably, while on the lingual side both caps follow the unbroken line of the papilla. The temporary first molar (see Fig. 21) at this stage of develop- ment is of considerable size and importance. It presents in this sec- tion two cusps, of which the lingual is quite noticeably higher than the Fig. 20. Permanent Cuspid. E, enamel-cap ; D, dentine-cap ; C, row of odontoblasts ; P, papilla. Magnified 25 diameters. buccal, although the latter is but little less developed than the former. The papilla is a bulky mass of myxo-fibrous connective tissues, abundantly supplied with capillary blood-vessels. Corresponding to the valley between the two cusps, the papilla is narrower, bulging from this point upward and outward. The summit of the papilla of the lingual cusp is higher and more pointed than that of the buccal. The papilla exhibits a row of odontoblasts only upon the lower third of the lingual aspect ; everywhere else its surface is made up of medullary tissue, without a trace of odontoblasts. The summit of the papilla of the lingual cusp exhibits a zone of myxomatous tissue 40 DENTAL PATHOLOGY AND PRACTICE. similar to that described in the papilla of the cuspid. The dentine- cap forms a continuous investment around the cusps, being narrow in the valley between them and slanting toward the base of the papilla, reaching farther downward upon the buccal than upon the lingual side. It is fully developed, and composed of a narrow non-calcified and a broad calcified layer, the border-line between the two por- tions being more globular in the buccal than in the lingual cusp. The enamel is likewise continuous, fully developed, and calcified, being a trifle broader at the summit of the lingual than at that of the Fig Temporary First Molar. BC, buccal cusps; LC, lingual cusps; E, E, enatnel-cap ; D, D, dentine-cap; P, P. papilla ; O, row of odontoblasts. Magnified 50 diameters. buccal cusp. In the valley between the cusps it appears somewhat broader than the layer of dentine. The permanent first bicuspid (see Fig. 22), the product of the bud from the first temporary molar, at birth corresponds to a temporary tooth four and a half months old. It is cone-shaped and composed of medullary tissue, with only scanty capillary blood-vessels at the base of the cone. As might be expected, there is not even a trace of odontoblasts visible. The papilla is covered with a layer of columnar epithelium, the so-called inner epithelium of the enamel-organ, not as yet transformed into ameloblasts. TEETH OF THE LOWER JAW AT BIRTH. 41 The point of recurvature of the inner into the outer epithelium is deeper down upon the buccal than upon the lingual aspect of the papilla. The outer epithelium is still recognizable as being com- posed of short columnar epithelium, surrounded by fibrous connec- tive tissue. Between the inner and the outer epithelium there is a well-developed myxomatous reticulum, the enamel-organ. The inter- mediate layer is present, though as yet not pronounced. In the Fig. 22. Permanent First Bicuspid. 6', summit of papilla; B, base of papilla; IE, inner epithelium; OE, outer epithelium; EO, enamel-organ ; /, intermediate layer ; C, cancellous bone lined by osteoblasts ; R, recurvation of inner into outer epithelium. Magnified 50 diameters. specimen from which the illustration is taken, the upper portion of the enamel-organ is torn and partly missing. The temporary second molar in our specimen (see Fig. 23) has two well-developed cusps, of which the lingual far surpasses the buc- cal in size. This does not, as a matter of course, show the relation between the two cusps with certainty, since it is quite possible that the lingual cusp was caught by the knife at its center, and therefore 42 DENTAL PATHOLOGY AND PRACTICE. at its greatest height, while the buccal cusp may have been taken in a more peripheral portion and thus appear smaller than it really is. Between the two cusps there is an elevation, covered only by den- tine, which likewise may represent a cusp cut near its periphery. The papilla is plainly myxo-fibrous connective tissue, and freely sup- plied with blood-vessels. Rows of odontoblasts are seen only at a small portion of its periphery. The height of the papilla is three times greater at the lingual than at the buccal portion. A striking feature is the sharp boundary-line at the lingual aspect, between the portion of the papilla which is covered with dentine and that without Fig 23 Temporary Second Molar. BC, buccal cusps ; LC, lingual cusp ; E, E, enamel-cap ; D, D, dentine-cap ; P, P, papilla ; O, O, row of odontoblasts. Magnified 50 diameters. it, and the bulging out of the latter. The dentine-cap is present all over the upper surface of the papilla, somewhat broader at the sum- mit of the lingual cusp than on the summit of the buccal one. It is a trifle broader at the height of the central elevation than in the valleys at either side. The difference between the calcified and the non-calcified portions of the dentine is quite marked. There are two enamel-caps, one each formed over the lingual and buccal cusps ; the former almost twice the breadth of the latter. The permanent second bicuspid (see Fig. 24) is still younger in its TEETH OF THE LOWER JAW AT BIRTH. 43 development ; it corresponds to a temporary tooth in the fourth month of embryonal life. The papilla is a blunt cone divided into a conical upper portion, surrounded by the inner epithelium, and a broad base surrounded by fibrous connective tissue. It is made up entirely of medullary tissue, and shows blood-vessels at its base in small num- bers. The inner epithelium is quite conspicuous by the columnar shape of its constituent elements. The same elements also produce Fig. 24. Permanent Second Bicuspid. P, papilla; IE, inner epithelium; OE, outer epithelium; R, recurvation of inner into outer epithelium; £0, enamel organ; /, intermediate layer; C, fibrous connective tissue. Magni- fied 50 diameters. the row of outer epithelium, which appear shortened only at the summit of the enamel-organ. The enamel-organ itself is not as yet fully developed, its points of intersection being large, the meshes, on the contrary, narrow. The intermediate layer is but slightly pro- nounced. In this specimen the enamel-organ was unbroken. The permanent first molar is an unusually well-developed tooth in our series. (See Fig. 25.) It has two well-pronounced cusps, the largest 44 DENTAL PATHOLOGY AND PRACTICE. being the lingual. The papilla is composed mainly of myxomatous and medullary tissue, with an admixture of some delicate fibrous con- nective tissue. Its vascular supply is as yet scanty. It shows deep in- cisions on both the lingual and buccal aspects, corresponding to the termination of the dentine-caps, beneath which the papilla bulges quite noticeably. Rows of odontoblasts are seen along the greater extent of the surface of the papilla, and especially upon the lingual aspect, which shows an uninterrupted row of these formations. A second row is seen in the valley between the two cusps, where as yet no den- tine has formed. There are separate dentine-caps for each cusp, that over the lingual cusp being especially well developed. Fig. 25. Permanent First Molar. E, enamel-cap ; D, dentine-cap ; /, depression on surface of papilla ; P, papilla ; O, row of odontoblasts ; IE, inner epithelium ; OE, outer epithelium ; EO, enamel-organ ; 71/, medul- lary tissue. Magnified 50 diameters. The enamel- caps are, as is the rule in all developing teeth, shorter than the dentine-caps ; that of the lingual cusp being at its summit twice as thick as that upon the buccal. The row of inner epithelia is transformed into ameloblasts over both cusps, and there is a distinct layer of medullary tissue present between the ameloblasts and the fully-developed enamel. The outer epithelium begins to break up at its upper portion, where the enamel-organ forms a broad layer of myxomatous tissue. TEETH OF THE LOWER JAW AT BIRTH. 45 Huxley,* as early as 1853, speaking of the development of dentine, says, that " it is not explicable by the cell theory." How true this statement, made so many years ago. I do not, however, agree with his assertion that the pulp-tissue takes no part in the formation of dentine. Any one who considers the so-called cells as stable and un- changeable formations will be at a loss to explain the formation of any tissue of the teeth. The latest researches in histology have proven that, so far as the morphological elements are concerned, there is nothing stable during the advancing formation of the organism and its constituent parts ; nor during full development, at the height of life ; and far less is this the case during its decline. Before a tissue is fully formed there are repeated oscillations forward and backward, in the appearance of the morphological elements ; the intervening stage invariably being their reduction into the stage of indifferent, medul- lary, or embryonal tissue. It has been proven that the papilla of the developing teeth may proceed to the formation of the myxomatous, nay myxo-fibrous connective tissue. At its periphery this tissue, sprung from medullary corpuscles, falls back to medullary corpuscles, which unite into large branching protoplasmic bodies, resembling columnar epithelia, the so-called odontoblasts. These are by no means the dentine-producers proper ; no more so than the osteoblasts are the real bone-formers. Each of these formations is nothing but a pre-stage toward the formation of dentinal or bone tissue, as the case may be. Odontoblasts break up once more into medullary corpus- cles, from which at last, by their infiltration with basis-substance and the immediate deposition of lime-salts, first non-calcified, and at last calcified dentine is produced. The zigzag line of development of dentine, therefore, is first embryonal or medullary tissue ; second, myxomatous or myxo-fibrous tissue ; third, embryonal or medullary tissue ; fourth, odontoblasts ; fifth, again embryonal or medullary tissue ; and sixth and last, non-calcified then calcified dentine. Every reduction to embryonal tissue is followed by a further step in advance in the development of the organ, until at last the most perfect tissue, such as dentine, will make its appearance. It is a question in my mind whether the dentine, as we see it at the time of birth, is a lasting formation, or the same as we see it in the fully-grown tempo- rary or permanent tooth. The size of the papilla and the dentine- cap are, at birth, far too small in comparison with what we see at the time of eruption. It is quite possible, therefore, that the first formed dentine- cap is not necessarily lasting, but may eventually be reduced once more into medullary tissue, before the permanent breadth of dentine corresponding to the transverse diameter of a fully-formed tooth is reached. Similar oscillations must, of necessity, — if this^ * Quarterly Journal of Microscopical Science, 1853. 46 DENTAL PATHOLOGY AND PRACTICE. change occurs, — take place in the production of the pulp, and the dentine of the roots. At the time of birth, only the papilla of the crown is present, sharply bordered downward by fibrous connective tissue. This latter tissue is reduced to its embryonal condition in order to produce the necessary material for the production of the den- tine of roots. Further observation will be required in order to settle the question as to how the dentine and cementum of the roots are formed. We meet with the same puzzles in the history of the development of the enamel. At the time of birth, the myxomatous enamel-organ is far too small to enable us to understand the formation of a broad enamel layer, such as we see at the time of eruption. Even the first established enamel-caps are far too small in comparison with the diam- eter of the crowns of either temporary or permanent teeth. Heitzmann and Bbdecker, in their above-quoted publication, the result of eight years' hard labor, came to the conclusion that the elements of the original epithelial pegs are reduced to medullary tissue, afterward to fibrous connective tissue, next to medullary tissue, and eventually to ameloblasts. Ameloblasts, according to their notion, are not direct enamel-formers, no more so than odontoblasts are direct dentine- formers. The ameloblasts are reduced to medullary corpuscles, which after infiltration with the basis-substance and immediate deposition of lime-salts, at last produce enamel-prisms. From a study of their specimens and my own, I am convinced that these views are correct. Should the first enamel- cap which appears prove too small for a fully-grown tooth, nothing is left to solve the puzzle of development but the assumption that even the fetal enamel-cap is not lasting, and must undergo reduction, or possibly repeated reductions to medullary tissue, before the fully-developed tooth is reached, such as we see at the time of eruption. CHAPTER V. CONGENITAL DEFECTS IN ENAMEL.* Every dental practitioner is more or less familiar with the condi- tion of imperfect or defective enamel found upon the crowns of per- manent teeth (more especially the incisors and first molars), which I propose to consider under the above heading. These imperfections usually concern the summit of the crown or its vicinity. We see * Abbott. Dental Cosmos, i^<)i. CONGENITAL DEFECTS IN ENAMEL. 47 upon an otherwise well-developed crown an almost circular ridge, above which the enamel appears of a grayish-brown color, and in the shape of numerous pointed, thorny projections, the masticating sur- face of molars appearing as if provided with numerous minute stalac- tites or stalagmites. (See Fig. 26.) In some cases there are only a few blunt or pointed hillocks of enamel, between which the dentine is entirely destitute of such covering. In others the dentine is nearly covered with enamel, leaving rows of small round or oblong holes through it to the den- tine. These defects appear, as before stated, only in permanent Fig. 26. CONGENITALLY IMPERFECT CrOWN OF LoWER MOLAR. S, shortened crown ; C, C, cones of enamel ; D, dentine with no enamel covering. Magnified 4 diameters. teeth, and very seldom are any of these except the incisors and first molars involved. Whether or not the complete absence of enamel from the crowns of incisors, as is sometimes seen, is of the same nature, and due to the same causes, I am not prepared to say, although it seems probable. Teeth of this description are a source of the greatest annoyance to the patient, since the portions not covered with enamel are usually most exquisitely sensitive, rendering mastication difficult and painful. Operations upon them are so very distressing, that the dentist often 48 DENTAL PATHOLOGY AND PRACTICE. finds himself almost helpless to afford relief to his patient, except by the extraction of the teeth. In looking with the naked eye at a longitudinal section through a molar affected as just described, we at once recognize the deficiencies of enamel, the stalactite or stalagmite appearance, and the shortening of the crown sometimes one-eighth of an inch, caused by these defi- ciencies. These blunt and pointed elevations are made up partly of healthy- looking and partly of a greenish-brown enamel. Between the eleva- tions are areas partly covered by an extremely thin layer of enamel Fig. 27. Section of Masticating Surface, showing Partial Covering of Enamel. E, well-developed enamel; L, isolated lumps of enamel; D, D, dentine; /, /, interglobular spaces. Magnified 100 diameters. and partly destitute of any. By grinding the crown of such a tooth in longitudinal section, for microscopical examination, the masticating surface presents an extremely striking image. (See Fig. 27.) A well- developed, though slightly-pigmented, enamel is seen gradually tapering toward the masticating surface, showing marked deficiencies of the outermost layer. These deficiencies consist of conical depressions at the surface and granulations near it. Obvi- ously this condition was caused by an incomplete calcification of the enamel, from the fact that it has taken up or absorbed a deep brown CONGENITAL DEFECTS IN ENAMEL. 49 pigmentation. The tapering layer of enamel stops abruptly, leaving the dentine entirely uncovered, as is seen in several places ; besides, there are irregular hillocks of an irregularly contoured enamel, of a deep brown color. These hillocks give to the grinding-surface the appearance of groups of stalactites. Slabs exposed to the action of a half of one per cent, solution of chloride of gold for one hour exhibit a dark violet color of the dentine in the crevices between the Fig. 28. Isolated Lump of Enamel, vekv Imperfect. Z', P, P, protoplasmic projections into the enamel from the dentine ; C, transverse section of enamel-prisms. Magnified 500 diameters. enamel lumps, which means that a portion of the lime-salts has been dissolved out, although no destruction of the organic portion of the dentine has taken place. At the usual distance from the interzonal layer are seen interglobular spaces. Let us magnify a lump of enamel in this locality h\-e hundred diameters. (See Fig. 28.) 50 DENTAL PATHOLOGY AND PRACTICE. We notice in this specimen narrow prisms, markedly wavy, and interrupted by faint concentric striations. The prisms, as usual, do not reach the surface of the enamel, but at a given distance from it they are replaced by irregular angular pieces. The outermost por- tion of the lump is of a dark brown color. Penetrating the enamel at varying heights are seen numerous pear-shaped prolongations of the dentinal canaliculi, some extending nearly to the surface. These spaces contain protoplasm, and are stained a deep violet color by the chloride of gold. Aside from these irregularities the lump seems to Fig. 29. Imperfect Enamel. E, well-developed enamel, transverse section ; G, G, granular layer of enamel, with pear- shaped protoplasmic enlargements ; Z>, dentine, canaliculi in transverse and oblique sections; /, interglobular spaces. Magnified 600 diameters. be thoroughly calcified, except in a few spots upon the surface, which have taken a slight violet stain. The exposed dentine is also deeply stained the characteristic violet color in this locality, denoting insuffi- ciency of lime-salts, or an excess of organic material over the normal proportion. I wish at this point to call attention to a paper prepared by Dr. John I. Hart, of New York, in which he has shown beyond a possi- ble doubt, by means of protracted staining with chloride of gold, that imm-ediately beneath the enamel, within the dentine, there is a very minute reticulum of living matter, considerably more than is found CONGENITAL DEFECTS IN ENAMEL. 51 in Other portions of the dentine. This corroborates what Dr. Bodecker stated in 1878, and also explains more satisfactorily the clinical fact that at this particular portion of a carious cavity in a tooth, the sensibility is much more acute than in other parts of the same tooth. In some' instances the crown of the tooth may be nearly covered with a well-developed or a stratified and slightly pigmented enamel, the other portions being coated with a thin layer, highly pigmented, again denoting deficiency in lime-salts. (See Fig. 29.) We present here a transverse section of the crown of a molar. The thin and irregularly contoured enamel exhibits only transverse sections of prisms, of a deep brown color. At the interzonal layer numerous pear-shaped protoplasmic spaces are seen penetrating the enamel, and in the region nearest to the dentine the prisms appear as if they are granular or sieve-like (perforated with numerous small holes), indicative of a lack of proper calcification. Extremely interesting and instructive anomalies are sometimes found in the formation of this tissue, viz : two distinct varieties of enamel, one upon the other. First, we have an anomalous portion grafted or deposited upon a normal enamel, and again anomalous enamel first deposited, with the peripheral portion fairly normal. (See Fig. 30.) This represents a cusp of a molar, with a conspicuously defective enamel deposited upon a nearly normal one. The normal portion is slightly pigmented, slightly stratified, and supplied with a moderate number of granulations near the interzonal layer. The outer or peripheral portion exhibits a layer which ends abruptly on one side, and gradually blends with the normal enamel on the other. This portion is remarkably defective in its structure. At the boundary- line between the two portions the enamel-prisms are abruptly devi- ated, their longitudinal course being suddenly changed to a trans- verse direction. In the latter portion a few oblique sections are seen alternating with the transverse. The whole portion superadded to the normal enamel is pierced by innumerable granulations, which, owing to their violet color, we must conclude are protoplasmic in structure and, of course, deficient in lime-salts. The granulations are in some places arranged in rows, in others scattered irregularly. If a large mass of enamel exhibits prisms almost rectangular to their original normal direction, it is not an evidence of the interlacing of such prisms, but of their unusually wavy courses. An originally deficient enamel upon which is deposited a normal one is represented in Fig. 31. Here we observe numerous layers made up of extremely narrow, interrupted prisms, upon which at a given line prisms of normal width appear, first in transverse, then in 52 DENTAL PATHOLOGY AND PRACTICE. longitudinal sections. This specimen affords a good opportunity to trace one and the same prism in longitudinal, oblique, and transverse section. In all the teeth I have examined with imperfect enamel, the so-called interglobular spaces were present in the dentine, indicating a deficient calcification of territories at the period of development Fig. 30. Imperfect, Grafted upon Perfect Enamel. X*, dentine; ^, boundary zone (interzonal layer); £, perfect enamel; £i, imperfect enamel. Magnified 100 diameters. which corresponds with that of the formation of enamel. In only one specimen have I seen a devious course of the dentinal fibers and stratification of the dentine. In one instance peculiar formations were seen in the cementum. (See Fig. 32.) The cementum here exhibits distinct lamellations and scattered CONGENITAL DEFECTS IN ENAMEL. 53 cement-corpuscles, with their longitudinal diameters mostly arranged vertically to the direction of the lamellae. The cementum was abruptly interrupted by the pericementum dipping downward to the close vicinity of the dentine, in which situation the prolongations of the pericementum were hardened by globular depositions of lime- salts, which were conspicuous by their high degree of refraction. Fig. 31. Perfect, Grafted upon Imperfect Enamel. .£1, irregular and imperfect layer of enamel ; E^, regular layer of enamel ; D, dentine ; /, interglobular spaces. Magnified 500 diameters. This anomaly — altogether different from the process of absorption of the roots of temporary teeth, or that of bone — must have originated at the time of the development of the cementum, which, as is well known, takes place after the formation of the dentine. The morbid process was undoubtedly pericementitis, which led to a partial destruction of the pericementum. At these points, consequently, no cementum was deposited. 54 DENTAL PATHOLOGY AND PRACTICE. A remarkable feature in connection with this specimen was the apparently perfect condition, in the mouth, of the gum and alveolus. The microscope revealed nothing anomalous in the pericementum except a few scattered calcified patches. It is hardly possible that there was any special connection between this condition and the morbid process in the enamel, as the enamel is completely formed at a much earlier period than this could have occurred. Fig. 32. Irregularities of Cementum.. P, pericementum; C, stratified cementum with cement-corpuscles; E, excavations of cementum filled with pericementum; C, globular stratified depositions of lime-salts ; D,D, dentine. Magnified 100 diameters. As to the causes which lead to imperfections in the enamel and other portions of the teeth during the process of development, A. Jacobi, M.D., says in an article on " Dentition and its Derangements," 1862,— " The enamel of the teeth is subject to several anomalies. It may be either defective or discolored. Its defective formation appears either in excavations dispersed over the surface of the tooth, or there are complete furrows or transverse notches around the crown of the tooth, the body being still covered with or entirely deprived of enamel. This atrophy is the result of those severe diseases which the child may have been suffering from during the development of the enamel. Acute exanthems are said to produce the dispersed excavations ; acute inflammatory diseases, the furrows ; and rachitis CONGENITAL DEFECTS IN ENAMEL. 55 has often been observed to be the cause of the entire absence of the enamel. The incisors of rachitic children are usually small, appear late, and are very liable to become carious. Acute exanthems are counted among the causes of this anomaly, especially by such writers as classify the teeth with the dermal tissue. Smallpox is related to produce isolated excavations which have a great similarity to the cicatrices remaining after smallpox. To vaccination, also, some have attributed the defective development of the enamel. The mucous membrane of the mouth is very irritable, being accustomed only to amniotic liquor in fetal life, and to milk in the early stage of extra-uterine existence. Every change in the diet, therefore, the bad quality of the material, or artificial nipples, the use of candy, sucking bags, or alcoholic beverages, coffee, or stimu- lants of whatever kind, will act as irritants, producing hyperemia or inflammation in a more or less severe form. ... A more severe form is that known by the name of aphthous stomatitis. The super- ficial layers of the epithelium are not thrown off" during the hyper- emic swelling of the mucous membrane, as in erythematous stoma- titis,, but a real and visible change takes place in the anatomical structure of the follicles. There is a circumscribed, punctated, vas- cular injection around a follicle which is gradually infiltrated by exu- dation. The consecutive swelling increases in proportion, the folli- cles will burst and exhibit a superficial erosion or ulceration, and the adjacent mucous membrane will be sympathetically affected." In " Contributions to the Development of the Teeth" (Heitzmann and Bodecker, hidependent Practitioner, vols, viii-ix) will be found several descriptions of anomalies of deciduous teeth depending upon congenital rachitis. In "Studies of Pathology of Enamel of Human Teeth, with Special Reference to the Etiology of Caries" (see Chapter VI), refer- ence is made to pigmentation, stratification, and white spots in the enamel, all of which are attributed to imperfect calcification. Con- genital disturbances of the epidermis are known to influence the devel- opment of teeth to no small extent. Edmund Lesser says, "In the majority of haired men, which means congenital growth of hair all over the face (hirsuties), I have hitherto observed that defects or irregularities of the dental system were present, since not only a number of teeth, but the corresponding alveoli, were missing. In some cases with normal dentures a broad- ening of the alveolar processes was apparent. We know that the enamel originates from the epithelium of the oral cavity of the embryo. At the development of two months of the fetus we can trace an epithelial peg which leads to and is in con- nection with the epithelium of the oral cavity. This peg is prolonged 56 DENTAL PATHOLOGY AND PRACTICE. inwardly, and in the third month of development becomes club- shaped at its deepest extremity. It is well known that this epithelial peg, more especially its club-shaped portion, serves for the formation of the enamel-organ. At about the third month, lateral epithelial offshoots begin to appear from the main peg. The former furnishes the material for the production of the enamel of the temporary tooth, while the lateral pegs furnish the enamel-organs of the permanent teeth. Although of epithelial origin, the enamel-organ is of a myxomatous structure, and thus represents a variety of connective tissue. The history of development of enamel (which makes its appearance about the seventh month of fetal life) is well understood, as far as tempo- rary teeth are concerned, up to the time of birth of the child. Still we know nothing as to the progress of the lateral pegs in laying the foundation of the enamel-organ and the enamel of the permanent teeth. We simply conclude that the process is identical with that of the temporary teeth, in its development during the earliest years of extra-uterine life. Since the imperfections of enamel, as described, are observed upon permanent teeth only, I venture the hypothesis, without fear of contradiction, that diseases of the oral cavity only affecting the epithelial layers, and the pegs derived therefrom, must cause these defects. Such diseases occur in the oral cavity of young children, under the headings of inflammation (stomatitis), from many causes, leading to the formation of blisters, ulcers, and abscesses. Growth of mildew (so-called thrush) is known to be a fertile source of both such superficial and deep-seated disturbances. Acute exanthems, which sometimes spread to the mucous mem- brane of the oral cavity, undoubtedly play an important part in causing inflammation of the enamel-organ, which results in produc- ing defective enamel. We can appreciate the probability that inflammation will partially destroy either the original epithelia or the enamel-organ derived therefrom, and thus be the direct cause of defective enamel. The simple obliteration of a number of blood-vessels which surround this organ would suffice to so interfere with its proper function as to diminish the amount of lime-salts deposited ; the enamel-prisms in such case might develop normally as to size, but show deficiency in calcification. If, with the inflammation and obliteration of blood-ves- sels, hemorrhage takes place into the enamel-organ, or infusion of hemoglobin should occur, pigmentation of the deficiently calcified prisms would become intelligible. We can realize that the medullary tissue giving rise to enamel- prisms will, in consequence of inflammation, be so altered or mis- placed that the outcome would be imperfect, incomplete, or devious PATHOLOGY OF THE ENAMEL. 57 prisms. As shown in Chapter VI, the formation of enamel takes place in the shape of layers for the crown and layers for the neck. We may thus grasp the possibility that the earliest crown layers may be fully and regularly developed, while the last crown layers are interfered with and become defective. Should, therefore, an inflammatory pro- cess start at the time of the appearance of the earliest crown layers, and soon abate, the enamel nearest to the dentine will be found imper- fect. If the inflammatory disturbance continues for a long period, the result will be a thin and incompletely calcified layer of enamel. Should portions of the enamel-organ be completely destroyed by suppuration, entire absence of enamel at such points will be the result. A number of so-called miliary abscesses in the enamel- organ will lead to a porous or ' ' pitted' ' enamel. A limited number of somewhat larger abscesses would cause larger holes or pits, or possibly the entire enamel-organ might be destroyed, so that the dentine would be entirely unprotected. In all the cases of teeth with defective enamel that I have exam- ined, the dentine has been found fully developed and perfectly calci- fied, with the exception of quite numerous interglobular spaces. These appear in the dentine at the period of development during which the enamel-organ was affected, indicating very positively that the disease or diseases which caused the production of imperfect enamel was local rather than general, as has been supposed by some pathologists. CHAPTER VI, STUDIES OF THE PATHOLOGY OF ENAMEL OF HUMAN TEETH, WITH SPECIAL REFERENCE TO THE ETIOLOGY OF CARIES.® Recognizing the fact that pathological conditions of the dental organs frequently result from congenital defects in the structure of the enamel, more especially of the permanent teeth, I purpose to con- sider in this chapter the importance of these imperfections as factors in the predisposing causes of the early destruction of the teeth by the carious process. One of the most important questions in dentistry has always been the pathology and etiology of caries. Thoughtful dentists have long agreed that there is a marked difference, not only among indi- viduals, but also in races, in the liability of teeth to decay. Not many years since a prominent dentist of New York directly accused civil- * Abbott, Denial Cosmos, 1885. 58 DENTAL PATHOLOGY AND PRACTICE. ization of being the most conspicuous factor in its production. It is an undeniable fact that, with advancing refinement of individuals and nations, decay of teeth is more prevalent. It seems to me, how- ever, that even this recognized fact will not altogether explain the rapidly growing tendency to this disease under all circumstances. It has many times occurred to me that there must be an anatomical deficiency to fully explain the liability to caries in each single in- dividual, aside from the acquired local causes to which caries has usually been attributed heretofore. Unquestionably, there are auxil- iary agents in producing or forwarding decay of teeth, such as certain kinds of food, more especially sweets, which are too often retained in the fissures always found in the grinding-surfaces of certain teeth, between the teeth, upon irregular teeth, uneven surfaces of the enamel, etc. But all these cannot fully explain the fact that the simple change in modes of living should manifest itself in the sudden and rapid de- struction of these organs. Strong, healthy individuals, upon being transferred from a country with comparatively simple habits of life into a country of high refinement, may soon become victims of caries of their teeth. Modern Germans and Irish, immigrating to America and enjoying luxuries (similar to those enjoyed by comparatively civilized old Egyptians, in whose mummies we observe, not without some surprise, a pronounced tendency toward decay of the teeth), soon discover, to their great discomfort, at least, that their teeth are becoming diseased. With these questions in mind, I undertook to examine a large number of teeth which had been ground into thin slabs, with the precaution of preserving their soft parts, especially their living mat- ter, a method first introduced into microscopic technique by Dr. C. F. W. Bbdecker. The results of my observations, though not ex- haustive, are highly satisfactory, inasmuch as they explain, quite positively, the tendency of certain teeth to decay, the cause of which is in direct relation to and dependent upon imperfections in their anatomical structure. Upon these observations, I claim that certain deficiencies in the minute structure of the enamel must be certainly considered as playing a most important part in the etiology of caries. Before entering upon a description of the anomalies of enamel which I have observed, I wish to briefly recapitulate the description of the structure of this tissue, and its relation to dentine, as first dis- covered and published by Bodecker, in his essay entitled " The Dis- tribution of Living Matter in Human Dentine, Cement, and Enamel. ' ' (^Dental Cosmos, 1878-1879.) According to this observer, the enamel is composed of rods and fibers having a slightly wavy course, inter- laced between delicate interstices. In these interstices run delicate fibers of living matter, sending into the enamel-rods minute off- PATHOLOGY OF THE ENAMEL. 