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Histopathology of the Dentin and Enamel*
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T h e Journal of the American D ental Association
olism th an of food intake, and (7 ) the individual child w ill eat am ple am ounts
H IS T O P A T H O L O G Y
OF
of, for him, th e rig h t kind of food as long as he is given th e opportunity.
THE
D E N T IN
A N D
ENAM EL*
By T H E O D O R E B EU ST , D .D .S., Louisville, Ky.
H E N considering th e dictionary in terp retatio n of th e te rm “ p ath ology” in its application to the h ard stru ctu re s of the teeth, one is re
W
pow ers th a t could enable these tissues to effect biologic changes w ith in th e ir sub stance. S tru c tu ra l and fu nctional chang es can occur only in stru ctu res possessing
Fig. 1.—Caries. L T , translucent zone; L O , lateral opaque chromophilic zone. m inded th a t m any doubt the existence of *From the Research L aboratory of the School of D entistry, U niversity of Louisville. *W ork supported in p a rt by a g ra n t from the R esearch Commission of the A m erican D ental Association. *Read at the Seventy-F ifth A nnual Session of the A m erican D ental A ssociation in con junction w ith the C hicago C entennial D ental Congress, A ug. 9, 1933. Jour. A .D .A ., A p ril, 1934
the a ttrib u te of reactivity. A piece of g ran ite is n ot th u s en d o w ed ; nor is a piece of lead or silver. T h e y lack the vital elements. T h e h ard substances of th e teeth, ac cording to m any authors, are therefore not eligible fo r classification w ith tissues capable of reacting, in a pathologic sense, to irritatio n . G . V . Black, A rth u r
Beust— Histopathology of D entin and Enamel
647
H opew ell-Sm ith an d J . L eon W illia m s have regarded calcified to o th substance as in e rt and unchangeable. T h is opinion has been reflected by th e large m ajo rity of d ental practitioners, b u t this point of view is open to grave objection.
reactions occur in both th e den tin and the enam el. I call atten tio n to the pos sibility of in jectin g th e enam el of recent ly erupted teeth by causing stains applied to th e pulp cavity 1 to follow th e n a tu ra l channels leading from th e pulp into the
Fig. 2.— Sclerosis follow ing abrasion of a low er incisor, stained a fte r treatm ent of tooth w ith ether and alcohol. (H a lv ed tooth.)
Fig. 3.— A b rad ed sclerosed cuspid, halved tooth, stained fo r one m onth in strong alcoholic fuchsin. A fte r staining, the p a la tal enam el w as rem oved. Repeated exposure to the stain failed to affect the opened tubules.
N o th w ith stan d in g m uch excellent w ork and the m any exhaustive argum ents supporting the tw o sides of this question, recent histologists, in view of th e many convincing observations indicating the oc currence of posteruptive anabolic proc esses in th e to o th ’s calcified parts, now incline m ore and m ore to the view th a t
enamel tissue. T h is experim ent has been corroborated by M u m m ery ,2 C . F . Bo1. Beust, T . B. : D . Cosmos, 54:659 (June) 1912. 2. M um m ery, J. H . : B rit. D. J., 4 3 :607 (July) 1922.
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decker ,3 Sm reker 4 and F ish .5 T h e m ere com parison of results attained in young teeth w ith like attem pts m ade la te r in life, w hen such com m unications no long er exist, suffices to prove th a t such changes occur. T h is is not a ll: In the dentin, w here the tubules of the recently erupted tooth conduct fluids w ith eagerness and com m unicate these to th e d entinal ground substance, sim ilar experim ents u n d erta k en w ith th e teeth of the aged reveal th a t this conductivity has been reduced to nil,
Fig. 4.— A b rad ed bicuspid w ith opaque sclerosis of tubules involved. A p lug of sec ondary dentin covers the tubules. O bservation of such specimens by transm itted lig h t creates the erroneous im pression of “ d ead” tubules containing necrosed fibrils. (T ran sm itte d light photograph, stained specimen.) SO, sclerosed opaque dentin, T S , tran sp are n t secondary den tin.
o r is lim ited to isolated w ell defined regions o r exists only in th e younger 3. Bodecker, C. F .: P erm eability of E nam el in R elation to Stains, J.A .D .A ., 10:60 (Jan .) 1923. 4. Sm reker, E. : Z tschr. f. Stomatol., 24:460, 1926. 5. Fish, E. W .: C irculation of L ym ph in D entin and E nam el, 14:804 (M ay) 1927.
dentin in the im m ediate vicinity of the pulp. T h e changes here described gave rise to my concept of to o th m a tu ratio n ,6 a te rm and concept th a t has since been adopted by C . F . B odecker .7 T o o th m a t uration, as th e nam e implies, embodies the final changes occu rrin g as a resu lt of pulp cavity o b literation by d en tin dep osition, resu ltin g in loss of m etabolic ac tivity in th e enam el, in th e d en tin al fib ril, in th e m a trix substance, in the tubules and finally in the pulp. T h e dem onstration of th e changes m entioned leaves no doubt th a t the calci-
Fig. 5.-^-Reflected lig h t photograph of speci men show n in F igure 4. T h e zone SO is re vealed as chrom ophobic sclerosed dentin.
fied too th stru ctu re s change d u rin g life and th a t as long as v ital pulp is present, they are biologically functioning p arts of th e organism . D u rin g th e life of the pulp, the tooth, in com m on w ith oth er tissues, m ay react to trau m a, physiologic stress, continued irrita tio n and possibly n u tritio n al disturbance. 6. Beust, T . B. : R eactions of D en tin al F ibril to E x ternal Irrita tio n , J.A .D .A ., 18:1060 (June) 1931; J. D . Res., 11:267 (A p ril) 1931; P osteruptive C hanges in M a tu ratio n of T eeth, J.A .D .A ., 18:2186 (N ov.) 1931; J. D. Res., 11:619 (A ug.) 1931. 7. Bodecker, C. F., and A pplebaum , E d m u n d : D . Cosmos, 74:1177 (Dec.) 1932.
