Clinical management of deep carious lesions

CLINICAL Clarence

MANAGEMENT P. Canby, D.D.S.,

Washington, United

OF DEEP

States

CARIOUS

and George II’. Burnett,

LESIONS D.D.S.,

Ph.D.,

D. C. Army

Institute

of

Dental

Research

INTRODUCTION

T

HE preservation of teeth and contiguous structures is a major aim of denis . . . to consider all tistry. According to Gabel, 3 “the modern viewpoint operative procedures from the standpoint of the patient’s general welfare rather than that of the teeth and their supporting structures alone.” Occasionally this concept has resulted in compromise operative procedures balanced between the preservation of the teeth and what may be considered essential to the patient’s health and welfare. There is general agreement on maintaining the integrity of the tooth pulp. This principle is sometimes compromised by the traditional procedure of removing all decayed dentine, even when it will expose a viable pulp. Traditionally, if any affected dentine remains, the pulp will be jeopardized by continuing or recurrent decay beneath the restoration or by residual bacteria penetrating to the pulp via the dentinal tubules. This concept is expressed by McGehee and colleagues2 as follows: “On completion of these [operative] procedures, the cavity should be thoroughly inspected for any remaining traces of caries, which should be completely removed.” Gabe13 expresses an opposing concept : “When discolored and decalcified dentin lies at such a depth that its removal would be likely to result in exposing a pulp, which from its history and clinical tests, is apparently healthy, it should be well sterilized with one or two applications of 50 per cent thymol-alcohol or other suitable antiseptic. Thermal or electric tests of this pulp from time to time will serve as a check on its condition.” A number of investigators have suggested leaving carious dentine to protect the pulp under certain circumstances in preference to pulp exposure.4-13 Some have insisted that residual carious dentine be “sterilized” by germicides or antiseptics that are equally toxic for bacteria and pulp tissue (nonselective toxicity) before the restoration is inserted. Removing all carious dentine and jeopardizing a vital pulp with no significant untoward history or reaction would seem to be a questionable method and a needless contribution to the complexity of treatment and the loss of teeth. The purpose of this article is to describe a method for the clinical management of certain deep carious lesions where removal of all carious dentine would expose the pulp. We shall present representative examples from more than two decades of clinical experience. 999

IGverMally every dentist must, t rest dcq) carious lesions whose roentgenograms suggest that the advancing ca rious front has ittvolvcd tht: pulp. Whtu the pulp is irrcparahlc or dcvitalizctl, t,he treatrneut is either mdotlontic or exodontic. When the carious front involrcs au cutircly vital pulp that exhibits 110 significant untoward rcl;lctious, the usual l)t.ac*ticr is to extract thcl tcwth irnmediatcly 01’ to csposc? the pull) hy rrlnoving all ca,rious dcntinc and therr resort to cndodontic trcatmc’nt. Tf this is inc+fcctual, the tooth is estracttd. Fig. 1. shows reprcscntatirc casts 01’ pil.rticular conditions likely to IN ct~countered in the managerner~t of tlcq) c:l.t4ous lesions in teeth usually c~onclemnc~tl to either extraction or enclotlontic trcatllrcnt 1)~ removal of ail various dentine. The vitality of thcl l)ulp WRS nlaint.air~c~tl snc:e~sfull~ in (iach (~Ns(: tliagu(Js(bcl as being favorable for tIY'iltlll('tlt. C’ASE

