Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment

Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment

Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment Fábio Luiz Camargo Villela Berbert, DDS, Ph...

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Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment Fábio Luiz Camargo Villela Berbert, DDS, PhD,a Mário Roberto Leonardo, DDS, PhD,b Léa Assed Bezerra Silva, DDS, PhD,c Mário Tanomaru Filho, DDS, PhD,a and Clóvis Monteiro Bramante, DDS, PhD,d São Paulo, Brazil UNIVERSITY OF THE STATE OF SÃO PAULO AND UNIVERSITY OF SÃO PAULO

Objective. The objective of this study was to evaluate the histopathologic response of periapical tissues after root canal treatment of necrotic dog teeth with chronic apical periodontitis by using 2 calcium hydroxide–based root canal dressings and 2 root canal sealers. Study design. Seventy-eight root canals were instrumented by using 5.25% sodium hypochlorite as the irrigating solution, after which a calcium hydroxide paste (Calen/PMCC or Calasept) was placed for 30 days as a dressing. The root canals were then filled by using cold lateral gutta-percha condensation and an endodontic sealer (Sealapex or AH Plus). After 360 days, the animals were killed by anesthetic overdose; then, the teeth were histologically prepared, sectioned, and stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical tissue repair. Results. Statistical analysis showed that the poorest histopathologic results were observed in the Calasept/AH Plus group and that the Sealapex sealer overall resulted in better apical repair than the AH Plus sealer. The histopathologic results of Calen/PMCC paste with both AH Plus and Sealapex and Calasept paste with only Sealapex were statistically similar but were different from the results of Calasept with AH Plus. Conclusions. The results of this study in the dog showed differences in apical and periapical tissue repair of teeth with chronic apical periodontitis by using 2 calcium hydroxide root canal dressings and 2 sealers. More research is necessary to determine the best combination of dressings and sealers.

(Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;93:184-9)

Chronic periapical lesions after root canal treatment have been attributed to the persistence of bacterial infection.1,2 Biomechanical preparation of teeth with pulp necrosis and chronic apical periodontitis acts especially on microorganisms located in the lumen of the root canal.3 Bacteria located in ramifications of the root canal system, especially in areas of cementum erosion,4,5 can only be reached with the topical application of antibacterial root canal dressings.6 Calcium hydroxide has been recommended as a root canal dressing because of its antimicrobial action on aAssistant Professor, Department of Endodontics, School of Dentistry of Araraquara, University of the State of São Paulo, UNESP, Araraquara, São Paulo, Brazil. bProfessor, Department of Endodontics, School of Dentistry of Araraquara, University of the State of São Paulo, UNESP, Araraquara, São Paulo, Brazil. cProfessor, Department of Clinical Pediatrics, School of Dentistry of Ribeirão Preto, University of São Paulo, USP, Ribeirão Preto, São Paulo, Brazil. dAssistant Professor, Department of Endodontics, School of Dentistry of Araraquara, University of the State of São Paulo, UNESP, Araraquara, São Paulo, Brazil. eProfessor, Department of Endodontics, School of Dentistry of Bauru, University of São Paulo, USP, Bauru, São Paulo, Brazil. Received for publication Aug 7, 2000; returned for revision Jan 5, 2001; accepted for publication May 18, 2001. Copyright © 2002 by Mosby, Inc. 1079-2104/2002/$35.00 + 0 7/15/117803 doi:10.1067/moe.2002.117803

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most aerobic and anaerobic microorganisms. The antimicrobial effect of calcium hydroxide is attributable to its high alkalinity.7.8 Calcium hydroxide in polyethylene glycol, mixed with small amounts of camphorated paramonochlorophenol, increases penetration of root dentin. It also extends the period of action8 due to the formation of calcium parachlorophenolate.9 The hermetic seal of root canals is also believed to be an important factor for successful endodontic treatment. Sealapex sealer is outstanding for its biological properties and for tissue mineralization around the apical foramen after endodontic treatment of teeth with chronic periapical lesions.10 A new epoxy resin-based sealer, AH Plus, has shown biocompatibility with apical tissues after root canal treatment of teeth with vital pulp.11 The purpose of this study was to evaluate the histopathologic response of periapical tissues after root canal treatment of dog teeth with pulpal necrosis and chronic apical periodontitis by using 2 calcium hydroxide–based root canal dressings and 2 root canal sealers.