59 shoots in a prevailingly vertical direction, thus producing the cross- lines which have long been known to exist in the enamel-rods, but which were shown by him to be far more delicate and more numerous than had ever before been described. The square pieces of the enamel- rods are again subdivided into minute fields ; they are separated from one another by delicate light interstices, and in all probability contain fibrillae of living matter. The enamel is thus raised to the dignity of a living tissue instead of a mere calcareous deposit, as under the old conception. At the place of junction of the enamel with the dentine a direct connection is often seen between the enamel and den- tine fibers. More commonly dentinal fibers run into the enamel varying distances, without a direct union between them and the enamel-fibers ; as the latter do not generally reach the surface of the dentine, but terminate, at different heights, above its level, while the zone close above their terminations is occupied by a delicate irregular net-work. In many places the dentinal canaliculi, upon entering the enamel, suddenly become enlarged and form spindle or pear-shaped cavities of varying diameters. They invariably contain protoplasm which is in direct connection with the terminations of the dentinal fibers, and on their periphery with the fibers of living matter of the enamel. In the teeth of young persons the spindle-shaped enlargements are comparatively larger and more regular than in the teeth of old people. The boundary line between the dentine and enamel is usually slightly wavy and with more or less deep, bay-like excavations, the concavi- ties of which are directed toward the dentine. I. — Anomalous Relation between Dentine and Enamel. In examining a large number of specimens of ground teeth, I met with formations in two instances which are to be considered as anomalous, although not strictly pathological. In one case, that of a temporary molar, there was on the buccal surface a protrusion of dentine into the enamel with a fluted surface, which was produced by a series of bay-like excavations, which were present also at the junction of the dentine with the enamel in this tooth in general, but not so marked as in this protruding spot. (See Fig. 33.) The center of this protrusion was occupied by an eccentric protoplasmic formation, differing in shape from the ordinary interglobular spaces. The dentinal fibers at the periphery were bifurcated in the usual man- ner, but very few of them penetrated the enamel. The portion ol the enamel nearest to the protrusion was destitute of prisms, while in the immediate vicinity such prisms were traceable almost in contact with the dentine. The zone immediately above the protrusion was but slightly brownish, whereas the prisms of the enamel exhibited a very distinct brown pigmentation. 6o DENTAL PATHOLOGY AND PRACTICE. In a second case, that of a permanent cuspid, also on the buccal surface near the edge, a protrusion of dentine was observed, occu- pying nearly one-half of the breadth of the enamel. (See Fig. 34.) This protrusion was of a conical shape, and without a distinct bound- ary, but blended with an oblong field of enamel of quite remarkable structure. The dentinal canaliculi exhibited at their peripheral por- tions numerous bifurcations, and terminated in small pear-shaped enlargements, many of which could be traced in connection with dentinal fibers, whereas the most peripheral ones, owing to their devious course, looked isolated. The adjacent enamel showed but Fig. 33. Protrusion of Dentine into Enamel. E, enamel ; D, dentine ; H, hill of dentine with fluted summit ; P, protoplasmic bodies in the dentine. Magnified 400 diameters. very indistinct rods, the main mass of the enamel being occupied by brownish globular fields, separated from one another by irregular in- terstices closely resembling the interglobular spaces of dentine, though of considerably smaller size. The deepest pigmentation and the largest number of such interprismatic spaces occurred along the periphery of this anomalous formation, especially toward the outer surface of the enamel. The vicinity of the enamel proper was marked by the presence of slightly pigmented rods, more wavy in their course than normal. Toward the dentine the anomalous forma- tion was sloping, and the line of demarkation between the normal and anomalous enamel exhibited either brown and very wavy prisms or PATHOLOGY OF THE ENAMEL. 6l small interprismatic spaces, decreasing in diameter the nearer they approached to the dentine. I wish to emphasize and call particular attention to the fact that the dentine of this tooth was nowhere tra- versed by interglobular spaces ; the anomalous structure being con- fined to the enamel. Fig. 34. Protrusion oi-' Dentine into Pathological Enamkl. £, enamel; Z?, dentine ; G, granular enamel; ^, summit of the dentine; 6', sloping borders of the granular enamel. Magnified 200 diameters. II. — Stratification of Enamel. It is known that dentine, without exhibiting pathological features, is sometimes composed of strata, more or less distinctly marked, slightly deviating from its normal sti'ucture, and altogether different from the formations known as secondary dentine. We often meet with similar formations in the enamel. We observe layers varying in width and more or less sharply marked by a straight line, which in longitudinal sections of teeth exhibit concentric layers, the broadest portion always corresponding to the cusps, the narrowest always to the neck, of the tooth. (See Fig. 35. ) At the outer periphery of the enamel there may occur strata, which, 62 DENTAL PATHOLOGY AND PRACTICE. Fig. 35. . Diagram of Stratification of Enamel. P, pulp-chamber; D, dentine ; CL\ CL-, CL\ CL\ cusp-layers of enamel ; NL\ NL^-, neck- layers of enamel. PATHOLOGY OF THE ENAMEL. 63 contrary to the general structure as above described, are broadest toward the neck and narrowest toward the cusp, though never reaching its summit. In transverse sections the enamel shows simply concentric lines separating from one another layers of greatly varying diameters. With higher powers of the microscope we ascertain the fact that the lines of stratification, as a rule, do not alter the general course of the enamel-prisms, — in other words, a single enamel-prism will show an oblique line of demarkation, corresponding to the gen- eral line of stratification, without being altered in its construction or its course. An exception to this rule occurs only at the peripheral portions of enamjel, occupied by the tapering ends of the above- described secondary strata, which I would like to term neck-layers, in contradistinction to the central cusp-layers. The tapering ends of the neck- layers may exhibit enamel-rods, almost parallel with the surface of the enamel, a feature which is never seen at the outer periphery of the cusp-layers, where the enamel-rods are invariably directed more or less vertically to the surface. A knowledge of the stratification of the enamel is of the utmost importance for the understanding of its pigmentation and granulation. As I will show later on, both the pigmentation and granulation corre- spond to the general strata of the enamel, showing in longitudinal sections of teeth a fan-like appearance. It can scarcely be doubted that the stratification of this tissue is in close relation to the history of its development. We know that the first appearing enamel-cap of temporary teeth, in the seventh month of intra-uterine life, has the configuration of the innermost cusp-layer, — i.e., it is broadest in the direction of the future cusp, and tapers toward the future neck of the tooth. It seems reasonable to assume that the subsequent layers of enamel form on the plan of the first, but there may be a temporary stoppage of construction, due perhaps to slight ailments of the mother before delivery of the child, or slight ailments of the infant after delivery, which cause interruptions in its organization. Slight ailments of a general nature will not interfere with the final result of an otherwise sound enamel ; whereas severe ailments, particularly those of a local character, may lead not only to stratification, but to a decidedly pathological condi- tion, which I have before called pigmentation and granulation. These conditions invariably involve a deficient deposition of lime-salts. III. — Anomalous Arrangements of the Enamel-Rods. In normal enamel longitudinal sections will, in the majority of cases, exhibit slightly wavy rods, interlaced by comparatively small bundles, cut in a transverse direction. Toward the periphery the curvatures of the rods gradually become less, until, close to the 64 DENTAL PATHOLOGY AND PRACTICE. surface, they present a nearly straight course. I have never seen transverse sections of enamel-rods directly in contact with the inter- zonal layer. Deviations from this rule seem to be rare, and then the enamel- rods seem to lack all regularity in their arrangement. It may occur that close to the interzonal layer the enamel-rods show extensive fields occupied by these transverse sections, which gradually blend with oblique and longitudinal, producing a wavy appearance, to such an extent that beautiful figures arise, reminding one of the grain of lignum-vitcB . (See Fig. 36.) Still more complicated figures arise if Fig. 36. Extremely Irregular Course of Rods in Slightly Pigmented Enamel. The longitudinal rods deviating to a great extent from the field of the specimen, show oblique and transverse sections. The interstices are widened and contain very conspicuous enamel- fibers. Magnified 800 diameters. the transverse bars of the longitudinal rods are unusually conspicuous. In such enamel it may occur that the curvatures of the rods remain very marked up to the surface ; and consequently groups of transverse sections may be seen directly at the outer surface. Enamel of this description may be seen on only one portion of the tooth, while the remainder is normal. With this curly appearance of the enamel-rods, in all my specimens, pigmentation is combined as a marked feature, and the interstices between the rods are a trifle PATHOLOGY OF THE ENAMEL. 65 wider than normal. Both of the latter features must involve a defi- cient calcification, and consequently extreme brittleness. It is very difficult to obtain perfect specimens of such enamel. The dentine subjacent to such anomalous formations is freely supplied with inter- globular spaces (which is likewise a sign of deficient calcification). IV. — Deficient Calcification of the Enamel without Pigmentation. The friability alluded to under the previous heading is in some in- stances very marked, — so much so, in fact, that it is impossible to ob- tain an unbroken slab of a tooth even with the finest grinding-stones. With low powers of the microscope we observe that the broken ends of the enamel-rods look as if corroded, or as if some of them had been displaced or torn off in the process of grinding. Neither pig- mentation nor an anomalous course of the enamel-rods is necessarily connected with such a condition of the tooth. The most striking feature, however, which is visible even with low powers, is that the enamel-rods are unusually narrow, the interstices between them unusually wide, and their tenants, the enamel-fibers, very prominent. The cross-lines of the enamel-rods are likewise considerably widened and irregular, so that the fields of basis-substance look unusually small and irregular. The reticulum in the immediate vicinity of the interzonal layer is also unusually prominent. Such a condition of the enamel may occur both in temporary and permanent teeth, and may be combined with pigmentation. It is a feature of such deficient enamel that it readily stains with an ammo- niacal solution of carmine, which normal enamel will never do. The subjacent dentine, under such conditions, may either be perfectly de- veloped, as before stated, or be deficient in its formation, as shown by the presence of more or less numerous interglobular spaces. All clinicians have observed congenital white or yellow spots in the enamel of teeth, which if broken into are found to be of the consist- ence of chalk. Such spots have been termed "white decay," although they do not correspond to the process of caries as we usu- ally understand it. They really mean nothing but deficient calcifica- tion. Again, all clinicians have seen teeth across which a row of pit- holes exists, where in many instances in the bottom of the depressions no enamel is to be found. This condition is also always congenital, and closely related in its origin to pigmentation and the white or yellow spots. In other instances an originally smooth enamel is mu- tilated mechanically by the process of mastication, with the result of loss of substance, leaving abruptly broken, jagged edges. Again, we see teeth with a great portion of their crowns covered, in place of enamel, by a brownish-yellow substance which is so soft as to be easily 6 66 DENTAL PATHOLOGY AND PRACTICE. removed, leaving the dentine bare of its covering and extremely sen- sitive to the touch of an instrument, the pressure of food in masti- cation, etc. These conditions, again, are, in most instances at least, connected with pigmentation and the white or yellow spots. We might call them exaggerated cases of the same condition. Obviously these congenital defects are dependent upon deficient deposition of lime-salts in the basis-substance, rendering the enamel less resistant and more friable. V. — Pigmentation of Enamel. One of the most common pathological conditions of the enamel is its pigmentation. Sometimes it is so slightly marked that the naked Fig. 37. EP EG ER Pigmented and Granular Enamel. D, dentine ; ER, layer of slightly pigmented rods broken off; EG, layer of highly pigmented and granular enamel ; EP, stratified pigmented enamel. Magnified 400 diameters. eye discovers only a slight yellow-brown discoloration ; in other instances the abnormality is quite prominent and readily discernible. Specimens of such teeth under the microscope will correspondingly exhibit either a dim yellow tint in the enamel or a very marked brown discoloration. The pigmentation may occur either in non-stratified or in stratified enamel. (See Fig. 37.) In the first instance there is no de- markation of the brown spot toward the colorless enamel ; only faintly- marked oiTshoots from the main spot, tapering toward the dentine. PATHOLOGY OF THE ENAMEL. 67 and running in an oblique direction, will indicate the fact that pig- mentation has occurred during its formation. In the second instance, on the contrary, where pigmentation invades stratified enamel, there is a close relationship between the two, inasmuch as the deepest stain invariably corresponds to the boundary line of the strata, tapering toward the neck, and gradually fading toward the proximal end of each stratum. Thus, in longitudinal sections, a beautiful fan-like configuration is produced. The pigmentation may invade all layers of the enamel, often being more marked in the deeper than in the superficial portions. Higher powers of the microscope reveal the following facts : First, that the brown discoloration concerns the basis-substance of the enamel-rods only. Second, that the interstices between the pigmented enamel- rods are widened in appearance, not due to contrast in color, but to a deficiency in the formation of the basis-substance. Third, that the transverse lines of the enamel-prisms are likewise (at least in many in- stances) enlarged. Fourth, that the enamel-fibers and their lateral ofif- shoots are more conspicuous than in normal enamel, and more so even than in the enamel of temporary teeth, and in many places distinctly beaded. Pigmented portions of the enamel are very prone to take up a red stain on being treated with an ammoniacal carmine solution. As to the origin of the brown discoloration, I have to say, as a suggestion simply, that at the time of the formation of this tissue there must have been a disturbance in the enamel-organ which in- terfered with the proper building up of the basis-substance and the deposition of lime-salts. What this disturbance really was, I am unable to say. All pigments of the body depend upon and are closely related to the coloring-matter of the blood. I am loath, however, at this time, to attribute pigmentation of enamel to the extravasation of blood-corpuscles or diffusion of the coloring-matter of the blood. Careful studies in the history of the development of this tissue must be made before an attempt at a solution of this question will be admissible. One point I am positive about, how- ever, is that this pigmentation is congenital, invading temporary as well as permanent teeth. Acquired pigmentation of enamel seems to be of comparatively rare occurrence, except as a result of caries. I have seen pigmentations of its surface, of a deep orange color, not penetrating the enamel-tissue in the least. Caries on the surface often causes an orange discoloration, diffused and fading toward the normal portions. Several of my specimens plainly show an invasion of the enamel by caries, on spots pigmented congenitally ; second- arily, an orange diffused discoloration has taken place, which is prone to take up the carmine stain before referred to ; thus beautiful shadings of brown, orange, and red are to be seen, the brown being 68 DENTAL PATHOLOGY AND PRACTICE. congenital, the orange acquired, and the red artificial. What chem- ical may lead to an acquired pigmentation or discoloration of the enamel I cannot say. VI. — Granulation of Enamel. Under this heading I propose to describe a very peculiar patho- logical condition of this tissue, which my specimens seem to indicate as being by no means rare. It consists of pear, spindle, and club- shaped spaces in the interior of the substance of the enamel. Such spaces have heretofore been shown to exist at the junction of the dentine and enamel only. They may appear in pigmented, and invariably do in stratified enamel ; the stratification in the latter in- stance being due to their presence. Club-shaped spaces may appear at the distal boundary of one of the cusp-layers, or there may be several rows of such spaces, varying in extent and degree, but it sometimes occurs that only the outermost cusp or neck layers are freely supplied with them, whereas the remainder of the enamel is normal or more or less pigmented. Higher powers of the microscope demonstrate that the spaces are enlargements of the interstices between the prisms and the tenants of the interstices. The enamel-fibers are in direct connec- tion with the contents of the spaces, — i.e., with living matter. The spaces, accordingly, at their stem-like beginnings, run parallel with the interstices ; but in their broader portions they may cross the enamel-prisms in different directions. If they are few in number they may protrude from the boundary line of a cusp-layer, and pen- etrate the adjacent cusp-layer obliquely to the main direction of the enamel-rods. In the case illustrated (Fig. 38) I could trace the connections of the enamel-fibers even with the club-shaped ends pro- jecting into the neighboring cusp-layer. If these spaces are present in large numbers, the enamel, with lower powers of the microscope, will look dark and granular ; hence the name ' ' granulation of enamel" which I have given it. Fig. 34 represents this condition of granulated enamel with a low power. Fig. 38 shows the condition under a high power. In stratified and granular enamel, single strata may be produced by an interruption of the pigmented enamel-rods, by convex ends of the club-shaped spaces directed toward the adjacent peripheral cusp-layer. (See Fig. 37.) The inierprismatic spaces of the enamel bear some resemblance to the interglobular spaces of the dentine. One of my specimens shows both conditions in a highly-marked degree. Whenever these interprismatic spaces are present along the border of a cusp-layer they considerably lessen the degree of consistence of the enamel, which, PATHOLOGY OF THE ENAMEL. 69 upon being ground, breaks off easily along the dark granular line. The nature of the interprismatic spaces is plain enough. They mean an incomplete formation of the enamel, owing to some deficiency of function in the enamel-organ during its formation. Obviously not only is the basis-substance deficient, but the amount of lime-salts is also considerably less than normal ; hence the brittleness and prone- ness to decay. Under the foregoing headings I have described a number of patho- logical conditions of the enamel, which, at least so far as stratifica- tion, pigmentation, and granulation are concerned, mean a deficient Fig. 38. Intergranular and Slightly Pigmented Enamel. Club, spindle, pear-shaped, and irregular spaces at the boundary of a cusp-layer in the middle of enamel. Magnified 800 diameters. formation of the basis-substance, together with decreased deposition of lime-salts. These conditions are, in my judgment, of the utmost importance in the etiology of caries. Ailments either of the mother during gestation or of the infant in the earliest periods of life obvi- ously cause such anomalies in this tissue. These ailments are known to occur far more frequently in refined people, debilitated, as it were, by civilization, than in strong, hard-working, plain-living people, con- tinually engaged in the struggle for life. Thus, I have directly demon- strated and anatomically shown, in a measure, at least, the reasons why refined people are far more subject to caries of the teeth than people lacking such refinement. 7© DENTAL PATHOLOGY AND PRACTICE. CHAPTER VII. CARIES OF HUMAN TEETH.* After having studied this subject more or less continuously, both practically and microscopically, for the past sixteen years, I have still to adhere essentially to the views published by me in 1879. Having for several years previously held opinions differing more or less from those of any writer upon this subject, though without defi- nite data to stand upon, I concluded to investigate the subject thor- oughly, and thus to either prove my theories correct or abandon them {qx facts which I expected to establish. Very much to my gratifica- tion, my researches confirmed my former views, with very little if any variance. Notwithstanding the fact that nearly all investigators to whose writings access was had, accounted for the decay of teeth in what seemed apparently to the profession a satisfactory way, still there were practical facts which led me to view the subject differently, and for which it was difficult to account from their standpoint. In attempt- ing to explain these facts, I have been careful to make no statement which I am not able to prove to any one who will take the trouble to study the specimens carefully under the microscope. Dr. C. F. W. Bodecker had then recently discovered and described some important though previously unnoted facts in the minute structure of human teeth. My own researches are corroborative of Bodecker' s discoveries, which are here briefly recapitulated in order to a full understanding of the morbid processes, which is possible only upon a correct knowledge of the normal conditions. Since Dr. C. Heitzmann brought to evidence that, with the exception of dry horny tissue (epidermis, nails, and hair), all other tissues of the living body ai^ endowed with life, and that the presence of living matter is demonstrable not only in the formerly so-called cells, but also in the basis-substance (matrix), the question rose whether a normal tooth, attached to a living body, was not in itself possessed of this same living matter. It was to be expected, judging from the phenomena of growth, of decay, of restitution, etc., that a tooth was provided with such living matter just as well as bone, which it resembles so greatly in its minute structure ; but the full evidence of its presence in the tissues of the tooth was first demonstrated by Dr. Bodecker. The dentine is traversed by innumerable canaliculi, which ramify both toward the enamel and the cement. Each canaliculus con- tains a delicate fiber of living matter, which is in direct connection * Abbott, Dental Cosmos, 1879. CARIES OF HUMAN TEETH. 7 1 with the protoplasmic formations within the pulp-cavity, with the off- shoots of the cement-corpuscles, and with the fibers between the enamel-rods. Every dentine-fiber sends innumerable delicate conical threads through the cavity of the canaliculus into the basis-substance between the canaliculi, where a very minute net-work of living matter is present, uniting the dentinal fibers with one another throughout the entire tissue of the dentine. The basis-substance is analogous to that of bone, therefore glue-giving, and at the same time infiltrated with lime-salts. Around each dentinal canaliculus the basis-substance is denser than between the canaliculi. The cement is identical in every respect with bone ; its basis-sub- stance is traversed by larger cavities, which contain nucleated proto- plasmic bodies, — the cement- corpuscles. From these arise larger offshoots in a radiated arrangement, and the protoplasmic body as well as all its larger ramifying offshoots send delicate offshoots of living matter into the basis-substance, which latter is pierced by a net-work of living matter, this being in uninterrupted connection with the net- work within the basis-substance of the dentine, the boundary being termed, formerly, the interglobular space ; by Dr. Bodecker, " interzonal layer." The enamel is provided between its polyhedral rods with very slender fibers of living matter, which also send extremely delicate offshoots into the basis-substance of the rods. These offshoots traverse the cement-substance between the rods, and form an extremely minute net-work of living matter within the rods themselves, its meshes being occupied by dense depositions of lime-salts. Again, the net- work of living matter of the enamel is in direct union with that of the dentine, and, at the neck of the tooth, with the net-work of the cement. From these facts it necessarily follows that we must consider a tooth which is normal in its structure, and in close connection through the periosteum with the jaws, as a living body ; consequently, it follows that morbid processes will result in a reaction of the living matter in the tooth just as well as in bone or any other living tissue of the body. What this reaction essentially consists in during the process termed caries I have, to my own satisfaction at least, pretty clearly settled. And it occurs to me that, through my researches, new standpoints have been revealed of considerable value, both for abstract science and practical use. Methods. — The results obtained with regard to the minute structure of the teeth have been arrived at by methods different from those pre- viously in use. As a matter of course, the specimens from dried teeth, which were formerly used almost exclusively, did not reveal any of the soft parts within the hard dental tissues. Only the frame of the tissue was left, and we may readily understand why the investigations 72 DENTAL PATHOLOGY AND PRACTICE. of the carious process did not pass above hypotheses and specula- tions. For preparing dentine and cement, there is no better method known than slow decalcification by means of a one per cent, solution of chromic acid. In my experience large quantities of this solution are needed for a few teeth. A few drops of hydrochloric acid may be added to the chromic acid solution every other day, in order to hasten the decalcifying process. And the solution itself should be changed frequently, say once every week. The process of decalcification ought to proceed very slowly ; so much so, that at least two months should be required for preparing the superficial layers of the tooth for cutting with a razor. The teeth thus prepared, after the water had been extracted from them with strong alcohol, I imbedded in paraffin with a small quan- tity of wax added. The sections obtained from the specimens were stained with carmine, this being, in my experience, the best method for the demonstration of the carious condition of the tooth. After this I mounted the specimens in glycerin, diluted one-half with dis- tilled water, and lastly inclosed them with ordinary asphalt varnish. The enamel of teeth prepared in the foregoing manner can never be cut, because it becomes extremely brittle ; therefore, I was obliged to resort for its examination to the method first practiced by Dr. Bodecker, which consists essentially in grinding perfectly fresh teeth down to the necessary thinness, always under water. The thin slices should be kept for twenty-four hours in a very dilute solution of chromic acid, for decalcification. A saturation of this solution of over one-half of one per cent, is in my opinion deleterious to the enamel, which if completely decalcified shows only a minute net-work of living meatier, as I first observed, with no trace of the enamel-rods and prisms. A little practice will enable any one to obtain ground specimens of a whole tooth, of such extreme delicacy that they are fit for even the highest magnifying powers, over one thousand. A perfectly transparent condition should be the main property of a specimen of a carious tooth, because only with such specimens are we enabled to study the minutest changes of the tissues to our satisfaction. Ground specimens can be stained with carmine and mounted in the same way as those obtained by cutting. The old method of mounting specimens of teeth in damar varnish or Canada balsam has proved so very unsatisfactory, owing to the high degree of the clearing process, that it has been abandoned by our best microscopists. This method was good enough for specimens of dry teeth, in which the compartments in the dentine and enamel were filled with filth and air ; but as we nowadays wish to see more of CARIES OF HUMAN TEETH. 73 the soft tissues within the hard framework, we employ the only relia- ble methods as yet discovered, as described above. Etiology. — Although the examination of a carious tooth can reveal the cause of the disease only to a limited degree, I do not hesitate to express my conviction in this respect, on the foundation of many years of practical experience. There is not the slightest doubt in my mind as to the origin of caries of teeth. The first lesion under all circumstances is due to the action of an acid, which in a merely chemical way dissolves out the lime-salts from the enamel. No doubt quite a strong acid is neces- sary for decalcification of so solid a tissue as the enamel of a tooth. And the question often arises. Where does this acid come from ? First let us take into consideration the starting-points of the morbid process. I fear no contradiction on the part of my professional breth- ren when I say caries never begins on the smooth surfaces of a tooth, which are exposed to the friction of mastication, but always starts at points which, owing to their anatomical structure, form receptacles for food, etc. , or at places between the teeth where, owing to want of cleanliness, decaying material can accumulate. It is therefore not to the friction between the single teeth (Salter) (which, as we know, is possible to a certain extent in the normal condition), but to the acid generated from the decaying material retained between the two flat or concave surfaces which the teeth present to each other, that the beginning of the destruction of enamel in this locality is due. That this decaying material may be sought for and found in the food I think will hardly admit of a doubt ; and, as it occurs to me, mainly in such kinds of food as through their decomposition are apt to produce an acid, not very strong, perhaps, in itself, but possessing a high degree of affinity for lime-salts, viz, lactic acid. First among the varieties of food ranks meat, which by putrefaction may produce free lactic acid ; next are the saccharine materials ; and last the amylaceous, which being converted into dextrin by the action of the saliva, may be transformed, if brought in contact with putrefying meat, into lactic acid. There is no doubt that the or- ganic portion of teeth, as it advances to the stage of decomposition in the process of caries, plays a very important part in the formation of this acid. Perhaps the sour decomposition is assisted locally by the action of micrococci and leptothrix ; although these organisms are known to prosper only in alkaline, and not in acid fluids. These vegetable organisms are present in innumerable quantities on the healthiest gum ; tartar is crowded with them. And even in the highest degrees of development of tartar caries is absent. In fact, when decayed cavities in teeth become filled with tartar, the carious process is as 74 DENTAL PATHOLOGY AND PRACTICE. effectually stopped as It is possible for it to be when such cavities are filled in the most perfect manner, with gold or any other favorite material. Hence I do not consider the views of those authors correct who claim that micrococci and leptothrix play any important part in producing, or even supporting, the carious process. I fully concur, however, with the views of those who claim that the resistance of the teeth against caries, owing to their amount of lime- salts, greatly varies in different people. The color of the teeth, as is well known, is indicative to some extent of the proportion of lime-salts they contain. The microscope shows a considerable variety, with regard to the presence or the degree of density, of that layer of the basis-substance surrounding the dentinal canaliculi. E. Neumann first drew attention to this layer, which is sometimes so dense and so well defined, owing to its greater refracting power than that of the basis- substance between the canaliculi, that it may be regarded almost as a protecting sheath to the living matter within the canaliculi. This layer is well marked even in fossil teeth ; it resists somewhat the action of strong acids and alkalies, but it is almost completely absent in a number of carious teeth which I have examined. I have also re- marked that of a number of teeth, treated in exactly the same manner with chromic acid solution, some become soft in a markedly shorter space of time than others. The general health or constitution may have considerable influence upon the quantity of lime-salts deposited in the basis-substance of the teeth, although it has been claimed that people of so-called scrofulous and tuberculous constitutions on the average have better teeth than strong and vigorous persons. Nations of high civilization, which inevitably leads to bodily and mental depri- vation, as a rule have a greater percentage of carious teeth than those of a low degree of culture, or of no culture at all. However this may be, the fact that caries of the teeth begins as a chemical process will scarcely, in my opinion, be questioned. On a dead tooth, natural or artificial, as well as on teeth manufactured from the dentine of the elephant or the hippopotamus, the process will remain, under all circumstances, a chemical one, assisted only by the putrefying remains of the organic material of the tooth ; while on a live tooth either acute or chronic reaction-changes take place, which I intend presently to consider. Caries of Enamel. The clinical phenomenon of caries, in its very origin, consists essen- tially in a discoloration of the enamel. A whitish or grayish spot on the surface of the enamel is indicative to an experienced eye of the beginning of decay, the spot proving when touched with an instru- ment to be soft and crumbly. Often a brown spot is visible on the CARIES OF HUMAN TEETH. 