Beust— Histopathology of D entin and Enamel CARIES
I n o rd er th a t new er phases of reactions m ay be presented, the know n facts of to o th destruction by caries as first laid dow n by L eber and R ottenstein 8 and la ter modified by W . D . M ille r and
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is of in terest to note th a t th e d ark fibers in question, w hich w ere first rem arked on by W . D . M ille r, are chrom ophilic. (F ig . 1.) T h e conclusion arriv ed at in my papers w as th a t this area represents a hyperchrom ophilic im flam m atory zone
Fig. 6.— Form ation of “developm ental” lines by aggregations of clouded tissue into lines.
others w ill be om itted. F o r this p a rt of th e w ork, reference is m ade to the excel len t w o rk of K ro n feld .9 T h e question of form ation of visible fa t in the tubules su rro u n d in g the tran sp a ren t zone de m ands some com m ent. K ronfeld, quottin g W e b er, E u ler, M ey er and Liesegang, implies th a t fa t globules appear in th e tubules adjacent to the tran slu cen t zone. F a t soluble stains w ere used in the determ ination of th e presence of fa t in this case. T h e area involved w as discussed a t len g th in tw o of m y recent papers. I n the first ,10 th e pulpal and the term inal ends of the tubules and th eir relation to th e tran slu ce n t zone w ere described. I t 8. L eber a n d R ottenstein: U ntersuchung ueber die K aries der Z aehne, B e rlin : H irschfeld, 1860. 9. K ronfeld, R u d o lf: H istopathology of T eeth, P h ila d e lp h ia : Lea & Febiger, 1933. 10. Beust, T . B .: R eaction of D entin to A d v ancing Caries, J.A .D .A ., 20:631 (A pril) 1933.
Fig. 7.— E nlarged section of most conspicu ous line show n in F igure 6.
w hich m arks th e tran sitio n of th e norm al tu b u le into th e tran slu cen t form of den tin . T h is conclusion appears justified in view of th e fact th a t both zones m ay ap pear u n d er early caries, and th a t they th e re afte r keep pace w ith th e advance of
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th e lesion, both la terally and centripetally, u n til th e caries has reached extrem e dimensions. As I showed in an earlier paper 11 th a t fa t soluble Sudan I I I colors any tubules th a t are susceptible to fuchsin stain, the reaction noted in this hyperchrom ophilic zone does not necessarily denote th e pres ence of fat. T h e question of a fa t con te n t of these tubules is of c u rre n t interest, as C . F . Bodecker regards fa t as the
potency of D r. B odecker’s supposed fat deposits as barriers to fluids, tw o photo graphs are offered by him in re b u tta l .12 In these, he claim s to have succeeded in dissipating the opacity of th e tubules by boiling in xylene. A s he has recently ex pressed d oubt concerning his ow n experi m ent ,18 and as th e insignificant differences in opacity m ay be attrib u tab le to d if ferences in th e substage illu m in atio n and other conditions incident to th e heating
Fig. 8.— Diffuse d ap p lin g of dentin.
agent th a t prevents perm eation of th e tubules by fluids. T h e presence of fa t in this hyperperm eable zone therefore w ould add another paradox to th e m uch confused state of our know ledge of the reactions to caries. A s I doubted the
11. Beust, T. B.: D. Cosmos, 74:541 (June) 1932.
of the specimen, th e m a tte r dem ands fu r th e r atten tio n . SCLEROSIS OF T H E D E N T IN
Sclerosis of th e dentin, p articu larly of 12. Bodecker, C. F .: D . Cosmos, (Ja n .) 1933 (Figs. 14-15). 13. Footnote 12 (Footnote 15).
75:21
Beust— Histopathology of D entin and Enamel the zones found u n d er abrasion and caries, has been given m uch consideration by d ental authors d u rin g the past tw o years. T h e contention m ade in my paper read at D en v e r in 193014 and in a paper presented before the Chicago section of th e In te rn a tio n a l Association fo r D en ta l R esearch 15 th a t irrita te d dentin o rd in ari ly became sclerosed m et w ith expressions of skepticism. T o d ay , both the view and the te rm used to express the condition are regarded m ore favorably. T h e fact th a t a sclerosis occurs can no longer be doubted, yet th e actual condition of the affected tissue still constitutes a problem .
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ositions laid over th e ir cen tral ends by the pulp. A s th e physical n atu re of den tin containing necrosed fibrils m u st be conducive to perm eation by alcoholic fuchsin stain, th e m a tte r w as given f u r th e r atten tio n . C a re fu l tests have con vinced me th a t th e pulpal seal of second ary den tin show n by au th o rs who regard it as a b arrier does n ot ord in arily cover open tubules, b u t th a t th e tubules are im perm eable th ro u g h o u t th e ir length. (F ig . 3.) T h e p u lp al seal m ust therefore be re garded as a reinforcem ent of dentin thac has already undergone sclerosis. (F ig s. 4 and 5 .) D E V E L O P M E N T A L LINES
Fig. 9.— Superficial “hypoplastic” enamel lesion, stained.
M y published experim ents proved th a t this tissue is im perm eable to fluids. C . F . Bodecker has claim ed th a t abraded areas analogous to those show n in F ig u re 2 are perm eable from w ithout, b u t th a t a cal cified p lug of secondary dentin seals the p u lp al ends of th e tubules. E . W . Fish has also held th a t abraded fibrils die dow n to th e pulp, and th a t these fibrils undergo necrosis and are sealed by dep 14. Footnote 6, first reference. 15. Footnote 6, second reference.