REPORTS

CASE 1 (Fig. 1, A).-The patient,, a 15.year-old girl, came to the dental clinic complaining of pain. This pain, together with an apparently hopeless roentgenographic picture, indicated pulpal involvement and the alternatives of cndodontic or cxodontic treatment. Neverthelcss, the vitality of the pulp was maintained lay proper opcrativc management. CASE 2 (Fig. 1, II).-This case illustrates it rather common situation in which an impaction resulted in an extensive carious lesion on t,hca distal surface of the se~ortd molar. Roentgenographically, the pulp scemtd to IJO involved, lmt it responded normally and was vital. The extensively decayed dentinc was tough and leathery rather than mushy or liquefied, which indicates a favorable prognosis. The pulp was not so extrnsivcaly involved that its vitality could not be maintained by proper trratment. CASE 3 (Fig. 1, C) .--I IL this case’ the roentgenogram indicated pulpal involvrment hy the advancing carious lesion of an upper right cmtrd incisor. EIstr:rction of the tooth seemed to be indicated? and tile paticut, was referred to a prosthodontist for consultation about the rcstorat,ion. The prosthodontist concurred in the, opinion that extraction was required and recommended restoration with a prosthesis. More careful examination, however, indicated that the tooth did not need to IW extracted, for thcl pulp \vas vital iu spite of the roentgenographic eviden(>e. The decayed dmtinc~ was “hartl” and “dry,” and the lesion extended distolingually, so that, it was superimpose~l on thci pulp in ttrc roentgt~nogram PVW t,hough it had not reached t11r pulp. CAse 4 (Fig. I, I>).-‘l’hiii I%SF is showa tjccausr, as intlicatcd in the roentgenogram, the pulp of the upper first molar obviously extended into tllct ostensive c*arious lesion. The various dentine was tough and leathery, however, and the pulp was vita1 when examined and there was no history of previous untoward or Irdinful reactions. In the treatment of this lesion it was necessary to leave some carious dentine in the cavity in order to prevent physical Nevertheless, the vitality of t.hc pulp was maintained and loss of the tooth was exposure. prevented by such operative procedures. CASE 5 (Fig. 1, E).-This case is representative of those in which extensive recurrent decay occurs in an area about or beneath a restoration. The patient came to the dental clinic complaining of intermittent, odontalgia of 3 weeks’ duration. An examination revealed that the margin of the restoration in t,he lower right second molar was defective, allowing Even though roentgenographic evisalivary fluids to enter the area beneath the filling. dence indicated that carious dentine apparently involved the pulp, the pulp was vital and responded normally on clinical examination. In preparing the cavity, it was necessa’ry to leave some decalcified dentine to prevent exposure of the pulp, which was maintained intact and viable indefinitely.

rJ%x:r ‘s”

DEEP

CARIOUS

LESIOXS

1001

CASE 6 (Fig. 1, F) .-The carious first and second molars represented two contrasting situations. In one the vitality of the pulp could not be maintained by proper clinical management, and in the other the pulp was kept vital, even though both lesions had progressed to about the same stage. The carious dentine of the first molar was mushy and liquid, and the pulp was exposed, infected, and extensively degenerated as indicated by a lack of response to heat or cold. No attempt was made to preserve the pulp of the first molar because of its degenerated condition. Conversely, the carious dentine of the second molar

l.-Cases 1 to 6 Six representative cases in which removal of all carious dentine 9 he operative de&l procedures would have resulted in exposure of the pulp and durinp jeopardy of the tooth. In each instance, except for the case shrmm in F, diagnosis was favorable for restoration in that the various dentine was leathery and flrm and the pulp was vital. pulps were maintained intact All of the carious teeth treated responded favorably, and the and viable indefinitely.