75 enamel as a sign of the softening process. The less pigmentation present, the more rapid is the process of decay. On the contrary, the more distinct the discoloration, the slower is the softening process. Nay, dark-brown spots may be present in the enamel for many years without being followed by softening. The brown discoloration, as such, cannot be considered as an essential feature of caries of enamel, but it usually accompanies the carious process, and does so the more surely the slower the morbid process runs. In microscopic specimens we meet with decayed pits in enamel without any discoloration of this tissue. In other specimens we have a very marked orange or brown hue on the decayed part as well as in its neighborhood, and some- times scattered specks are to be seen some considerable distance from the diseased part. The brown discoloration is located in the basis- substance of the enamel-rods, the outlines of which are much more marked than when in a healthy condition. The interstices between the rods here are plainly visible even with a magnifying power of only five hundred diameters. This power will reveal delicate beaded fibers of living matter within the interstices, which in healthy enamel cannot be seen distinctly with a lower power than eight hundred to one thousand. Besides the discoloration, no material changes are seen on the enamel-rods. To what process the pigmentation of the enamel is due I cannot say, but it occurs to me that we have no right to look upon this process as a merely chemical reaction upon the basis-substance of the rods. That in fact it is the basis-substance holding the pigment, and not the lime-salts deposited therein, is proven by specimens from which the lime-salts have been extracted to a considerable extent by chromic acid, and which still show the brown stain. I dare say that this brown discoloration is a strong proof of the presence of life in the enamel, as in teeth where the pulps are dead such stains never appear, nor can they be produced by artificial means. The process of decay in the enamel can best be studied on superficial erosions of the same, a sample of which I have illustrated. In this instance the brown discoloration of the decayed part was but trifling, and entirely absent in its vicinity, so that we have to consider it as a case of acute caries. We see at E, E, Fig. 39, the unchanged enamel partly deprived of its lime-salts. Toward the periphery a zone appears in which the enamel- rods are spotted, evidently owing to their partial decalcification. Close to this and immediately below the decayed part (see P, P) a zone is visible in which the enamel is granular, and looks precisely like normal enamel from which, by a somewhat stronger solution of chromic acid, the lime-salts have been dissolved out. Here the protoplasmic condition of the enamel is re-established simply by decalcification, and there is no doubt that this is the very condition of the enamel 76 DENTAL PATHOLOGY AND PRACTICE. by which the white spot is produced upon the surface while the tooth is still in the jaw. On the boundary of the enamel we see a shallow depression (C) filled with protoplasmic bodies, which represent either complete enamel-prisms or lumps of such prisms. All these proto- plasmic formations are united to one another by delicate threads ; they exhibit but a slight brown discoloration, readily imbibe carmine, and if the specimen be stained with a half per cent, solution of chlorid of gold these bodies assume a dark-blue tinge, while the unchanged enamel is but little affected by this reagent. On the outermost layer we see several flat epithelial bodies (N) attached to the proto- plasm, which in the transverse section look irregularly spindle-shaped, .and are possibly the remnants of the so-called Nasmyth's membrane, Fig. 39. V z . 1 . --i. _ r^^ ^--/. j : \ i 1 -i - . ■ ' ' ' - -^ c- -Jt J* or enamel-cuticle. On the level of the enamel we also recognize such flat epithelia (/,, Z,). Beneath them on the right side of the drawing there is present a zone of decalcified enamel, while on the left side the division into protoplasmic bodies is fully accomplished. Not a trace of micrococci or of leptothrix is visible in or above the decayed pit of the enamel, which again proves that these organisms do not play any important part in the process of caries ; at least, do not materially interfere with the tooth in its normal condition. The way in which the caries proceeds downward is plainly shown by the figure. There are small, irregular, bay-like excavations on its boundary, and in the midst of the decayed part a wedge-shaped elongation is running downward into the softened enamel. The shape in which caries appears in the enamel, however, varies greatly. PLATE A. CARIOUS ENAMEL, LONGITUDINAL SECTION. a, a, Normal enamel ; h, h, disorganized condition of enamel, show- ing marked inflammatory reaction. X 600. CARIES OF HUMAN TEETH. 77 Besides the wedge shape as illustrated in the wood-cut, caries pro- ceeds in the form of shallow or conical excavations, excavations with abrupt walls, fissures, and grooves. On the bottom of the main excavation we sometimes see a smaller cavity, having either a narrow or wide communication with the main decayed mass. Besides the peculiar medullary elements forming the contents of a carious cavity of the enamel in its initial stage, I have not very rarely met with dark-brown, irregularly-shaped clusters filling the entire cavity. How such changes of medullary corpuscles are produced I am unable to say, although it seems to be kindred to the so-called colloid or hyaloid metamorphosis which we observe in other tissues, the only difference being that in caries the colloid clusters are deeply saturated with a uniform brown pigment, the origin of which, as mentioned above, is unknown. Caries of Dentine. Upon examining a large number of teeth with carious dentine, we are struck by conditions to the presence of which but few observers have drawn attention. Sometimes the dentine, when attacked by caries, looks but little changed on its periphery. A narrow zone of yellowish color forms the boundary toward irregular, shallow Fig. 40. ^:*:^M-^^'^5?St«i^ excavations. (See Fig. 40, a.) At other times, besides the bay-like excavations on the periphery, there are visible elongations, cylin- drical, conical, pear-shaped, or leaf-like, passing down into the dentine to varying depths. (See Fig. 40, b.') There is no doubt that this form of decay of the dentine occurs with the least prelimi- nary changes of the tissues ; it evidently runs a slow course, and I feel justified in calling it chronic. It seems evident that decay of a tooth assumes an acute or a chronic form just in proportion to its per- fect or imperfect calcification. Dead teeth in which the pulps have been destroyed either by necrosis as a natural process, or by artificial 78 DENTAL PATHOLOGY AND PRACTICE. means with caustics, very frequently run this kind of slow or chronic decay. The decay of artificial teeth, either human or ivory, in all probability runs either an acute or a chronic course, according to the amount of lime-salts infiltrated into the glue-giving basis-substance. I have examined a piece of a hippopotamus tooth which was worn in the mouth of a patient for a period of about one year, upon which a spot about the size of a hemp-seed became decayed. I softened this piece with chromic acid solution, imbedded it in paraffin and wax, and cut thin sections with a razor. On the bottom of the decayed pit numer- ous conical spots appeared running downward into the dentine, char- acterized by the absence of coloring matter in specimens stained with carmine. Aside from this no material change was observable; even the dentinal canaliculi did not look enlarged. The bottom of the carious cavity was covered with a layer of finely granular, evidently disinte- grated, organic material, and above this the masses ordinarily filling carious cavities in teeth, viz, micrococci and leptothrix, were visible. In chronic caries the process is principally a chemical one, which is assisted by putrefaction of the organic constituents of the tooth. Here first the solution of the lime-salts of the dentine takes place, either along the bay-like excavations or in the shape of longitudinal de- pressions. Very slight if any reaction follows this process. The glue- giving basis-substance being deprived of its lime-salts shows a yellow discoloration, and only traces of the dentinal canaliculi. The basis- substance then breaks down into an indistinct granular mass, which is immediately filled with a new growth of low vegetable organisms, viz, micrococci and leptothrix. My specimens plainly show that these organisms are not the ad- vance guard in the process of decay. The first change that takes place is exposure of the basis-substance by the chemical action of some acid, independent of the organisms referred to, which come to view only after complete disintegration of the basis-substance. I never have seen the penetration of these organisms into the dentinal can- aliculi until a thorough decalcification of ihe basis -substance had taken place. No doubt, however, the decayed mass itself may be crowded with such organisms. In the great majority of my speci- mens I have met with formations on the diseased boundary of the dentine which demonstrate a considerable degree of reaction, pro- duced by the irritating power of the same agent to which the lime- salts of the dentine yield. In fact, this was the case in all teeth which were alive when attacked by the carious process, or rather when removed from the jaws. On the boundary of this process we see irregularly-shaped elongations running a certain depth into the tissue of the dentine. The more superficial the elongations are, the surer the morbid process may be termed a slow one ; and, on the con- CARIES OF HUMAN TEETH. 79 trary, the deeper the elongations, the more certain we may be that the morbid process has advanced rapidly. The elongations mainly have the shape of fissures filled with a dark granular material, if viewed with a low power. These fissures run independently of the direction of the dentinal canaliculi ; nay, very often cross them. (See Fig. 41, <2, a.) In the specimens they look as a rule as if communicating with one another, and also directly or indirectly with the decayed outer surface. Sometimes the fissures look completely isolated, though we may assume that they are separated from the communication with analogous and more superficial formations only by the method of preparation, \\z, cutting into thin lamellae. Fig. 4t. On the surface of the carious portion of dentine we see irregular cavities filled with the same granular mass that is present in the fis- sures, consisting evidently of debris of the former tissue, together, perhaps, with micrococci, and very often fine thread-hke leptothrix. The more rapidly the destruction of the dentine has advanced, the more irregular islands of dentine are left on the surface. (See Fig. 41, b, b.) In our figure the decay evidently has proceeded rapidly ; hence the remnants of the former dentine, recognizable by the presence of the canaliculi, are very small and irregular on the outer periphery of the dentine. The outermost portion of the decayed part is, as a rule, brittle, and crumbles away in chromic acid specimens. Where it is left it shows a swarm of leptothrix and micrococci, without any distinctly recog- 8o DENTAL PATHOLOGY AND PRACTICE. nizable remnants of the former tissue. On the boundary of the carious portion we meet with a yellow discoloration of the dentine before mentioned, which is evidently produced by a chemical agent, which produces an irritation of the contents of the canaliculi, causing it to increase in bulk and become liquefied, thus breaking down their walls of lime-salts, which eventually are dissolved by acids and washed away. In live teeth the yellow discoloration usually takes place in the shape of longitudinal strings of different diameters, run- ning mainly parallel with the longitudinal direction of the dentinal canaliculi. Nay, we often see single yellow strings running from the bottom of a carious cavity in the enamel through the entire depth of the dentine to the pulp-chambers. (See Fig. 41, c, c.) The best method for demonstrating these strings is doubtless the staining of chromic acid specimens in an ammoniacal solution of carmine. While the unchanged dentine readily takes up the carmine, the strings, the deep yellow color of which is undoubtedly due to the action of the chromic acid, remain unstained. With a power of about five hundred diameters, we recognize under the microscope, in longitudinal section of the dentine, that sometimes the yellow discoloration has taken place only within the limits of a few dentinal canaliculi, while at other times quite a number of these have undergone discoloration. Still sharper defined is the yellow discoloration on transverse sections. Here we see that the canaliculi and their immediate neighborhood mainly have taken up the yellow color in the shape of sharply-circumscribed dots, which are larger the nearer they approach to the periphery of the decayed part. The basis-substance between these yellow spots has taken up more or less carmine. Let us examine such a cross-section with a magnifying power of one thousand diameters under the microscope. At a certain distance from the decay the canaliculi look unchanged, and each contains the central transverse section of the dentinal fiber, with its delicate radiated offshoots. (See Fig. 42, «.) Nearer to the decay we meet with moderately- enlarged canaliculi, the center of which is occupied by a cluster of protoplasm, the granules and threads of which have readily taken up the carmine. (See Fig. 42, b, b.) One step farther we find the canaliculi considerably enlarged, to double or treble their original size, and they are filled with yellow protoplasm, plainly exhibiting the net-like arrangement of the living matter. (See Fig. 42, c, c.) The most peripheral granules send delicate conical offshoots through the surrounding light space toward the unchanged basis-substance. In some of the enlarged canaliculi accumulations of living matter are seen of the same shape as nuclei ; sometimes two or more such nuclei may be seen surrounded by a varying amount of protoplasm. (See Fig. 42, d, d.) Still nearer to the decay the canali- PLATE B. CARIOUS DENTINE, LONGITUDINAL SECTION. «, Normal dentine ; b, b, b, b, dentine reduced to its medullary con- dition through inflammatory reaction ; c, zone of inflamed dentine, showing a generally disorganized condition, and greatly enlarged canaliculi ; d, dentine breaking down after decalcification, death and putrefaction. X 600. PLATE C. CARIOUS DENTINE, CROSS SECTION. a, Normal dentine ; b, b, swollen canaliculi from inflammation. CARIES OF HUMAN TEETH. 8r culi are enlarged to ten or fifteen times their original diameter, and the cavities thus produced are all filled with a partly-nucleated protoplasm. (See Fig. 42, \tv^ K^\^ Antrum Spray. To be used, with antiseptic solutions, in cases of persistent accumulation of pus in the sinus. drachm to an ounce of the carbolic acid solution. Here I wish to remark that my first idea of the use of a spray, as a more perfect means of medicating the antrum, was obtained from Dr. J. L. Mew- born, of Memphis, in 1884. He, however, uses the remedy warm, and applies it by means of a hand atomizer with a single jet. I use compressed air, with a pressure of thirty to forty-five pounds to the square inch, and a multiple spray. The pressure forces the remedy into every irregularity of mucous membrane, and the multiple spray reaches all parts of the cavity. This mode of applying remedies to the cavity of the antrum I consider of incalculable service in the suc- cessful treatment of many cases, and I cannot, nor do I think the profession in general can thank Dr. Mewborn enough for this valuable addition to their armamentarium for the treatment of this disease. DISEASES OF THE ANTRUM, I33 After thoroughly medicating as above described, means must be taken to prevent the opening from closing too rapidly. This is done by means of cotton wound upon a roughened bit of wood, or a bit from a whisk broom, as near as can be judged the size of the open- ing. This is dipped into carbolized oil of sweet almonds (one part of carbolic acid to fifteen of the oil), then placed in position, and tied with silk to an adjoining tooth. This treatment is followed up every day, and as soon as all signs of pus have disappeared the plug is each day made smaller, until the opening is closed entirely. I never use a drainage-tube. In order to test for the presence of pus, peroxid of hydrogen may sometimes be used to advantage. In cases where from the history it is evident that a specific poison has to be combated, iodid of potassium is given in five-grain doses three times a day, and each day the dose is increased one grain until the patient becomes perceptibly affected by it, which will be mani- fested by a decrease, and finally a cessation of the discharge of pus. Many cases yield readily to the effect of sulfid of calcium, given in one-tenth grain doses three times a day. It is frequently the case that patients are anemic, consequently the disease yields slowly, if at all, to local treatment. In such cases ammonio-citrate of iron, in from five to ten-grain doses, three times a day, is found of excellent service. Quinin sulfate in two-grain doses, three times a day, is found useful. Persons who take very little out-door exercise, especially if past middle age, should be di- rected to take such exercise liberally and systematically every day. It will be observed that I have spoken of but one means of gain- ing an entrance to the antrum. Other modes are adopted by some surgeons, some of which I do not approve of Some years since, I listened to the description of an operation for this purpose, and saw the patient upon whom the operation had been performed. It was at a meeting of the New York Odontological Society. The operation consisted in making an incision from the corner of the mouth back past the external antral wall, dissecting the soft tissues from the wall, and making an opening into the antrum over the molar teeth. It was spoken of as a great and very successful opera- tion. This may have been, so far as the cure of the disease was con- cerned ; but it seems to me that the means adopted were alto- gether too heroic and not at all necessary. Here was, from the history of the case, a simple abscess from a pulpless tooth emptying into the antrum, which would have been treated, and probably cured, in a few weeks by a competent dental surgeon, with no surgical work whatever except the removal of the offending tooth and the enlarging of one of the sockets. In my judgment, dental surgeons ought to openly discourage, in the strongest manner possible, such uncalled- 134 DENTAL PATHOLOGY AND PRACTICE, for surgical work as was shown in this case. Patients suffer quite enough when such cases are treated in the most conservative manner possible. A most interesting and instructive case came under my observation some years ago. A gentleman some thirty-five years previously had received a scratch on the cheek, by the left side of the nose, which, despite all the efforts of the best-skilled physicians in this country and Europe, would not heal. It was pronounced a rodent ulcer, or flat cancer. It increased in size and annoyance very slowly indeed, so much so that at times it was thought to be more or less under control. Some twenty years before I saw him professionally,, he had had the pulp destroyed in the left upper second molar, and the tooth filled in Paris. Some ten years after this, his dentist in this city had refilled the cavity in the crown of the tooth, but had done nothing with the roots, they seeming to be filled satisfactorily, as no trouble had been experienced from them. While summering out of the city, shortly before I was called in, the face on that side commenced to swell ; the eye became pushed up very considerably, causing severe and constant pain. Upon examination, I concluded that the pulpless molar had caused an abscess in the antrum. I was requested by his dentist and attending physician to remove the tooth. This I did, and found my diagnosis correct. Immediately upon its removal quite a quantity of black, fetid matter was discharged. This kept up during the following night and a part of the next day. Upon prob- ing the antrum, it was found nearly filled with a mass which proved to be cancerous. From this time forward the growth of the cancer was very rapid. In a few months' time I had removed all the teeth in the upper jaw, and several other operations had been performed, large masses of the growth being removed to prevent suffocation. Death finally relieved him of his sufferings. The lesson to be learned from the case is this : where an incurable disease is present upon the face, great care should be taken that the dental organs are not allowed to become an auxiliary in its progress, thus increasing, to a great extent, the sufferings of the patient, and, in consequence, very considerably shortening his life. In this case the seat of the disease was apparently changed from his face, outside, to the antrum, caused undoubtedly by this pulpless molar. Its more rapid development, and consequent increase of suffering and shortening of his life, was the result. ABSCESSES IN THE SALIVARY GLANDS. 135 CHAPTER XV. ABSCESSES IN THE SALIVARY GLANDS. ' Fortunately, abscesses in the salivary glands are comparatively- rare. Their occurrence, however, is frequent enough to demand a passing notice. The recognized causes of abscess in the salivary glands are three : First, and the most common, is the deposit of a calculus ; second, external injury ; and third, a severe and long- continued cold. It has been my privilege to see and have under treatment only cases caused by calculi. Primarily these cases probably start from an embolus, as of a clot of blood, or a uric-acid crystal, which lodges in one of the minute capillary blood-vessels of the gland, thus form- ing a nucleus around which the calcular deposit is built up. As the size of the calculus grows, an uncomfortable feeling in the region is noticed, which increases as the augmentation of the deposit goes on, until severe neuralgic pains are experienced. The sufferer is then liable to go through a protracted treatment for neuralgia before sup- puration takes place. As this occurs a severe chill (rigor) is mani- fested, and very soon the true nature of the disease is determined. It is no uncommon occurrence for the discharge of pus to take place through the duct from the gland leading into the mouth. This may go on for months, and even for years, before the duct by some means becomes clogged, and the discharge in that direction is stopped. The pus accumulating rapidly, another exit will soon be made, which in some instances is out through the skin : in the case of the parotid, near the angle of the jaw ; and with the submaxillary and sublingual below the inferior maxilla, in their respective neighborhoods. More frequently, however, the discharge is through the mucous membrane into the mouth. The treatment of these abscesses consists in removing the calculus and washing out the abscess with antiseptics. The removal of the calculus, however, is no slight undertaking. In fact, it is one of the most delicate and difficult operations the surgeon is called upon to perform, provided it is done in the most conservative manner. It consists in enlarging the opening through which the pus is discharg- ing, when with a long, delicate instrument with a minute spoon- shaped end, made especially for the case, the stone is removed. This may be done in a few minutes, or it may take hours. Should the calculus form near the opening to the duct leading to the mouth from either the submaxillary or sublingual glands, it may be forced forward, after suppuration has occurred, into the duct. 136 DENTAL PATHOLOGY AND PRACTICE. forming a plug. The saliva, being prevented from passing, accumu- ■ lates, distends the duct, until the annoyance to the patient causes him to consult a surgeon, when a tumor, soft, fluctuating, and trans- lucent, is found under the tongue. Upon careful examination, the calculus may be located with the finger. The treatment of such a tumor consists in opening the cyst, re- moving the stone, and thoroughly cleansing the sac with antiseptic washes. An astringent wash may be used for some days by the patient, to facilitate the healing process. A false opening for the dis- charge of saliva will in most cases be established at the point where the tumor was opened. CHAPTER XVI. SALIVARY CALCULUS AND PYORRHEA ALVEOLARIS. These lesions are so often referred to by writers and speakers as one and the same condition, that I propose to consider them to- gether ; not that I believe them to be essentially the same, for I do not. Salivary calculus I hold to be an evidence of organic dis- turbance, or functional disorder of the digestive tract, or of the kidneys or liver, as a result of which the excrementitious materials are not fully eliminated from the body. Prominent among these waste products of nutrition is the excess of lime-salts taken into the system which should pass out through these natural channels. These salts are in consequence retained in the circulation until they find some other mode of exit, mostly through the salivary glands. This is generally termed a constitutional disturbance, manifesting itself locally by the excessive calcareous deposit upon the teeth, and often in the salivary and other glandular structures. One of the most marked cases I have ever seen was in the mouth of a patient who was suffering from diabetes, which caused his death in a few years. It is very evident that with every organ in the body in normal condition, i.e., in perfect health, consequently performing its function, excessive salivary calculus would be unknown. On the other hand, pyorrhea alveolaris is found to attack teeth in the mouths of many persons who are never troubled with excessive calcular deposits upon their teeth. Both conditions may of course be present, a circumstance which very greatly complicates the case so far as treatment is concerned. Pyorrhea alveolaris (discharge of pus from the alveolus) — under- stood by laymen as a disease of the gums which results in the loss of SALIVARY CALCULUS AND PYORRHEA ALVEOLARIS. 1 37 the teeth — is a condition (I hardly think it should be called a disease) which has been more or less prevalent from time immemorial. It would seem that with the ancients it was the only condition that de- manded the removal of the teeth, as lead or copper forceps are the instruments for that purpose spoken of in ancient history, indicating that they had become extremely loose, and their sockets nearly or quite destroyed before their extraction was resorted to. Let us consider for a moment the primary cause of pyorrhea. Is it an excessive deposit of calcareous matter upon the teeth ? From my studies and experience I should say no, and I believe this would be the answer of every observing practitioner. Does it not begin in the mouths of children who habitually neglect their teeth so far as personal care is concerned, and who never seek the services of a dentist, by an accumulation of particles of food under the free margin of the gums ? This serves as a lodgment for any lime-salts which come that way in the saliva, so that at the age of ten or twelve years or earlier a narrow ring of tartar may be found under the gum. Unless removed, this slowly increases until marked gingivitis is ob- servable. At this time if a small portion of the soft mixture be taken from under the gum, mounted upon a slide, and placed under the microscope, pus-corpuscles will be found in quite large numbers, showing that ulceration has already commenced. If this case be let alone and watched, it will be found that by the time the patient, or rather person, is forty years old, or perhaps much earlier, the teeth will have become loose, their sockets nearly or quite destroyed, and the gums will have resumed a turgid, hyper- emic, and ulcerating condition, with pus constantly exuding from the sockets of the soft tissue, to which the teeth are now attached. The progress of the destruction of tissue is now so rapid that in a few years more these same persons will be masticating upon their gums, or wearing a beautiful set of artificial teeth. Another and very prevalent cause of pyorrhea is mercurial poison- ing. It is well known that mercury, or its salts, has a very irritating effect upon the salivary glands, causing them to secrete an excessive amount of saliva, which, in turn, is poured into the mouth through the ducts leading from the glands. It is also well known that the active principle of saliva — ptyalin — in excess is a powerful irritant to the mucous membrane of the mouth. This irritation very soon be- comes a marked inflammation, especially around the teeth. By this inflammation circulation is impeded, the nourishment of the gum ceases, and its detachment from the necks of the teeth is the result. Thus a pocket is formed for the reception of particles of food, lime- salts, etc. It must be borne in mind that in this position and under these circumstances lime-salts need not come from the saliva at all, as 138 DENTAL PATHOLOGY AND PRACTICE. the periosteum (pericementum), which has taken on the inflammatory- stage, its functional activity therefore being greatly stimulated, is working hard to protect itself from further injury, by secreting in excess this ingredient of the tartar. All the stages known, ' ' from start to finish," in pyorrhea alveolaris, are observable in these cases of ptyalism. It will be observed that in neither of the typical cases of this tooth- or socket-destroying malady is there any general disturbance, neces- sarily, of any organ or set of organs, except in the second, where the salivary glands become involved temporarily. Treatment. — In considering the treatment of salivary calculus, it must first be observed that we have present in the mouth evidences of some organic or functional disorder, and that the case is one which should be referred to the general practitioner. Locally, however, all that is possible must be done to prevent permanent injury to the teeth and gums. This consists in securing and maintaining as thor- ough cleanliness as possible. The patient should be instructed to brush the teeth inside and out, after each meal, and have them cleansed by the dentist at least four times a year. In order to fur- ther the work of cleansing, and as a prophylactic against caries, a suitable dentifrice should be recommended. This, together with the proper kind of brush to use, and the manner of using it, will consti- tute the directions for the local care of the teeth, except the removal of portions of food from between them, which can be best done by the use of quill toothpicks, and silk. For general use as a dentifrice I would recommend what is known in the market as Handicap tooth- powder. Where teeth decay rapidly, I would recommend the follow- ing as a prophylactic (antiseptic) : R — Precip. chalk, .^ ij ; Pulv. orris root, Piilv. Castile soap, aa ^j ; Bicarbonate of soda, .^ ss ; Salicylic acid, gr. xij. Flavor with peppermint, wintergreen, and anise to suit the taste. The tooth-brush best calculated to keep the teeth clean, with the least amount of brushing, should be composed of four rows of bristles, not stiff" nor too soft, set as close together as practicable, so that a very narrow brush is the result. With such a brush the teeth can readily be brushed longitudinally (up and down). Cross-brushing should be scrupulously avoided. It will be observed that with a brush such as described the slightest movement will produce friction upon the teeth, so that the minimum amount of time may be devoted to this part of the toilet, with clean teeth as the result. In pyorrhea alveolaris we have a different condition to deal with. SALIVARY CALCULUS AND PYORRHEA ALVEOLARIS. I39 There being no evidence of any organic or functional disorder, the case is amenable to local treatment only. We are often asked if such cases can be cured. The answer is, if taken at the beginning of the trouble, yes ; while if the accumulation upon the teeth is consider- able, the remaining periosteum thickened, the teeth consequently more or less loose, the answer is, no, but that the mouth can be rendered healthy, the discharge of pus from the sockets stopped, and the teeth made firm again in the remaining portions of the sockets. The only change from a normal condition will be a loss of more or less of the alveolus and an atrophied condition of the gums around the teeth, leaving not only their necks, but, in many cases, a large portion of their roots uncovered. Many remedies, as astringents, stimulants, escharotics, etc., have been recommended, and even constitutional treatment has been resorted to with, so far as my knowledge and experience goes, very questionable success. The real remedy is the careful removal of all foreign substances from the roots of the teeth. This alone will suffice, and nature, " the great restorer," will do the healing of the soft parts. Should the alveolus be exposed and a portion of it dead, as is some- times the case, of course it must be thoroughly cut away. This, however, in some few cases I have seen, is not followed by recovery as readily as one could wish. Should it be deemed advisable to apply astringents, etc. , to facilitate the healing of the soft parts or allay pain, after cleansing thoroughly the following are recommended : R — Tannic acid, Carbolic acid, Tr. iodin, aa 5 ss ; j- Astringent, antiseptic, and stimulant. Glycerin, Distilled water, aa ^ ss. J M. Sig.— Spray. If the parts are painful after the removal of tartar, the following will be found very grateful to the patient: R — Carbolic acid, Tannic acid, aa 5 ss ; Sulphate of morphia, gr. iv ; Glycerin, Distilled water, aa ,f ss. M Sig.— Spray. - Sedative, antiseptic, and astringent. 140 DENTAL PATHOLOGY AND PRACTICE. Fig. 57. Mouth and Throat Spray. To be used in most cases and varieties of stomatitis, pharyngitis, or laryngitis. The above cut represents the apparatus with which the foregoing remedies are appHed in spraying lacerated gums, or any inflamed con- dition of the mucous membrane of the mouth or throat where such treatment is considered proper. The proper mode of removing the tartar from the roots of teeth is greatly a matter of personal fancy. With some the instruments used are of a chisel-like shape, and the movement is a pushing one toward the end of the root. This proceeding I object to seriously, as it is productive of an unnecessary amount of laceration of the soft parts, and, consequently, unnecessarily painful. Of course cocain (four per cent, solution) may be used to render the parts in a measure insensible to pain, but it does not lessen the laceration. In fact, I am inclined to think that under its use the parts are injured consider- ably more than when the work is done without it, I have always followed the other mode of procedure, — viz, a pull- ing movement for the removal of the deposits. It has been my pleasure to have introduced at various times three different sets of instruments for this work (see illustrations), and all of them have been constructed upon this principle. The laceration of the gum and consequent pain to the patient is greatly lessened, and I believe the work is more easily and thoroughly done than by the other method. However, we are such creatures of habit that possibly all could not operate in the- same manner, even if special advantages were shown in favor of one particular mode. ^ SALIVARY CALCULUS AND PYORRHEA ALVEOLARIS. 14I Fig. 58. r- ill I 3 4 S 6 7 Set of Small Scalers, No. L (1S68.) Nos. I, 3. For cleansing the anterior surfaces of lower front teeth. N0S.2, 4, 6. For cleansing the lingual surfaces of lower front teeth. Nos. 3, 4, 5. For cleansing labial, palatal, and lateral surfaces of the upper front teeth, and buccal, palatal, and approximal surfaces of molars and bicuspids. No. 7. For cleansing under the gum around upper front teeth. Nos. 8, 9. For cleansing under the gums of lower back teeth. Fig. 59. 12 13 Set of Scalers, No. II. 142 DENTAL PATHOLOGY AND PRACTICE. These scalers are so shaped as to cut either forward, backward, or laterally. The following description will indicate their special adaptation, but they will be found very useful for a large variety of cases : Nos. I, 2. For removing calcular deposits from between the lower front teeth anteriorly. Nos. 3, 4, 5. For the same teeth posteriorly; also around the necks of all teeth, both upper and lower. No. 6. For the extreme lingual portion of the lower incisors and cuspids. No. 7. For any tooth, under the gum, to which its shape is adapt- able. No. 8. For any of the upper front teeth, under the gum. Nos. 9 and 10. For lingual portions of lower front teeth, under the gum. Nos. ir, 12, 13, 14 are rights and lefts, for cleaning under the gum, s of lower back teeth. Fig. 60. 2 3456 7S910 Set of Root Scalers. These instruments are intended more particularly for cleansing the lateral, or approximal, surfaces of the roots of the teeth. They will, \^'f^ however, be found useful in cleansing almost every surface of roots in whatever location. Nos. I, 2, 3, 6, 7, 8 are adapted to rather heavy work beween the back teeth, while Nos. 4, 5, 9, 10 are intended for the front teeth, and the finer work between the back ones. FACIAL NEURALGIA. 