In the discussion of deviations from the norm al, w e are confronted w ith the difficulty of discerning betw een the physi ologic or anatom ic and the pathologic. Ju d g in g n o rm ality by th e frequency of occurrence w ould be futile, as some con ditions th a t are supposed to be evidence of m aldevelopm ent are universally rep re sented in teeth. I call atten tio n to the in terg lo b u lar spaces and th e tu fts. Be cause of o u r inability to differentiate ac curately, it w ould be p ertin en t to include in this paper any condition th a t is being regarded as a hypoplasia o r defect. T h e alinem ent of in terg lo b u lar spaces into row s roughly follow ing th e contours of the dentin, called the lines of C zermak, are adequately know n. O th e r lines pu rsuing the same course, caused by su d den deflections in the course of the tu bules, are know n as O w e n ’s lines. I wish to rep o rt on a th ird v ariety of line caused by differences in th e calcification of the dentin. R ow s of poorly calcified areas distinct from , b u t evidently related in origin to, th e in terg lo b u lar spaces are le ft in th e m a trix as dentin developm ent proceeds. (Figs. 6 and 7 .) T h e individual spots are m orphologically identical w ith those causing th e dappling of th e dentin
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found associated w ith caries. H ere, the dappling becomes intensified as caries progresses, as if the tissue w ere in a hyperem ic state. O ccasionally, teeth are m et w ith th a t display this dappling th ro u g h o u t the den tin of the crow n por tion. (F ig . 8 .) A s th e irre g u la r spots causing th e dappling appearance are sus ceptible to staining, it is evident th a t they represent poorly calcified areas in the m atrix. ENAMEL
E xperienced practitioners of dentistry
pear “ chalky” and have th e appearance of having been decalcified by an acid. O n e or m any teeth m ay be affected. T h e areas are usually w hite, o r m ay v ary from a cream color th ro u g h various hues of reddish brow n to deep brow n. A loss of surface co n tin u ity is n ot in evidence. W h e n subjected to p ro tra cted exposure to alcoholic aniline stains, these areas are found to be perm eable. (F ig . 9 .) T h is differentiates them from th e norm al enam el of a d u lt teeth, w hich fails to stain. D entists, and also certain histol ogists 9 reg ard these affected areas as
Fig. 10.— Superficial enamel lesion showing clouding of rod substance and surrounded by increased visibility of striations.
are fam iliar w ith th e occurrence of v aria tions in th e translucency of the enam el covering the teeth. T h e norm al lu ster of th e enam el gives place to modifications th a t indicate changes in its physical o r chem ical stru ctu re . O n e of these anom a lies m anifests itself in th e occurrence of spots o r even of large areas th a t may cover a w hole to o th surface and th a t ap-
caries. In fact, some of these areas m ay be caries; yet it is also w ell established th a t teeth so affected are n o t necessarily carious an d fu rth e rm o re th a t they m ay rem ain free from caries th ro u g h o u t the life of th e subject. Lesions resem bling these are exhibited on th e teeth of th e low er anim als, the pig being a com mon example. M icroscopic exam ination of the
Beust— Histopathology of D entin and Enam el unstained specimens discloses th e same opacity th a t is perceptible to the unaided eye. T h e striations, “beading,” of the rods is seen to be exaggerated and the w hole tissue appears clouded. (F ig . 10.) In th e stained specimens, th e affected areas are diffusely stained, the substance of th e rod itself being colored. R arely, th e interprism atic substance appears to
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m y experim ents conducted in 1924tG show th a t enamel, especially th e enam el
Fig. 13.—Worn intact tooth with multiple deep-seated areas of hypoplasia, stained. (Re flected light photograph.)
Fig. 11.—Extensive deep-seated underdevel opment of enamel, stained. The fissure caries is independent of the lesion.
Fig. 12.—Deep-seated underdevelopment of enamel, stained. The progress of the fissure caries does not appear to be influenced by it. (Reflected light photograph.)
be m issing and the rods appear intact. T h e enam el is affected to varying depths. I t m ay be said in support of th e as sum ption th a t th e enam el u n d er discus sion has been decalcified by acids form ed u n d er colonies of aciduric bacteria th a t
Fig. 14.—Diagonal sections of stained tuft “fibrils” proving that rods are intact. 16. Beust, T . B. : Contribution to Etiology of M ottled Enamel, J.A.D.A., 12:1059 (Sept.) 1925.
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of recently erupted teeth, w hen treated by very d ilu te acids, can be decomposed to various depths w ith o u t th e loss of su r face continuity. W e have in these lesions a m orphologic parallel to the affliction know n as “ m ottled enam el.” A ccepting
norm al w e w ould have a clue to the causes of this anom aly. A cknow ledging th e difficulties of in te r pretatio n presented by th e superficial le sion, above described, a problem of far greater com plexity is presented by th e oc-
Fig. 15.—Close-up of stain conducting capillary spaces or fibrils, showing intact rods.
