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 -#MiGr05G0piGal Studies^^ 
 
 ■U"I=03Sr THE 
 
 llisorptioo of tlie Roots of Temporarj Teetk 
 
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 WHITNEY MEMORIAL PRIZE ESSAY OF THE DENTAL SOCIETY 
 OF THE STATE OF NEW YORK, 1S84. 
 
 By frank rABBOTT, M. D 
 
 RepHn'ed from the IiVDEPEA'DEX T PRACTITIONER 0/ July, 1884. 
 
 NEW YORK DENTAL juL'RNAL ASSOCIATION, 
 No. 35 West 4<ith Street, New York.
 
 
 Microscopical Studies Upon tlie Absorption of the 
 Roots of Temporary Teeth. 
 
 The fact that temporary teeth, previous to the appearance of the 
 permanent ones, are considerably reduced in size, often lacking 
 roots, often consisting only of a thin shell, and exhibiting a cor- 
 roded festooned surface, has long since attracted the attention of 
 observers. It has never been doubted that a persistent, though 
 graded, irritation causes the absorption ; but what the real cause of 
 this irritation is we cannot tell. The idea that in all cases the 
 pressure of the growing permanent tooth is the direct cause must 
 be abandoned, since clinical observation shows that the absorption 
 of a temporary tooth may take place though far distant from the 
 permanent one ; nevertheless, we maintain that the growth of the 
 latter, indirectly at least, causes the irritation, and consequent 
 absorption. 
 
 The assertion of Tomes that it is due to the presence of 
 freely vascularized papilla does not explain the decrease of the 
 dental tissues, for the papilla is nothing but medullary tissue, 
 such as we meet with in any part of the organism where one tissue 
 is about to change into another. Such a papilla can be the cause 
 of the absorption, as well as its result. Another assertion, that 
 the medullary cells eat out the dental tissues by their active growth, 
 or by their ameboid motions, is insufficient for the explanation of 
 the loss of the lime-salts in the dental tissue, the presence of circu- 
 lar or semi-circular excavations and bays, so characteristic of the 
 melting process of the cementum and dentine of deciduous teeth. 
 
 Since we know that pieces of dead bone or ivory may be absorbed 
 with figures similar to those found on the surface of temporary 
 teeth, the idea j)ossibly becomes admissible that, owing to the 
 presence of an acid, first the lime-salts are dissolved out within
 
 certain territories of the dead bone tissue in a merely chemical or 
 passive way, whereupon the soft medullary tissue penetrates the 
 spaces thus established. Quite different, however, will be the con- 
 ception of this process if we bear in mind that the temporary 
 teeth, as well as the permanent ones, are made up of living tissues, 
 and an active participation of these tissues must be expected in the 
 process of transformation of the dental into that of medullary 
 tissue. As the process of absorption is closely allied to the process 
 of inflammation, and active changes of the dental tissues have 
 been proven to follow inflammation beyond any doubt, we may a 
 priori expect such changes of the bone tissues of the temporary 
 teeth in the process of absorption also. I shall try to prove in this 
 paper that such changes really do occur. In the light of the most 
 advanced modern views concerning the structure of the dental 
 tissues, we consider cementum, dentine, and enamel as endowed 
 with properties of life, or, in other words, as pervaded by living 
 matter in the shape of an extremely delicate reticulum. In this 
 view not only the cement "corpuscles and their coarser offshoots 
 contain living matter in the shape of so-called " granular proto- 
 plasm," but the whole basis-substance present between the cement 
 corpuscles is alive also, only the minute meshes of the living reti- 
 culum holding a gluey basis-substance saturated with lime-salts. 
 In the dentine, not only the tenants of the dentinal canaliculi (the 
 dentinal fibers) are alive, but the whole mass of gluey and calcified 
 basis-substance between the dentinal canaliculi is also living. The 
 same holds good for the enamel, in which the delicate fibrilge be- 
 tween the enamel prisms have positively been proven to be living 
 matter, but the prisms are pierced by living matter, though the 
 latter has not been demonstrated directly, but indirectly in morbid 
 changes of the enamel. Of the cementum, we know that each 
 cement corpuscle occupies the center of a more or less globular 
 territory of basis-substance. If, therefore, circular fields of absorp- 
 tion appear in the process of inflammation and absorption of the 
 cementum, we can readily trace these territories in following out 
 the portion affected by the process of absorption. But how shall 
 we explain the bay-like excavations in the dentine aad enamel so
 
 often seen in reduced temporary teeth, where there is nothing 
 known of territories? Here the first difficulty sets in, due to the 
 lack of knowledge of the history of the development of dentine 
 and enamel. Czermak's interglobular spaces indicate the presence 
 of such territories in the dentine, the presence of which, however, 
 can be proven only after accurate researches in the history of devel- 
 opment. 
 