143 CHAPTER XVII. FACIAL NEURALGIA. In order to give a clearer understanding of the diffusion of pain through the face, head, and body from irritation of the dental nerves , I have thought it best to quote, by permission, the excellent descrip- tion of the fifth pair and its connections, written by Professor Harrison Allen. The Fifth Pair of Nerves. " Theji/th pair of nerves (trifacial, trigeminus) — the largest of the cranial nerves — arises by two roots — an anterior motor and a posterior sensory root — the latter bearing a ganglion. The analogy between it and a spinal nerve is exact. ' ' The nerve has, therefore, two origins, one for each of its roots. The sensory root has been traced to the lateral tract of the medulla oblongata behind the olivary body. Its precise point of origin is not certainly known. The motor root has been generally said to be traceable to the anterior pyramid of the medulla oblongata, although this has been disputed by Alcock. Both roots have an apparent origin from the medulla oblongata from the side of the pons Varolii, and both remain distinct while within the cranium, and are inclosed in the same membranous sheath. Toward the apex of the petrous bone, both nerves pass through an opening of the dura mater, to which, however, the ganglion remains firmly attached. The sensory root is larger than the motor, less compactly arranged, and both softer and coarser. Its ganglion, known as the ganglion of Gasser (semi-lunar ganglion), lies within a shallow depression at the apex of the petrous bone. It is of crescentic figure, with its convexity directed forward. "It is joined at its inner side by several sympathetic filaments from the carotid plexus. Minute recurrent branches are distributed from it to the tentorium, and according to Luschka, to the dura mater of the middle cerebral fossa. "The motor root lies beneath the ganglion, a little to the inner side of its center. It is distinct from the ganglion, and is received entirely within the inferior division of the extra-cranial portion of the nerve. ' ' The nerve divides in advance of the ganglion into three main divisions : (I) the ophthalmic, (II) the siiperior maxillary, and (III) the inferior maxillary nerves. 144 DENTAL PATHOLOGY AND PRACTICE. (I) The Ophthalmic Division. " The nerve, after leaving the ganghon of Gasser, enters the cav- ernous sinus and passes forward and upward along its outer wall, in which situation it has a plexiform structure. It is a somewhat flat- tened cord of about an inch in length. Just before entering the anterior lacerated foramen, it gives off a small recurrent branch and receives some sympathetic filaments. It then divides into three branches, the lachrymal, th.e frontal, and nasal. ' ' The lachrymal nerve enters the orbit through the narrowest and highest part of the anterior lacerated foramen in a separate sheath of dura mater. It is the smallest of the main branches of the ophthal- mic nerve. It keeps near the outer wall and is in close connection with the periosteum of the orbit, and passes in a straight line along the upper border of the external rectus muscle to the position of the lachrymal gland. It here receives a filament of the orbital branch of the superior m,axillary division, and gives small filaments to the lach- rymal gland and the conjunctiva. The nerve then pierces the palpe- bral ligament and supplies the outer part of the upper eyelid, anasto- mosing with branches of the facial nerve. Cruveilhier describes a small ascending temporal branch which is lost in the integument of the anterior temporal region. " Theyr(?;z/a/ nerve is the continuation of the trunk of the ophthal- mic hoth. in size 3.n6. direction. It enters the orbit in the center of the anterior lacerated foramen. It passes horizontally forward between the periosteum and the levator-palpebrae muscle, which it crosses at an acute angle, and divides into two unequal branches in the supra- trochlear and supra-orbital. The supra-trochlear, some- times called the internal frontal, is as a rule the smaller of the two, and escapes from the orbit near the pulley of the superior oblique muscle. It pierces the orbicularis palpebrarum, and turns upward on the forehead to the occipito-frontalis muscle, terminating in the integument. At the region of the pulley it gives off a descending- branch which joins the iyifra-trochlear branch of the nasal, and gives filaments to the upper eyelid, and according to Cruveilhier to the root of the nose. ' ' The supra-orbital branch passes from the orbit at the supra- orbital notch of the frontal bone. It divides into ascending and descending branches. The latter are two or three in number, and pass vertically downward in the substance of the upper eyelid to sup- ply the mucous membrane. Meibomian glands, the ' skin and hair- bulbs ; one of them running horizontally outward under the orbicu- laris palpebrarum to anastomose with branches of the facial. The ascending passes to the forehead as in the preceding branch, and, sooner than it, perforates the occipito-frontalis muscle, and is dis- FACIAL NEURALGIA. I45 tributed to the scalp, as far back as the lambdoidal suture. Accord- ing to Cruveilhier, a very remarkable branch of this nerve enters a minute osseous canal, beginning at the supra-orbital foramen, to emerge from the canal at the frontal eminence, where it becomes subcutaneous. ' ' The nasal branch arises from the under side of the ophthalmic trunk and enters the orbit at the largest part of the anterior lacerated foramen, in company with the third (between the superior and inferior branches) and fourth nerves, and to the inner side of the frontal. According to Sappey, it here appears to be surrounded by nerve- trunks which form for it a sort of sheath. It pierces the ligament from which arises the external rectus muscle, and passes between the two heads of the latter structure. It then is inclined obliquely inward, crossing the optic nerve and lying between it and the levator palpebrae, superior oblique, and superior rectus muscles to reach the internal aspect of the orbit. It here occupies the cellular interval which separates the internal rectus muscle from the superior oblique, and divides into its terminal branches. Before division, the nasal nerve gives off the following branches : ' ' (a) A branch to the ophthalmic ganglion which rises from the trunk before entrance into the orbit according to Cruveilhier, or be- tween the heads of the external rectus according to Arnold. It lies to the outer side of the optic nerve, and constitutes the long root of the ophthalmic ganglion. ' ' {b) The spheno-ethmoidalhrdinch. is described by Luschka as pass- ing through the posterior ethmoidal foramen, and thence to supply the mucous lining of the sphenoidal sinus and the posterior eth- moidal cells along the anterior border of the body of the sphenoid bone. ' ' (f) The long ciliary nerves, two or three in number, placed to the inner side of the optic nerve. They are in connection with fila- ments from the short ciliary nerves {q. v.), thence to the sclerotic coat of the eye, and are distributed to the anterior portion of the eye, including the ciliary muscles, cornea, and iris. " {d) According to Sappey, a few distinct filaments join the sym- pathetic net-work about the ophthalmic artery. ' ' Of the terminal branches, the continuation of the nerve {internal nasal) passes through the anterior ethmoidal foramen, where it is held by a doubling of dura mater, to enter the brain- case. It runs a short distance to the outer side of the olfactory groove of the eth- moid bone, to descend vertically behind the ala ethmoidalis into the nose. It here divides into two branches : one (external) forms for itself a canal or groove on the under surface of the nasal bone, and either obliquely perforates this structure to become superficial, or 146 DENTAL PATHOLOGY AND PRACTICE. continues downward to the free border of the bone to pass between it and the upper lateral cartilage, and is then lost in the skin of the tip and alae of the nose. The other (internal) is smaller than the preceding. It crosses the roof of the nose, and is distributed to the mucous membrane of the nasal septum as it lies within the nasal vestibule. ' ' The remaining terminal branch (the infra-trochlear) leaves the main nerve as it lies beneath the superior oblique muscle parallel to the internal border of the internal rectus muscles. "It receives a small filament from th.e supra-trochlear n&rve, and escapes from the orbit at the position of the pulley. It divides into two sets of branches ; one set passing to the superficial structure of the upper eyelid, and the other set (a greater number) supplying the skin at the root and sides of the nose, and the caruncle, lachrymal sac, and duct. They anastomose with th.e frontal 3ind facial nerves, (II) The Superior Maxillary Division. ' ' The superior maxillary nerve effects exit from the cranium through the round foramen. It is at first somewhat loosely fascicu- lated, but afterward becomes firmer as it crosses the pterygo-maxil- lary fossa, where it is surrounded by fibro-adipose tissue. It is here nearly straight and inclined a little downward. The main course of the nerve is continued across the space, and lies within the infra- orbital canal. The nerve is now called the infra- orbital. The trunk of the superior maxillary nerve may be described as confined to the pterygo-maxillary fossa, the infra-orbital being its branch of continu- ation. This will, therefore, be first given. ' ' The infra-orbital nerve as it lies in the infra-orbital canal is curved a little inward. It terminates at the infra-orbital foramen, in the sub-orbital branches, which form a rich mesh of branches lying beneath the levator labii superioris. These branches are arranged, according to Sappey, in three distinct sets : the ascending, which are slender, generally two in number, lie in a groove or canal of the bone, and penetrate the fibers of the superior elevator to be distrib- uted to the skin and conjunctiva of the lower eyelid. One of the branches sends filaments to the facial at the outer palpebral angle. Among these branches is one which is directed inward and anasto- moses with the external nasal. The descending are more numerous than the preceding. They are distributed to the skin of the upper lip, to the glands thereof, and to the mucous membrane and adjacent gum. The internal are distributed to the skin of the wing of the nose as well as to the outer skin-lining of the nasal vestibule. "Just before the infra-orbital nerve terminates as above, it gives off" the anterior dental branch. This nerve preserves an unusual FACIAL NEURALGIA. I47 course, as follows : According to Cruveilhier, it is often so large as to be held as one of the two terminal branches of the infra-orbital. This description is here adopted. The nerve passes from the main trunk horizontally inward within a special canal, then vertically- downward, turning round the margin of the anterior opening of the corresponding nasal fossa to reach the floor of the fossa. About two lines from the anterior orifice it expands into a great number of as- cending and descending filaments. The ascending are reflected upward within the anterior nasal spine, where they terminate ; the descending supply dental nerves to the incisors, cuspids, and first bicuspids. Some of the latter incline outward, and anastomose with branches of the posterior deyital nerve. In the first and third portions of the above course the nerve is deeply situated ; in the second it becomes very superficial and approaches the external table of the superior maxilla. ' ' The collateral branches of the superior maxillary nerves are as follows : ' ' {a) The orbital. This branch arises directly in front of the fora- men rotundum from the upper side of the trunk, passes through the spheno-maxillary fissure to the floor of the orbit, where it divides into two branches, the lachrymal and temporo-malar. The lachrym,al receives a branch from the lachrymal branch of the ophthalmic, and supplies the lachrymal gland. The temporo-malar pierces the orbital portion of the malar bone, and is distributed to the anterior part of the temporal muscle to join the anterior deep temporal branch of the inferior m.axillary nerve. It perforates the temporal aponeurosis, according to Quain, about one inch above the zygoma, and ends in cutaneous filaments over the temple. The 7nalar division lies first in the loose fat at the lower angle of the orbit, pierces the maxillary portions of the malar bone, and divides into two filaments to anasto- mose with the facial nerve. ' ' [b) The posterior dental nerves arise from the superior maxillary within the pterygo-maxillary fossa. These are arranged in two sets, the superior and the inferior. The superior pass through the base of the malar process, and are distributed to the canine fossa and there anastomose with the anterior dental. The inferior, larger than the preceding, curve below the malar process, and, passing through the posterior dental foramina, supply the molar teeth, outer wall of the maxillary sinus, and filaments to the alveoli and the gum tissues. Some minute branches terminate within the superior maxilla. (Ill) The Inferior Maxillary Division. " The inferior maxillary nerve escapes from the cranium through the oval foramen of the sphenoid bone. It descends vertically, and, 14b DENTAL PATHOLOGY AND PRACTICE. according to Luschka, immediately gives off a recurrent branch. This at once passes through the spinous foramen in company with the middle meningeal artery, and runs backward to the middle cere- bral fossa, and divides into an anterior and a posterior branch. Thfe former enters various openings in the substance of the greater wing of the sphenoid bone ; the latter passes within the petro -squamous suture to the lining membrane of the mastoid cells. " The main trunk of the inferior maxillary nerve divides into two great branches : ( i) an anterior and smaller branch, which is for the most part motor, and (2) a posterior or larger branch, which is in the main sensory. "(i) The anterior root divides into the following branches : (a) the deep temporal^ (b) the masseteric^ {c) the internal pterygoid, (d) the external pterygoid, {e) the inylo-hyoid nerves. "(a) The deep temporal nerves arise a little distance below the oval foramen, commonly by two roots. The anterior root unites with the sensory filaments of the buccinator where the latter nerve runs through or beneath the external pterygoid muscle. The pos- terior root is entirely motor. The nerve passes at first forward, then obliquely upward and outward, and finally vertically upward through the deep part of the temporal muscle. It perforates the temporal fascia about a finger-breadth above the zygomatic arch, and then ascends beneath the skin to anastomose with the auriculo -temporal znd facial nerves. ' ' {b) The masseteric nerve, larger than the preceding, arises acutely from the main nerve by a thick root behind the deep temporal, with which it may have a common stem. It passes backward and outward in contact with the roof of the zygomatic fossa, between it and the external pterygoid muscle. It is then reflected downward over the upper part of the muscle to gain the sigmoid notch, upon which it is again deflected to descend vertically between the ramus and the deep surface of the masseteric muscle. Cruveilhier asserts that filaments of this nerve can be traced in the substance of the deep layer of the muscle to its insertion. The branches of the nerve are, — a small branch of union with the deep temporal, a separate branch to the temporal muscle, mentioned by Sappey as the deep posterior tcmpo?'al, and a branch to the temporo-maxillary articulation. ' ' {c) The internal pterygoid nerve. This, the shortest branch of the inferior maxillary , is interesting from its connection with the palate and ear. It arises from the anterior and internal side of the trunk, on the level with the otic ganglion. It runs constantly between the lingual nerve and the otic ganglion, after passing through the latter structure from before backward to gain the inner side of the internal pterygoid muscle. It sends a motor root to the otic gan- FACIAL NEURALGIA. I49 glion, a twig to the tensor palati muscle, and delicate filaments which traverse the ganglion to go to the tensor tympani muscle. " (a? ) The external pterygoid nerve. As a rule, this branch is con- fined in its distribution to the muscles of the same name, and is often a twig from the preceding branch. Sometimes it arises in common with the buccinator. " {e) The mylo-hyoid nerve. This nerve, generally recognized aS a branch of the inferior dental, has been determined by Luschka and Sapolini to be a motor nerve, and as such traceable to the motor trunk of the inferior maxillary nerve. As its name implies, it is distributed to the mylo-hyoid muscle. It lies within a faint groove on the inner side of the lower jaw, where it is confined by fibrous membrane. Some of its filaments pierce the mylo-hyoid muscle to join the Ihigual. " (y) According to Sapolini, a motor branch of the inferior max- illary nerve passes along the entire length of the inferior dental canal, to be lost in the soft parts about the mental foramen. "(2) The sensory division of the inferior Tnaxillary nerve is divided into the following branches : (a) The auriczdo-temporal, (U) the buccinator, {c) the lingual, and (a?) the inferior dental nerves. ' ' (a) The auriculo-teinporal nerve. This arises by two unequal roots, between which is seen the internal maxillary artery. The roots soon unite to form a flattened trunk, inclined with a convex border outward toward the condyle of the lower jaw. It then winds round the neck of the condyle, and, in the language of Cruveilhier, ascends vertically between the articulation and the external auditory meatus. It becomes subcutaneous and divides into several filaments, which may be traced to the highest point of the temporal fossa. During its course the nerve gives off a very remarkable anastomotic branch, which arises behind the neck of the condyle, and is reflected upon it so as to run forward beneath the facial nerve, with which it is blended opposite the posterior border of the masseter muscle. It may be regarded as tributary to the facial, which becomes notably larger after receiving it. The main nerve gives off some plexiform branches, directed horizontally backward to the temporo-maxillary articulation, as well as to the auditory meatus, which enter between the osseous and cartilaginous portions, and sends a branch to the tympanic membrane. Of the branches, the auriciilar, according to Luschka, pass through the space between the tragus and helix, to the concave surface of the auricle. A filament is directed toward the handle of the malleus. Ouain asserts that a small branch joins the otic ganglion. ' ' The main nerve accompanies the temporal artery, about which it 150 DENTAL PATHOLOGY AND PRACTICE. forms a sort of plexus, and then divides into filaments for the skin, traces of which can be detected as far as the crown of the head. Meckel mentions a branch of communication between this and the occipital. The lower division of the nerve is as large as the ascend- ing portion. It forms a plexiform arrangement of fibers about the internal maxillary artery, behind the condyle, and, according to Cruveilhier, sometimes presents a small ganglion. Its branches go to the parotid gland ; others anastomose with the auricularis magnus nerve, while another extremely fine filament joins the inferior dental nerve. " (b) The buccinator nerve arises from the outer side of the inferior maxillary nerve by from one to three roots, which either perforate the external pterygoid muscle or pass between it and the internal. It rarely perforates the temporal muscle, according to Cruveilhier. The branches of the nerve are then directed downward, between the coronoid process of the mandible and the tuberosity of the superior maxilla, and become superficial midway between the lobe of the ear and the angle of the mouth. Before reaching the cheek, the follow- ing branches are given off : "(i) Two or three muscular branches to the external pterygoid muscle. " (2) Temporal branch {anterior deep^, which penetrates the thick- est portion of the temporal muscle, and ordinarily unites with the temporal branches of the orbifo-temporal nerve. It then pierces the temporal aponeurosis, a little beneath and behind the external frontal process. It here divides into a pencil of filaments, which for the most part terminate in the skin of the temple. Two or three branches anastomose with filaments of the facial. Sometimes a small branch becomes subcutaneous a short distance above the zygo- matic arch. " (3) A descending branch, according to Cruveilhier, supplies the temporal muscle, about its insertion in the coronoid process. " Upon the cheek the biiccinator nerve is divided into an upper and a lower branch. The upper is cutaneous, and goes to the skin of the malar and buccal region. One of them forms an anastomotic arch with t\ve facial behind the parotid duct. The lower branches are in part cutaneous about the oral angle ; others pierce the buccinator muscle, to be distributed to the buccal mucous membrane. Turner has recorded an example in which a separate branch of the inferior maxillary nerve passed to the buccinator muscle, while the branches to the mucous membrane were derived from the superior maxillary nerve. ' ' (<:) The lingual or gustatory. This nerve lies between the ex- ternal pterygoid muscle and the pharynx, to the inner side and in FACIAL NEURALGIA. I5I front of the inferior dental nerve, to which it is united by a slender commissure at its origin. It Hes directly beneath the mucous mem- brane opposite the molar teeth ; passes thence beneath the mucous membrane of the alveolo-lingual groove, at the floor of the mouth, above the submaxillary gland and the mylo-hyoid muscle, and outside of the hyoglossus, beneath the sublingual glands and over the duct of Wharton, which latter structure it crosses at an acute angle. " The lingual nerve is joined by the chorda tympani nerve during the passage of the former between the pterygoid muscles. Although this is at first a mechanical union, the chorda tympani becomes inti- mately associated with the lingual. ' ' The branches of the lingual are as follows : ■ " (i) A communicating branch with the hypoglossal. This remark- able nerve is described by Luschka as running recurrent in the sheath of the hypoglossus nerve. Its branches in part are distributed to the wall of the internal jugular vein, and in part to the sinuses and can- celli of the occipital bones, which are reached by the branches thereto passing through the anterior condyloid foramen. ' ' (2) A small branch to the palato-glossal fold, which passes also to the tonsil. " (3) Sublingual branches to the mucous membrane of the floor of the mouth and gum-tissue. " (4) Lingual branches which pass between the longitudinal fibers and those of the genio-hyoglossus muscle. Those to the border of the tongue are joined at the level of the middle third of the hyo- glossus muscle by a filament derived from the mylo-hyoid muscle. " (5) Below it from its convex surface branches are directed to the submaxillary gland. " According to Sappey, the lingual^ in addition, gives a few plexi- form branches beneath the tongue, and some terminal branches to the mucous membrane about the under surface of the tip of the tongue and the glands of Niihn. " {d) The inferior dental nerve. This nerve is directed downward between the two pterygoid muscles, and afterward between the lower jaw and the internal pterygoid muscle, from which it is separated by a fibrous lamina. It is here in association with the mylo-hyoid nerve, which is generally described as a branch of this nerve. The inferior dental in reality gives off no branches outside the lower jaw, save one which unites with the lingual. "The nerve enters the dental canal by the posterior dental fora- men, and passes along the entire length of the dental canal, giving filaments of supply to the molar and bicuspid teeth. At the anterior (mental) dental foramen the nerve divides into two sets of branches; by far the larger set effects exit through the mental foramen, where 152 DENTAL PATHOLOGY AND PRACTICE. Its branches are arranged in a plexiform fashion into two planes : one anterior, to supply the skin, lip, and inferior part of the cheek ; the other posterior, which crosses between the muscular layer and the glandular layer to terminate in part in the glands and in part in the labial mucous membrane. The other set, confined to a few delicate filaments, continues with the cancelli of the lower jaw, as far as the symphysis, to supply the cuspid and incisor teeth. The Ganglia of the Fifth Pair of Nerves. " The fifth pair of nerves is remarkable for the possession of a number of accessory ganglia. These are in close association with the sympathetic system. Each ganglion possesses, in addition to its nerves of distribution, a motor-sensory and a sympathetic filament. " These ganglia are usually enumerated as follows : "(I) The ophthalmic, or lenticular, pertaining to the ophthalmic division. "(II) The spheno-palatine, pertaining to the superior maxillary division. "(Ill) The otic; and "(IV) The submaxillary ganglia, pertaining to the inferior max- illary division. * ' In addition to these, an inconstant accession of ganglionic mat- ter may be met with on the face beneath the infra-orbital foramen, and within the anterior palatal foramen. These are not described here. (I) The Ophthalmic Ganglion, " The ophthalmic ganglion is small, flattish, lenticular, or more or less quadrangular in shape. It has a diameter of about one line. It is placed between the external rectus muscle and the optic nerve, at about its posterior third, and is generally in contact with the ophthal- mic artery. It lies two or three lines from the optic foramen, sur- rounded by a quantity of loose fat. ' ' The branches of communication of this ganglion are as follows : " (a) Motor branch, from the inferior division of the third cranial nerve, — short and thick. This branch is sometimes duplicated. It joins the ganglion at its posterior inferior angle. "((^) Sensory branch, from the ?iosal nerve, while still retained in the cavernous sinus. It is long and slender, and joins the ganglion at its posterior superior angle. Hyrtl mentions an occasional junc- tion from a filament of the lachrymal nerve. "(f) Sympathetic branch, from the parotid plexus, — and thence, according to Cruveilhier, from the superior cervical ganglion. It may join the sensory filament instead of the ganglion. FACIAL NEURALGIA. 153 ' ' The branches of distribution of the ophthalmic ganghon are the short ciliary nerves. They arise by two distinct bundles, each com- posed of six to eight filaments. Those from the anterior superior angle pass between the optic nerve and the superior straight muscle. Those from the anterior inferior pass between the optic nerve and the inferior straight muscle. They are joined by some filaments of the nasal nerve, and are distributed to the eyeball by piercing the scle- rotic coat and passing forward between it and the choroid coat, as far as the iris, within which they are lost. (II) The Spheno-Palatine Ganglion. ' ' The spheno-palatine ganglion is the largest of the ganglia of the fifth pair. It is situated in the pterygo-maxillary fossa close to the spheno-palatine foramen. It is of a triangular or parallelogram shape. Its posterior extremity is tapering, and composed of gray matter. Its anterior is broader, and contains little or no gray matter. The ganglion is surrounded by fat. Its branches are as follows : ' ' («) The orbital branches. These are delicate, and enter the orbit through the spheno-maxillary fissure, and are lost about the periosteum. Some, according to Arnold and Longet, are distributed to the neurilemma of the optic nerve, Luschka describes among this group, under the name of the spheno-ethmoid branches, two or three filaments which pass through the spheno-maxillary fissure, to ascend to the hinder part of the internal orbital wall, where they pass through the posterior ethmoidal foramen, and enter the brain-case. They reach the sphenoidal sinus, and supply the posterior ethmoidal cells, by passing between the sphenoid and ethmoid bones, Boch describes a branch of the orbital, ascending to join the sixth nerve, "(3) The nasal branches. These pass horizontally inward, and enter the nasal cavity through the spheno-palatine foramen. "They consist of two branches, an upper nasal v4\\\q\x consists of several small nerves which supply the upper and posterior part of the septum, the mucous membrane covering the superior and middle nasal scrolls, and the posterior ethmoidal cells. The larger and more important division of the waj-^/ branches (naso-palatine) crosses the roof of the nasal chamber, and is directed vertically downward, then horizontally forward along the nasal septum, to which, however, it gives no branch, nearly joins its fellow of the opposite side, and emerges from the nasal chamber to be distributed to the anterior portion of the hard palate through the incisorial or anterior palatine foramen. Within this foramen, the nerve of the right side is in advance of the left. "(c) The descending palatal branches. These consist of three 154 DENTAL PATHOLOGY AND PRACTICE. sets : the large anterior palatal, the small posterior palatal, and the small external. ' ' The large anterior palatal descends within the posterior palatal canal, to emerge thence to be distributed to the side of the hard pal- ate in company with the posterior palatine artery ; it lies in a groove of the hard palate, and extends nearly to the incisor teeth. It sup- plies the gums, glands, and mucous membrane, and anastomoses in front with the naso-palatine nerves. While within the canal it sends a small branch to the middle and lower turbinate, and just before leaving it another small branch to the latter ; about the same point with the foregoing, a filament from the hinder part of the trunk passes through a separate canal to the soft palate. The latter branches are described by most authors when well developed under the name of the middle palatine nerves. ' ' The small posterior palatal enters the small posterior palatine canal, and is divided as follows : one set of filaments proceeds to the levator palati and azygos-uvulae muscles, and another sensory set to the mucous membrane on the superior aspect of the soft palate and its glands. According to Sappey, this nerve must be held as a de- scending branch of the great superficial petrosal, which in turn is a member of the facial group of filaments. ' ' The external branches are very small. They pass between the superior maxilla and the external pterygoid muscle, enter a small canal between the superior maxilla and the pterygoid process of the palatal bone, and are thence distributed to the uvula, tonsil, and soft palate. ' ' id) The Vidian or pterygoid branch. This nerve is continuous with the gray matter of the ganglion. It contains gray matter for some distance from its origin ; is finally continuous as a distinct trunk with the inferior or deep petrosal, and is lost in the sympa- thetic net-work about the carotid artery. Sometimes it arises as a distinct branch from the spheno-palatine ganglion. The Vidian is directed directly backward, and, passing through the Vidian canal of the sphenoid bone, pierces the fibro-cartilage occupying the median lacerated foramen, within which the carotid branch is given off, and becomes the great superficial petrosal nerve. This is now directed outward, passes beneath the ganglion of Gasser, from which it is separated by a delicate leaf of the dura mater. It thence passes to the anterior face of the petrous bone, and enters the hiatus Fallopii to reach the yaa'a/ nerve at the intumescentia gangliformis. This, the standard description, it is now believed, should be so modified as to read : that the nerve arises from the facial nerve, passes toward, not into the ganglion, and is continued thence to the palate as the posterior palatal nerve. FACIAL NEURALGIA. 155 "(e) The p/iaryngea/ branches. These are often described as branches of the Vidian. They may, however, rise distinct ; they are placed within the pterygo-palatine canal, whence they appear on the lateral wall of the pharynx, about and behind the orifice of the Eustachian tube. ' ' (/") The superior branches. These are generally two in number, and serve to unite the trunk of the superior maxillary nerve to the trunk of the ganglion. Many of the fibers pass directly through the gray matter of this structure to appear below as the descending ^■ Sedative. Anesthetic. Ether, ^xv. M. J Constitutional Remedies. R — Croton chloral hydrate, oU! Glycerin, ^ ij ; Water, q. s. ^ iv. M. Sig. — A teaspoonful three times a day. R — Quinin sulph., ^ij ; Morph. sulph., gr. iij ; Strychnin sulph., gr. ij ; Arsenious acid, gr. iij ; Ex. aconit., gr. xxx. M. F. — Pills, div. No. LX. One three times a day. CHAPTER XVIII. HYPEROSTOSIS OF ROOTS OF TEETH.