Root canal treatment with calcium hydroxide

Root canal treatment with calcium hydroxide

Root canal treatment with calcium hydroxide II. Effect of instrumentation beyond the apices R. Holland, C.D., D.C., L.D.,* M. J. Ney, C.D., D.C.,** ...

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Root canal treatment with calcium hydroxide II. Effect of instrumentation

beyond the apices

R. Holland, C.D., D.C., L.D.,* M. J. Ney, C.D., D.C.,** W. de Mello, I/. de Sousa, C.D., D.C., L.D.,** P. F. E. Bernabt, C.D.,** und J. A. Otoboni Filho, C.D.,** SZo Pa&o, Brazil FACULDADE






Root canals of dog premolar teeth were instrumented beyond the apices and enlarged up to the size of a No. 40 or 80 file and filled with calcium hydroxide up to the foramen. Ninety days later the histologic data showed more favorable results with the root canals instrumented until file No. 80.


everal factors could influence the results of fillings with calcium hydroxide, and among them we have studied the instrumentation beyond the apices. The overinstrumentation crushedthe pulp stump and periapical tissues, producing a lesion of unexpected results. Seltzer and associates’found that the inflammatory reactions in teeth whose canals were instrumented beyond the apices were much more severe than in the teeth whosecanalswere instrumentedshort of the apex: large periapical granulomatous lesions invariably developed within a few weeks after instrumentation, and these lesions persisted throughout the experimental period. Nygaard Ostby’ induced bleeding purposely by pushing files beyond the apical foramen and found that a blood clot enhancedrepair in the apical third of the root canals. However, whereasSeltzer and associates’only closed the accessopenings, Nygaard Ostby filled canals short of the apices of the teeth. Besidesthe overinstrumentation, other factors, such as the size of the apical foramen and the filling material, could affect the periapical healing process. Nevertheless, the purposeof this investigation wasto study periapical repair after instrumentation of root canals beyond the apices with files of different sizes, and then filling with calcium hydroxide up to the apices. MATERIAL


Root canalsfrom 20 premolar teeth of three mongrel dogs, each 2 years old, were used in this study. Deparhnent of Endodontics. **Assistant Professors. Department of Endodontics





The C V. Mosby


Fig. 1. Root canal instrumented up to file No. 40. The periodontal ligament (PL) shows some chronic inflammatory cells. There is bone repair (BR) next to the apical foramen (AF). (Hematoxylin and eosin stain. Original magnification, x 100.) up to file No. 40. The hardFig. 2. Root canalinstrumented tissue deposition was partial and the periodontal ligament shows some chronic inflammatory cells. (Hematoxylin and eosin stain. Original magnification, X40.) 93

‘The tloors ot’ the pulp chambers ot‘ all teeth were covered with ;I layer of Cavit. and the acct‘ss openings were closed \\iith amalgam. Ninety daqs later. the animals were killed by administration of excessive amounts of anesthetic. The pieces were tixed in IO percent neutral buffered formalin solution ~ltld decalcified in formic acid-sodium iitrntc SegmelltS 01 tt1c JWS, cad1 ~ontaliiin~ c,ne tooth. were prepared for histologic examination in the usual manner. The specimens were embedded in paraffin and serially sectioned to an average thickness of 6 Fm. and the sections were stained with hematoxylin and eosin. RESULTS Root canals

Under ~enoral anesthesia. and ccith thr ruhber dam in place. the pulpal chamber of each tooth was opened and the pulps M’CK rclllo\~etl. The c,anals wert‘ instrumented 1 mm. bqoncl the apices. as ~~ontirmed by radio~rama nith files in the root canals. The apices were perforated and cnla~yxl up to the No. AC) or X0 Kerr file. In both c*perimt-ntal groups. the canals ficl-t’ ii-w sated thorouzhlv with saline during and following instrumt2ntation. After final irrigation, all the canals uere i~~refull! dried with paper points. dressed with it ~orticoid-~rntibic)ti~ solution:, anti s~alcd ol‘t’ t-or I wcuh with cotton pelltYs and a temporal-! tilling of /inc o\tid+cuycnoi and phosphate cclnent During the second trealment. the root canals L\erc irrigated agal \vith saline. dried with paper points. and lilled with calcium hydroxitlc paste (calcium hydrouide 2nd distilled water). Attempts wcrc made not to force the material beyond the root apices.


up to file No. 40

In the description of the results, we will consider the main root canal with a greater size. made by the instrumentation. and the small accessor! canals with cementum walls. normally found in dog teeth apices. The accessor> canals showed closure by hard-tissue deposition. c\icept in I5 percent of them. Mhere the hard-tissue deposition ;vas partial or absent. In these last C;WS. dehria was usually observed on the pulp \tump surface. The hardtlssuc depoaltion was partial or absent in I I main root canals. In these specimens. thcrc was bone repail and iI fibrous connecti\c tissue at the apical t‘orunlen. A t’cw chronic inflammatoq cells w!ere also observed in the periodontal ligament (Figs. 1 to 3). In six basks. there was ;I closure by cementum dcposition. There was also boric and cemrntum repair. and the periodontal ligament was free of inflammator) cells Connectl\e tissue Ingrowth into the nlain root canal was obscrvcti in three cases. This connective tissue showed \ome chronic inflammatory cells. mainly macrophagcs. There M ;I:, cementum deposition along the walls of the main root canals; this deposition repaired sonit’ resorbed areas. Bone tissue \\as repaired and locali& next to the apical foramen. The periodontal lig-