Fig. 16.—Parallel tuft rows seen from side in tangential slice from molar.
th e as yet unsubstantiated hypothesis of m o ttled enam el etiology, w hich assumes a p reeruptive substitution of foreign in gredients, in this case fluorine, fo r the
currence of sim ilar changes in th e deeper regions of th e enam el. T h is form m ani fests itself as changes in hue to lig h ter or d ark er involving sm all o r large areas, or
Beust— Histopathology of D entin and Enamel even w hole teeth. T hese differ in ap pearance from the superficial form in th a t the o u te r region of th e enam el stru c tu re is norm al, th e teeth exhibiting in this case th e usual luster. W h e n subjected to my test for perm eability ,15 it can be observed th a t th e o u te r region of the enam el is norm al, th e inner p a rt of the
655
moved from outside influences. (F ig . 13.) T h e etiologic significance of caries, o r an attac k by acids, is here en tirely excluded. T h e substitution theory, m entioned in connection w ith th e superficial form , also loses significance as substitutions logically follow developm ental laws, the lesions in question occurring quite erra t-
Fig. 17.— Group at lower left of Figure 16, magnified.
tissue displaying the anom alous condition seen in the superficial lesion. T h e enamel w hich answ ers this description (Figs. 11-1 2 ) has not been influenced by breaks in surface continuity lying near th e plane from w hich th e section w as m ade. In fact, th e lesion may be found in serial sections m ade from in tact teeth. I t frequently appears in isolated spots lying in the depth of th e enam el, re-
ically. F o r p ractical purposes, these le sions may be term ed hypoplasia. TU FTS
O th e r anom alies of th e enam el, if the reports of m any histologists are given credence, are th e enam el tu fts. T u f ts have ord in arily been referred to as de fects. N o tw ith s ta n d in g th e publication of several investigations discussing the
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T h e Journal of the American D ental Association
m orphology, distribution and n atu re of tu fts ,17 authors continue to regard them as defects. O rb a n 18 regards them as poorly calcified enam el rods and cem ent ing substance. K ronfeld, in his new w ork, 19 expresses th e same view. Some
1928, L . E . V an K irk 20 published a la borious investigation p ictu rin g enam el “ defects” w hich w ere described as “ g ra n ulated rods.” T h e se so-called defects are nothing m ore th a n side views of tu f t rows. T h e re can be no doubt th a t the
Fig. 18.— Sections of tuft rows springing from dentin and out in enamel tissue, believed by some to be defective enamel rods.
new editions of textbooks even om it to m ention these conspicuous structures. In 17. Beust, T . B .: Physiologic Changes in Enamel A fter Tooth Eruption, J.A.D.A., 11:396 (M ay) 1924 (Figs. 2 -4 ); Capillaries of Enamel and Relation to Mottled Teeth, ibid., 13:980 (July) 1926; Morphology and Biology of Enamel T u fts; Relation to Caries, ibid., 19:488 (July) 1932; J. D. Res., 12:601 (Aug.) 1932. 18. Orban, B alint: Histology and Embryol ogy of Teeth, P hiladelphia: P. Blakiston’s Son and Co., 1929, p. 44. 19. Footnote 9, p. 25.
in terpretatio n s placed on th e tu fts by these authors are n o t borne o u t by care ful study. In my w o rk on th e tu fts, I insisted as early as 1912 and on various la te r occasions th a t th e tu f t “ fibrils” in early youth w ere capillary spaces p artly surro u n d in g th e enam el rods. T h e y oc cu r in th e space usually occupied by the in terprism atic substance. I f tu fts con sisted of poorly calcified prisms, th e 20. Van Kirk, L. E. : Variations in Structure of Human Enamel and Dentin, J.A.D.A., 15:1270 (July) 1928.
' Paffenbarger and Sweeney— Impression Compounds ■ stained tu fts in cross-section w ould not be nearly flat o r half-m oon shaped, b u t w ould resem ble a cross-section of the enam el rod. (F igs. 14-15.) T h is is not the case . 21 A n o th er fact th a t m ilitates against an assum ption of defects is the observation th a t th e tu f t elem ents regu larly become occluded by calcific or horny deposition as th e subject increases in age and thus th a t by th e tim e m atu rity is reached, th e tu fts no longer conduct stains. T h e m orphology of these structures is n o t yet generally understood. I showed in 1923 th a t tu fts w ere arranged in v erti cal parallel ro w s .22 D iscussion of these w ould not be indicated here, b u t I wish 21. Footnote 17, third reference. 22. Footnote 17, first reference.
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to add photom icrographs (Figs. 16-18) show ing how sh o rt segments of p arallel row s can sim ulate enam el defects in longitudinal sections of teeth. (F ig. 18.) V iew s of this k ind o ften result w hen m olars are sectioned vertically in such a m anner th a t th e cu t passes diagonally across th e crow n fro m corner to corner. I n this w ay, ta n g en tial sections are often secured w hich present views of the row s from the side. T h ese rem arks o n th e supposedly de fective o r hypoplastic tu f t fibrils, al though presenting a negative viewpoint, nevertheless co nstitute a contribution to th e histopathology of th e enamel, as th e elim ination of this item from the list of know n defects n arro w s th e field con siderably. 129 East Broadway.
A SECOND SURVEY OF D ENTAL IMPRESSION COM POUNDS AND OF INLAY CASTING WAXES* By GEORGE C. PAFFENBARGER,t D.D.S., and W. T. SWEENEY,f A.B., Washington, D. C. U R S U A N T to the policy 1 of the Research Commission, the research associates purchased on th e open m arket five brands of impression com pound and six brands of inlay w ax. A ll of these m aterials either had a guarantee on the package statin g th a t they complied
P
*Publication authorized by the Executive Board of the Research Commission of the American Dental Association. fResearch associate for the American Den tal Association at the National Bureau of Standards. 1. Dental Research Fellowship at National Bureau of Standards—Research Commission, J.A.D.A., 20:1040 (June) 1933. Jour. A.D.A., A pril, 1934
w ith th e specifications 2 of the A m erican D en ta l Association o r w ere form ally certified to th e Research Commission. T hese products w ere th en tested to de term ine w h eth er they conform ed to the Association’s specifications .2 T ab les 1, 2, 3 and 4 are based upon th e results of these tests. D uplicate tests w ere carried through 2. Taylor, N. O .; Paffenbarger, G. C. ; Sweeney, W . T .: Specification for Inlay Casting Wax, J.A.D.A., 18:40 (Jan.) 1931. Taylor, N. O .; Sweeney, W . T .; Paffen barger, G. C. : Specification for Dental Im pression Compound, J.A.D.A., 18:53 (Jan.) 1931.