(‘I,INI

C!AL

I’ROCEDURP’i

11

The proper clinical management of tleep carious lesions approaching or (VCI~ reaching pulps which arc ncvcrthclcss vital requires, initially, thra determination of pulpal damagc3 and r(>gcnerative capacity. If such pulps arc vital, normal in their rcsJ)onses, and have no history of unt,oward reactions, opcrativc treatment proccdurrs which will not, traumatize and expose them should bc LC& even though all carious dentine is not removed before the final rrstoraCon is placed. In det,crmining the status of the pulp, one should look for clues that will establish the prognosis. Jf pain has occur~d, an attempt should be made t,o establish locality, temporal factors, circumstances under which it occurs or is aggravated, and factors affecting its intensity. The determination of these factors is indispensable to an appraisal of pulpal damage and an estimation of the capacity of the pnlp to survive. It is important to establish whether the pulp reacts normally to heat, and cold, is hypcremic or inflamed (pulpitis), or is hyporcactive. It is also important to establish any involvement of the periodontal mcrnbranc. ltoentgenograms are of litt,le use in determining the status of a pulp; they arc of limited LISP in determining the condition of the periodontal membrane. 1:ccausc of the many variables associated with their use, electric pulp testc>rs cannot bc relied on ronsistently to determine the physiologic or pathologic status of a pulp; thermal tests and sensitivity t,o pressure arc more reliable measures. When a favorable prognosis is established for cases in which the deep dentinal carious front approaches or even reaches a vital and normally reacting pulp whose carious dentine is tough and leathery rather than soft and mushy, one should apply operat,ive treatment procedures which will assure that the pulp will not 1~~ cxposcd. No ancsthet,ie should be used initially, for it will mask pulpal responses during diagnosis and t,he critical stage of removing carious dcntinc. An anesthetic may bt used at any time after the carious dentine has been rcmovad. Jn the initial operative procetlures, wccss to the cavity is established, followed by the removal of leathery carious dentine with round burs. The carious dentine should nrvcr be pcnctratcd by an explorer or other sharp instrument which will product an exposure and traumatize t,he pulp. Excavators should not bc used, for they are more likely to cause pulpal exposure. Also, if excavators are used, the operator cannot accurately determine when the pulp is approached. In decayed dentine, the odontoblastic processes probably no longer transmit sensation and the norma,l response of the pulp is obscured until one approaches the point where the odontoblastic processes are viable. The sensation elicited as the pulp is approached is usually in response to the small amount of pressure exerted in r(amoving the decaying dentine. One should carefully remove all essential decay but should not expose the pulp. Exposure can best be avoided by slow and careful removal of decayed dentine in the

Volume 16 Number 8

DEEP

CARIOUS

LESIONS

1003

region of the pulp only to the point where light operative manipulation elicits a mild response. At this point a protecting barrier of demineralized dentine remains between cavity and pulp. If only teeth with dry and leathery dent,ine are selected for treatment, the value of applying “sterilizing” agents is questionable. No current cavitysterilizing agent has a select,ive toxicity. In other words, such agents have the same toxicity for bacteria and pulpal tissue cells, and their use may weaken rather than augment the resistance of pulp tissue. Furthermore, the efficacy of current cavity-sterilizing agents is questionable. In the operative procedures subsequent to removal of the carious dentine, the operator should keep trauma to a minimum in order to maintain the pulp at maximum resistance. After the preparation is completed, the toilet of the cavity is performed, and the cavity is filled with a thick, heavy mix of zinc oxide and eugenol. The permanent restoration can be placed immediately or within a few days if the prognosis is favorable. If the prognosis is questionable, the temporary filling may be allowed to remain for as long as 6 months. When the permanent restoration is inserted in such cases,the temporary filling is removed and the vitality of the pulp is reconfirmed. RESULTS

Some of the results obtained in the treatment of deep carious lesions are presented in the following cases,which are representative of many treated during the past two decadesby the method outlined. CASE 7.-A medical officer (Fig. 2) came to the dental clinic in 1952, complaining of having had discomfort in the upper right maxilla. Roentgenograms revealed nothing other than an overhang on the mesial aspect of the upper right second molar, with some eementum exposed (Fig. 2, A). An examination revealed no untoward symptoms. Since the patient was not in pain, he was dismissed without treatment. About 3 months later the patient returned to the clinic, complaining of pain in the upper right maxilla. A critical examination indicated caries on the distal aspect of the upper second molar involving a crown which served as a bridge abutment. The bridge was removed, revealing an extensive carious lesion beneath the crown in which the involved dentine was firm and leathery (Fig. 2, B). The carious dentine encroached on the pulp, which was vital and reacted within normal limits. Most of the carious dentine was removed, although some of it was alloTed to remain to prevent exposure and to protect the pulp. Removal of all carious dentine would have exposed and endangered the pulp. A zinc oxide-eugenol filling was placed immediately An amalgam restoration was later placed after completion of the operative procedure. (Fig. 2, C) as a base for a gold crown which served as a bridge abutment (Fig. 2, 2)). The pulp responded favorably to such treatment and has reacted normally since 1952.