MATERIAL AND METHODS Seventy-eight root canals with completely formed apices in 6 mongrel dogs, aged 1 to 11⁄2 years, were used. The animals were first anesthetized with an intra-

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Fig 1. Radiograph of a dog’s mandible with periapical lesions. The sizes of the lesions are representative of all lesions in the experiment.

venous injection of Nembutal (30 mg/kg body weight, pentobarbital sodium; Abbott Laboratórios do Brasil Ltda., São Paulo, Brazil). An access opening was made, and the pulp tissue was removed. The teeth were left exposed to the oral environment for 7 days. The access openings were then closed with a zinc oxide/eugenol-based cement (immediate restorative material; Dentsply, Petrópolis, Brazil), and control radiographs were done every 15 days until periapical radiolucent areas of similar sizes were observed (Fig 1). After isolation with a rubber dam and disinfection with 0.3% iodoethanol (0.3% iodine in 70% alcohol), the root canals were instrumented by using the crown-down pressureless technique and the irrigation was performed with abundant 5.25% sodium hypochlorite (Instituto de Química da UNESP, Araraquara, Brazil). The apical foramen was enlarged with sequential K-files (sizes #15 to #30) in the total length of the root. The apical delta was removed. Working length was established at 2 mm short of the radiographic apex. Instrumentation was performed sequentially with K-files to size 70 to the working length, confirmed radiographically, with irrigation using 3.6 mL of 5.25% sodium hypochlorite solution at every file change. The teeth in each animal were randomly divided into 4 experimental groups, so that all dressings and obturation methods could be tested in the same animal. This resulted in 40 roots filled with AH Plus and 38 roots filled with Sealapex. Calen/PMCC paste (2.5 g calcium hydroxide, 1 g zinc oxide p.a., 0.05 g colophony, 2 mL polyethylene glycol 400, 0.04 g

camphorated paramonochlorophenol; S.S. White Artigos Dentários Ltda., Rio de Janeiro, Brazil) was used as the root canal dressing in groups I and II, and Calasept paste (Scania Dental AB, Knivsta, Sweden) in groups III and IV. These pastes were introduced into the root canal by using a threaded plunger syringe (S.S. White Artigos Dentários Ltda.). A long, 27-gauge needle (Becton Dickinson Ind. Cirúrgicas Ltda., Juiz de Fora, MG, Brazil) was used for the Calen/PMCC paste, which was applied until it passed through the apical foramen, a state that was confirmed radiographically. The occlusal cavity was then sealed with zinc oxide–eugenol cement (immediate restorative material; Dentsply). After 30 days, the root canal dressing was removed and the root canals were filled by using the lateral condensation technique, with gutta-percha cones and Sealapex endodontic sealer (Sybron Kerr Industria e Comercio Ltda., Guarulhos, SP, Brazil) for groups I and III and AH Plus (Dentsply De Trey Gmbh, Konstanz, Germany) for groups II and IV. The access opening was restored with silver amalgam (Velvalloy; S.S. White Artigos Dentários Ltda.) over a glass-ionomer base (Vitremer, 3M Dental Products, St Paul, Minn). All 4 treatment combinations were tested in each animal. After 360 days, the animals were euthanized with an anesthetic overdose. The maxilla and mandible were removed in each. The teeth were individually separated and fixed in a buffer solution of sodium cacodylate with saccharose and glutaraldehyde. The samples were demineralized with EDTA in a microwave oven (Continental Aw 42; B.S. Continental S.A. Utilidades Domésticas, São Paulo, Brazil) and prepared for

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Fig 2. Calen/PMCC-Sealapex: Complete sealing of the apical opening with mineralized tissue. Periapical region with mild inflammatory infiltrate.

histology. Thirty to 40 serial 6-µm-thick sections were obtained from each root and stained with hematoxylin and eosin. A Zeiss binocular photomicroscope was used to subjectively evaluate the following: (1) whether the level of the root canal filling was considered as slightly short (1-2 mm), to the level of, or beyond the apical opening; (2) whether closure of the apical opening with mineralized tissue was absent/initial, partial, or complete; (3) whether inflammatory infiltrate was absent/slight, moderate, or severe; (4) whether cementum and dentin resorption was absent, only cement, or cement/dentin; (5) whether bone resorption was absent or present; and (6) whether periodontal ligament was normal or slightly thick, moderately thick, or severely thick. The pathologists who evaluated the specimens were calibrated and blinded to the groups being evaluated. Values of 0, 1, or 2 (best to worst) were given to each parameter analyzed for statistical analysis. Statistical analysis of the influence of root canal

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Fig 3. Calen/PMCC–AH Plus: Complete sealing of the apical opening with mineralized tissue.

dressings and sealers on apical periodontitis repair was carried out with the nonparametric Kruskal-Wallis test and the 2-by-2 comparisons of the Dunn method.