T h e Journal of the American D ental Association
olism th an of food intake, and (7 ) the individual child w ill eat am ple am ounts
H IS T O P A T H O L O G Y
OF
of, for him, th e rig h t kind of food as long as he is given th e opportunity.
THE
D E N T IN
A N D
ENAM EL*
By T H E O D O R E B EU ST , D .D .S., Louisville, Ky.
H E N considering th e dictionary in terp retatio n of th e te rm “ p ath ology” in its application to the h ard stru ctu re s of the teeth, one is re
W
pow ers th a t could enable these tissues to effect biologic changes w ith in th e ir sub stance. S tru c tu ra l and fu nctional chang es can occur only in stru ctu res possessing
Fig. 1.—Caries. L T , translucent zone; L O , lateral opaque chromophilic zone. m inded th a t m any doubt the existence of *From the Research L aboratory of the School of D entistry, U niversity of Louisville. *W ork supported in p a rt by a g ra n t from the R esearch Commission of the A m erican D ental Association. *Read at the Seventy-F ifth A nnual Session of the A m erican D ental A ssociation in con junction w ith the C hicago C entennial D ental Congress, A ug. 9, 1933. Jour. A .D .A ., A p ril, 1934
the a ttrib u te of reactivity. A piece of g ran ite is n ot th u s en d o w ed ; nor is a piece of lead or silver. T h e y lack the vital elements. T h e h ard substances of th e teeth, ac cording to m any authors, are therefore not eligible fo r classification w ith tissues capable of reacting, in a pathologic sense, to irritatio n . G . V . Black, A rth u r
Beust— Histopathology of D entin and Enamel
647
H opew ell-Sm ith an d J . L eon W illia m s have regarded calcified to o th substance as in e rt and unchangeable. T h is opinion has been reflected by th e large m ajo rity of d ental practitioners, b u t this point of view is open to grave objection.
reactions occur in both th e den tin and the enam el. I call atten tio n to the pos sibility of in jectin g th e enam el of recent ly erupted teeth by causing stains applied to th e pulp cavity 1 to follow th e n a tu ra l channels leading from th e pulp into the
Fig. 2.— Sclerosis follow ing abrasion of a low er incisor, stained a fte r treatm ent of tooth w ith ether and alcohol. (H a lv ed tooth.)
Fig. 3.— A b rad ed sclerosed cuspid, halved tooth, stained fo r one m onth in strong alcoholic fuchsin. A fte r staining, the p a la tal enam el w as rem oved. Repeated exposure to the stain failed to affect the opened tubules.
N o th w ith stan d in g m uch excellent w ork and the m any exhaustive argum ents supporting the tw o sides of this question, recent histologists, in view of th e many convincing observations indicating the oc currence of posteruptive anabolic proc esses in th e to o th ’s calcified parts, now incline m ore and m ore to the view th a t
enamel tissue. T h is experim ent has been corroborated by M u m m ery ,2 C . F . Bo1. Beust, T . B. : D . Cosmos, 54:659 (June) 1912. 2. M um m ery, J. H . : B rit. D. J., 4 3 :607 (July) 1922.
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decker ,3 Sm reker 4 and F ish .5 T h e m ere com parison of results attained in young teeth w ith like attem pts m ade la te r in life, w hen such com m unications no long er exist, suffices to prove th a t such changes occur. T h is is not a ll: In the dentin, w here the tubules of the recently erupted tooth conduct fluids w ith eagerness and com m unicate these to th e d entinal ground substance, sim ilar experim ents u n d erta k en w ith th e teeth of the aged reveal th a t this conductivity has been reduced to nil,
Fig. 4.— A b rad ed bicuspid w ith opaque sclerosis of tubules involved. A p lug of sec ondary dentin covers the tubules. O bservation of such specimens by transm itted lig h t creates the erroneous im pression of “ d ead” tubules containing necrosed fibrils. (T ran sm itte d light photograph, stained specimen.) SO, sclerosed opaque dentin, T S , tran sp are n t secondary den tin.
o r is lim ited to isolated w ell defined regions o r exists only in th e younger 3. Bodecker, C. F .: P erm eability of E nam el in R elation to Stains, J.A .D .A ., 10:60 (Jan .) 1923. 4. Sm reker, E. : Z tschr. f. Stomatol., 24:460, 1926. 5. Fish, E. W .: C irculation of L ym ph in D entin and E nam el, 14:804 (M ay) 1927.
dentin in the im m ediate vicinity of the pulp. T h e changes here described gave rise to my concept of to o th m a tu ratio n ,6 a te rm and concept th a t has since been adopted by C . F . B odecker .7 T o o th m a t uration, as th e nam e implies, embodies the final changes occu rrin g as a resu lt of pulp cavity o b literation by d en tin dep osition, resu ltin g in loss of m etabolic ac tivity in th e enam el, in th e d en tin al fib ril, in th e m a trix substance, in the tubules and finally in the pulp. T h e dem onstration of th e changes m entioned leaves no doubt th a t the calci-
Fig. 5.-^-Reflected lig h t photograph of speci men show n in F igure 4. T h e zone SO is re vealed as chrom ophobic sclerosed dentin.
fied too th stru ctu re s change d u rin g life and th a t as long as v ital pulp is present, they are biologically functioning p arts of th e organism . D u rin g th e life of the pulp, the tooth, in com m on w ith oth er tissues, m ay react to trau m a, physiologic stress, continued irrita tio n and possibly n u tritio n al disturbance. 6. Beust, T . B. : R eactions of D en tin al F ibril to E x ternal Irrita tio n , J.A .D .A ., 18:1060 (June) 1931; J. D . Res., 11:267 (A p ril) 1931; P osteruptive C hanges in M a tu ratio n of T eeth, J.A .D .A ., 18:2186 (N ov.) 1931; J. D. Res., 11:619 (A ug.) 1931. 7. Bodecker, C. F., and A pplebaum , E d m u n d : D . Cosmos, 74:1177 (Dec.) 1932.