CASE 8.-A dental officer came to the dental clinic in January, 1954, requesting adjustment of the occlusion of his lower left second premolar; otherwise, he had no particular pain or discomfort. The roentgenogram revealed nothing untoward (Fig. 3, a). The second premolar was not suspected, since its crown had been placed rather recently. An occlusal adjustment was made, but the patient returned the following day still complaining of malocclusiop and discomfort. During examination of the margins of the crown of the second premolar, an explorer was inserted beneath its distobuceal angle, easily dislodging it. Coronal dentine was extensively destroyed, with only the buccal enamel wall remaining intact (Fig. 3, B). The earious dentine was firm and leathery. Observations made during the initial operative procedures indicated that removal of all carious dentine would expose the

Fig. L--The stages in the treatment of Case 7. The in A. R shows the extensive carious involvement of the the bridge abutment. G shows the amalgam restoration final restoration of a crown for bridge abutment.

Fig. 3.-Case 8. The treatment of extent give caries second premolar in spite of its normal arx jearance coronal dentine is suf%cient to endanger the vi able and tion with crown is shown in C.

affected upper aftw

occurring

upper right molar is shown right molar after removal of trwtmcnt, am1 D shows the

beneath

(A). The extensive normal-reacting pulp

a crown

destruction

on a lower of the restora-

(B). Final

DEEP pulp. The patient, a dentist, was so carious dentine to protect the vital preparation of the cavity, the crown restoration was not made until 1958, (Fig. 3, C). There was no untoward at the time of the final restoration the pulp did not liquefy or increase the final restoration.

CAR,IOUS

1005

LESIOXS

informed and concurred in the decision to leave sufficient pulp from exposure. After removal of the dentine and was recemented over a zinc oxide-eugenol base. Final when the crown was replaced at a university dental clinic pulpal reaction from 1954 to 1958, and the pulp was vital in 1958. The small amount of carious dentine protecting in the interim, and it was not disturbed at the time of

CASE 9.-In June, 1949, a medical student came to the dental clinic, complaining of vague pains in the lower left mandibular region (Fig. 4). The previous February the distal marginal ridge of the lower second premolar had broken down; this was followed by episodes of pain which could be relieved by cleansing the lesion with a toothbrush. Because the pain could be relieved and because the pressure of medical school studies was great, the patient postponed visiting a dentist until the following June, when roentgenograms revealed an extensive carious lesion extending to the pulp (Fig. 4, a). However, the pulp was vital and responded normally. The carious dentine was leathery and firm, indicating a favorable prognosis. Because of the long history of pain and trauma to the pulp, a relatively thick wall of leathery carious dentine was left behind for protection of the pulp (Fig. 4, B). A temporary zinc oxide-eugenol filling was placed, and the patient was observed carefully for the 3 months of the summer, with the pulp reacting normally. Since the pulp responded so favorably to treatment, no further attempt wva4 made to remove additional decayed dentine. Before the student returned to school in the fall, cavity preparation was completed with minimal operative trauma and the tooth was restored with an inlay. This case was observed for 2 years during the patient’s vacations from medical school. There has since been no untoward pulpal reaction, even with the decalcified dentine remaining in the cavity.

Fig. pulp (A). Restoration

4.-Case 9. Extensive B shows the relatively was completed with

carious lesion in a lower second premolar thick wall of carious dentine left behind zinc oxide-eugenol and an inlay.

endangering to protect

a vital the pulp.

Fig.