* Under the term " hyperostosis" I propose to consider all the forms of pathological new growths of cementum, including what authors are wont to term osteoma, exostosis, hypertrophy of the cement, etc. As to the causes of this not very infrequent disease, the following may be enumerated : * Abbott, Dental Cosmos, 1SS6. lyo DENTAL PATHOLOGY AND PRACTICE. A. Direct irritation of the pericementum through sHght long- standing caries of the crown or neck ; or, exposure of the pulp,, mainly the result of caries. B. Localized irritation of the pericementum of constitutional origin, as from gout or syphilis. C. Irritation of the pericementum of upper teeth after the removal of their antagonizing teeth of the lower jaw, the result of or induced by gravitation. Obviously, irritation of the pericementum is considered by all authors as the cause of outgrowths of cementum. All tumors are considered as the result of a chronic irritation of the mother tissue ; not sufficiently intense to produce symptoms of inflammation, with its typical termination in hypertrophy, or, should suppuration have preceded, in cicatrization. Tumors are unlimited growths, caused probably by a constant local irritation, first of the mother tissue, and later on of the already formed tumor itself Cohnheim proposed the theory that " all tumors are the result of a misplacement of embryonal germs." Unquestionably such a mis- placement may occur, but in many instances it either is not traceable, or the embryonal tissues may be found misplaced in normal tissues without ever having given rise to the formation of a tumor. That a chronic irritation of the pericementum, whatever the cause may be, may result in a new formation of cementum, nobody will doubt ; nay, it has been clearly proven by Bodecker that a circumscribed hyper- ostosis of the cementum may arise from chronic pericementitis. The question, however, is, can a diffiised enlargement of the cementum occur in consequence of pericementitis, either of a local or constitu- tional origin, after the cementum has once been fully formed ? This question I feel constrained to answer in the negative, and I base my opinions upon microscopical studies of such tumors. My conviction is that hyperostosis of cementum of a diffiised character is in most instances a fetal malformation. If a carious tooth be extracted, and the roots be found in a hyper- plastic condition, the first impression, of course, would be that inflammation of the pulp had led to pericementitis, and the latter to hyperostosis of the roots. This in some instances may be the case, more especially when the process of caries has attacked a lateral surface of the crown or the neck of a molar, and the root or roots nearest to the point of irritation of the pulp are found to be enlarged ; but if all the roots of a molar are uniformly enlarged, or fused together, we hardly feel justified in stating that caries was the primary and hyperostosis of the roots the secondary cause, or the result of such a primary cause ; for it is possible that the hyperplasia of the roots has been present long before the caries made its appear- HYPEROSTOSIS OF ROOTS OF TEETH. I71 ance. The latter assumption becomes almost a certainty when, upon grinding such teeth for microscopical research, we find either that the caries has not penetrated sufficiently deep to cause inflammation of the pulp, or that the dentine is in a condition which could not be the result of simple "eburnitis," but can have been the result only of a malformation at the beginning of its growth in fetal life. After a careful study of a large number of specimens of hyperos- tosis, I feel entitled to the statement that such teeth were sound and their pulps alive long after the bony growth had formed. Whenever a tooth is deprived of its nourishment from the pulp, I doubt the possibility of an osseous new formation upon the cementum ; and, further, I believe that should such a new formation have existed previously, its growth would undoubtedly cease the moment the life of the pulp was gone. Should a dentist extract a sound-looking tooth to relieve excessive pericementitis, or neuralgia suspected to arise from pericementitis, and find the root or roots considerably enlarged, he would hardly be justified in concluding that the pericementitis and neuralgia had caused the growth upon the roots ; but, on the contrary, he would naturally conclude that the growth had been the primary and the pericementitis and neuralgia the secondary features of the disease. If a large number of sound-looking teeth be removed from the same person's upper jaw, for instance, to relieve neuralgia, the roots of all of which are found to be considerably enlarged, we con- clude that these roots were malformed at the earliest stage of their development. I have in my possession six upper molars, all removed from the same person's mouth, to relieve neuralgia, the roots of all of which are more or less enlarged ; three of them have no decay what- ever in their crowns, and the other three are but slightly affected. At the time of birth only the crowns of the temporary teeth are found to have been formed, and nothing is known as to the exact period of beginning of the formation of cementum upon the roots ; probably it is during the first year of extra-uterine life, the process beginning upon the permanent teeth several years later. Cementum being identical in its construction with bone-tissue, we are safe in concluding that their development is likewise identical. Bone, the same as any other tissue, originates or is built from med- ullary or embryonic tissue. It makes no difference whether carti- lage is formed first, as in the lower jaw-bone, or fibrous connective tissue, as in the flat skull bones ; the changes in order to produce bone are the same — each is first converted into medullary or embry- onic tissue, from which the bone proper is formed. Some of the older authors (Tomes, Shelly, and others) adhere to the theory that medullary corpuscles (osteal cells) ' ' secrete or accumulate about them an outer investment of basis-substance, and afterward, being 172 DENTAL PATHOLOGY AND PRACTICE. hollowed out, form the lacunae, while the canaliculi are made on the plan of pore-canals of plants." To-day we know that the lacunae contain living protoplasm, the so-called bone-corpuscles, and the canaliculi hold for tenants delicate offshoots of the bone-corpuscles, — i.e., fibers of living matter. To-day we also know that the basis- substance arises from medullary corpuscles, the same as the bone- corpuscles themselves. The theory of secretion of intercellular sub- stance is a theory of the past. All good and reliable observers agree that only one portion of the protoplasm is transformed into basis- substance,— viz, the lifeless liquid, which changes into a solid glue- yielding mass, which forms the matrix and is the seat of infiltration of lime-salts, the living protoplasm remaining unaltered in the bone- corpuscles, and the liviyig portion of their offshoots is preserved in the basis- substance within the canaliculi. No growth of any tissue is possible without its being first partially reduced to medullary ele- ments. An augmentation of the cementum is impossible without a preceding augmentation of the medullary tissue, which again is caused by increased nutrition, or, as it is generally expressed, an irritation. Bodecker has demonstrated that in normal cement the lacunae con- tain protoplasm, a portion of which is living matter, and that the entire basis-substance is traversed by a delicate reticulum, — far more delicate, indeed, than previous observers have thought canaliculi to exist. This reticulum contains the threads of living matter in a cobweb arrangement. Thus, it was proven that the cementum is not an inert mass, a deposition of lime-salts, with hollow lacunae and canaliculi. I propose to show that cementum, in a pathological (hyperplastic) condition, is endowed with properties of life the same as in its normal state. Thus it becomes explicable that hyperplastic cementum itself may become the subject of pathological processes, particularly of inflammation. Hyperplastic cementum may and often does become partially destroyed by cementitis and transformed into medullary tissue, from which, evidently, an additional new growth of cementum may start. It is only the knowledge that cementum is a living tissue all through that enables us to understand the process of its development, its growth, its enlargement, its destruction, and its re-formation. Since the beginning of the present century a good many reliable observers have described and depicted anomalous teeth with hyper- ostosis in varying degrees of development. Some of these illustra- tions are striking examples of the excessive growths to which cemen- tum may attain, and still be tolerated by the sufferer. All observers, and clinicians generally, I think, agree that this disease attacks bi- cuspids and molars only, incisors and cuspids appearing to be exempt ; HYPEROSTOSIS OF ROOTS OF TEETH. 173 and, again, that the teeth of the upper jaw are more frequently affected than those of the lower. Facial neuralgia of the most severe and unyielding character is frequently caused by these malformations. At the same time the symptoms which point to a diagnosis of hyperostosis of the roots are not very marked. When observable at all, however, they consist of a slight continued uneasiness in the jaw (as sometimes expressed by a patient, " I can't call it real pain, but I am constantly aware that I have a tooth in that locality"). It is akin to pain, with slight sore- ness of the tooth or teeth upon biting, while excessive pressure upon it in any direction is productive of quite severe and prolonged pain. Eventually the soreness becomes more marked, — the pain being con- stant or intermittent, — and finally terminates in possibly an abscess, severe mental derangement, or the removal of the tooth as a cure. It is not infrequently the case that a patient suffering from neu- ralgia applies to a dentist to have a certain tooth extracted for relief, the case being to the dentist so obscure that he takes the patient's word for it, and removes the tooth ; but to his disgust the patient, after a few moments, turns to him and says, "Why, doctor, that isn't the tooth ; the pain is just as bad as it was before you took it out. ' ' This operation is repeated over and over again with the same result, until finally, perhaps, the last tooth in the jaw when taken out reveals the cause of this long suffering, in an enlarged root or roots from hyperostosis. A peculiar feature in these cases is the long-continued and most distressing pain that follows such extractions, relief coming but very slowly. As custodian of that portion of the museum of the New York College of Dentistry which pertains to my department, I have come into possession of a large number of teeth exhibiting hyperostosis of the roots, and this comparatively large collection prompts me to try to classify the different varieties as they occur to me. I will here add that about one-third of these teeth are sound or very nearly so. Previous authors have simply described different forms, more or less striking, without observing any system in the arrangement. I. — Circumscribed Hyperostosis. Under this title are included osteoma and exostosis of the authors, which are characterized by an outgrowth of bone-tissue from the cementum, of a limited size, varying from that recognizable with the microscope only to that of a lentil or a pea. Their surfaces usually present a nodular appearance, and sometimes they are adjacent to newly-formed cancellous structure of bone, evidently caused by oste- itis of the socket. I would subdivide this group into : 174 DENTAL PATHOLOGY AND PRACTICE. A. Osteoma on the body of the root (Fig. 65, a, b). B. Osteoma on the apex of the root (Fig. 66, a, b). Either of these appears mostly upon teeth the crowns of which are more or less destroyed by caries, with probably a long-standing exposed pulp, which seems to plainly indicate that their cause is likely to be accounted for in localized pericementitis from this source. If, however, we bear in mind that the destruction of the life of the pulp prevents or stops the formation of osteoma on the roots, we must come to the conclusion that such tumors had commenced their formation long before the exposure of the pulp, or that the pulp must have remained alive for a very long time after its exposure before it died, causing during this long time a slight but constant irritation of this tissue, which was transferred to the pericementum. Fig. 65. Fig. 66. As soon as severe pericementitis sets in from an exposed pulp, unless vigorous steps are taken for its relief, the pulp is in a fair way to become lifeless very soon. After its death severe pericementitis and its distressing terminations are too well known to practitioners to need mentioning here. In neither of the latter instances would we expect a bony outgrowth on the roots. It is only an irritation of the pericementum while the pulp is living that, in my judgment, can result in an increased cementum. In some persons, or conditions of persons, a very superficial decay, more particularly upon the necks of teeth, will produce marked peri- cementitis and neuralgia. We may infer from this fact that in other persons or conditions (or possibly the same), perhaps under the influence of constitutional disturbances, a local irritation of the pericementum is induced, causing exostosis, long before exposure of the pulp had occurred. II. — Diffused Hyperostosis with Roots Separated. (Fig. 67, a, b, c.) Under this heading a large number of specimens of my collection can be included, both of otherwise sound teeth and those decayed HYPEROSTOSIS OF ROOTS OF TEETH. 175 or filled. As I have said before, I will admit that pericementitis from caries is a cause of hyperostosis only when one root or two be in- volved, and others in a normal condition, the enlarged root or roots corresponding to the carious cavity either on the neck or crown of the tooth. When all the roots of molars are affected, without the least symptom of disease upon the exposed portion of the tooth in the mouth, I can see no other correct course but to seek for the cause of the malformation in the beginning of the formation ■of the cementum, to wit, during the first year of extra-uterine life. Hyperostosis of this kind invades the roots from the apex to the middle, to two-thirds their length, sometimes even to their necks. The enlargement either blends with the crown, without a distinct boundary line, or there is a more or less marked bulging of the augmented tissue. The enlarged portion is either in a more or less horizontal line or is fluted, with here and there irregular prolonga- FiG. 68. tions toward the crown. In one instance I have seen a small enamel-nodule corresponding exactly to the summit of a marked conical prolongation of the cementum. Sometimes the bulging of the cementum reaches the crown, and may be distinctly seen over- lapping the enamel. Such formations are usually either smooth or slightly nodulated. Sometimes they are corroded as if by inflamma- tion ; and, again, upon a comparatively smooth mass there may be found bulging forth an irregular nodule of circumscribed osteoma, evidently the result of an excessive formative pericementitis. In one of my specimens, a left upper second molar, there is upon the anterior surface of the buccal root a pit two and a half millime- ters in diameter and one [millimeter in depth, the base of the pit being finely corroded and nodular. On the same surface numerous small nodules are scattered about. On the neck the hyperplastic cementum is one millimeter in thickness, and terminates all around it in a nearly abrupt line. (Fig. 68, a.) On a right upper second molar the palatal root exhibits at its apex a cauliflower-like excrescence, upon a comparatively smooth osteoma, about one millimeter in thickness, occupying the upper 176 DENTAL PATHOLOGY AND PRACTICE. two-thirds of the root. The excrescence sends a delicate conical offshoot to the mass which cements the buccal roots together. The posterior portion of the crown of this tooth has a carious cavity in it the size of a French pea, with the pulp-chamber opened. (Fig. 68, b.) Roots of this kind look very clumsy and shortened, for the reason that at the place of their union the hyperostosis forms a heavier mass, which has more or less filled the space between them ; still they remain separate to a considerable extent. III. — Diffused Hyperostosis with Roots United. This group may be subdivided as follows : A. Apices free and straight. B. Apices free and curved. C. All roots united their entire length. Teeth of group A are characterized by an osseous outgrowth of cementum accumulating at the point of junction of the- roots, — the roots themselves being either slender and free from osteoma or slightly thickened. An upper third molar presenting this anomaly has five roots, three of which are normal at their apices, the fourth being the seat of a diffused hyperostosis encircling it, and the fifth root being rudimentary. All, however, are united into a common mass a short distance from their apices, which mass gradually blends with the enamel. (Fig. 69, a.) Fig. 69. Teeth of group B exhibit a union of the roots with markedly devious but slender apices. A left upper second molar of my collec- tion shows this evidently rare anomaly. The palatal root is slightly devious, with an apex arising from the main mass of the root at a right angle. The buccal root (there is but one) shows two curva- tures, both at right angles. The osteoma is only moderately large, and on the posterior surface, at the point of junction of the roots, there is wedged in a sessile oblong nodule, below which is a shallow furrow, indicating the original point of separation of the two roots. The crown of this tooth is not decayed. (Fig. 69, b.) Teeth of group C are rather common. In third molars or wisdom- teeth, both of the upper and lower jaws, a union of the roots is quite HYPEROSTOSIS OF ROOTS OF TEETH. 177 generally their normal condition. Osteoma, when found upon such roots, is either a clumsy nodular mass without any sign of a pre- vious separation, or slight furrows may be visible indicative of such separation of the roots. (Fig. 69, c.) There is a history connected with a lower left third molar in my collection that I will give in abstract, feeling that it may be of inter- est to some. It exhibits a diffused osteoma, ridged and nodulated, with a bent apex toward the ramus. It was extracted from the mouth of a lady some -years since by my friend. Dr. S. A. Main, of this city, who kindly presented it to me with the following history : For some ten years this lady had suffered most excruciatingly from facial neuralgia. She consulted the best medical talent at home without obtaining the slightest relief Finally, some three years before the tooth was removed, she went to London, where it was determined by the surgeon who was called to attend her that, in order to afford any relief, it would be necessary to sever the facial nerve upon the side which seemed the most affected, which was done, — with, how- ever, only temporary relief With the hope that the slight cessation of pain would be speedily followed by permanent cure, she went to Paris, anticipating the pleasure of a comfortable tour of the Continent, but in a few days the pain again returned with renewed energy. She then consulted a surgeon, who decided that the only chance for permanent relief was to have the facial nerve divided upon the other side of the face. The operation was done with no better results than from the first. Finally she concluded to return to her home in New York, there to spend the few days (as she supposed) which she had to live as comfortably as possible. Shortly after arriving at her home she consulted her dentist (whom, by the way, she had never thought to consult before in reference to her neuralgia), and as.ked him to look at this tooth, saying at the same time that it often felt quite sore to the touch. (Its antagonist had been taken out many years before.) After examination, she was ad- vised to have it taken out, which was done. Immediately upon its removal the lady realized that the cause of her long-continued, fear- fully distressing, and very expensive neuralgia had been found at last, which proved to be true. She then told Dr. Main that that tooth had cost her ten thousand dollars. IV. — Union of Two Teeth through Hyperostosis. Of this rare occurrence of the osseous union of teeth I have eight or ten fine specimens. The subdivision suggesting itself is as follows : A. Union of the roots at their apices (Fig. 70, a, b). B. Union of the roots at their middle (Fig. 71, a, b). C. Complete union of the roots (Fig. 71, c). 13 178 DENTAL PATHOLOGY AND PRACTICE. The first group is characterized by a union of devious roots of neighboring teeth. As both of my specimens show a partial carious destruction of their crowns, the idea may suggest itself that, owing to a destruction of the intervening alveolar wall, and owing to gravi- tation, the roots became attached to each other through an inflamma- tory process. At the same time serious objections may be raised against such a view. The main objection is that an inflammation of the pericementum sufliciently intense to destroy the alveolus would be very liable to destroy the pericementum itself, to such a degree as to render the secondary new formation of cementum necessary for agglutination of the neighboring roots quite impossible. Should we assume that the septum was originally absent, the only way of explaining such formations is to assume that at least one of the germs of the coalesced teeth was malposed at the time of the embryonic arrangement. In this view, it will be observed, the alveolar septum did not form at all, and at the time of development of the roots the mutual pressure was sufficient to cause irritation leading to a new formation. I conclude, therefore, that the carious destruction of the crowns was merely a coincidence rather than a cause. (Fig. 70, a.) The roots of one tooth are mere stumps left after carious destruction of the crown and a portion of the roots. Here the hyperplastic cementum of the stumps is jagged and nodular, plainly indicating that the already formed outgrowth of cementum has been destroyed by cementitis in a secondary manner. (Fig. 70, d.) Fig. 70. Fig. 71. Group B shows a concretion of neighboring roots of molars at the middle upon one side, and at the apices upon the other. (Fig. 71, a.) One of the crowns is slightly affected by caries, — by no means, how- ever, to such a degree as to account for agglutination of the two teeth, the enlarged cementum of which is mainly smooth. Fig. Ji, 6, rep- resents two molars grown together nearly the entire length of their roots ; both teeth being otherwise sound. One of them shows at its neck an " enamel-drop," which feature I consider a further proof of the embryonal malformation of such teeth. Some exostoses from HYPEROSTOSIS OF ROOTS OF TEETH. 179 the sockets are attached to the roots, which in my judgment proves merely a secondary hyperplastic pericementitis. Group C is represented by, but one specimen, — an upper cuspid united with a neighboring lateral incisor. This seems to be a case which may be considered an exception to the rule, — viz, that only bicuspids and molars are thus affected. In this case the union is perfect the entire length of the roots, and only shallow furrows on the outer and inner surfaces, reaching nearly to a common apex, in- dicate the previous separation. The apex presents but one large common foramen. At the necks of both teeth there is shallow ca- rious destruction, — not, however, exposing the pulp-chambers. All these features furnish us proof of a fetal malformation. Fig. 72 Longitudinal Section of Hyperplastic Cementum slightly bulging toward the Neck of the Tooth (Upper Bicuspid). D, dentine ; N, neck ; P, pericementum ; O, globular or osteo-dentine ; G, granular layer ; H, hyperplastic cementum irregularly lamellated, with irregularly distributed cement-cor- puscles; il/, medullary canal. Magnified 150 diameters. For the purpose of examining this disease microscopically, I have ground quite a large number of specimens from teeth which were placed in dilute alcohol immediately after their extraction, in order to keep them constantly wet, and to preserve their soft parts. During the process of grinding they were also kept under water. All the specimens showed a number of features in common which are represented with a comparatively low power in Fig. 72. Those which I wish to call attention to are as follows : The dentine in some specimens, perhaps in several localities in the l8o DENTAL PATHOLOGY AND PRACTICE. same specimen, was found in a normal condition ; and in others it exhibited the so-called interglobular spaces, varying greatly in size and number, indicative of an incomplete calcification. In some specimens the dentinal canaliculi of the roots were arranged in bundles, between which were found areas scantily provided with or altogether destitute of canaliculi. In these areas, are often seen small interglobular spaces, sometimes in direct union with a few canaliculi. The interzonal layer between dentine and cementum invariably exhibited formations known under the name of osteo-dentine, or globular dentine, either as the result of " eburnitis" or of incomplete calcification. It is a condition kindred to the interglobular spaces of Czermak. Such formations, as a rule, extend into the neck of a tooth, — where, however, they are more scanty than on the roots. A striking feature is their entire absence at the point of junction of the roots. Here the cementum is found in contact with an irregular formation of dentine (vaso-dentine), which will be described farther on. Wedl seems to have been the first to illustrate this formation, — without, however, making an allusion to it in his text. Next to the layer of osteo-dentine a layer is invariably found which, under lower powers of the microscope, looks coarsely granu- lar, and which in consequence I propose to call the granular layer. It is destitute of cement- corpuscles, and as a rule is the only layer of cementum of the neck of the tooth, whenever this gradually slopes from the hyperplastic cementum to the enamel. Next follows the enlarged cementum itself, usually characterized by a large num- ber of irregular lamellae more or less concentric to the axis of the root. Some areas may be found destitute of lamellae ; others very abundantly supplied "wdth them. At the border of the cementum toward the crown, where the former is often found bulging to a consid- erable extent, the lamellae are found parallel with the outer periphery of the cementum, inosculating with the granular layer at obtuse angles. In the lamellated basis-substance are found scattered cement-cor- puscles. The most striking features of these corpuscles are as follows : First, they are far more irregularly distributed in the basis-sub- stance than in normal cementum. In some portions of the hyper- plastic cementum such corpuscles are comparatively few, whether the lamellae be plainly marked or not ; in other portions they are arranged in groups or clusters without apparently any regularity. Second, the cement-corpuscles, as a rule, are smallest near the gran- ular layer, and largest toward the periphery ; at the latter portion their offshoots are much wider and more irregular, often piercing the" lamellae at right angles. No constant relation between lamellae and cement- corpuscles is to be found. Third, the cement-corpuscles are to be seen occasionally in large numbers clustered together in longi- HYPEROSTOSIS OF ROOTS OF TEETH. I8l tudinal groups. This is probably caused by the previous presence of medullary canals, the tissue of which, at a comparatively late period, has given rise to a large number of cement-corpuscles, with a comparatively small quantity of basis-substance between them. The hyperplastic cementum is often traversed by medullary canals carrying central blood-vessels. These are most numerous at or near the point of junction of the roots, where, as first described by Tomes, even normal cementum may sometimes contain medullary canals. The vessels of these medullary canals, also first described by Tomes, with whom I am pleased to agree, are in direct connection and an- astomose with the blood-vessels of the pericementum. In one of my specimens the cementum of the neck exhibits peculiar features. Fig. 73- S v.: ••■--'; AT- Hyperplastic Cementum of the Neck of a Molar. Longitudinal Section. N, zone of coarsely-granulated cementum, traversed by bundles of coarse canaliculi ; G, granular zone, destitute of canaliculi ; O, zone of globular dentine ; D, dentine with canaliculi stopping short of the cementum. Magnified 500 diameters. Instead of the coarsely-granular layer usually present, and previously alluded to, there is a zone traversed at nearly right angles by bun- dles of canaliculi, very broad and having no connection whatever with cement-corpuscles. Above this zone is the ordinary granular zone, bordered toward the dentine by a thin layer of globular dentine ; next is the finely-granular layer of the dentine itself, with very few or no canaliculi, and at last we come to the canaliculated dentine of normal development. (Fig. 73.) l82 DENTAL PATHOLOGY AND PRACTICE. High amplifications plainly reveal the structure of the interzonal layer between dentine and hyperplastic cementum. The dentine often shows interglobular spaces, which as a rule are filled with granular protoplasm, and serve as the termination of some dentinal Fig. 74. Interzonal Layer between Dentine and Hyperplastic Cementum of a Molar. Longitudinal Section. D, dentine with small interglobular spaces ; O, osteo-dentine, above which, in the granular layer G, there is a large irregular interglobular space ; C, C, cement-corpuscles with long par- allel ofishoots. Magnified 600 diameters. canaliculi ; especially for their tenants, their fibers of living matter. The interglobular spaces nearest to the cementum sometimes inoscu- late directly with the interstices between the globular masses of calci- fied basis-substance, constituting the tissue termed osteo-dentine or globular dentine. The globules themselves vary greatly in size. They usually, however, correspond with the bulk of one or of a lim- HYPEROSTOSIS OF ROOTS OF TEETH. 183 ited number of medullary corpuscles present before their transforma- tion into basis-substance. The interstices between the globules also vary in size, and send offshoots into the larger globules, subdividing them into incomplete smaller ones. All of them contain granular protoplasm. In the granular zone next to the layer of osteo-den- tine we sometimes meet with very large and irregular interglobular spaces, apparently having no direct connection with the offshoots of cement- corpuscles. In several specimens I have seen arising from the cement- corpuscles very long and slightly wavy offshoots, which, owing to their parallel course, bear a close resemblance to dentinal canaliculi. Formations of this kind occur only In those layers of hyperplastic cementum nearest to the dentine, and always lose them- selves in the granular layer above the osteo-dentine without directly communicatmg with the dentinal canaliculi proper. (Fig. 74.) The medullary canals traversing the enlarged cementum either contain me- dullary corpuscles and capillary blood-vessels, or they are filled with highly-refracting granules and globules of lime-salts, as described by Wedl. Should their canals become obliterated, they give rise to groups of cement-corpuscles within a scantily calcified basis-substance. At the point of junction of the enlarged roots I have met with a peculiar formation of dentine in several of my specimens, which, owing to the presence of a large number of vascular canals, I propose to term vaso-dentine. To the naked eye, in the prepared speci- men, is presented a high degree of transparency, which at once dis- tinguishes it from the neighboring opaque portions of normal den- tine and from cementum. Low powers of the microscope reveal in this dentine a varying number of medullary canals, in either a par- allel or plexiform arrangement. The canaliculi contain medullary tissue and capillary blood-vessels, one or two in each canal. Some- times glistening granules of lime-salts are found, more especially in dilated portions of the canals. Offshoots of such canals may inoscu- late with very narrow canals containing granular protoplasm only. The surrounding basis-substance is scantily supplied with extremely fine canaliculi, running, without any apparent regularity, either in fan- shaped groups or parallel with the medullary canals, or in the shape of a fountain, encircling the canals with the most beautiful and striking figures. Some portions of the basis-substance may look granular and devoid of canaliculi ; others (and these form a vast majority) are apparently homogeneous, and scantily supplied with extremely minute canaliculi. The cementum is directly on the border of the vaso-dentine, without any intervening layer of granular dentine, and the cement-corpuscles nearest to the dentine are in direct connection with the dentinal canaliculi themselves. (Fig. 75.) Higher powers of the microscope brought to bear upon the vaso-dentine plainly DENTAL PATHOLOGY AND PRACTICE. show the medullary contents of the medullary canals, in which may also be seen one or two capillary blood-vessels. Both the canals and blood-vessels produce loops, as indicated by their abrupt termina- tions in vertical sections, and are unquestionably in communication with the blood-vessels of the pericementum (Tomes). A peculiar feature of the vaso-dentine is that portions freely supplied with vas- cular canals contain a considerably larger number of dentinal cana- liculi than those devoid of vascular canals. Fig. 75. LV-D Vaso-Dentine from the Junction of the Enlarged Roots of an Upper Molar. Longitudinal Section. Z>, primary dentine; F'-Z', vaso-dentine traversed by medullary canals in a plexiform ar- rangement. The canals contain either blood-vessels or glistening depositions of lime-salts. B, basis-substance of dentine scantily provided with extremely delicate canaliculi ; in some places fan- and fountain-shaped figures of dentinal canaliculi are discernible ; C, hy- perplastic cementum, lamellated, and containing a medullary canal. Magnified 50 diameters. The canaliculi in the neighborhood of the vascular canals are very irregular in their course, as before stated, and often loop-shaped, starting from and inosculating with the same vascular canal. Again, we find them starting from club, pear, spindle, and irregular-shaped spaces, containing medullary corpuscles, or granular protoplasm, but no blood-vessels (Fig. 76). As an additional feature of hyperostosis of the roots, I would mention that in all my specimens the pulp- chamber and often the canals appear considerably narrowed by heavy formations of secondary dentine. Besides, the pulp-tissue was found to contain the formations of secondary dentine known as pulp-stones, or was crowded with globular calcareous depositions hav- ing no distinct structure. In the majority of the teeth the enamel also HYPEROSTOSIS OF ROOTS OF TEETH. 185 was imperfectly formed, generally presenting a highly pigmented and imperfectly- calcified appearance, with the enamel-rods very irregular and curly. Fig. 76. m_v-D ^B-JD Vaso-Dentine from the Point of Junction of the Enlarged Root of an Upper Bicuspid. Longitudinal Section. V-Z>, a portion of vaso-deiitine with three parallel vascular canals, and very irregular, often looped, canaliculi, some starting from the vascular canals and others from smaller medullary spaces. B-D, dentine of great transparency, with scanty canaliculi. The boundary line be- tween the two portions is abrupt, with numerous bay-like excavations. Magnified 500 diame- ters. A Striking feature in all microscopical specimens of hyperplastic cementum is the great number and large size of the offshoots of the cement-corpuscles, the formerly so-called canaliculi. The reason for this seems to be that both the corpuscles (lacunae) and their i86 -DENTAL PATHOLOGY AND PRACTICE, coarser ofifshoots (canaliculi) are filled with air, or with dirt from the grinding, which causes them to look black. If, however, we place a carefully but not completely decalcified portion of this tissue, mounted in glycerin, under a very high power, we are struck with its beautiful and graceful appearance. It is identical in structure with normal cementum. The basis-substance forms cavities which contain nu- cleated protoplasmic bodies, the cement-corpuscles proper, having a markedly reticulated structure. Between the periphery of the cement-corpuscles and that of the lacunae there is a narrow light rim, obviously corresponding to a space which serves for the circulation of the nutritive fluids. The lacunae at its periphery are interrupted by numerous offshoots, more irregular Fig. 77. Hyperplastic Cementum of an Upper Molar. Cross Section. Magnified 1500 diameters. and wider than those of normal cementum. These canaliculi form an extremely delicate reticulum throughout the basis-substance, interconnecting the neighboring lacunae (indeed, all lacunae) of the cementum. Starting from the periphery of the cement-corpuscles, conical ofif- shoots run into the canaliculi ; the broader, of course, the wider the canaliculus. The coarsest ofifshoots still exhibit a reticular structure ; whereas the finest are merely beaded threads occupying the middle of the canaliculi. Thus it will be seen that all canaliculi hold filaments of living matter in a cobweb-like arrangement, and thus it becomes plain that hyperplastic as well as normal cementum is a living tissue throughout. The reticular structure of the living matter in the CONDITIONS UNFAVORABLE TO DENTAL OPERATIONS. 1 87 corpuscle itself is plainly visible. The inert basis-substance, which is infiltrated with lime-salts, is located in the meshes of the reticulum of the canaliculi, and between the basis-substance and filaments of living matter a slow circulation is going on, the liquid carrying nourishment and taking away the effete material. (Fig. 77.) Thus it is that pathological changes of a pathological tissue become intelligible, and cementitis of hyperplastic cementum, as described and illustrated by Wedl, under the term "perforating resorption," is understood. I have already described this condition macroscopically. Under the microscope it is characterized by the presence of cavities filled with medullary corpuscles, or multinuclear protoplasmic masses, and bounded toward the unchanged cementum with numerous bay-like excavations. The destruction may involve superficial portions of the tumor only, or the entire mass down to the dentine. As there is little tendency to suppurative pericementitis, the termination of the inflammatory process undoubtedly results often in a re- formation of cementum, the same as takes place during the process of absorp- tion of the roots of temporary teeth. Under these circumstances the bay-like excavations are refilled with bone-tissue, and the bays are recognizable by sharply-defined lines corresponding to the ter- ritories of the cement-corpuscles. Some of my specimens exhibit bay-like excavations separating the cementum from the dentine, and the bays filled with bone-tissue crowded with cement-corpuscles. In other specimens certain portions of the hyperplastic cementum show distinct circular, semicircular, or crescentic lines corresponding to the territory of one or more cement-corpuscles. CHAPTER XIX. CONDITIONS OF PATIENTS DURING WHICH SEVERE DENTAL OPERA- TIONS SHOULD BE AVOIDED. It is a well-understood fact among general practitioners, surgeons particularly, that in some conditions of the system the periosteum is more susceptible to slight irritation than in others. These conditions are anemia, as found in scrofula, and general debility from overwork, either mental or physical ; during gestation and lactation, and during active constitutional syphilis. All such cases appeal to the gentlest care of the practitioner of dental surgery, as he can do very little without, in a measure, disturb- ing this delicate covering of the bones (alveoli) and of the roots of the teeth. 