Beust— Histopathology of D entin and Enamel CARIES
I n o rd er th a t new er phases of reactions m ay be presented, the know n facts of to o th destruction by caries as first laid dow n by L eber and R ottenstein 8 and la ter modified by W . D . M ille r and
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is of in terest to note th a t th e d ark fibers in question, w hich w ere first rem arked on by W . D . M ille r, are chrom ophilic. (F ig . 1.) T h e conclusion arriv ed at in my papers w as th a t this area represents a hyperchrom ophilic im flam m atory zone
Fig. 6.— Form ation of “developm ental” lines by aggregations of clouded tissue into lines.
others w ill be om itted. F o r this p a rt of th e w ork, reference is m ade to the excel len t w o rk of K ro n feld .9 T h e question of form ation of visible fa t in the tubules su rro u n d in g the tran sp a ren t zone de m ands some com m ent. K ronfeld, quottin g W e b er, E u ler, M ey er and Liesegang, implies th a t fa t globules appear in th e tubules adjacent to the tran slu cen t zone. F a t soluble stains w ere used in the determ ination of th e presence of fa t in this case. T h e area involved w as discussed a t len g th in tw o of m y recent papers. I n the first ,10 th e pulpal and the term inal ends of the tubules and th eir relation to th e tran slu ce n t zone w ere described. I t 8. L eber a n d R ottenstein: U ntersuchung ueber die K aries der Z aehne, B e rlin : H irschfeld, 1860. 9. K ronfeld, R u d o lf: H istopathology of T eeth, P h ila d e lp h ia : Lea & Febiger, 1933. 10. Beust, T . B .: R eaction of D entin to A d v ancing Caries, J.A .D .A ., 20:631 (A pril) 1933.
Fig. 7.— E nlarged section of most conspicu ous line show n in F igure 6.
w hich m arks th e tran sitio n of th e norm al tu b u le into th e tran slu cen t form of den tin . T h is conclusion appears justified in view of th e fact th a t both zones m ay ap pear u n d er early caries, and th a t they th e re afte r keep pace w ith th e advance of
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th e lesion, both la terally and centripetally, u n til th e caries has reached extrem e dimensions. As I showed in an earlier paper 11 th a t fa t soluble Sudan I I I colors any tubules th a t are susceptible to fuchsin stain, the reaction noted in this hyperchrom ophilic zone does not necessarily denote th e pres ence of fat. T h e question of a fa t con te n t of these tubules is of c u rre n t interest, as C . F . Bodecker regards fa t as the
potency of D r. B odecker’s supposed fat deposits as barriers to fluids, tw o photo graphs are offered by him in re b u tta l .12 In these, he claim s to have succeeded in dissipating the opacity of th e tubules by boiling in xylene. A s he has recently ex pressed d oubt concerning his ow n experi m ent ,18 and as th e insignificant differences in opacity m ay be attrib u tab le to d if ferences in th e substage illu m in atio n and other conditions incident to th e heating
Fig. 8.— Diffuse d ap p lin g of dentin.
agent th a t prevents perm eation of th e tubules by fluids. T h e presence of fa t in this hyperperm eable zone therefore w ould add another paradox to th e m uch confused state of our know ledge of the reactions to caries. A s I doubted the
11. Beust, T. B.: D. Cosmos, 74:541 (June) 1932.
of the specimen, th e m a tte r dem ands fu r th e r atten tio n . SCLEROSIS OF T H E D E N T IN
Sclerosis of th e dentin, p articu larly of 12. Bodecker, C. F .: D . Cosmos, (Ja n .) 1933 (Figs. 14-15). 13. Footnote 12 (Footnote 15).
75:21
Beust— Histopathology of D entin and Enamel the zones found u n d er abrasion and caries, has been given m uch consideration by d ental authors d u rin g the past tw o years. T h e contention m ade in my paper read at D en v e r in 193014 and in a paper presented before the Chicago section of th e In te rn a tio n a l Association fo r D en ta l R esearch 15 th a t irrita te d dentin o rd in ari ly became sclerosed m et w ith expressions of skepticism. T o d ay , both the view and the te rm used to express the condition are regarded m ore favorably. T h e fact th a t a sclerosis occurs can no longer be doubted, yet th e actual condition of the affected tissue still constitutes a problem .
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ositions laid over th e ir cen tral ends by the pulp. A s th e physical n atu re of den tin containing necrosed fibrils m u st be conducive to perm eation by alcoholic fuchsin stain, th e m a tte r w as given f u r th e r atten tio n . C a re fu l tests have con vinced me th a t th e pulpal seal of second ary den tin show n by au th o rs who regard it as a b arrier does n ot ord in arily cover open tubules, b u t th a t th e tubules are im perm eable th ro u g h o u t th e ir length. (F ig . 3.) T h e p u lp al seal m ust therefore be re garded as a reinforcem ent of dentin thac has already undergone sclerosis. (F ig s. 4 and 5 .) D E V E L O P M E N T A L LINES
Fig. 9.— Superficial “hypoplastic” enamel lesion, stained.
M y published experim ents proved th a t this tissue is im perm eable to fluids. C . F . Bodecker has claim ed th a t abraded areas analogous to those show n in F ig u re 2 are perm eable from w ithout, b u t th a t a cal cified p lug of secondary dentin seals the p u lp al ends of th e tubules. E . W . Fish has also held th a t abraded fibrils die dow n to th e pulp, and th a t these fibrils undergo necrosis and are sealed by dep 14. Footnote 6, first reference. 15. Footnote 6, second reference.