 Granted that the dissolution of lime-salts takes place in globular 
 territories in the dental tissues, the next question will be, how do 
 the medullary elements appear in such spaces ? Do they migrate 
 or penetrate from without, or do they originate, in part at least, 
 from the living material present in all dental tissue ? 
 
 ABSOKPTION OF CEMENTUM. 
 
 The process of absorption of a provisional tooth begins on the 
 cementum of the roots. The latter exhibits before the beginning 
 of this process the features of cementum of permanent teeth. 
 Primarily, the absorption is marked by the appearance of the 
 well-known fields so commonly met with in the process of osteitis, 
 that is, excavations on the surface, either semi-circular or composed 
 of a varying number of semi-circular festoons, all of which are 
 filled with medullary elements, multinuclear bodies, or a delicate 
 myxometa, in part a bony, in part fibrous connective tissue, blend- 
 ing with the adjacent myxometous or fibrous pericementum. The 
 communication of the excavations with the pericementum is either 
 widely gaping or through a narrowed neck on the surface of the 
 cementum. Sometimes, however, in the sections the excavations 
 appear isolated, without any communication with the surface, 
 which latter instance, however, will certainly not entitle us to deny 
 the existence of such a communication on a plane above or below 
 that of the section. In the excavations the cementum is unques- 
 tionably reduced first into medullary, afterward into myxometous 
 or fibrous tissue. By closely watching excavations of a more 
 recent date at the periphery of those in communication with the 
 pericementum, we notice that the lime-salts and the basis-substance 
 proper are missing, and are replaced by a uniformly granular
 
 protoplasm, or a varying number of faintly marked medullary 
 elements, each of which may contain a central nucleus. We can 
 trace a gradual change of the tissue of cementum from a dissolu- 
 tion of lime-salts to the appearance of a mass of granular proto- 
 plasm, and at last to the formation of medullary corpuscles. The 
 circular shape of the excavation is in all cases undoubtedly due to 
 a dissolution of the lime-salts, and afterward of the basis-substance 
 proper, within the territory of a cement corpuscle. Sometimes we 
 see an enlargement of the lacuna and the cement corpuscle itself, 
 the latter splitting up into a varying number of glistening lumps, 
 which are readily stained by an ammoniacal solution of carmine. 
 In other instances the whole territory of a cement corpuscle is 
 transformed into protoplasm, and the reappearance of such proto- 
 plasm is traceable through broad offshoots to neighboring cement 
 corpuscles. In a third instance a varying amount of the territory 
 has assumed a delibate fibrous appearance, caused by an early group- 
 ing of the medullary corpuscles into fibrillse. In neither of these 
 instances will it be doubted that the cement corpuscles themselves, 
 or the living matter held in their territories, have in an active way 
 taken part in the reappearance, first of protoplasm, and afterward 
 of medullary corpuscles. The theory that immigrated medullary 
 corpuscles, or "leucocytes," have replaced the former cement tissue 
 must be abandoned as soon as we can trace a gradual transforma- 
 tion of the tissue of the cementum into medullary tissue. The 
 latter immediately assumes the characteristic features of a myxome- 
 tous or fibrous connective tissue, in connection with the perice- 
 mentum (Fig. 1). 
 
 From this point of view there is no diflBculty in explaining the 
 appearance of multinuclear bodies, so-called " myelo-plaxes," in the 
 dissolved territories. We know that such formations represent a 
 stage of development of cementum, and they simply reappear as 
 soon as the basis-substance of an already-formed cementum is dis- 
 solved or liquefied. In fact, nothing else is required but a reforma- 
 tion of basis-substance and its recalcificatiou, in order to reproduce 
 new bony tissue, such as we often meet with on the periphery of 
 absorbed cementum.
 
 The result of the absorption is, next a myxometous or fibrous 
 connective tissue freely supplied with newly-formed blood vessels. 
 
 ea 
 
 
 Fig. 1. — ABSORPTION OF CEMENTUM. 
 
 C, — Cementum, whose corpuscles are in part in a process of division. 
 F. — The basis-substance of cementum transformed into a delicate fibrous 
 tissue, in connection with a considerably enlarged and split up cement cor- 
 puscle. M. — Multinuclear protoplasmic mass, sprung from the cementum 
 after liquefaction of its basis-substance. The large offshoots of this mass 
 show the process of transformation of the basis-substance into medullary cor- 
 puscles. F. C. — Fibrous connective tissue, the result of the liquefaction of 
 cementum. Magnified 500 diam. 
 