1 88 DENTAL PATHOLOGY AND PRACTICE. The filling of teeth with gold for patients during the existence of any of the above debilitated and debilitating conditions should be carefully avoided ; teeth should never be extracted if it is possible to keep them comfortably in the mouth. In short, no operation that will produce severe irritation of this membrane should be undertaken while such condition continues. During gestation there is generally a greater tendency to caries of the teeth than at any other period of adult life. This is probably due to the fact that slight irritation of the system is usually present, which causes more rapid fermentation of particles of food around and between the teeth than is usually the case, consequently a more acid condition of the fluids of the mouth. It has been suggested that for the building up of the osseous structure of the fetus during gestation lime-salts are withdrawn from the bones and teeth of the mother, thus rendering the teeth more frail, and liable to more rapid destruction by caries. This, I am convinced, is, generally speaking, a false theory. The teeth, however, like all other organs of the human body, require nourishment ; and if, during this period, the mother suffers from daily and almost constant nausea, so much so that suffi- cient nourishment cannot be retained for herself and the building up of the fetus, then it may be possible that the deficiency in osseous material is drawn from that of the mother. Under such circum- stances the ' ' morning sickness' ' may be, and is, controlled in a great measure by the use of ingluvin given in ten to twenty grain doses three or four times a day ; the following also are said to be effica- cious in relieving this distressing condition : R — Oxylate of cerium, gr. j ; Subnitrate of bismuth, gr. v. Sig — Three times a day. R — Fl. ex. valerian, ^j ; Fowler's sol. arsenic, ""Kxvj ; Bicarbonate of soda, 5J. Sig. — A teaspoonful every two or three hours. Should these fail to relieve the patient, then syrup of lacto- phosphate of lime should be given, in tablespoonful doses, in half a glass of water, three times a day, half an hour before eating, every alternate week, to not only provide the necessary amount of lime- salts for the proper sustenance of the equilibrium of the mother's osseous structure, but to furnish that which the fetus may need ; but in cases where the usual nourishment is taken and retained by the mother, the phosphate of lime is not indicated. During lactation also the drain upon the mother is often very severe, reducing the system to a condition of anemia quite sufficient to permit CONDITIONS UNFAVORABLE TO DENTAL OPERATIONS. 1 89 it to be seriously affected by any undue local injury. Consequently, in teeth requiring filling either cement or gutta-percha should be used until a more robust conciition of health has been secured. Duringthecontinuanceof these two conditions (gestation and lacta- tion) the teeth of mothers, as before stated, are subject to excessive caries, and are generally extremely sensitive ; so much so that severe neuralgia often supervenes. To relieve this, a solution of bicarbonate of soda C^iss to water 3viij) should be used to rinse the mouth with several times during the day (a teaspoonful of the solution may be swallowed each time it is used), and an antiseptic tooth-powder should be used morning and night. By this means the neuralgia is con- trolled, and the teeth in a short time placed in a condition to admit of their being partially cleansed, and filled as before indicated. Active constitutional syphilis is diagnosticated by the usual eruption upon the face, neck, and chest, and the mucous patches upon the lips, inside of the cheeks, or upon the tongue. When these symptoms are present, the general practitioner should be consulted at once, before any dental work is undertaken. If, however, for any reason slight local treatment is at once necessary, great care must be taken to prevent inoculating one's self or any subsequent patient. In the first place, the operator should carefully examine his hands to see if any abrasion of the skin is to be found. Should such be the case, flexible collodion should be applied as a protection to the parts, and after the operation all instruments should be thoroughly disinfected. This should include not only the steel instruments, but the mouth-mirror (usually neglected), and the glass from which the patient may have taken water. The napkins used should be burned. If no physician be at hand or easy of consultation, one may prescribe the classical remedy — bichlorid of mercury, one-sixteenth grain, three times a day. This should be given until the eruption and mucous patches have disappeared. Even then severe dental opera- tions should not be performed, but any carious teeth should be filled temporarily, as in the other cases. The effect of mercury upon the periosteum, especially of the mouth, is such as to render it susceptible to the slightest undue irri- tation ; consequently, while a patient is under mercurial treatment, great care should be exercised in any work done upon the teeth. Should any periosteal disturbance follow this mild treatment, or present at any subsequent time, in the mouth of such patient, iodid of potassium should be given, beginning with ten-grain doses thrice daily, increasing the dose one grain daily, until the progress of the disease locally has been checked. The differential diagnosis between mucous patches and canker sores — water cancer — is of great impor- I go DENTAL PATHOLOGY AND PRACTICE. tance. In mucous patches, an indurated base and raised edges are always present, with a color slightly darker than the membrane around them ; while in canker sores these conditions are absent, and instead the base is soft, slightly lighter in color than the surrounding membrane, and the edges are even with it. The presence of canker sores in the mouth indicates either a con- dition of the system below that which would be considered as good health, due perhaps to indigestion or functional disorder of some other organ or organs, or that a local injury from the tooth-brush or some artificial appliance worn in the mouth has been received. In anemia as generally presenting in scrofulous conditions or in patients suffering from malarial poison, it is not safe to perform long and tedious operations upon the teeth. Undue irritation of the periosteum in such cases is not readily relieved, but continues until perhaps the death of the pulp. An abscess and necrosis of the alveolus follow. These are cases, again, where the general prac- titioner should be consulted and proper restoratives given. In case no physician be at hand or can be consulted readily, Scrofulous patients should be advised to take cod-liver oil in tablespoonful doses three times a day after eating, to which may be added five drops of the syrup of iodid of iron, which may be increased, after a few days, to ten drops, if the patient be an adult. In persons suffering from malarial poisoning, quinin and iron are indicated. The quinin may be given either in liquid form or in cap- sules. The latter mode is preferable, as the liquid preparation is usually so strongly acid that injury to the teeth is to be feared. From two to four grains, three times a day, should be given. There are several excellent preparations of iron, any one of which is of undoubted value in these anemic cases, such as tincture of the chlorid of iron, ammonio-citrate of iron, dialyzed iron, syrup of iodid of iron, etc. For its rapid restorative properties the tincture of the chlorid is often preferred ; it has its disadvantages, however. As its name indicates, it is strongly acid, and frequently does great harm to the dental organs. For this reason, some one of the other preparations is used, unless the case is an urgent one In such event, and when quinin is given in liquid form, the mouth should be most thoroughly washed out at intervals of not more than one hour during the day with the solution of bicarbonate of soda, above recommended, and the teeth thoroughly cleansed with an alkaline tooth-powder twice a day. All teeth with carious cavities should be treated locally with the soda until they can be partially prepared for filling, and temporary fillings placed in them until the general health of the patient will admit of more permanent work. STOMATITIS ; VARIETIES, CAUSES, AND TREATMENT. IQI CHAPTER XX. STOMATITIS ; VARIETIES, CAUSES, AND TREATMENT. Inflammation of the mucous membrane of the oral cavity is a common and, in some instances, a very distressing disease. During infancy the mouth is subject to a variety of inflammatory conditions which are seldom seen by dental surgeons, but the effects of which are often, in after-years, brought to his notice in the form of imper- fect enamel of the teeth, a study of which will be found in Chapters V and VI. Those varieties which come under the care of the dental surgeon are, mercurial, spontaneous, and aphthous stomatitis, ulitis, and gin- givitis. Mercurial stomatitis is the result of ptyalism (salivation). Mer- cury, when taken in large doses or oft-repeated small doses, mani- fests its presence in the system by a persistent, severe irritation of the salivary glands, causing them to secrete saliva to an extraordinary extent, producing a coppery taste, swelling and sponginess of the gums, and, unless checked, involving the entire mucous membrane of the mouth, including the tongue. Such cases are much more severe and promise less from treatment, so far as the teeth are con- cerned, if they have previously been neglected and tartar has been allowed to collect upon them. The treatment consists in thoroughly removing all foreign accumu- lations from the teeth, repeating the operation every two or three days until a decided change for the better is manifest. In the mean time the mouth should be rinsed every half-hour with a solution of soda bicarbonate, one drachm to eight ounces of water, to which may be added, with advantage, three grains of salicylic acid. The soda neu- tralizes the acid condition always present, and the salicylic acid checks fermentation. The necks and roots of the teeth which have become denuded are thus prevented from becoming so very sensitive, as they are apt to do in such conditions. Milk of magnesia with equal parts of water may be substituted for the soda bicarbonate. lodin will produce salivation in some persons, although of a less severe type than that resulting from mercury. Spontaneous stomatitis is a condition of inflammation of the mouth which has apparently no local irritating cause. It is characterized by a thickened, puffy feeling of the mucous membrane, which becomes in a few hours very sensitive to the touch, even of food, in eating, with a constant smarting pain. This occurs upon one side of 192 DENTAL PATHOLOGY AND PRACTICE. the roof of the mouth, then sometimes upon the other, or upon both sides at the same time, the lower jaw being seldom attacked. This is undoubtedly the local manifestation of some constitutional disturbance induced by a slight injury to the mouth, with tooth-pick, tooth-brush, hot drinks, or by biting upon some hard substance against the gum. The treatment consists in thorough cleansing of the mouth and teeth, and painting the inflamed parts with tincture of iodin, or spraying them with the following : R — Tannic acid, Carbolic acid, Tr. iodin, aa 5 ss ; Glycerin, Distilled water, aa .^ ss. M. This treatment may be repeated every day until relief is obtained. Aphthous stomatitis (canker sores) is characterized by the appear- ance of ulcerated patches, sometimes of the size of a mustard-seed and thence to the size of a silver five-cent piece. They are first noticed as slight translucent elevations upon the gums, tongue, and the inside of the lips and cheeks, and are filled with a watery liquid. After a few hours, these vesicles open either spontaneously or are broken by mastication, etc., when it is discovered that penetrating to the submucous tissue is an ulceration, which has been effected by the contents of the vesicle before it was opened. These aphthous ulcers are, until they begin to mend, usually very painful, the pain being of the smarting variety. As to the etiology of canker sores, it seems that it is not well under- stood by the profession, the only cause assigned being general debil- ity or a low physical condition, due to indigestion, etc. There is no doubt that this is a great factor in their production, but I have long believed that some local disturbance, such as injury of the parts with the tooth-brush or by some other means, has much to do with pro- ducing them. In fact, I have known many cases where an injury with the tooth-brush or some artificial appliance has caused them, where none of the constitutional troubles, usually given as their cause, were present. The treatment consists in washing them with warm water, drying the surface as well as practicable, and with a pellet of cotton, satu- rated with a solution of ten grains of permanganate of potash to one ounce of water, thoroughly impressing the ulcerated surface with the drug, by holding the pellet upon it for half a minute or more. Two or three applications are usually sufficient to effect a cure. Nitrate of silver (lunar caustic) is a very good remedy, as is also burnt CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. I93 alum. Pure carbolic acid arid wood creasote are recommended by some practitioners as efficacious in the treatment of these ulcers. Ulitis is a circumscribed inflammation of the gums, caused by the presence of foreign substances (tartar) upon the necks and roots of teeth. Gingivitis is an inflammation of the gingival margins of the gums, due to the same causes as ulitis. The treatment in each consists in thoroughly removing all foreign accumulations from the teeth and keeping them clean. Where excessive inflammation is present, the parts may be painted with tincture of iodin to advantage. Everything, however, depends upon cleanliness of the teeth. If the gums become lacerated in removing the tartar, spraying them with the recipe above given will be found beneficial. CHAPTER XXI. CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS.* Modern histologists agree that the animal body is composed of only four varieties of tissues, — viz, connective, muscle, nerve, and epithelial. All attempts at basing a nomenclature of tumors on strictly anatomical or histological grounds must be in agreement with this division of the normal tissues. In fact, there is not a single morbid growth to be found which does not have an analogue in some physiological tissue. Among the four varieties, it is only the connective that carries blood- and lymph-vessels. Muscle-fibers and epithelia are destitute of vessels, being supplied with nourish- ment by the surrounding and subjacent layers of connective tissue, or rather the vessels contained therein. The nerve-fibers are surrounded by vascularized connective tissue, while the gray substance of the nerve-centers is considerably mixed with it, although a satisfactory distinction between the gray sub- stance and this tissue — the so-called neuroglia — has never been made. The normal connective tissue in its perfect development appears in four varieties, — viz, the myxomatous, the fibrous, the cartilaginous, and the osseous. In accord with this subdivision, we find a number of varieties of tumors which are composed entirely of a myxoma- tous, fibrous, cartilaginous, or bony tissue, being termed myxoma, fibroma, chondrorna, and osteoma. These are the representatives of *Heitzmann and Abbott, Dental Cosmos, 1888 14 194 DENTAL PATHOLOGY AND PRACTICE. a type of tumors known clinically as benign, since they grow very slowly, do not cause pain, do not ulcerate except after local injuries, and do not produce secondary tumors in internal organs, and even after many years' growth never cause death directly. Fat-tissue is a sub-variety of myxomatous, and tumors largely composed of such tissue are termed lipoma. If blood- or lymph- vessels are abundant in a tumor, it is called vascular, or an angioma. If muscles enter the structure of the tumor we speak of it as a myoma, and if nerve-fibers are present in great numbers the designation is neuroma. In all these instances more or less fibrous connective tissue (the carrier of blood-vessels) enters into the architecture of the tumor, and even in certain varieties of angioma, the so-called cavernous — the fibrous connective tissue bounding the caverns filled with venous blood — carry, as a rule, capillary blood-vessels. According to the prevailing structure present, we designate a given tumor ; as a myo- fibroma if the muscle-tissue predominates, or fibro-myoma if the fibrous connective tissue is in excess over the muscle-tissue. Here again we have four typical varieties of tumors, which we call benign from a clinical point of view. The unripe or embryonal condition of all forms of connective tissue is termed indifferent or medullary. Tumors that are built up of .such tissue belong, as Virchow showed many years ago, to the group of connective-tissue tumors, for which he proposed the term sarcoma. These grow rapidly, causing more or less pain and sometimes ulcera- tion, besides being very prone to excite the formation of secondary tumors in internal organs, thus directly leading to the death of the patient. Clinically they are known as malignant tumors. Since the term would indicate a fleshy tumor, we propose to abandon the name sarcoma and substitute for it the word myeloma, which really desig- nates what the tumor is composed of, viz, medullary tissue. It is impossible to tell why a myeloma should possess properties which enable it to transform all sorts of tissues and organs into its own peculiar structure. Neither do we understand the reason why mye- loma appears mainly in children and young persons, in contradis- tinction to carcinoma, which is, in the great majority of cases, a disease of advanced life. The main constituents of myeloma are globular or spindle-shaped corpuscles, with very little intervening basis-substance. This feature furnishes the most important point for a differential diagnosis between the benign and malignant forms of tumors of the connective-tissue series. There are, however, transitional forms in which portions of the new growth are well supplied with basis-sub- stance of any of the four types named above, while other portions are composed mainly of medullary tissue. It also occurs that we find CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. I95 nests of medullary corpuscles in the middle of a benign tumor, usually in the neighborhood of the sources of nutrition, — i.e., around the blood-vessels. In accordance with the foregoing nomenclature, tumors of such a mixed character are designated as myxo-myeloma, fibro-myeloma, chondro-myeloma, and osteo-myeloma. Combinations like these always mean a tumor which grows rapidly, is prone to recur after operations not skillfully performed, and gradually to assume the characteristic features of purely malignant myeloma. In such cases attempts at eradication, such as cauterization, or injuries of any nature, hasten the transformation of a slightly malignant growth into one markedly so. The fourth group of tissues, the epithelial, never produces a tumor alone, since it is invariably combined with more or less vascularized connective tissue. If the latter produces papillary elevations, covered on the outer surface with stratified epithelium, we term it a warty growth, or papilloma. If the epithelium produces acinous or tubular prolongations into the depth of the connective tissue, we have a glandular tumor, or adenoma. Both of these types are clinically benign ; whereas the third type, in which epithelial and connective tissue are intermixed without any regularity, is designated cancer, or carcinoma, being decidedly malignant. Again we are unable to say wherein rests this pronounced capacity of carcinoma to infect all sorts of neighboring tissues, more especially the adjacent lymph- ganglia, and to transform normal tissues into its own substance. A few years since, Scheiirlen, of Wiirtemberg, Germany, demon- strated the presence of bacilli of a characteristic form and growth, which he claims to be the elements which cause cancer. Schill, of Dresden, claims priority for this discovery, and maintains that bacilli similar to those of cancer are also to be found in sarcoma or myeloma. One large group of tumors is represented by closed cavities filled with liquid or semi-solid contents, the so-called cysts. Such growths arise mainly in organs which, in a physiological condition, contain epithelial or glandular structures. In many instances a new forma- tion of glandular tissue (an adenoma) precedes the appearance of a cyst. Closed cavities, however, are not infrequently found in both benign and malignant types of connective-tissue tumors, and in such cases we are in the dark as to the origin of the cysts, and designate the new formation cysto-fibroma, cysto-osteoma, cysto-myeloma, etc. As to the cause of tumors, the theory of Cohnheim suggests mis- placed embryonal germs. This brilliant theory was subsequently limited by its author to certain varieties, such as primary cancer in the bone or in lymph ganglia. Unfortunately, however, this theory 196 DENTAL PATHOLOGY AND PRACTICE. cannot be proven, either by direct observation or by experiments upon animals. We are positive of only one fact, viz, that an acute traumatism or oft-repeated slight injuries — in short, a local irritation — furnishes in many instances the explanation of the appearance of abnormal growths. In several of our specimens the trace of a previous traumatism was found under the microscope, in the shape of clusters of pigment, the result of a hemorrhage that must have occurred long before. Inflammations of the gum and the pericementum are acknowledged to be fertile sources of tumors, as well as traumatisms or other irritations. Our observations are based upon seventeen different tumors. These embrace the most common types of both benign and malig- nant tumors of the jaws. The great majority were primary on the jaws, and only two cases, one of myeloma and one of carcinoma, are secondary to the jaws by contiguity. We excluded from our consideration all tumors of the teeth proper. I. — Myxoma. This variety of tumor is not rare on the gums around the teeth. The specimen under observation is of the size of a robin's egg, with a nodulated surface, originally of a blood-red color, of rather soft consistence, and grew upon the gum of the lower jaw, left side, between the second bicuspid and first molar. It recurred at every pregnancy, this being the third, in the mouth of a lady aged about twenty-six years. Tumors had been removed from the same locality four different times, when the patient was a girl from twelve to four- teen years of age. With low powers of the microscope the raspberry or papillary appearance was well defined upon the surface, as represented in Fig. 78. The surface is coated with a single row of columnar epithelium, the boundary of which toward the subjacent connective tissue is in- distinct, — so much so that the lowest portions of columnar epithelia and the bodies wedged in between them blend with the adjacent layers of medullary tissue. The so-called structureless layer can be made out in but few places. The main mass of the growth consists of an extremely delicate net- work of fibrous connective tissue with inter- spersed nuclei, mainly at the points of intersection. The meshes of this net-work contain as a rule only one medullary corpuscle ; but near the surface such corpuscles are present in such numbers that the reticulum is rendered invisible. The corpuscles are comparatively small and nearly compact near the periphery, while they are granular and markedly larger in the deeper portions. The outermost portions of the tumor, owing to the abundance of medullary corpuscles, have the character of a myeloma ; but the gradual appearance of a myxo- CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 1 97 matous basis-substance in the deeper portions proves that the tissue is myxomatous, and the clusters of the medullary corpuscles merely signify a rapid growth at the surface. Fig. 78. Myxoma or Granuloma of the Gum of the Lower Jaw. Z,, longitudinal, 7", transverse section of the papillae on the surface; 71/, myxomatous tissue; F, blood-vessels traversing the myxomatous tissue. Magnified 100 diameters. igo DENTAL PATHOLOGY AND PRACTICE. A striking feature of this growth is the large number of wide capillary blood-vessels, which run mostly in a vertical direction to the surface, and therefore appear in transverse sections where the pa- pillae are cut transversely. The arrangement of the capillaries in a tassel-like manner seems to account for the papillary or nodular architecture of the surface. The so-called proud-flesh or granula- tion-tissue of suppurating wounds has the same structure as the tumor under consideration, and some authors speak of a granuloma corresponding to the structure of a myxoma, but produced by an inflammatory process. In the deeper portions of the tumor delicate bundles of fibrous connective tissue are visible, and most of the vessels are accompanied by tracts of such tissue, by which an adven- titial coat is produced, even around the capillaries, which is not visi- ble in normal tissue. In the deepest portions the fibrous connective tissue is rather abundant, the medullary corpuscles being at the same time scanty, and the blood-vessels bearing the character of veins. Growths of this kind are sometimes seen arising from the gum be- tween the teeth, owing to some constant irritation. It is quite possi- ble that the lady in whose mouth the tumor grew irritated her gums, perhaps mechanically, by allowing particles of food or tartar to accu- mulate. The microscope does not enable us to draw sharp boundary lines between products of inflammation and tumors proper. Good authorities — for instance, Virchow — claim that a tubercle or a gumma due to syphilis is a tumor composed of granulation-tissue, and is therefore granuloma, although most modern writers agree that the nodules mentioned are caused by local inflammation. II. — Myxo-Fibroma. This variety of benign tumors is likewise known as occurring fre- quently, taking issue either from the gums or. the periosteum. Its consistence is harder than that of a pure myxoma, and softer than that of a pure fibroma. (See Fig. 79.) The illustration is taken from the deepest portions of the myxoma above described. It consists of interlacing bundles of a delicate fibrous connective tissue, exhibiting therefore an indistinct reticular arrangement. The meshes between the bundles are filled with a finely-granular basis-substance, in which medullary corpuscles are stored up in varying numbers. The blood-vessels are comparatively scanty, consisting of capillaries and veins, all of which are sur- rounded by a distinct layer of fibrous connective tissue. The endo- thelia of the capillaries are unusually thick and bulging into the lumen. In some places the capillary appears to be supplied with two or more endothelial layers, which add considerably to the thick- ness of the vascular wall. The specimen affords a good opportunity CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. I99 for the study of the manner in which, first, myxomatous tissue arises from medullary, and fibrous from myxomatous, a process which, as is well known, is of frequent occurrence in the history of develop- ment of normal fibrous connective tissue. At first the tissue is Myxo-Fibroma of the Gum of the Lowkr Jaw. M, myxomatous tissue, composed of delicate fibrous bundles ; M i, the bundles coarser, still exhibiting the reticular arrangement ; 71-/2, the fibrous bundles, broad, inclosing fields of a myxomatous basis-substance ; K, V, large capillary blood-vessels. Magnified 200 diameters. 200 DENTAL PATHOLOGY AND PRACTICE. apparently nothing but an aggregation of indifferent or medullary corpuscles, the tissue nature of which is determined only by the fact that all the corpuscles are united with one another by means of deli- cate threads. The corpuscles themselves are originally small homoge- neous lumps, of a high degree of refraction. Soon afterward a num- ber of such indifferent corpuscles assume a granular appearance, and between them an extremely delicate reticulum appears as the first trace of a reticular structure. Some authors have noted, at this stage of development, which we often see in inflamed tissue, the exist- ence of an adenoid or lymph-tissue, by which designation • is meant the appearance of a delicate myxomatous reticulum In the next stage many of the medullary corpuscles are transformed into a myxo- matous basis-substance, which with lower powers of the microscope looks either homogeneous or finely granular. Fields of such trans- formed medullary corpuscles have either one or several corpuscles unchanged, and are bordered by a delicate fibrous reticulum, at the points of intersection of which small oblong or globular corpuscles are seen. In this stage of development the tissue is called purely myxomatous. If, by a further splitting up of the medullary corpuscles into deli- cate spindles, the fibrous reticulum is augmented, and the fields of myxomatous basis-substance narrowed, we have a transition from myxoma into myxo-fibroma, and this transition is the more marked the broader the bundles of fibrous connective tissue. All these stages, to be sure, cannot be traced in direct transition from one into another, but we conclude, from observing the successive portions of the same tumor, medullary at the periphery and fibrous at the base, that the former are the youngest and least developed, and the latter the oldest and most advanced. With the long-accepted theory of secretion of basis-substance, we were at a loss to account for all these phenomena ; whereas the theory first advanced by the late Max Schultze (1861), known as the "transformation theory," renders the formation of basis-substance explicable, provided we keep in mind that it is nothing but protoplasm altered chemically. III. — Fibroma. Solid and dense tumors of a very slow growth, starting from the periosteum of the jaw-bones, are of rather frequent occurrence and well known to surgeons. The name given to them was * ' epulis, ' ' which means a tumor growing upon the gum. Obviously this is a mis- nomer, since we know that tumors of this description take issue as a rule from the periosteum, and invade the gum in a rather secondary way. One of the striking features of such benign tumors is the CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 20I presence of protoplasmic masses with a varying number of nuclei, the so-called giant-cells of previous pathologists. They are present in greatly varying numbers, mainly in that portion of the tumor nearest to the periosteum, often arranged in groups, and entirely absent from the peripheral portions of the growth. (See Fig. 80.) When such bodies are visible, they are as a rule surrounded by em- FiG. 80. Base of Fibroma with Multinuclear Bodies, so-called Giant-Cells. 5', spindle-shaped medullary corpuscles ; F, fibrous basis-substance having originated from spindle-shaped medullary corpuscles ; M, multinuclear body retracted from the surrounding medullary tissue ; Mi, multinuclear body in connection with large medullary or endothelial elements. Magnified 600 diameters. bryonal tissue, and it is easy to observe their origin from a varying- number of medullary corpuscles. The latter coalesce, thereby losing their individual boundary lines, and produce a uniformly granular mass of protoplasm, in which we recognize either scattered nuclei 202 DENTAL PATHOLOGY AND PRACTICE. or coarser granules, so-called nucleoli. Around the corpuscle, which is often of irregular shape, sending offshoots into the neighbor- ing medullary tissue, the adjacent medullary corpuscles produce a kind of capsule, between which and the multinuclear bodies a gap is not infrequently seen, — caused, as it were, by the shrinkage of the " giant-cell." It is known that bodies of this description are often met with in the normal medullary tissue of forming and growing bone. We often find them in those bay-like excavations that appear in the ce- mentum and dentine of temporary teeth during the process of their absorption. The prevailing idea as to their significance is that they grow by the coalescence of leucocytes or medullary corpuscles from without into the cement or dentinal tissue, liquefying and breaking up these tissues lying in their way ; hence their name, " osteoclasts," or "bone-breakers." We must disagree decidedly with this view, since we have seen multinuclear protoplasmic bodies arising from the living matter of cementum and dentine itself, after the dissolution of the lime-salts and the liquefaction of the basis-substance. We have furthermore often seen such bodies in the medulla, preceding the formation of bone-tissue. Since the territories of formed bone-tissue are often transformed into such multinuclear bodies, the idea becomes admissi- ble that they can appear previous to development of the osseous territory ; and their presence in the periosteal portion of fibrous tumors is consonant with this view. We admit, however, that this theory does not account for the presence of so-called giant-cells in every instance, since, as we shall show later on, they accompany blood-vessels, and are known to exist in inflammatory products, — for instance, in tubercles. The tumor before us (Fig. 8i) appeared on the alveolar process of the upper jaw in the shape of a sessile nodule, the size of half a hickory-nut, in a youth about twenty years of age. The surface of the tumor looked comparatively smooth to the naked eye, but microscopical specimens show remnants of the pa- pillae of the gum, rather shallow and blunt, and some distance apart. The outer coating is made up of stratified epithelium, whose layers are noticeably diminished, probably owing to the pressure of the growth from within. The first row of columnar epithelia is well marked only in the valleys between the remnants of the papillae, while on their summits the first row is composed of short columnar, or rather cuboidal epithelia. In these places the epithelia of both the first and the adjacent layers exhibit central vacuoles, or plasmatic spaces, from which the nuclei have dropped out. The bundles of fibrous connective tissue are of considerable CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 203 breadth throughout the mass of the tumor, but their breadth increases •from the outer to the deeper portion. The protoplasmic tracts are Fibroma of the Alveolar Process of the Upper Jaw. E, stratified epithelium of the gum ; P, blunt papillae of the gum ; Z., L, longitudinal, T, T, transverse sections of bundles of fibrous connective tissue; C, C, capillary blood-vessels. Magnified 200 diameters. well marked between the bundles, both in longitudinal and transverse sections. The bundles are freely decussating or interlacing, by which 204 DENTAL PATHOLOGY AND PRACTICE. is produced an extremely dense trestle-work, similar to that of the derma of the skin. The vessels are scanty throughout the tissue, and consist mainly of capillaries. At the outer portion of the tumor, between the bundles, small nests of medullary tissue are discernible. The deepest portions, on the contrary, are made up largely of medullary tissue, composed of globular and spindle-shaped corpuscles, with a goodly number of interspersed multinuclear bodies. The latter feature does not mean a transformation from the benign fibroma into a malignant myeloma, but the juvenile condition of the connective tissue, and a somewhat accelerated growth from beneath, as was proven by the fact that the tumor did not return after removal. IV. — LiPO-FlBROMA. In our collection there is no tumor from the jaws made up of fat to such an extent as to warrant a diagnosis of lipoma. One specimen, however, the size of a cherry, removed from the lower jaw, shows a combination of fibrous connective with fat tissue, and thus gives the variety expressed in the title. The fat-globules are of greatly varying sizes, and either arranged in groups or scattered singly in the con- nective tissue ; arteries are accompanied by rows of such globules. Most of the latter contain vacuoles and peculiar star-shaped forma- tions in their centers, which very probably' are not crystals of mar- garic acid, as some previous observers have believed, but remnants of protoplasm, known to exist in each fat-globule. (See Fig. 82.) The connective tissue is of two kinds, viz, partly broad and heavy bundles, and partly narrow spindles, not arranged in distinct bundles. These two varieties are intermixed without any regular- ity throughout the entire tumor, the latter being especially con- spicuous in the neighborhood of the fat-tissue, where it produces a thin layer, carrying blood-vessels between the fat-globules, or sur- rounds groups of them. The connective tissue contains a number of clusters of medullary corpuscles, which, if flattened out and ren- dered polyhedral by mutual pressure, present the aspect of endothelia, and if coalesced into one mass represent multinuclear bodies or giant- cells. The history of development of fat-tissue demonstrates that each globule of a larger size arises from a number of medullary corpuscles, which are transforrrted chemically into fat, whereas the central portions remain unchanged protoplasm, with branching off- shoots ; much on the plan of territories with central cartilage or bone-corpuscles. Small fat-globules may be the products of trans- formation of single medullary corpuscles, or a limited number thereof It has long been known that, in animals in which emaciation is in- duced rapidly by starvation, each fat-globule breaks up into a CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 205 number of medullary corpuscles, — viz, into the embryonal material which originally gave rise to the formation of a globule. If we re- call the fact that each fat-globule is surrounded by a thin connective- FiG. 82. LiPO-FiBROMA OF Lower Jaw. F F, fat-globules ; M, clusters of medullary corpuscles ; G, multinuclear body or giant-cell /I, artery. Magnified 200 diameters. 