In the discussion of deviations from the norm al, w e are confronted w ith the difficulty of discerning betw een the physi ologic or anatom ic and the pathologic. Ju d g in g n o rm ality by th e frequency of occurrence w ould be futile, as some con ditions th a t are supposed to be evidence of m aldevelopm ent are universally rep re sented in teeth. I call atten tio n to the in terg lo b u lar spaces and th e tu fts. Be cause of o u r inability to differentiate ac curately, it w ould be p ertin en t to include in this paper any condition th a t is being regarded as a hypoplasia o r defect. T h e alinem ent of in terg lo b u lar spaces into row s roughly follow ing th e contours of the dentin, called the lines of C zermak, are adequately know n. O th e r lines pu rsuing the same course, caused by su d den deflections in the course of the tu bules, are know n as O w e n ’s lines. I wish to rep o rt on a th ird v ariety of line caused by differences in th e calcification of the dentin. R ow s of poorly calcified areas distinct from , b u t evidently related in origin to, th e in terg lo b u lar spaces are le ft in th e m a trix as dentin developm ent proceeds. (Figs. 6 and 7 .) T h e individual spots are m orphologically identical w ith those causing th e dappling of th e dentin
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found associated w ith caries. H ere, the dappling becomes intensified as caries progresses, as if the tissue w ere in a hyperem ic state. O ccasionally, teeth are m et w ith th a t display this dappling th ro u g h o u t the den tin of the crow n por tion. (F ig . 8 .) A s th e irre g u la r spots causing th e dappling appearance are sus ceptible to staining, it is evident th a t they represent poorly calcified areas in the m atrix. ENAMEL
E xperienced practitioners of dentistry
pear “ chalky” and have th e appearance of having been decalcified by an acid. O n e or m any teeth m ay be affected. T h e areas are usually w hite, o r m ay v ary from a cream color th ro u g h various hues of reddish brow n to deep brow n. A loss of surface co n tin u ity is n ot in evidence. W h e n subjected to p ro tra cted exposure to alcoholic aniline stains, these areas are found to be perm eable. (F ig . 9 .) T h is differentiates them from th e norm al enam el of a d u lt teeth, w hich fails to stain. D entists, and also certain histol ogists 9 reg ard these affected areas as
Fig. 10.— Superficial enamel lesion showing clouding of rod substance and surrounded by increased visibility of striations.
are fam iliar w ith th e occurrence of v aria tions in th e translucency of the enam el covering the teeth. T h e norm al lu ster of th e enam el gives place to modifications th a t indicate changes in its physical o r chem ical stru ctu re . O n e of these anom a lies m anifests itself in th e occurrence of spots o r even of large areas th a t may cover a w hole to o th surface and th a t ap-
caries. In fact, some of these areas m ay be caries; yet it is also w ell established th a t teeth so affected are n o t necessarily carious an d fu rth e rm o re th a t they m ay rem ain free from caries th ro u g h o u t the life of th e subject. Lesions resem bling these are exhibited on th e teeth of th e low er anim als, the pig being a com mon example. M icroscopic exam ination of the
Beust— Histopathology of D entin and Enam el unstained specimens discloses th e same opacity th a t is perceptible to the unaided eye. T h e striations, “beading,” of the rods is seen to be exaggerated and the w hole tissue appears clouded. (F ig . 10.) In th e stained specimens, th e affected areas are diffusely stained, the substance of th e rod itself being colored. R arely, th e interprism atic substance appears to
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m y experim ents conducted in 1924tG show th a t enamel, especially th e enam el
Fig. 13.—Worn intact tooth with multiple deep-seated areas of hypoplasia, stained. (Re flected light photograph.)
Fig. 11.—Extensive deep-seated underdevel opment of enamel, stained. The fissure caries is independent of the lesion.
Fig. 12.—Deep-seated underdevelopment of enamel, stained. The progress of the fissure caries does not appear to be influenced by it. (Reflected light photograph.)
be m issing and the rods appear intact. T h e enam el is affected to varying depths. I t m ay be said in support of th e as sum ption th a t th e enam el u n d er discus sion has been decalcified by acids form ed u n d er colonies of aciduric bacteria th a t
Fig. 14.—Diagonal sections of stained tuft “fibrils” proving that rods are intact. 16. Beust, T . B. : Contribution to Etiology of M ottled Enamel, J.A.D.A., 12:1059 (Sept.) 1925.
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of recently erupted teeth, w hen treated by very d ilu te acids, can be decomposed to various depths w ith o u t th e loss of su r face continuity. W e have in these lesions a m orphologic parallel to the affliction know n as “ m ottled enam el.” A ccepting
norm al w e w ould have a clue to the causes of this anom aly. A cknow ledging th e difficulties of in te r pretatio n presented by th e superficial le sion, above described, a problem of far greater com plexity is presented by th e oc-
Fig. 15.—Close-up of stain conducting capillary spaces or fibrils, showing intact rods.
Fig. 16.—Parallel tuft rows seen from side in tangential slice from molar.
th e as yet unsubstantiated hypothesis of m o ttled enam el etiology, w hich assumes a p reeruptive substitution of foreign in gredients, in this case fluorine, fo r the
currence of sim ilar changes in th e deeper regions of th e enam el. T h is form m ani fests itself as changes in hue to lig h ter or d ark er involving sm all o r large areas, or
Beust— Histopathology of D entin and Enamel even w hole teeth. T hese differ in ap pearance from the superficial form in th a t the o u te r region of th e enam el stru c tu re is norm al, th e teeth exhibiting in this case th e usual luster. W h e n subjected to my test for perm eability ,15 it can be observed th a t th e o u te r region of the enam el is norm al, th e inner p a rt of the
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moved from outside influences. (F ig . 13.) T h e etiologic significance of caries, o r an attac k by acids, is here en tirely excluded. T h e substitution theory, m entioned in connection w ith th e superficial form , also loses significance as substitutions logically follow developm ental laws, the lesions in question occurring quite erra t-
Fig. 17.— Group at lower left of Figure 16, magnified.