 In this tissue an active new formation of bony trabeculae of bone 
 takes place, characterized by the presence of large and irregular 
 bone corpuscles. The widened socket, or dissolving surface of an 
 absorbing provisional tooth, is not infrequently filled with newly 
 formed bone. The newly formed layer of cementum in part shows 
 circular fields (territories) of bone tissue, each of which may con- 
 tain a varying number of bone corpuscles, or there is a uniform 
 reduction of the original cementum, the boundary of which is
 
 made up by regularly arranged medullary corpuscles, so-called "os- 
 teoblasts." 
 
 Fig. 2. — ABSOBPnoN op neck op tooth. 
 N. — Dentine of neck of tooth not supplied with canaliculi. D. — Canali- 
 culi of dentine stopping short of the surface of the neck. B. — Bay-like exca- 
 vations in the middle of dentine, filled with a pale and finely granulated 
 protoplasm, nuclei beginning to appear. G. — Excavation filled with coarsely 
 granular protoplasm, tending toward an active new formation of medullary 
 corpuscles. M. — Multinuclear protoplasmic bodies, the so-called "myeloid 
 cells," in connection with fibrous connective tissue on the surface. Magnified 
 600 diam. 
 
 On the neck of the tooth the excavations penetrate not only the 
 layer of the cementum proper, but also the layer of the subjacent 
 dentine, which we know to be destitute of dentinal canaliculi. Here 
 again we observe at first a dissolution of the basis-substance in 
 globular fields, which appear filled at first with a finely granular 
 protoplasm, lacking nuclei, afterward with usually nucleated med- 
 ullary corpuscles, and at length with a slightly fibrillated tissue, the 
 latter undoubtedly originating from a splitting of the medullary 
 corpuscles into a number of delicate spindles. The surface of the
 
 neck of the tooth likewise exhibits the characteristic bay-like ex- 
 •cavations which are filled with nucleated medullary corpuscles, or 
 with multinuclear protoplasmic bodies. From Avhat I have seen, I 
 cannot doubt that the nuclei under all circumstances are secondary 
 formations, and cannot be regarded as the future bone corpuscles. 
 A territory of bone tissue will form only after the protoplasm has 
 assumed a uniform granulation, and the bone corpuscles will develop 
 out of this protoplasm, by an increase of living matter at certain 
 regular intervals. The result of the absorption and reappearance of 
 the embryonal condition of the tissues, constituting the neck of the 
 tooth, results in the formation of new bone tissue, either in the 
 shape of globular fields (territories) of newly-formed bone tissue, or 
 in the formation of a thin layer of regularly lamellated bone tissue, 
 blending with that formed out of the cementum of the roots. 
 
 Bodecker, in his article on the distribution of the living matter 
 in the dentinal tissues (Dental Cosmos, 1878-79), describes and 
 illustrates the neck of a tooth, calling it an anomalous formation of 
 cementum. From what I have seen I cannot doubt that his figure 
 is taken from a deciduous tooth, exhibiting newly-formed bone 
 tissue on the neck. Unquestionably such bony formations are not 
 lasting, but are reformed into medullary tissue with the advancing 
 absorption of the dental tissues, either leading to the formation of 
 new bone or of fibrous connective tissue. 
 
 ABSORPTION OF DENTINE. 
 
 The most striking features in the dentine of deciduous teeth are 
 the bary-like excavations on the surface after a complete disappear- 
 ance of the covering cementum. The excavations contain medul- 
 lary corpuscles, multinuclear bodies, or fibrous connective tissue, in 
 connection with the surrounding pericementum, or periodontium. 
 The appearance of such fields in the dentine gave rise to the theory 
 that a foreign tissue grows into the dentine, destroying it in the 
 manner in which dead bone is destroyed. If, however, we bear in 
 mind that the tissue of dentine is composed of globular territories, 
 the'same as that of bone, we at once are in the position to under- 
 stand the striking appearance of globular fields of absorption in the
 
 dentine. The question can only be, is the dentine absorbed in a 
 merely passive way, or does it share in the formation of medullary 
 tissue, so long, at least, as it is the seat of life in itself? My re- 
 
 FIG. 3. — ABSOBPTION OP DENTINE. 
 