2o6 DENTAL PATHOLOGY AND PRACTICE. tissue corpuscle, invariably supplied with a nucleus, fat at once appears as a variety of myxomatous tissue, the difference being only a chemical alteration of the protoplasm into carbohydrates or fat, instead of a mucoid basis-substance. From this point of view, the clusters of medullary or endothelial corpuscles would simply represent a pre-stage of future fat-globules or remnants of previous ones. Since multinuclear bodies or giant- cells are known to result from a coalescence of medullary or endo- thelial corpuscles, there is good reason to assume that these bodies likewise would represent eventually either a previous or a past stage of fat-globules. A fat-globule, according to our view, is a globular territory with a central protoplasmic body, growing in exactly the same manner as a territory of myxomatous, cartilaginous, or osseous tissue ; the nucleus always belonging to the capsule around the globule, and not to the globule itself A territory of any of the tissues named will break up, in the physiological process or during reduction to pathological conditions, into clusters of medullary cor- puscles, or into multinuclear protoplasmic bodies. V. — Angioma. A boy, eleven years of age, presented himself with a tumor the size of a small hickory-nut on the gum of the lower jaw, occupying the region of the right lateral incisor and cuspid, and having its origin in a somewhat narrow pedicle between the teeth. The surface was nearly smooth, slightly lobulated ; its consistence rather soft, and it was easily compressible ; its color dark red. Pressure with the finger rendered the tumor pale, considerably diminishing its bulk at the same time, but as soon as the pressure ceased the previous size and color returned. Three months previously a similar tumor had been removed from the same place, but it almost immediately commenced to grow again with alarming rapidity, causing a slightly uneasy feeling, but no pain. Vertical sections through the body of the tumor revealed the fact that its interior was composed mainly of blood-vessels, but that its outer and inner portions differed from each other in structure. The former exhibited the features of a lobular, the latter of a cavernous, angioma. A, Lobular Angioma. — The surface of the vascular or erectile tumor is covered with a stratified epithelium, being normal in its breadth at the borders, and much thinned in the middle portions of the tumor. In the former numerous rather shallow papillae are visible, a certain number of which are united into a group by deep epithelial valleys. In the central portions only a limited number of layers of cuboidal epithelia are discernible, the deepest layer being absent, and CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 207 replaced by medullary corpuscles to such an extent that no boundary line could be made out between the epithelium and the subjacent connective tissue. (See Fig. 83. ) Fig. 83. Lobular Angioma of the Gum of the Lower Jaw. EP stratified epithelium whose columnar epithelia toward the right side are breaking up into medullary corpuscles ; EN, endothelial layer traversed by radiating tracts of a delicate fibrous connective tissue; C, capillary blood-vessels in the endothelial layer; Z., /., lobules composed mainly of capillary blood-vessels. Magnified 200 diameters. 2o8 DENTAL PATHOLOGY AND PRACTICE. The connective-tissue layer beneath the epithehum is made up of nucleated granular corpuscles, closely packed together, — so much so that they flatten each other into broad spindles. Bodies of this description are termed endothelia. A limited number of tumors of this variety have been known since Bizzoziro, of Italy, drew attention to their occurrence, and dubbed them endothelioma. They are usually found in connection with lipoma and angioma. The endothelia appear to be arranged in clusters, between which delicate tracts of a fibrous connective tissue run in a somewhat radiating order, which tracts, if examined with higher powers of the microscope, appear to be made up of narrow, partly-nucleated spin- dles. The tracts spread toward the periphery in a fan shape, and no clear distinction is possible here between the broad spindles of the endothelia and the narrow spindles of the tracts. Some distance below the epithelia, or close beneath them, a large number of capillaries are seen cut in longitudinal, oblique, and trans- verse sections, which means that these blood-vessels are coiled up into a lobular shape. Between the lobules there are either tracts of endothelia mixed with fibrous connective tissue or bundles of the latter alone, and these interstitial tracts bear capillaries of their own, independently of those within the lobules. The most striking feature in the endothelial layers is the formation of the red blood-corpuscles and blood-vessels. At first isolated lumps appear in the endothelia, characterized by a high degree of refraction, and yellow in color. They are smaller than red blood- corpuscles, and are known by the name of " hsematoblasts." In- creasing in size, they assume the appearance and structure of red blood-corpuscles. Clusters of haematoblasts, or fully-formed red blood-corpuscles, are surrounded by circular tracts of endothelia, which, being hollowed out in part, lead to the formation of capillaries already filled with blood, while a number of endothelia of rather large size furnish their walls. Thus the formation of red blood- corpuscles precedes that of blood-vessels, as stated some fifty-odd years ago by Rokitansky, of Vienna. Thus it also becomes plain that the tissue form termed endothelioma is, at least in many instances, a pre-stage of angioma. Obviously the newly-formed blood-vessels, though containing blood-corpuscles from the very issue, are closed tubes or saccules, which later, through a continued vacuolation of the endothelia, inosculate with already-formed blood- vessels ; their tenants, the blood-corpuscles, entering into the circu- lation. B, Cavernous Angio^na. — The lower portions of the tumor under consideration have a different structure, gradually blending with that of lobular angioma. Here we notice large cavities, at first CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 20q lined by several layers of endothelia, and containing a varying number of red blood-corpuscles, until eventually very large spaces make their appearance, filled with red blood-corpuscles ; and thus the character of a cavernous angioma is established. (See Fig. 84.) Fig. 84. Cavernous Angioma from the Base of a Vascular Tumor of the Gum. C, C, cavernous spaces filled with venous blood ; K, K capillary blood-vessels of the tra- beculse bounding the cavities; £, E, endothelia in transition, partly into myxomatous and partly into fibrous connective tissue. Magnified 200 diameters. 15 2IO DENTAL PATHOLOGY AND PRACTICE. We observe tracts of endothelia accompanied by a delicate fibrous connective tissue, with irregular calibers, in which liquefaction of a certain number of endothelia has taken place, as indicated by their hydropic condition, to such an extent that only a delicate frame- work of previous endothelia is discernible. A certain number of endothelia also have been transformed into red blood-corpuscles ; another set furnishes colorless blood-corpuscles, or possibly these arise from the nuclei of previous endothelia. This process is known to histologists by the term, " vacuolation of the endotheha." The openings at first are very irregular, 'being bounded by several layers of endothelia, and it sometimes occurs that tolerably well-formed calibers of the same vessel are connected with one another by narrow canals, owing to the presence of endothelia only slightly changed. Blood-corpuscles may be seen in one part, while they are absent in another, so long as the vessels are not complete. The remaining endothelia are large and supplied with oblong nuclei of considerable size. Fully-formed cavities in connection with the physiological vessels are characterized by smaller endothelia, not surpassing in size those of normal veins. The trabeculae inclosing the venous cavities are made up of fibrous connective tissue, carrying their own capillary blood-vessels. In many places, however, even the trabeculae are made up of endothelia, and it is easy of demonstration that the en- dothelia are merely the medullary or embryonal stage of connective tissue, since we can trace its transformation into both myxomatous and fibrous connective tissue. This portion of the tumor contains solid masses of a dense fibrous connective tissue, which in all prob- ability are not newly formed, but represent residues of the former tissue of the gum or the periosteum. VI. — Myeloma. We have already given the reasons why we prefer the term myeloma to that of sarcoma. These tumors are by no means of rare occur- rence, as is shown by the fact that our comparatively small collection embraces five specimens of myeloma and its combinations out of seventeen representatives of tumors in general. All these tumors are considered malignant with one exception, which concerns the variety termed "epulis sarcomatosa, " or, as we propose to call it, fibro-myeloma. This variety is well known to surgeons as admitting of a radical cure if thoroughly extirpated. Multinuclear bodies are of such frequent occurrence that an authority like Virchow speaks of a variety which he calls "giant-cell sarcoma," growing in the majority of cases from the periosteum. We have described, under a previous heading, benign tumors, especially fibroma, containing a CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 2,11 varying number of so-called giant-cells in their juvenile portions, where medullary tissue prevails, and we have insisted that no stress is to be laid upon the presence of "giant-cells." If the tumor is intermixed with medullary tissue throughout, the diagnosis will be fibro-myeloma, which is still of a low degree of malignity, as shown by clinical experience. We can state positively that the number of multinuclear bodies is of great value in determining the degree of malignity in any given case. The greater their number, the surer it is that the tumor is not very malignant and will not recur if radically removed. On the contrary, the smaller their number the greater is the malignity and the danger of recurrence ; in the worst cases of pure globo or spindle myeloma, multinuclear bodies are lacking altogether. In such cases the danger to the life of the patient is imminent, in spite of all attempts at thorough eradication. According to our nomenclature, we shall dwell upon combinations such as myxo, fibro, and osteo-myeloma, and finally consider the two purely malignant forms, — viz, globo and spindle myeloma. Any of these forms may arise primarily from the periosteum or medulla of the jaw-bones, or start in the nasal cavity, the antrum of High- more, or the soft palate, and invade the upper jaw in a secondary manner. In several instances of primary myeloma we found, in the tissue of the tumor, clusters of pigment, indicative of a previous hemorrhage, possibly in connection with a traumatism (blow, kick, fall, etc.), which, as is admitted, often causes — for reasons unknown — the growth of malignant tumors. A, Myxo- Myeloma. — This specimen originally started on the soft palate of a young lady nearly twenty years of age, and after extirpa- tion recurred on the base of the upper jaw-bone, invading in turn both the antrum and the nasal cavities. With low powers of the micro- scope the tumor shows a thin investment of fibrous connective tissue, fibers from which penetrate the morbid growth, scantily supplied with blood-vessels, and producing imperfect septa, by which an indistinct alveolar structure results. The alveoli are filled with protoplasmic bodies, either globular or spindle-shaped, or provided with numerous offshoots, by means of which a net-like structure is established. (See Fig. 85.) Globular corpuscles are arranged in clusters, with a scanty inter- vening basis-substance. Spindle-shaped corpuscles are arranged in tracts, freely connecting at acute angles, and separated from one an- other by a slight amount of a finely-granular basis-substance. This latter form would correspond to that variety of myeloma termed by Virchow "net-cell sarcoma." The prevailing formation within the alveoli, however, corresponds to the illustration, being composed of very large polymorphous protoplasmic masses, containing, in some 212 DENTAL PATHOLOGY AND PRACTICE. parts, a number of nuclei,, and interconnected by comparatively nar- row offshoots in all directions. The basis-substance between these formations is conspicuous, and traversed by an extremely delicate reticulum, which arises from the delicate offshoots in a brush-like manner. This tissue is myxomatous in structure, which, because it predominates over the structures before mentioned, entitles the tumor to the name of myxo-myeloma. The myxomatous tissue contains MVXO-MVELOMA OF UPPER JaW FILLING THE ANTRUM OF HiGHMORE. F, tract of fibrous connective tissue ; V, capillary blood-vessel ; 5", S, nucleated protoplas- mic tracts branching and finely interconnecting ; B, B, myxomatous basis-substance with a delicate reticulum in connection with the protoplasmic bodies. Magnified 600 diameters. no blood-vesSels, which are found invariably in tracts of fibrous con- nective tissue, at rather distant intervals. As the consistence of the tumor was soft, almost jelly-like, the basis-substance must be of the mucoid or myxomatous variety. In cases where the basis-substance is more firm the tumor has been termed chondro-myeloma, or ma- CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 213 lignant chondroma, although we would consider the latter term as illogical. B^ Fib ro- Myeloma. — Among several tumors of this variety, we have selected the present specimen for description, its clinical history- being better known. It was located upon the right side of the lower jaw of a man about thirty-five years of age, the size of half a hen's ^^^, occupying the space between the first bicuspid and the ramus ; the teeth in this locality having previously been removed. Its con- sistence was firm, its surface slightly nodular, its color purple, and there were nowhere signs of ulceration. For a while previous to its removal it caused considerable pain of a shooting character. It had grown within about two years. Under the microscope the tumor appears to be composed of inter- lacing tracts of fibrous connective tissue, with interstices filled either with medullary corpuscles or wdth multinuclear protoplasmic bodies ; the fibrous portion being everywhere in excess over the medullary tissue. (Fig. 86. ) The clusters of medullary corpuscles are rather numerous, exhibiting an endothelial appearance. In some places blood-vessels are seen to be surrounded with or accompanied by such medullary corpuscles, and in a few places multinuclear bodies are visible in small numbers, but in a remarkably regular arrangement. The fact that blood-vessels traverse the clusters excludes the conclu- sion that they are of an epithelial nature, and therefore the diagnosis of cancer, which could be made upon a superficial glance at the tumor, is untenable. This tumor we would not consider a very malignant one, and the diagnosis of a fibroma would be admissible if the med- ullary nests were not so profusely scattered throughout the tissue. A far more malignant case of fibro-myeloma is the following : A man about twenty-five years of age showed a hard swelling upon the right upper maxilla, which had developed within three years. The tumor occupied not only the region of the alveolar process, but also the antrum of Highmore. Most of the teeth had become loose and been removed, the last two molars being left, but very loose, and nearly imbedded in the dark-red mass of the tumor. The diagnosis was malignant tumor, either cancer or myeloma. The whole right maxilla was extirpated, and a portion of the alveolar process with a tooth in it came into our possession. At the microscopical examination no trace of a bony structure could be found ; the mass of the tumor consisting mainly of clusters of small globular shining corpuscles, between which an indistinct fibrous reticulum was discernible. The clusters were separated from one another by bundles of fibrous connective tissue, greatly varying in amount ; the surface of the tumor was bordered by an indistinct capsule of the same tissue, which itself contained smaller clusters of 214 DENTAL PATHOLOGY AND PRACTICE. myeloma corpuscles, and showed irregular, blunt elevations belonging to the gum, and covered with a thin layer of stratified epithelium. In the neighborhood of the tooth the pericementum was still recog- FiG. 86. Fibro-Myeloma with Multinuclear Bodies from the Lower Jaw, Z, Z,, longitudinal, 7", transverse sections of bundles of fibrous connective tissue; M,M, clusters of medullary corpuscles ; G, G, multinuclear bodies or so-called giant-cells, retracted from the adjacent connective tissue ; V, blood-vessel in transverse section surrounding a clus- ter of medullary corpuscles. Magnified 6oo diameters. CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 215 nizable, in the shape of straight bundles of fibrous connective tissue, remaining in connection with the cementum, but crowded with my- eloma corpuscles. (See Fig. 87.) Fig. 87. Fibro-Myeloma of the Upper Jaw invading the Pericementum. C, cementum ; B, B, bundles of fibrous connective tissue ; 5, S, clusters of myeloma cor- puscles between the bundles ; 51, transformation of the bundles into the tissue of myeloma, with scanty traces of the bundles. Magnified 200 diameters. 2l6 DENTAL PATHOLOGY AND PRACTICE. The conditions make it evident that the tissue of the myeloma grew at the expense of the fibrous connective tissue of the pericementum. In some places the bundles of the latter tissue are still broad, con- taining in their middle slit-like groups of medullary corpuscles. In other places these corpuscles have replaced the bundles to a great extent ; still deeper, only scanty and thin bundles are seen traversing the tissue of the myeloma. Finally eler^ents of myeloma occupy large fields, with scanty fibrous tissue or none at all between them. Obviously the process of transformation is explicable only if we ad- mit that the whole of the fibrous connective tissue, the protoplasmic bodies as well as the basis-substance, is supplied with living matter, from which the new formation of the medullary corpuscles takes its origin. If we confine ourselves to the examination of a limited portion of this tumor, no differentiation between myeloma and an acute inflam- matory process can be made out, since the medullary corpuscles constituting myeloma are identical with inflammatory corpuscles about ready to break up into pus. It should also be borne in mind that a rapidly-growing cancer may change its character into that of a myeloma, or fibro-myeloma, as was first stated by Virchow. In speci- mens of such rapidly-growing tumors we have always to keep a sharp lookout for epithelial nests, the presence of which would be evidence of cancer ; should such nests be absent, we diagnosticate myeloma. Either of these tumors involves considerable danger to the life of the patient. C, Osteo- Myeloma. — This tumor was found in the mouth of a lady aged about thirty, in the region of the bicuspids upon the left upper jaw, and had reached the size of half a robin's &^^ in a year and a half, the teeth having previously been removed. The tumor exhib- ited the structure of a fibro-myeloma, invading principally the alveo- lar process, which .was reduced to minute remnants of bone scattered throughout the tissue. (See Fig. 88.) The term osteo-myeloma is confined to growths primarily arising in the medulla of bone, or to growths holding newly-formed bone- tissue. As the tumor in this instance started in the medulla of the alveolar process, and is largely intermixed with fibrous connective tissue, its proper title would be osteo-fibro-myeloma. The remnants of bone-tissue give evidence of its transformation into the mass of the tumor through the intervening stage of medullary tissue. In a few places we find near the border of trabeculae enlarged lacunae containing several medullary corpuscles, obviously sprung from pre- vious bone-corpuscles, and still surrounded by a calcified basis-sub- stance. In other places a number of bone-corpuscles are seen con- nected by means of broad offshoots into chains. In still others, the CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 21J first step toward the dissolution of the bone-tissue is the appearance of bay-Uke excavations corresponding to a previous territory, in which protoplasm makes its appearance ; or the border of the bone Fig. 88. Osteo-Fibro-Myeloma of the Alveolar Process of the Upper Jaw. F, F, fibrous connective tissue with numerous clusters of medullary corpuscles clusters of pigment-granules ; 5. trabeculse of bone indistinctly lamellated with normal corpuscles ; H, medullary space with central blood-vessels ; D, bay-like excavation bone. Magnified 200 diameters. P, P, bone- of the 21 8 DENTAL PATHOLOGY AND PRACTICE. is split up into a number of medullary corpuscles, which are not yet entirely freed from basis-substance. All this is strong proof that the bone participates actively in the new formation of the morbid tissue, the same as it participates in the process of inflammation. To say, as some authors do, that the bone is simply eaten up from without by the newly-formed tissue, does not argue much acuteness of obser- vation ; since it is by no means difficult to satisfy one's self as to the active proliferation of the bone-corpuscles within the lacunae. It is invariably the medullary corpuscles that first appear from bone-tissue, and by subsequent splitting into spindles and reinfiltration with basis- substance give rise to the fibrous portion of the morbid growth. Fig. 89 Globo-Myeloma of the Periosteum of the Alveolar Process of the Upper Jaw. B, delicate bundles of fibrous connective tissue ; G, globular corpuscles of myeloma in dif- ferent stages of development. Magnified 600 diameters. D, Globo-Myeloma. — This specimen was obtained from a tumor taken from the mouth of a young lady about twenty years of age. It was located on the right upper jaw, in the region of the bicuspids, and had grown to the size of half an English walnut in about two years. The teeth had previously been removed. It was diffusely infiltrated toward the neighboring tissue, and evidently started from the periosteum. (See Fig. 89.) The most striking feature was the scarcity of fibrous connective tissue, which traverses the growth in delicate bundles without any regularity. The main mass is composed of medullary corpuscles, either globular or polygonal, the latter produced by mutual pressure. Between small groups of such corpuscles extremely delicate septa of fibrous tissue are visible, in which the blood-vessels are located, though present only in small numbers. Higher powers reveal two facts : first, that the corpuscles are inter- CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 219 connected by- delicate radiating offshoots, traversing the narrow spaces between them ; second, that in a limited field of the tissue all stages of development of myeloma can be made out. We see small granules of a high refraction, structureless, not even reaching the size of colorless blood-corpuscles. We see larger gran- ules and lumps with a varying number of vacuoles in their interior. We furthermore see lumps with large, compact nuclei, and at last corpuscles with reticulated nuclei, with granules in their interior, and of the ordinary reticulated structure of protoplasm Any gran- ule within the protoplasm may grow to the size of a nucleus, or a nucleated corpuscle ; the nuclei themselves are in an active process of division, as shown by numerous dumb-bell forms, and figures of Fig. 90. Spindle-Mveloma of Upper Jaw. L, L, longitudinal sections of spindles ; T, T, transverse sections of spindles; P, P, clus- ters of pigment from previous hemorrhage. Magnified 600 diameters. double or treble nuclei within a single corpuscle. All this is proof of a very rapid multiplication of the corpuscles, causing an extremely rapid growth of the tumor, and indicative of a high degree of malig- nancy. In accord with the latter features, not a single multinuclear body or ' ' giant-cell' ' can be seen, not even where somewhat broader bundles of fibrous tissue, pr6bably belonging to the periosteum, are present. E, Spindle Myeloma. — This tumor, corresponding to what Virchow has termed " spindle- cell sarcoma," is represented in our collection by a specimen the history of which is unknown to us. All we can say is that it had grown in the upper jaw. (See Fig. 90.) The tumor is largely composed of spindles, but in some places 220 DENTAL PATHOLOGY AND PRACTICE. globular corpuscles are seen, a feature which would entitle the tumor to the name of a combined globo-and-spindle myeloma. The tumor has comparatively little of fibrous connective tissue, and in this scanty blood-vessels are seen. The spindles are arranged in interlacing groups ; in almost every field we meet with longitudinal and trans- verse sections of spindles, all of which are interconnected by delicate offshoots. The rapid growth of the tumor is indicated mainly by coarsely-granular nuclei, or chains of coarse granules replacing the nuclei. In some places clusters of red-brown pigment-granules are seen, but in such small numbers that the tumor cannot be properly called pigmented or melanotic myeloma. The pigment appears either in spindle-shaped or irregular clusters, partly within and partly be- tween the spindle-shaped corpuscles. These pigment-clusters are unquestionably the result of a previous hemorrhage, possibly caused by a mechanical injury, giving issue to the myelomatous new growth. VII. — Carcinoma. This type of tumors is characterized by the presence ot epithelial nests, scattered without regularity in the connective tissue, which may be either myxomatous or fibrous. Most pathologists claim that cancer may originate only in such tissues as are covered with or con- tain normal epithelia. The mucosa of both the oral and nasal cav- ities is the starting-point of cancerous growths, and in the upper jaw there is an additional source in the mucosa of the antrum. Again, the cancer may be primary in the tissue just named, or secondary by invasion from the skin or from any glandular formation, — for instance, from the salivary glands. There are three varieties of cancer recognized by modern patholo- gists : first, scirrhous, with comparatively small nests of epithelia, and a large amount of fibrous connective tissue around the nests ; second, epithelioma, with concentrically arranged flat epithelia fill- ing the nests, and a varying amount of fibrous tissue between them ; and, third, medullary cancer, with small and irregular epithelia in the nests, and a scanty fibrous tissue between them. Of these three varieties our collection contains examples of two, epithelioma and medullary cancer, both having reached the upper jaw from adjacent epithelial structures, skin and mucous membrane. A, Epithelioina. — We have two cases of this type of cancer, both from men over forty years of age. In one the tumor arose in the mucosa of the antrum, and in the other in that of the floor of the nasal cavity, both being similar in structure. (See Fig. 91.) In examining the specimen of epithelioma from the mucosa of the antrum, we observe marked differences in the structure of the epithe- lia. Near the boundary toward the connective tissue they are smaller CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 221 and narrower than in the middle portions of the nests. They are often replaced by a row of medullary corpuscles, to such an extent that no sharp boundary line exists between the connective tissue and Fig. 91. Epithelioma of the Mucosa of the Antrum. C, delicate fibrous connective tissue crowded with medullary corpuscles; y, capillary blood-vessels in the connective tissue; £, E, epithelial nests made up of concentrically arranged flat epithelia ; P, P, cancer-pearls composed of changed epithelia. Magnified 200 diameters. 222 DENTAL PATHOLOGY AND PRACTICE. the epithelial nest. Obviously this means a gradual transformation of the medullary into epithelial tissue, a process which leads to the increase of the bulk of the nests and a decrease of that of the con- nective tissue. Finally, even the blood-vessels being obliterated, the nests are deprived of nourishing material, and a local necrosis — viz, ulceration — takes place, which is a common feature in all cancers. The second prominent feature is an active new formation of living matter in the epithelia. This causes the nuclei to become homo- geneous ; then to assume an hour-glass shape, and lastly to divide into several nuclei. Not infrequently we see several nuclei or several medullary corpuscles within a considerably enlarged epithelium. Such formations have been termed ' ' mother cells' ' by previous path- ologists, but we now know that they are the outcome of an active endogenous new formation. Around the nucleus often are seen vacuoles, or plasmatic spaces, which evidently contain nourishing liquid, enabling the nucleus to rapidly increase its proportion of living matter, with the result of fission and division, and a rapid new forma- tion of epithelia. Except where the nucleus is surrounded by a vacuole, it is in connection with the adjacent protoplasm of the epi- thelium, by means of delicate conical oifshoots. Similar offshoots also traverse the cement-substance between the epithelia, thus uniting all into a continuous mass of protoplasm The central portions of the nests often contain groups of epithelia, which have assumed a high degree of refraction, a yellowish color, and a homogeneous appear- ance. At first the nuclei remain, though only faintly discernible ; but in the more advanced degrees of this metamorphosis even the traces of nuclei are lost, and a certain number of epithelia are trans- formed into structureless glistening plugs, representing the well- known cancer-pearls. The nature of this process is not yet known. The connective tissue is of either the myxomatous or the fibrous variety ; never very rich in blood-vessels, which are mostly capillaries and veins. In many places the connective tissue is crowded with medullary or lymph- corpuscles, between which a delicate reticulum is seen. Some authors regard this as the result of an inflammatory reaction of the epithelial upon the connective tissue, but we claim that it is the medullary condition of the connective tissue from which new epithelia arise. We base our views upon direct observation, since we know that if, after removal of cancer-nests, lymph-corpus- cles be left behind, even though at a great distance from the cancer itself, the disease will invariably recur. This fact urges upon us the necessity for removal of large portions of tissue in the neighborhood of cancer. Modern surgeons, by clinical experience, have reached the same conclusion, considering the course indicated the only safe- guard against relapses, which are so very common in this disease. CONTRIBUTIONS TO THE KNOWLEDGE OF TUMORS OF THE JAWS. 223 Unfortunately, we are not able to say why the lymph-corpuscles or the medullary tissue, into which the connective tissue is transformed in an almost identical way with inflammatory infiltration, should have such a marked capacity for changing into epithelia ; in other words, wherein the contagion of the tissue lies. B, Medullary Cancer. — Our specimen is taken from the enor- mously enlarged alveolar process of the upper jaw of a man over sixty years of age. Twelve years previous to his death he was first oper- ated upon for a so-called rodent ulcer, upon the left wing of the nose, which about fifteen years previously had originated from a slight injury, causing a shallow ulcer, which could never be induced to heal. The scooped-out particles of tissue from the first operation were ex- amined under the microscope, and showed the structure of a shallow or flat epithelioma, which previous authors termed "rodent ulcer." Repeated recurrences and operations took place afterward, until the left upper jaw began to swell, the left eye was pushed up and forward, and the teeth became so loose and troublesome that they had to be removed. The swelling of the face proved to be greatly aug- mented by an apparently long-standing abscess in the antrum, the result of the death of a second molar many years before, the roots of which penetrated its floor. Upon the removal of this tooth a large quantity of fetid pus escaped, and a temporary improvement was the result. Later the swelling invaded the front of the mouth and passed to the right side to such a degree that several operations were required to remove the fungoid, easily-bleeding masses of the alve- olar process, gum, and hard palate, which were almost choking the patient. The purpose of these operations was not to remove the cancer, but to prevent death from suffocation or starvation. This specimen is a type of medullary cancer. (See Fig. 92.) The specimen exhibited in some places an almost unchanged stratified epithelium covering the papillae of the gum. In other places the papillae are much enlarged and flattened. Still further, the papillae have entirely disappeared and the epithelial layer is con- siderably thinned, until at last the epithelium has disappeared, and an ulcerating cancer-tissue appeared upon the surface. In those places where the epithelial stratum of the gum appears thinned the deepest or columnar row of epithelia as well as the lower layers of cuboidal epithelia are absent, and are replaced by a medullary tissue of a myxomatous character, which has incidentally sprung from the previous epithelia. We feel the more confident of such change having taken place from the fact that at the border between the epithelial and medullary tissues the epithelial bodies themselves show a marked increase of living matter, and a gradual transformation into medul- lary corpuscles. 