5.-Case

flrst

IO. The permanent

clinical managemmt molars (A and

C).

of

I;

extensive carious and 1) show the

lesions twth

in after

lower right rwtoration.

an11

kf’t

CASE 1 O.-A 12.year-old girl came to the dental clinic for t~el’gc*u~y troatm(but I~(~causc of discomfort and mild pain in the mandibular region. There wt~ similar castmsivcb Icsions in the lower right and left first permanent molars (Fig. 5, 11 all11 (: j, wit11 each 113iort all, parently extending to the pulp. However, the pulps were vital and rc*latively normal in thcliz reactions. The carious dentine in each lesion was leathery, firm, ilrld ~OU~Il. ill spite Of thf? encroachment of the lesions on the pulps, the prognosis was considoretl very favorable. !rhe carious dentine was carefully removed, with a sufficient amount left to ensure protection of the pulp, and the operative procedures were completed. The cavities were then filled with a thick, heavy mixture of zinc oxide and eugcnol (Fig. 5, B and 1)~ and restored within a fr\\ days by an amalgam filling. This case was observed for several years wit,11 no uutolvartl pulpal reaction. CASES 11 .4ND 12.-These cases are also representative of those with extemsivc carious lesions in which removal of all carious dentine would expose t,he pulps and t~ntlangc~r their vitality. Case 11 (Fig. 6, n and B) exemplifies a situation in whiczh loss of the tooth would complicate preparation of a partial denture. The patient, a plrgsician, ~2s advised -1 vc’ars previously of the presence of a carious lesion but he had nothing done to correct it. Although there were no definite symptoms in the interim, (he deca,v was extensive about and beneath a distoelusal inlay at the time of the clinical examination (Fig. 6, rl). (‘oulplete removal of the carious dentine would have exposed a vital anti normal-reacting pulp. All leathery, carious dentine was removed except for sufficient amount adjacent to the pulp to protect the pulp from exposure. A thick mixture of zinc. oxide and eugenol was placed as a base, and the tooth was restored with a gold onlap. A part,ial denture eventually completed the restoration. The pulp responded favorably, and there have been no urrtoward reactions. Case 12 (Fig. 6, C and D) exemplifies the situation in which a carious lesion is so extensive as to endanger a second molar and attempts to save this tooth are often rather feeble because of the seemingly unfavorable prognosis and also because the unerupted third molar will eventually replace it. Such teeth are often sentenced to extraction without any attempt being made to save them. In this case, the pulp was vital and normal in its reactions. Further-

Volume 16 Number 8

DEEP

CARIOUS

Fig. B.--Cases 11 and 12, in which removal the pulps (A and C). B and D show the Anal behind to protect such pulps.

LESIONS

of all carious dentine would restorations in whkh carious

1007

have endangered dentine was left

more, the patient had no particular complaints or painful reactions. The method followed in the other cases of deep carious lesions was applied, and the integrity was preserved indefinitely (Fig. 6, n) .

of treatment of the pulp

DISCUSSIOS

There is a prevalent concept that unless all carious or decalcified dentine is removed from every carious lesion, the pulp will always be jeopardized by microbial invasion from recurrent or continuing decay. On the other hand, every dentist who practices operative dentistry is faced regularly with cases of deep and extensive carious lesions in which removal of all carious or decalcified dentine will expose the pulp and cause the loss of the tooth. The method presented here for the management of certain deep carious lesions is based on the concept of leaving a small amount of leathery, decalcified dentine to protect the pulp from exposure. The practice of always removing all carious dentine from a lesion, at the jeopardy of an otherwise viable and normal-reacting pulp, is questionable. The principle behind it is related mostly to two factors, neither of which has been unequivocally proved or disproved. One factor is concerned with the manner in which bacteria invade dentine to infect a pulp. The other is concerned with whether or not decay recurs from a small nidus of carious dentine remaining beneath an adequate restoration, eventually causing pulpal infection. The significance of the first factor has been adequately expressed by MacGregor, softening of the dentin precedes the inMarsland, and Batty : I4 “Whether vasion of organisms once the enamel has been breached, or if organisms are