Volume Number

47 I

Fig. 5. High-power view of specimen shown in Fig. 4. Closure of an ~cessory root canal {AR]. The pulp stump (CU-WW) maintain\ its vitalit) (Hematoxylin and eosin stain. Original niafnificrrtion. X 100.)

ament wa4 free of inflammatory cells, except for some macrophagesnear the main root canal foramen (see Table I). Root canals


up to file No. 80

The results in the accessory canals were similar to those already described in the previous group. In 12 main root canals, there was a closure by cementum deposition. The cementum barrier usually was thick, except in somecaseswhere there were thin areas. Repair was observed in bone and cementum, whereasthe periodontal ligament wasfree of inflammatory cells (Figs. 4 to 6). In three cases.the hard-tissuedeposition was partial. In five cases,it was absentand there was ingrowth of connective tissue into the root canals (Fig. 7). The morphologic data for these specimenswere similar to those already described for the samecasesin the other experimental group (see Table I). DISCUSSION

The results of this investigation were better in the experimental group where the root canals were instrumentedup to file No. 80. Theseresults were unexpected. because this experimental group’s procedure theoretically should have provoked a greater trauma on periapical tissues.However, if we analyze the subject, we can observe that various factors could have inter-

Fig. 6. High-power connective


vie& (0)

of specimen between



in FIN. bridge

1. The



bonetissueCRT]i\ free of inflammatorycells. (Hclnatoxylin and eosin stain. Original magnification. x 100.) Fig. 7. Root canal instrumented up to tile No. S(i. There is connective tissue inprowth (C/i into the maln ti)ot canal. Bone tissue and cemcntum were repaired. iHcmati~.ylin and co
fered with these results. The tirst factor would be that the larger size of the root canal tnakes it easier for the calcium hydroxide adaptation on the pulp stump surface. With the larger size of the root canals, their cleaning could be done more easily. In thesecases.the poasibility of the presence of debris on the pulp stump surface is less. and consequently the calcium hydroxide adaptation is more effective. In other studieh, we observed that the presence of debris in the pulp stump surface can prevent the periapical healing processwith calcium hydroxide. I. i With the larger size of the apical foramen. the dressing would allow for better control of the inflammatory reaction provoked by the trauma.” Besides this, the periapical exudate drainage into the root canal and the ingrowth of connective tissue would take place more easily. In this event, we would find a connective tissue on the periapical foramen in better condition for repair with calcium hydroxide. It was observedthat the dental pulp healing process, after treatment with calcium hy-



ct 01

droxide, is better in pulps with mild inflammator) reactions than in those with severe inflammatory reactions.6 The partial closure or connective tissueingrowth into the main root canals was observed in the two experimental groups. The ingrowth of connective tissuewas usually observed in casesof calcium hydroxide overfilling.7. x However, we can also admit that overfilling is more frequent in casesof apicesof greater size.” This explains the greater number of caseswith ingrowth of connective tissue in the experimental group where the canalswere instrumentedup to file No. 80. In this work we did not observe the pathologic lesions described by Seltzer and associates’when the> instrumentedroot canals beyond the apices. Nevertheless, our resultsare in agreementwith Nygaard Ostby.” In our researchand in Nygaard Ostby’s research, the canalswere filled after the instrumentation. Seltzer and associates’did not fill the root canafs. This data show5 that root canal fillings are an important factor for periapical tissue repair, although Seltzer and associates’ believe that the influence of root canal fillings on the results of endodontic treatment has not yet been precisely determined. CONCLUSION More favorable results were observed with the root canalsinstrumentedbeyond the apicesuntil file No. 80.

REFERENCES Sclvcr.. S.. Soltanofl’. iv.. Sinai. I.. Goldcnher~. A.. and Wcndcr. I B.: Biologic Ayccts of Endodontics. Part 111. Periapical rkue Reactions to Root Canal Instrumentation. OK&l SLIRG. 26: 531-536. 693-705. 1968. Nlgaard OAtby. B.: The Role of the Blood Clor III Endodonw Therap!. Acta Odontol. Stand. 19: 323-30X. 1961. Holland. R.. Souza. V.. and Milanezi. L. 4.: Behavlour or Pulp Stump and Pcriaprcal Ti\wes to Some Drugs Used a~ Root Canal Drewngs. A Morphological Study. Rw. Bras Pwq. Med. Biol. 4: 83-9s. I97 I. Lconardo. 111. R.. and Holland. R.: Healing Process After L’lral Pulp Extirpation and Immediate Root Canal filling With Calcium Hydroxide. Rev. Fat. Odontol. Arqccatuba 3: 159-169. 197-l. Holland. R.: Processo de Reparo do Coto Pulpar e dos Tecido\ Periapicai\ Apcis Biopulpcctomia e Obtuqjlo de Canal Corn Hydrcixido de Cllcio ou ifxido de %inco e Eugenol. Estudo Histol6gico em Dentca de Caer. Thesis. Fat. Odontol. Aqatuha. S. Paula, Brazil. 1975. Soura. V.. and Holland, R.. Treatment ot the Intllrmetl Dental Pulp, Aust. Dent. J. 19: 101-196. 1973. M. A: Obturacion de Conducto\ Maisto. 0. A.. and Capurro, Radlculares Corn Hidrcixido de C~lcio-Iodoformo. Rev. Awe Odontol Argent. 52: 167-173. 1963. Sutimherg. T.: Wound Healing After Total Pulpectomy 111 Dogs. A Comparatice Stud; Between Rootfillings I+:ith CalciumhJ&oxide, Dihaslc Calcmmphosphate. and Gutta Percha, Odontol Revy 20: 137.lhi. 1969.