224 DENTAL PATHOLOGY AND PRACTICE. Close beneath the medullary layer nests of epithelia make their appearance, separated from one another by, first, medullary, and deeper in by a delicate fibrous connective tissue, which latter has evidently originated from the former. We therefore maintain that a medullary tissue arising from previous normal epithelia may change into fibrous connective tissue, and vice versa, that medullary tissue Fig. 92. Medullary Cancer of thk Left Upper Jaw, Invading the Alveolar Process AND Gum. N, N, nests of irregular polyhedral epithelia ; C, C, delicate fibrous connective tissue be- tween the nests ; V, vein. Magnified 600 diameters. which arose from connective tissue may eventually be converted into the epithelia of cancer. The medullary nests are made up of very irregular bodies, which by pressure have assumed a polygonal form. In many instances a whole nest or a portion of it is made up of granular protoplasm, with SENILE ATROPHY OF THE UPPER JAW. 225 nuclei scattered at regular intervals, without any intervening cement- substance. Where the latter is present in the shape of a narrow ledge, it is invariably pierced by delicate offshoots or thorns, inter- connecting the single epithelial elements. The changes of the epi- thelia toward proliferation are much the same as in the epithelioma before described. The connective tissue shows a transformation into lymph- tissue to a great extent. Where it has retained its fibrous char- acter it is scanty, separating the epithelial nests and carrying a large number of protoplasmic bodies. The blood-vessels running therein are scanty, and are mostly capillaries and veins. The latter often show sinuous contours, and are replete with blood-corpuscles. As stated in the discussion of epithelioma, the secret of the general and local contagiousness of cancer has never been unveiled, but still awaits the future discoverer. CHAPTER XXII. SENILE ATROPHY OF THE UPPER JAW.« With advancing age the human organism is reduced in size and weight ; the more so, as a rule, after the " threescore years and ten" have passed. The whole body shrinks, as well as all its individual tissues. Age itself is disease. The old Roman proverb says, "And the aged returns to childhood, both mentally and physically." The questions which we'have tried to solve are. In what does this atrophy take place ? What are its visible signs under the microscope ? Through the kindness of Dr. Emmons Paine, superintendent of the insane hospital in Westborough, Mass., we came into possession of the upper jaw of a woman, who died at the age of seventy-five years. The jaw, immediately after removal, was placed in a one-half of one per cent, solution of chromic acid, in which it remained for several weeks for the purpose of softening the bony parts. We lay stress upon this fact, because previous researches upon senile bone have been made upon dried specimens, by which method we are con- vinced that the results of microscopical research must have been marred, if not rendered futile. The entire thickness of this jaw, from the oral to the nasal surface, was not more than from four to five mil- limeters ; the oral surface was perfectly smooth, without a trace of a tooth or a socket. A slight indication of the central raphe could be seen. Vertical sections through it give striking pictures of far-ad- vanced senile atrophy. (See Fig. 93.) *Heitzmann and Abbott, Dental Cosmos, 1892. 16 226 DENTAL PATHOLOGY AND PRACTICE. The stratified epithelium of the oral mucosa terminates in an almost even line without the least indications of former gums, the body of the epithelium being considerably narrowed. The papillae, so prominent in the region of the gums in a normal condition, are still Fig. 93. Atrophied Upper Jaw. Vertical Section. £, stratified epithelia of mucosa of oral cavity; Z, longitudinal bundles of fibrous connective tissue ; T, transverse bundles of fibrous connective tissue ; 5, spaces in connective tissue ; F, fat-globules; C, hyaline cartilage ; ^, artery, probably in a previous alveolar canal; ^.cancel- lous bone ; 71/, medullary space. Magnified 50 diameters. present, but considerably shortened and narrowed. The fibrous con- nective tissue is markedly reduced in its total quantity, as well as in the width of its bundles, as seen best in their transverse section. The SENILE ATROPHY OF THE UPPER JAW. • 227 connective tissue, including that of the former gums and that of the periosteum, runs an almost horizontal course, interlaced nearly rec- tangularly by bundles and tracts of the same tissue. It is traversed by numerous fissures, or slits, which were probably caused by me- chanical injury in the process of cutting. This feature in otherwise perfect sections would indicate that the connection of the bundles is an extremely delicate one. Fat-tissue, so abundant in both the periosteal connective tissue and the medullary spaces of the cancellous bone of the jaws of the young and middle-aged, is extremely scanty. The bone itself produces only thin ledges bordered by an irregularly cor- roded line, without a distinction between compact and cancellous structure. The medullary spaces vary greatly in size, and are filled either with a delicate fibrous connective tissue, or with granular matter, probably disintegrated protoplasm. The most striking feature is the presence of portions of hyaline cartilage, of the same height as the bony tissues left, which goes far to prove that the cartilage has grown from a former bony structure, and has in a measure replaced it. As is well known, hyaline cartilage is present in the lower jaw only at the earliest stages of embryonal life, up to the eighth week of devel- opment. Around and from this so-called primordial cartilage bone- tissue develops, and in the third month of intra-uterine life all vestige of cartilage is lost. How much hyaline cartilage has to do with the development of the upper jaw, we are unable to tell. Most anato- mists consider the upper jaw as having sprung from fibrous connective tissue, in a way similar to that of all flat facial and skull bones. However this may be, it is certainly remarkable that hyaline cartilage should reappear in the upper jaw of the aged, proving, as it were, that advanced age is a recurrence to childhood, even to intra-uterine life. Let us now consider the senile changes of the tissues involved in the formation of the upper jaw. I. Epithelium. — As mentioned before, the layer of stratified epithe- lium has been considerably reduced in bulk, although its three con- stituent portions are still recognizable, the main mass being made up of cuboidal epithelia, while the outermost or horny layer is com- posed of several rows of flat epithelia, and the border toward the connective tissue is established by a single row of columnar epithe- lium. (See Fig. 94.) Horizontal sections through the mucosa show the thinning of the epithelial layer even better than vertical ones ; in the former, also, the row of columnar epithelia is better marked than in vertical sections. Most of the epithelia are much less conspicuous than in childhood or middle age. This may be accounted for, first, by the fine granula- tion of both the protoplasm and the nuclei ; second, by a reduction 228 DENTAL PATHOLOGY AND PRACTICE. in the amount of the intervening cement-substance ; and third, by a noticeable reduction of the bulk of each epithelium. An additional feature is that many of the original epithelia seem to have split up into smaller lumps. In many instances, only faintly-outlined nuclei are to be seen, so closely packed together that but little intervening protoplasm is discernible. Fig. 94, Oral Epithelium of Senile Upper Jaw. Vertical Section. i^ layer of flat epithelia; Ci, cuboidal epithelia with solid nuclei'; C^, cuboidal epithelia of small size, with small vesicular nuclei; M, multinuclear layers of protoplasm; Co, columnar epithelium; V, F, capillary blood-vessels traversing the middle epithelial layer; O, O, myxo- fibrous connective tissue of oral mucosa. Magnified 600 diameters. In many cases cement-substance is lacking altogether, to such an extent that the impression of multinuclear bodies is produced ; wher- ever cement-substance is present, though its ledges be ever so narrow, the delicate thorns traversing it are invariably traceable. In some places, however, the nuclei of the cuboidal epithelia are SENILE ATROPHY OF THE UPPER JAW. 229 almost solid glistening lumps, such as we are accustomed to see in either a juvenile or an inflamed condition of epithelium. Broader epithelial valleys show in vertical sections narrow crevices, each holding a minute capillary blood-vessel. This may be explained by the shrinkage of previous papilla ; though this view is hardly tena- ble in the face of the fact that all well-pronounced papillae are supplied with a small number of blood-vessels. The view is more probable that capillaries with a little accompanying connective tissue have grown into the epithelial layer from without, thus causing, or at least assisting in, the atrophy of the epithelium. This much is certain, that the reduction of the sum-total of the covering epithelium is caused mainly by a reduction in the size of each epithelial body. We are, however, unable to say where the lost material has gone, unless it was absorbed by newly-formed capillaries grown into the epithelial layer. A transformation of the epithelia, first into medullary corpuscles, and afterward into connective tissue, a process so common in inflammation and the formation of tumors, could nowhere be satisfactorily proven in our specimens, and seems to be little probable, since, as stated above, the columnar epithelia appear unbroken ; possibly mastication has been more or less instrumental in removing layer after layer of epithelia. 2. Fibrous Connective Tissue. — The senile changes of the oral mucosa are explicable only upon the fact, established by Heitzmann in 1873, that the protoplasmic bodies lie between the bundles of the fibrous connective tissue, and that the bundles themselves are not alto- gether inert glue-yielding basis-substance, but are traversed by an extremely delicate, almost rectangular, net-work of living matter. The bundles, therefore, as well as the protoplasm itself, are possessed of life. Close around the epithelia, and in the remnants of the papillae, we notice delicate bundles holding a large number of finely granular bodies, and but a small number of capillary blood-vessels. This tissue certainly differs from what we are accustomed to see in youth and in middle age. It may be termed myxo-fibrous connective tissue, such as is seen in tumors of the skin and mucous layers, termed myxo-fibromata. This tissue exhibits the same aspect, both in vertical and horizontal sections of the senile jaw. (See Fig. 94, C>, C ) The fibrous tissue proper is, as mentioned above, noticeable by the small size of its constituent bundles, as shown both in their longitu- dinal and transverse sections. The changes of this tissue and its tenants, which are obviously the result of advanced age, are really surprising. (See Fig. 95.) The bundles quite frequently show, under lower powers of the 230 DENTAL PATHOLOGY AND PRACTICE. microscope, a faint granulation, which, if viewed with high powers, proves to be the reticulum of living matter already alluded to. This goes to show that the tissues, especially their matrices, or basis-sub- stance, remain alive to the last. Some of the longitudinal bundles appear split up into faintly-marked medullary corpuscles, visible especially in longitudinal sections. (Fig. 95, M.) Here, evidently, a Fjg. 95. Oral Mucosa of Senile Upper Jaw. Horizontal Section. Z,, longitudinal bundles of fibrous connective tissue ; T, transverse bundles of fibrous con- nective tissue; TV, TV, medullated nerve-fiber; A, artery; C, capillary blood-vessel partly nar- rowed, partly obliterated ; M, bundle of fibrous connective tissue split up into medullary corpuscles; /, cluster of indifferent corpuscles ; £■, elastic fiber ; /*, finely granular protoplasm. Magnified 600 diameters. slight liquefaction of the glue-yielding basis-substance has occurred, leading, as it were, to a rejuvenescence of the bundle, i.e., a reappear- ance of those embryonal corpuscles which in the earliest stage of development have built up the bundle. In other places clusters of glistening homogeneous globules make their appearance, scattered SENILE ATROPHY OF THE UPPER JAW. 23I through a finely-granular protoplasm. These globules are even smaller in size than the medullary corpuscles from which ameloblasts originate. (Fig. 95, /) Nests of this description are similar to those seen in inflammation of the fibrous connective tissue, but we conclude that the nests seen in our specimens, owing to their diminutive size and scantiness, are not inflammatory. There is no doubt in our minds that, exactly as in the process of inflammation, a recurrence of the juvenile or medullary condition has taken place. There is no doubt either that a liquefaction of the basis-substance has taken place in these nests, leading first to a reappearance of protoplasm, and after- ward to an increase of the living matter thereof, up to the formation of the glistening lumps under consideration. The nests are still traversed by faint vestiges of the former bundles, the same as we ob- serve in early stages of inflammation. The thinning of the bundles is unquestionably caused by their gradual transformation into protoplasm, since the interstices are found, in many instances, widened and filled with protoplasm of a finely granular character, which means a small amount of living matter. The ultimate fate of the bundles is, that the basis-substance is liquefied, and nothing is left but the framework of elastic fibers which have previously bordered the bundles, and which, on account of their chemical composition, are less destructible than ordinary glue-yielding basis-substance. (Fig. 95, E.) The result is that where formerly dense fibrous connective tissue was present a faintly granular protoplasmic mass is now seen, the living matter of which is scanty and pale, apparently on account of a hydropic infiltration of the same. This will explain the flabbiness of the tissues of the aged on the one hand, and the gradual loss of living matter on the other. For we realize that particles of living matter with serum imbibed will be gradually detached from the mother soil, disintegrated, and taken back into the circulation through the scanty blood- and lymph-vessels left. The general shrinkage of the body thus becomes intelligible. 3. Blood- Vessels. — The fibrous connective tissue of the oral mucosa is. as is well known, freely supplied with blood-vessels — arteries, capillaries, and veins — during the ascending period of life, while it holds surprisingly few vessels in advanced age. In our specimens we have a good opportunity to trace the manner in which the blood- vessels perish. Smaller arteries show in their muscular walls an augmentation of the nuclei to such an extent that the spindles of the smooth muscle-fibers become replaced by rows of minute glistening globules. (Fig 95, A.) An artery may thus become so changed in its aspect that it were impossible to tell its original character, except through its attachment to a less altered artery of which it forms a 232 DENTAL PATHOLOGY AND PRACTICE. branch. The endothelium of the inner coat Hkewise is thickened and . more or less crowded with coarse granules of living matter, by which means the lumen becomes at first narrowed and ultimately choked. The fibrous connective tissue of the adventitial coat behaves in a way similar to that of the mucosa generally, i.e., it is gradually reduced to its juvenile or embryonal condition. After an artery has thus become impermeable to the current of the blood, it is in turn transformed into a solid tract of fibrous connective tissue, and as such is subject to the changes above described. The capillaries being composed of a single endothelial wall only, are easily traceable in their course to final oblit- eration. The endothelia swell up, become coarsely granular, and, by their bulging, the caliber of the capillary is narrowed and rendered star- shaped. The augmentation of the living matter proceeds up to a com- plete occlusion of its walls, such as is often seen in the process of inflammation. The result is a solid cluster of protoplasm in place of the previously hollow vessel. It seems that the nests of the glistening globules above alluded to are more numerous in the neighborhood of blood-vessels, or in places where blood-vessels had previously been. (Fig. 95, C) Those who favor the- emigration theory in inflammation must be at a loss to explain the appearance of indifferent or inflamma- tory corpuscles in places where the blood-vessels have perished. With us who urge the origin of such corpuscles from the protoplasm — from both its living matter and the living matter of the basis-substance — the images furnished by the microscope are explicable without any diffi- culty. That veins are gradually being obliterated in a way similar to that of arteries and capillaries is almost a matter of course, although we have not been able to trace this process directly in our speci- mens. 4. Nerves. — Here and there we meet with medullated nerves, recog- nizable as such by their course and their connection with other little or entirely unchanged nerves, which exhibit striking changes. Such changes are usually met with in the process of neuritis ; but in this instance, neuritis not being present, they must be attributed to senile changes. There is nothing surprising in the similarity between in- flammation and senile metamorphosis, since both are essentially a re- turn to the juvenile or medullary condition. Some medullated nerves appear to be broken up into glossy lumps, owing to a splitting up of the myelin ; at the same time the parallelism of the contours is lost, and the nerves show spindle-shaped widenings, alternating with narrow tracts. (Fig. 95, N, N.) The shining lumps at least are probably transformed into protoplasmic or medullary bodies, which in turn are transformed into spindles, and ultimately into fibrous connective tissue. Thus both the constrictions in the course of the nerve and the augmentation of the perineurium become intelligible, as well as SENILE ATROPHY OF THE UPPER JAW. 233 the final loss of nerves, through their transformation into fibrous connective tissue. As to the changes of the axis-cylinders, we can say nothing, since meduUated nerves are unsuitable for the study of this particular portion. 5. Cartilage. — The appearance of hyaline cartilage (Fig. 96) in a senile jaw is, as we have before remarked, a most surjn'ising fact, going far to prove that rejuvenescence of the tissues takes place in old age. Hyaline cartilage is no doubt a transient or provisional tissue in Fig. 96. Cartilage from Senile Jaw. M, medullary corpuscles ; Z., small lumps of living matter; B, cartilage-corpuscles trans- formed into basis-substance ; G, cartilage-corpuscles, partly coarsely and partly finely granular. Magnified 800 diameters. early embryonal life, and the same seems to be the case in declining age, since it appears as a mere intermediate tissue between previous bone and the ultimate tissue, i.e., fibrous connective tissue. Hyaline cartilage in this case appears as a thin rounded-off plate, characterized by small and flat cartilage-corpuscles along the borders, while the central portions are made up of comparatively large and coarse granular bodies, when viewed with lower powers of the micro- 234 DENTAL PATHOLOGY AND PRACTICE. scope. The borders of this tissue are intimately connected with the fibrous connective tissue. (See Fig. 93, C.) The basis-substance is everywhere scanty, and partly hyaline, partly finely striated. Higher powers reveal a surprising variety in the sizes and shapes of these bodies. From the smallest lump (see Fig. 96, L) there are transitions to large oblong corpuscles, mostly arranged in groups and clusters. (See Fig. 96, M.) The shapes vary from small globules up to large protoplasmic masses, flattening one another where they are arranged like twins or triplets. Similar for- mations can be seen in almost any portion of normal cartilage, and such groups have been looked upon by histologists of olden times as striking examples of cell-division. Now we are aware that twin for- mations are visible in the earliest as well as in the latest formations of this tissue, and mean merely a grouping from the very origin, but no division. That at least the (comparatively speaking) active tissue should show lively division is beyond comprehension. Besides, how could the dense and tough basis -substance yield to make room for the rapid growth and division of cells ? Since the fact is established that the basis-substance of hyaline cartilage is traversed by living matter, as well as the protoplasmic bodies themselves, the changes in the forms and sizes of the corpuscles are easily comprehended. As the borders of the newly-formed cartilage exhibit small and finely- granular corpuscles, we are justified in assuming that the corpuscles in this situation are at rest. The central portions, on the contrary, show coarsely-granular bodies and clusters of medullary corpuscles, which seems to indicate that the latter portion Is breaking up into embryonal tissue in order to produce fibrous connective tissue, such as arises from a direct breaking up of bone-tissue. Intermixed with fully-developed cartilage-corpuscles we meet those which show only a central nucleus or nucleolus, while the protoplasm is extremely pale, and differs from the surrounding basis-substance only by Its slightly increased refraction. According to Spina, these forms mean, a gradual change of cartilage-corpuscles into basis-substance, a con- clusion which seems to be well founded. Basis-substance originates in protoplasm, and may return to the protoplasmic state at any time. This tissue strongly supports the view of the changeableness of protoplasm, and as strongly contra- dicts the old-fashioned ideas of the stability of cells. A variety in the forms of cartilage-corpuscles, as we have just described, is seen in the transitional cartilaginous tissue known as ' ' provisional callus' ' of shaft-bones. 6. Bone-Tissue. (See Fig. 97.) After individual teeth have been lost, their sockets, in time, disappear, and after all the teeth are gone the entire alveolar process fades away. This change, so common, is SENILE ATROPHY OF THE UPPER JAW. 235 known by the term "absorption," but we are not satisfied with the idea conveyed by this expression, for it is evident that a hard tissue like bone cannot be disposed of with so Httle ceremony. It would seem more reasonable to expect that it must first be reduced to its protoplasmic condition, which as such is more readily disposed oC Fig. 97. Senilk Changes of Bone of Upper Jaw. £, border of bone-tissue jagged and showing bay-like excavations; M, bone-corpuscles broken up into medullary tissue ; //, enlarged Haversian canal ; B, bone-corpuscles trans- formed into basis-substance. Magnified 800 diameters. The results of our studies in this case fully justify us in assuming that such changes do take place. Both the cortical and the spongy por- tion are much reduced, — the former, in some places, to a complete disappearance, the latter by a diminution of the bulk of its trabec- ulae. The way in which this is accomplished is twofold. The bone- tissue is attacked first upon its periphery, through the attachment of 236 DENTAL PATHOLOGY AND PRACTICE. the periosteum, and second, by an enlargement and new formation of Haversian canals in a previously perfectly-formed mass of bone. The borders are corro'ded, jagged, and amply provided with bay-like excavations, such as we see so frequently in the process of inflamma- tion of bone. The bays usually contain protoplasmic bodies of vary- ing sizes and shapes, but we have nowhere met with multinuclear bodies or giant-cells, which Kolliker termed in a rather humoristic way " bone- breakers" or "osteoclasts." The origin of these med- ullary corpuscles is occasionally traceable from former bone-corpus- cles that have been deprived of their surrounding basis-substance. (See Fig. 97, E.) Since in one connection the basis-substance is, though infiltrated with lime-salts, just as viable as are the bone-corpuscles themselves, we can readily understand that after a dissolution or liquefaction of the basis-substance protoplasmic bodies will reappear. The next stage is the elongation of the medullary corpuscles into spindles, and thence into fibrous basis-substance,' with a simultaneous new forma- tion of capillary blood-vessels. The new formation of Haversian canals proceeds in exactly the same manner as in osteitis, although on a much smaller scale. First a bone- corpuscle, or several neighboring ones, become enlarged by a liquefaction of the surrounding basis-substance. Next the living matter of such corpuscles increases in glistening homogeneous lumps. Some of the connecting canaliculi are widened into broad canals, the tenants of which increase in bulk. (See Fig. 97, M.) Thus protoplasmic masses appear in a solid basis-substance, in which, by a hollowing out of the living matter, new capillaries are produced, as noted by Heitzmann, in describing the process of osteitis, in 1872. An already-formed Haversian canal is widening by continual melting down or dissolution of the adjacent basis-substance, with a gradual reappearance of embryonal or medullary corpuscles (Fig. 97, //), the ultimate destiny of which seems to be the production of fibrous con- nective tissue. This tissue at last is liquefied into protoplasm in the manner before described. In fact, the widened medullary spaces mostly hold such protoplasm, with only a few fat-globules. An important question finds solution in the study of senile bone, viz : that of interstitial growth. Most modern histologists hold the opinion that bone-tissue grows by super-addition from without by apposition. A few writers, however, claim that bone may also grow by an increase of the basis-substance between the already-formed bone-corpuscles, which view seems to find support in the fact that the bone- corpuscles in old animals are farther apart than those in the young. Our studies enable us to account for this apparent inter- stitial growth as follows : It is a fact that with advancing age bone- SENILE ATROPHY OF THE UPPER JAW. 237 corpuscles become fewer in number, the reason for which is that many of them are transformed into basis-substance, the same as Spina has claimed that cartilage- corpuscles are. Here and there we meet with a pale, finely-granular bone-corpuscle without any vestige of a nucleus, and a refraction differing but slightly from that of the surrounding basis-substance. (See Fig. 97, B,^ Obviously a nucleated bone-corpuscle has changed into a finely- granular protoplasmic body, which means an approach to glue, and subsequently to calcification. In looking over the tissue changes from the earliest embryonal life to the approaching physiological end of the individual, one must arrive at the conclusion that there is not for a moment absolute rest in the tissues. Temporarily, single proto- plasmic bodies may make their appearance, such as we see in odonto- blasts and ameloblasts. Temporarily, tissues may come into exist- ence, as cartilage, which soon afterward are lost, or, speaking more correctly, become transformed into other tissues. So long as life lasts, protoplasm and the tissues sprung therefrom are unstable. All tissues arise from protoplasm, or its medullary or indifferent corpuscles, and all tissues return to this emb'-yonal or medullary state before they are absorbed. INDEX. Absorption of roots of temporary teeth, 94. Abscesses, treatment of, 121, 128, 135. Acid theory of decay, 73, 87, 89. Aconite as a counter-irritant, 121. Age, effect of on the human organism, 225. Alkaline treatment of sensitive den- tine, 106. Allen, H., description of fifth pair of nerves, 143. Alveolar abscess, differential diagnosis of, 124. treatment of, 124. Alveolar process, absorption of, 234. Amalgam as a filling-material, 112. Ameloblasts as enamel-formers, 38. development of, 20. Andrews, R. R., on development of dentine, 8. Anemia, dental operations in, 190. Angioma, 206. Anomalous relation between dentine and enamel, 59. Antiphlogistin, 121. Antral diseases, diagnosis and treat- ment of, 127. Antrum, function of, 127. operation for gaining entrance to, 133- Aphthous stomatitis, 192. Approximal cavities, filling of, 104. Arsenic in pulp-treatment, 114. Atkinson, W. H., on alveolar abscess, 115- plugging points, 103. Atrophy, senile, of upper jaw, 225. Automatic mallet, Abbott's, no. Beale, cell theory of, 5. Bell, T., on dental caries, 86. Benign tumors, 194. Blood-vessels, senile changes of, 231. Bddecker, C. F. W., on development of enamel, 18, 58, 70. on function of odontoblasts, 8, 35. Bodecker's enamel-fibers, 25. Bone, development of, 171. senile changes of, 234. Burnishing points, in. 238 Calculi, abscesses from, 135. Cancer, bacilli of, 195. varieties of, 220. Canker sores, significance of, 190. treatment of, 192. Carcinoma, 220. Cartilage, senile changes of, 233. Cavernous angioma, 208. Cavities, preparation of, 105. Cell theory, exceptions to, 23. Cement, caries of, 83. Cementum, absorption of, 96. Children's teeth, absorption of roots of, 94. treatment of, 90. Climacteric, influence of on antral dis- eases, 130. Cohnheim's theory of tumors, 170, 195- Creasote in pulp-treatment, 116. Dental caries, etiology of, 57, 73. Dental operations, conditions unfavor- able to, I 87. Dentifrices, antiseptic, 138, 139. Dentinal canaliculi, formation of, 7. Dentinal papilla, development of, 2. Dentine, absorption of, 99. caries of, 77. odontoblasts in relation to, 5. Ebner, Prof., on formation of dentine, 38. Embryonal malformation of teeth, 178. Enamel, absorption of, loi. anomalies of, 54, 59. asymmetry of in the growing tooth, 27. calcification of, 26. caries of, 74. congenital defects in, 46, deficient calcification of without pig- mentation, 65. development of, 15, 58. granulation of, 68. pigmentation of, 66, 75. preparation of for microscopical study, 72. sensitiveness of, 163. stratification of, 23, 61, INDEX. 239 Enamel chisels and hatchets, Abbott's, 105. Enamel-organ, development of, 2, 16, 26. myxomatous structure of, 56. Enamel-rods, anomalous arrangement of, 63. development of, 17. Endothelia, arrangement of in angi- oma, 20S. Epitheliomata, 220. Epithelium, senile atrophy of, 227. Epulis, 200. Epulis sarcomatosa, 210. Escharotics for alveolar abscess, 125. Facial neuralgia, causes and treat- ment of, 163. medicaments for, 169. False alveolar abscess, 121, 124, treatment of, 126. Fat-tissue, development of, 204. Fibril-cells, 8. identity of with odontoblasts, 36. Fibroma, 200 Fibro-myeloma, 213. Fibrous connective tissue, senile changes of, 229. Fifth pair of nerves, anatomy of, 143. extreme sensitiveness of, 163. function of, 156. First permanent molar, removal of, 92- Fox, J., on dental caries, 86. Fungous growth of the pulp, treat- ment of, 117. Gangrene of the teeth, 86. Gestation, treatment of teeth during, 188. Giant-cell sarcoma, 210. Giant-cells, presence of in benign tumors, 20 r. Gingivitis, 193. Globo-myeloma, 218. Gold as a filling-material, 102. Granular layer of dentine, 180. Granuloma of gum, 197. Gutta-percha as a filling-material, 113. Gutta-percha and wax in pulp-treat- ment, 117. Handicap tooth-powder, 138. Hart, J. I., on living matter in dentine, 50. Heitzmann, C, on development of enamel, 18. on protoplasmic development, 6, 8, 35, 70. 84. Herbst, W., method of gold filling, III. Highmore, N., description of antrum, 127. Hunter, J., on dental caries, 85. Huxley on development of dentine, 45- Hyaline cartilage, presence of in senile jaw, 233. Hyperostosis of roots of teeth, 169. Inflammation, effect of on enamel, 56, 86. Instruments for filling teeth, 103, 104, 105, 110, 112. sterilization of, 189. Interglobular spaces in dentine, 52. interprismatic spaces in enamel, 60, 68. Interstitial growth of bone-tissue, 236. Interzonal layer of dentine, 71, 182. lodin in antral diseases, 132. Iron, injury to teeth by, 190. use of in anemia, 190. Irregularities, prevention of in chil- dren's teeth, 93. Jacobi, a., on anomalies of enamel, 54- Jaws, senile atrophy of, 225. tumors of, 193. Klein, cell theory of, 5. Kolliker, A., on development of den- tine, 7. on development of enamel, 16, 18. Lactation, treatment of teeth during, 188. Leber and Rottenstein on dental caries, 87. ... Lesser, E., on ccnneclion of hirsuties with dental anomalies, 55. Lipo-fibroma. 204. Living matter in cementum, 172, 186. reticulum of in dentine, 50, 70. Lobular angioma, 206. Magitot, E., on dental caries, 86. Magnesia, preparations of for sensitive dentine, 107. Main; S. A., case of hyperostosis, 177- Malignant tumors, 194. Mallet-pluggers, Abbott's, 103. Malpositioned teeth, facial neuralgia due to, 165. Medullary cancer, 223. Medullary corpuscles as dentine-form- ers, 38. Mercurial poisoning as a cause of p>or- rhea, 137. Mercurial stomatitis, 191. Mercury, effect of on the periosteum, 189. Mercury bichlorid as an antiseptic, 1 19, 132. Mewborn, J. L., on antral diseases, 129. 240 INDEX. Micro-organisms, agency of in dental caries, 73, 76, 78, 87. Morning sickness of gestation, treat- ment of, 188. Mother cells of epithelioma, 222. Mouth, inflammatory conditions of, 191. Mouth and throat spray, 140. Mucous patches, significance of, 189. Myeloma, 210. Myxo-fibroma, 198. Myxoma, 196. Myxomatous tissue, formation of, 199. Myxo-myeloma, 211. Napkins, use of in filling-operations, 108. I Neck-layers in enamel, 63. Nerves, senile changes of, 232. Net-cell sarcoma, 211. Non-occlusion, neuralgia from, 168. Odontoblasts in their relation to de- 1 veloping dentine, 5, 35. Oral mucosa, senile changes of, 229. Osseous union of teeth, 177. Osteitis, distinction of from dental caries, 88. Osteoclasts, 202, 236. Osteo-dentine, 180. Osteo-fibro-myeloma, 217. Osteomata, 174. Osteo-myeloma, 216. Oxychlorid of zinc as a filling for pulp- less teeth, 120, 126. Perforating resorption of the ce- mentum, 187. Periostitis, aconite in, 121. neuralgia arising from, 168. Pluggers, hand, no. hand-burnishing, 104. Primitive dental groove, 2. Protoplasm, transformation of into basis- substance, 172. Provisional callus of shaft-bones, 234. Ptyalism, treatment of, 191. Pulp-capping, 115. Pulp-exposure, treatment of, 91, 114. Pulpless teeth, facial neuralgia due to, 167, treatment of, 118. Pulp-stones, 164. Pyorrhea alveolaris, 136. Rachitis, influence of on develop- ment of the teeth, 29, 55. Rodent ulcer, 223. Roots, hyperostosis of, 169. Rubber-dam, objections to, 108. Saliva, control of in filling-opera- tions, 107. Salivary calculus, 136. Salivary glands, abscesses in, 135. Saw and file carriers, 112. Scalers, varieties ot, 141, 142. Schultze, M. , transformation theory of, 5,6. Secretion theory of Virchovi^, 5, 16, 84. Sections, preparation of for the micro- scope, 28, 72. Sensitive dentine, treatment of, 106. Spindle myeloma, 219. Spontaneous stomatitis, 191. Spray, antral, J32. mouth and throat, 140. Stellate reticulum, function of, 15. Stomatitis, varieties and treatment of, 191. Syphilis, diagnosis of, 189. Syringe for treatment of antral dis- eases, 131. for treatment of pulpless teeth, 120. Tartar, arrest of caries by, 73. facial neuralgia from, 167. instruments for removal of, 141, 142. Teeth, caries of, 57, 70. deciduous, treatment of, 90. development of, i. filling of, 102. order of eruption, 90. osseous union of, 177. stage of development of at birth, 28. Tin as a fifling-material, 112. Tissues, rejuvenescence of in old age, 233- varieties of in the animal body, 193. Tomes, J., on dental caries, 89. on development of enamel-rods, 17, 18. on function of odontoblasts, 9. Tomes processes, 24. Tooth-brush, best form of, 138. local disturbances caused by, 192. Transformation theory of Schultze, 6. Tumors, cause of, 195. nomenclature of, 194. Ulitis, 193. Vacuolation of the endothelia, 210. Vaso-dentine, 183. Virchovi^, secretion theory of, 5, 16, 84. Waldeyer, F., on formation of enamel, 17. Wedging, methods of, 104. Wedi, C, on dental caries, 88. White decay of teeth. 65. Wood creasote in pulp-treatment, 116. Zinc chlorid as an escharotic, 125. Zinc phosphate as a filling-material, 113- 'i« •'■' "; »■ i 1 m. x^ -.'^ I ()#^