1008

C'AZl<\i

.iN1)

l~I‘KVIWrI , /

!I 5. 0 \I. a 0.1’ \UCliil, I’%~

present in dentin in advance! of this softening, is a probI(bm of morel than academic importance. ” The concept of “soft(~ning” (decalcification of’ th(h atlvanc~ing carions front) lkreceding the actual bacterial jnvasjon is supl~ortc~(l by Millor “. lG Black,’ J>orfman, Stephan, and Muntz.” and Stepharl’” a1rc1 mow recently by MacGregor, Marsland, and Batty. I4 The , opposite view. that, microorganisms precede the “softening” or decalcification autl hetlcc illi’ctci aI1 mlexposed pulp, is supported directly or indirectly by Sieberth,” Appleton,‘!’ and J tcaehrliqucxsusc~l by som(’ invcstigittors werbc not cntirc>ly atlcquatc~ to grow the Ini~robial fl0t.a of the various ICVCJIS of the rarious l&on, (*;lusillg clirclrgC*nt, rc~tlts ;~ntl (‘onc+lusions. l’he infcctioll ol’ pulps in twth with cIt:cp carious lwious is not, 1wr SC, evidence that this infection derives front InicroorgitnistlIs invading vi;), th(j dentinal tubules. Transient bacteremia of rather high itlc4dcncc lrtight IN ii source of such infection. The quostion of whcthcr the ;l(l~ancing carious front. precedes bacterial invasion or whether hact,crial invasjon prc~tlc~s th(J a(lvan(*ing carious front perhaps rc~lvcs into the possibility that both situations occur, with each situation mediated to some cxtcnt by the l)rosimity of’ t’h(> lesion to the pulp and to the tlogt*c~c!of dentine degradation (that is, whcth
Volume Number

16 8

DEEP

CARIOUS

LESIONS

1009

pulp might be erroneously interpreted to be infected. However, repeated and prolonged assault by acids probably results in irreparable damage to pulps. Although the answer is critical to the treatment of deep carious lesions, it has not been adequately determined whether the carious process will recur or continue beneath an adequate restoration. Nevertheless, the impression prcvails that recurrence occurs if any carious material remains in the lesion. The limited number of investigations have not unequivocally resolved this problem.*l There is very little positive evidence that small amounts of carious dentine remaining in the cavity, whether sterilized or not, will cause recurrence, provided the dentine does not have access to oral fluids. BesicW investigation indicates that several species of bacteria in carious material remain alive fox some time beneath a restoration but does not indicate that such bacteria involve or jeopardize the pulp. Certainly, even if carious material is removed most carefully, the cavity is not sterile and some bacteria undoubtedly remain to be enclosed by filling material. Clinical experience indicates that such rcsidual bacteria arc no serious threat to the pulp, provided that the restoration is adequate. It is obvious, however, that, recurrent decay continues or recurs when the restoration is not adequate and the cavity and residual carious dentine are accessible to the oral fluids and microbiota. I’crhaps the most important factor mediating pulpal infection or involvcmerit in deep dentinal lesions is the type and number of microorganisms in the most advanced front of dentinal caries. Streptococci and lactobacilli seem to predominate in the advancing carious front, with a number of contradicting reports supporting either species. Streptococci are involved most often in pulpal infection according to several bacteriologic studies.a2-2a Early workers postulated that the streptococci must have invaded the pulp via the dent.inal tubules, causing the pulpal reaction or degeneration.2G-30 Later investigators found streptococci in “deep dentine caries,” although the latter term is not, precisely defined.31-33 Conversely, Canby and Vernier 34 found that lactobacilli predominated in pure culture in “deep carious dentine” in selected types of carious lesions. Dorfman, Stcphan, and Muntzl’ concluded tha,t the number of bacteria in carious dentine decreases proportionately to the depth of the lcsinn. Unfortunately, they did not’determine the kinds of bacteria in the advancing carious front. Burnett and Scherp35 also found lactobacilli and proteolytic and caseinolytic microorganisms in deep dentinal caries. The samples of carious dentinc obtained were from the “deep levels” of all types of carious lesions but were not necessarily from the exact forefront of the advancing carious front,. Ccsic.21 in his studies of the fate of bacteria sealed in dental cavit,ies, found that sbreptococci and lactobacilli predominated and were, therefore, likely to predominate in the advancing carious front. More recently, WP reinvestigated the microbial flora of the advancing carious front in lesions containing a large bulk of a tough, leathery type of decalcified dentine. Organisms of the lactobacillus type predominated, rather than streptococci. Thus, more recent bacteriologic studies indicate that lactobacilli are predominant, if not exclusive, in the forefront of the advancing