 D. — Dentine provided with unchanged canaliculi. B. — Bay-like excavation 
 in the dentine, containing finely granular protoplasm, which is about to form 
 medullary corpuscles. F. — Medullary corpuscles elongated and split into deli- 
 cate spindles, the future fibrous connective tissue. M. — Globular protoplasmic 
 masses, the predecessors of globular territories of bone tissue, Q. — Globular 
 territories of bone tissue, with central bone*corpuscles. L. — Lamellated bone 
 tissue surrounding the outer surface of the absorbed tooth, or the inner surface 
 of its socket. Magnified 600 diam. 
 
 searches strongly point in favor of an answer in the latter direction. 
 In several instances I have been able to trace a slight widening of 
 the dentinal canaliculi on the border of the fields of absorption, 
 with an increase of living matter in the canaliculi. Such features 
 are very common in the process of caries, where the dilatation of 
 the canaliculi at the expense of the intervening basis-substance, and 
 a new formation of medullary elements out of the tenants of the 
 canaliculi, is a very common occurrence, provided that the caries 
 attacks the living dentine. Circumscribed bay-like excavations, 
 such as are common in the absorption of dentine, I have frequently 
 met with in caries.
 
 9 
 
 Sometimes such excavations, in caries, form independently of the 
 surface destruction, and with the lower powers of the microscope 
 even a well-versed eye, under these circumstances, would experience 
 difficulty in discriminating between carious destruction and absorp- 
 tion of temporary dentine. Higher powers, to be sure, reveal the 
 presence of micro-organisms in the former process, which are lack- 
 ing in the latter. The first step seems to be identical in both in- 
 stances; a dissolution of the lime-salts, or a displacement of the 
 lime-salts, by the liquefaction of the glue giving basis-substance. 
 After this, medullary elements arise out of the liquefied dentine 
 which are destined to decay in caries, and, on the contrary, pro- 
 liferate in the process of absorption, with the result of the new 
 formation of medullary tissue. In caries the process of softening, 
 or the removal of the calcified basis-substance, results in the death 
 and putrefaction of the tissue ; that is, its replacement by micro- 
 organisms. In the process of absorption, on the contrary, it ends 
 in an active proliferation of medullary tissue, with the non-inter- 
 ference of micro-organisms. 
 
 The result of the latter process is the same whether it occurs on 
 the cementum, on the neck of the tooth, or in canalicularized den- 
 tine. The newly-formed medullary tissue consists either of single 
 medullary corpuscles, usually with one oblong and faintly-marked 
 nucleus, or in the shape of larger protoplasmic masses with a vary- 
 ing number of oblong nuclei, so called " myeloid cells." At the 
 border of the bays I have sometimes been able to trace delicate 
 thorny projections from the multinuclear masses into the unchanged 
 basis-substance of the dentine. Sometimes I have seen broad off- 
 shoots of the multinuclear bodies penetrating the widened dentinal 
 canaliculi, and in direct union with the dentinal fibers. The latter 
 feature, especially, seems to point strongly toward an organic con- 
 nection between the unchanged and the dissolved out dentine. 
 
 The multinuclear bodies are, as is well known, the future terri- 
 tories of bone tissue, and therefore predecessors of bone tissue. The 
 formation of bony territories can easily be traced on the surface of 
 absorbed dentine. Just as in normal development of bone tissue 
 globular territories first appear, and afterward lamellated bone
 
 10 
 
 tissue, so also iu absorbed dentine, first multinuclear bodies, after- 
 ward globular territories of bone tissue, and at last lamellated bone 
 tissue forms on the surface, the latter producing, in many instances, 
 a continuous layer of bone all around the absorbed tooth. This 
 feature is correctly observed and described by Tomes. 
 
 As to absorption of the enamel I can say but little. It is well 
 known that bay-like excavations are seen in this tissue, in no way 
 differing from those of cementum and dentine. From this fact it 
 would follow that all the theories hitherto advanced with regard to 
 the development of enamel must be erroneous, and there must be 
 an arrangement in the enamel forming tissue leading to the produc- 
 tion of territories in a manner similar to that of dentine and 
 cementum. It seems that the process of destruction, starting on 
 the surface of the enamel, is in all instances caries, and not absorp- 
 tion. The latter process attacks enamel only from within. After 
 most of the dentine has been absorbed and transformed into myxome- 
 tous tissue, the enamel is attacked and thinned to a varying degree 
 by the same process. Thus it becomes intelligible that the shell of 
 enamel left, is coated by a layer of lamellated dentine, which is con- 
 tinuous all around the remnants of the provisional tooth. 
 
 Since we know that enamel is a live tissue in a living tooth, we 
 may anticipate its reduction into medullary tissue in the process of 
 absorption. Whether or not such a breaking down of enamel occurs 
 and its consequent participation in the formation of bone tissue, I 
 am unable to say.
 
 THE INDEPENDENT PRACTITIONER. 
 
 VOLUME V, 1884. 
 
 A PRACTICAL MEDICO-DENTAL JOURNAL, 
 
 EDITED AND PUBLISHED BY 
 
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 dentistry. 
 
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