tissue displaying the anom alous condition seen in the superficial lesion. T h e enamel w hich answ ers this description (Figs. 11-1 2 ) has not been influenced by breaks in surface continuity lying near th e plane from w hich th e section w as m ade. In fact, th e lesion may be found in serial sections m ade from in tact teeth. I t frequently appears in isolated spots lying in the depth of th e enam el, re-
ically. F o r p ractical purposes, these le sions may be term ed hypoplasia. TU FTS
O th e r anom alies of th e enam el, if the reports of m any histologists are given credence, are th e enam el tu fts. T u f ts have ord in arily been referred to as de fects. N o tw ith s ta n d in g th e publication of several investigations discussing the
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m orphology, distribution and n atu re of tu fts ,17 authors continue to regard them as defects. O rb a n 18 regards them as poorly calcified enam el rods and cem ent ing substance. K ronfeld, in his new w ork, 19 expresses th e same view. Some
1928, L . E . V an K irk 20 published a la borious investigation p ictu rin g enam el “ defects” w hich w ere described as “ g ra n ulated rods.” T h e se so-called defects are nothing m ore th a n side views of tu f t rows. T h e re can be no doubt th a t the
Fig. 18.— Sections of tuft rows springing from dentin and out in enamel tissue, believed by some to be defective enamel rods.
new editions of textbooks even om it to m ention these conspicuous structures. In 17. Beust, T . B .: Physiologic Changes in Enamel A fter Tooth Eruption, J.A.D.A., 11:396 (M ay) 1924 (Figs. 2 -4 ); Capillaries of Enamel and Relation to Mottled Teeth, ibid., 13:980 (July) 1926; Morphology and Biology of Enamel T u fts; Relation to Caries, ibid., 19:488 (July) 1932; J. D. Res., 12:601 (Aug.) 1932. 18. Orban, B alint: Histology and Embryol ogy of Teeth, P hiladelphia: P. Blakiston’s Son and Co., 1929, p. 44. 19. Footnote 9, p. 25.
in terpretatio n s placed on th e tu fts by these authors are n o t borne o u t by care ful study. In my w o rk on th e tu fts, I insisted as early as 1912 and on various la te r occasions th a t th e tu f t “ fibrils” in early youth w ere capillary spaces p artly surro u n d in g th e enam el rods. T h e y oc cu r in th e space usually occupied by the in terprism atic substance. I f tu fts con sisted of poorly calcified prisms, th e 20. Van Kirk, L. E. : Variations in Structure of Human Enamel and Dentin, J.A.D.A., 15:1270 (July) 1928.
' Paffenbarger and Sweeney— Impression Compounds ■ stained tu fts in cross-section w ould not be nearly flat o r half-m oon shaped, b u t w ould resem ble a cross-section of the enam el rod. (F igs. 14-15.) T h is is not the case . 21 A n o th er fact th a t m ilitates against an assum ption of defects is the observation th a t th e tu f t elem ents regu larly become occluded by calcific or horny deposition as th e subject increases in age and thus th a t by th e tim e m atu rity is reached, th e tu fts no longer conduct stains. T h e m orphology of these structures is n o t yet generally understood. I showed in 1923 th a t tu fts w ere arranged in v erti cal parallel ro w s .22 D iscussion of these w ould not be indicated here, b u t I wish 21. Footnote 17, third reference. 22. Footnote 17, first reference.
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to add photom icrographs (Figs. 16-18) show ing how sh o rt segments of p arallel row s can sim ulate enam el defects in longitudinal sections of teeth. (F ig. 18.) V iew s of this k ind o ften result w hen m olars are sectioned vertically in such a m anner th a t th e cu t passes diagonally across th e crow n fro m corner to corner. I n this w ay, ta n g en tial sections are often secured w hich present views of the row s from the side. T h ese rem arks o n th e supposedly de fective o r hypoplastic tu f t fibrils, al though presenting a negative viewpoint, nevertheless co nstitute a contribution to th e histopathology of th e enamel, as th e elim ination of this item from the list of know n defects n arro w s th e field con siderably. 129 East Broadway.
A SECOND SURVEY OF D ENTAL IMPRESSION COM POUNDS AND OF INLAY CASTING WAXES* By GEORGE C. PAFFENBARGER,t D.D.S., and W. T. SWEENEY,f A.B., Washington, D. C. U R S U A N T to the policy 1 of the Research Commission, the research associates purchased on th e open m arket five brands of impression com pound and six brands of inlay w ax. A ll of these m aterials either had a guarantee on the package statin g th a t they complied
P
*Publication authorized by the Executive Board of the Research Commission of the American Dental Association. fResearch associate for the American Den tal Association at the National Bureau of Standards. 1. Dental Research Fellowship at National Bureau of Standards—Research Commission, J.A.D.A., 20:1040 (June) 1933. Jour. A.D.A., A pril, 1934
w ith th e specifications 2 of the A m erican D en ta l Association o r w ere form ally certified to th e Research Commission. T hese products w ere th en tested to de term ine w h eth er they conform ed to the Association’s specifications .2 T ab les 1, 2, 3 and 4 are based upon th e results of these tests. D uplicate tests w ere carried through 2. Taylor, N. O .; Paffenbarger, G. C. ; Sweeney, W . T .: Specification for Inlay Casting Wax, J.A.D.A., 18:40 (Jan.) 1931. Taylor, N. O .; Sweeney, W . T .; Paffen barger, G. C. : Specification for Dental Im pression Compound, J.A.D.A., 18:53 (Jan.) 1931.