WC have presented a method for the clinical rnanagcrnc~nt of dec>p carioux lesions in which the advancing carious front has approached or even reached an otherwise vital pulp oshibiting no significant untoward reactions. When a favorable history is obtained and the carious dentine is tough and leathery, nontraumatic operative proccdurcs should be a.pplicd in the careful removal of all carious decalcified dentine clxcrpt for a small amount which is left. to protect the pulp from esposuro. A thick mix of zinc osidc and eugenoi is used t,o insulate the prepared cavity. If t,htx prognosis is favorable, restoration is complctcd immediatc~ly ; if not, the tcmpor’ary filling may be allowed to rttmain for as long as 6 months before final restorat,ion. Several rcprescntative ~~~CCSSfully trcaatcd cases in which th(l rrrnoval of all carious tlontine w01llt1 have ITsulted in pulpal exposure are prx9cntctl.

1. Black,

2. 3. 4. 5. 6. 7, X, !I. 10. 11. 1%. 13. 14. 15. 16. 17. 18.

G. V.: Opcrtttive Dentistry, Chicago, 1908, Medico-Deutal Publishing Company, vol. 2, p. 1. of Operative Dentistry, McGehee, W. H. O., True, H. A., and Inskipp, E. F.: A Textbook New York, 1956, McGraw-Hill Book Company, Inc. Babel, A. B.: Operative Procedures, Except Restoration With Inlays and Periodontal and Root Canal Therapy, In Ward, M. L.: American Text-Book of Operative Dentistry, ed. 9, Philadelphia, 1940, Lea & Febiger. Howe, I?. R.: A Method of Sterilizing, and at Same Time Impregnating With a Metal, Affected Dentinal Tissue (Silver Nitrate). Dental Cosmos 59: 891, 1917. Waas, M. J.: Medicant Free ??rom Caustic Gdects for Sterilization oi Deep Clarious Dentin (Germicide), Dental Cosmos 67: 901, 1925. Prime, J. M.: Further Extending Tise of Howe’s Ammoniacal Silver Nitrate in Control of 1)ental Caries, Dental Cosmos 77: 1046, 1935. Barker, J. N.: The Sterilization of Dentine, Australian J. 1)ent. 39: 156, 1935. Haley, P. S.: Some New Chemical Methods for Treatment of Dentine in Pulpless Teeth and in Vital Teeth Affected With Caries, Brit. J. D. SC. 74: 47, 1929. (Coolidge, E. D.: The Treatment of Deep Dentine Caries, Illinois 1). .J. 1: 363 1973. Osborn, I,. ,J.: Treatment of Dentine in Deep-Seated Cavities! 1). Rec. 44: 2&, !&?4. Miller, W. D.: On the Comparative Rapidity With Which ~~lffC?reJlt Antiseptics Penetrate Decalcified Dentin; or What Antiseptics Should he JTsed for Sterilizing Cavities Before Filling9 Dental Cosmos 33: 337, 1891. Rt,udies on Sterilization of Muntz, J. A., Dorfman, 8., and Stephan, R. M.: In Vitro Various Dentin. I. Evaluation of Germicides, 6. Am. Dent. A. 30: 1893, 1943. Stephan,. R,. M., Muntz, J. A., and Dorfman, A.: In Vitro Studies on Sterilization of Carlous Dentin. III. Effective Penetration of Germicides Into Carious Lesions, .I. Am. Dent. A. 30: 1905, 1943. MacGregor, A., Marsland, E. A., and Batty, I.: Experimental Studies of Dental Caries. I. The Relation of Bacterial Invasion to the Softening of Dentine, Rrit. I). J. 101: 230, 1956. Miller, W. D.: The Microorganisms of the Human Mouth, Philadelphia, 1890, S. 8. White Dental Mfg. Co. der Xikroorganismen auf die Karies der Menschlichen Miller, W. D.: Der Einfluss Zahne, Arch. f. exper. Path. u. Pharmakol. 16: 291, 1882. Dorfman, A., Stephan, R. M., and Muntz, .J. 9.: In Vitro Studies on Sterilization of Carlous Dentin. II. Extent of Infection in Carious Lesions, J. Am. Dent.. A. 30: 1901, 1943. Our Empiric Cavity Sterilization. Part III, Stephan, R. M.: Consultant Symposium: New York State D. J. 17: 155, 1951.

DEEP

CARIOUS

LESIONS

1011

19. Appleton, J. L. T.: Bacterial Infection in Dental Practice, ed. 4, Philadelphia, 1950, Lea & Febiger. 20. Kronfeld, R.: Histopathology of the Teeth and Their Surrounding Structures, ed. 3, Philadelphia, 1949 Lea & Febiger. 21. Besic. F. C.: Fate of Bacteria Sealed in Dental Cavities. J. D. Res. 22: 349. 1943. 22. Morse, F. W., Jr., and Yates, M. F.: Follow-up Studies of Root-Filled Teeth in Relation to Bacteriologic Findings, J. Am. Dent. A. 28: 956, 1941. 23. Hayes, R. L.: Clinical and Bacteriological Study of 340 Pulp Therapy Cases, J. D. Res. 22: 301. 1943. 24. Gruchalla, F. J., and Hamann, C. B.: Root Surgery, J. Missouri D. A. 27: 229, 1947. 25. Ostrander, F. D., and Crowley, Mary C.: The Effectiveness of Clinical Treatment of Pulp-Involved Teeth as Determined by Bacteriological Methods, J. Endodontia 3: 6, 1948. 26. Sieberth, 0.: Die Mikroorganisms der Krankm Zahnpulpa, Thesis, Erlangen, 1900. 27. Niedergesiiss, K.: Anatomische, Bacteriologische und Chemische Untersuchungen iiber die Entstehung der Zahnkaries, Arch. f. Hyg. 84: 221, 1915. 28. Henrici, A. T., and Hartzell, T. B.: The Bacteriology of Vital Pulps, J. D. Res. 1: 419, 1919. 29. Henrici! A. T., and Hartzell, T. B.: A Microscopic Study of Pulps From Infected Teeth, Brat. D. J. 42: 33, 1921. 30. Clarke, J. K.: On the Bacterial Factors in the Aetiolonv Y” of Dental Caries. Brit. J. Exper. Path. 5: 141,. 1924. 31. De Vries, J. J.: La canes dentaire et les streptocoques, Compt. rend. Sot. biol. 104: 1121, 1930. 32. Berenson! F. B.: Les aeido-baeteries de la cavite buceale saine, de la eavite buccale atternte de caries, et la flore microbienne des tissus necroses du foyer de carie, Rev. stomatol. 37: 479, 1935. 33. Tunnicliff, R., and Hammond, C.: Smooth and Rough Greening Streptococci in Pulps of Intact and Carious Teeth and in Carious Dentin, J. Am. Dent. A. 25: 1046, 1938. 34. Canby, C. P., and Bernier, J. L.: Bacteriologic Studies of Carious Dentin, J. Am. Dent. A. 23: 2083. 1936. 35. Burnett G. W., ‘and Scherp, H. W.: The Distribution of Proteolytic and Acidurie Bacteria in Saliva and in the Carious Lesion, ORAL SURG., ORAL MED. & ORAL PATH. 4: 469, 1951. 36. Canby, C. P., and Burnett, G. W.: Microorganisms of Deep Dentinal Caries, submitted to J. D. Res., 1962.