RESULTS There was no significant difference in the apical level of the root canal fillings. Group III (Calasept and Sealapex) showed the best closure of the apical openings, followed by groups I and II, with the poorest results observed in group IV (Calasept and AH Plus; P < .05). The least-inflammatory infiltrate was observed in groups I and III, in which Sealapex was used. Group II had some more inflammatory infiltrate, with the poorest results observed in group IV (P < .05). The apical periodontal ligaments were thinner in groups I and III (Sealapex) than in groups II and IV (AH Plus; P < .05). There were no statistical differences for the cementum-dentin resorptions among the groups (P > .05; Figs 2-5). Within each group, there was a positive correlation of the intensity of the parameters analyzed and the final

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Fig 4. Calasept-Sealapex: Partial sealing of the apical opening. The periapical region showed moderate inflammatory infiltrate.

result. The overall results were calculated by adding the values of all parameters studied for each group and then comparing groups. Analysis of these results showed that the poorest histologic repair occurred in group IV, which was statistically different from groups I, II, and III (P < .05).

DISCUSSION The results of this study showed that complete mineralized closure of the apical opening occurred in 3 roots when Calasept paste and Sealapex were used and in 2 specimens when Calen/PMCC paste and Sealapex were used. By using a similar methodology, but with Calen/PMCC applied for only 7 days, Tanomaru Filho et al10 failed to obtain complete apical closure with Sealapex for 270 days. This difference is probably attributable to the different time periods used in these 2 studies. Complete apical closure occurred in only 1 case of the 40 roots sealed with AH Plus (Calen/PMCC and AH Plus). Leonardo et al11 obtained 12.5% complete

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Fig 5. Calasept–AH Plus: Absence of sealing of apical opening. The periapical region showed severe bone destruction and the presence of intense inflammatory infiltrate.

apical closure and 75% partial closure after 90 days using AH Plus. It should be emphasized, however, that these studies reported treatment of the root canals of teeth with vital pulp.10,11 In the present study, a greater number of apical closures occurred with Sealapex than with AH Plus. This difference is probably associated with the solubility of Sealapex, leading to dissociation of Ca++ and OH–, providing antibacterial properties12 and enhancement of apical tissue mineralization.13 Epoxy resin–based cements are highly insoluble.14 The superiority of Sealapex over different root canal sealers in cases of pulpal necrosis and chronic periapical inflammations has been reported in other studies.10 In the 40 root canals in which AH Plus was used, severe inflammatory infiltrate was observed in 16 roots (40%), regardless of the dressing used. Conversely, in the 38 roots with Sealapex, severe inflammatory infiltrate occurred in only 3 (7.9%). These results are in agreement with those of Tanomaru Filho et al10 who reported a small incidence (5.26%) of severe inflammatory infiltrate with Sealapex.

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Table I. Frequency of samples and histopathologic findings, arranged according to the occurrences or intensity and the experimental groups Level of root canal filling

Closure of apical opening

Inflammatory infiltrate

Thickness of the periodontal ligament Cementum-dentin resorption

Bone resorption

Slightly short To the level Beyond Complete Partial Absent Absent/slight Moderate Severe Normal Moderately thick Severely thick Absent Only cement Cement/dentin Absent Nondefined Present

Calen PMCC-Sealapex

Calen/PMCC–AH Plus

Calasept-Sealapex

Calasept–AH Plus

12 3 4 2 9 8 7 10 2 8 8 3 18 0 1 12 0 7

14 2 4 1 9 10 7 5 8 1 13 6 19 0 1 16 0 4

11 3 5 3 10 6 8 10 1 10 6 3 17 2 0 14 0 5

12 2 6 0 2 18 3 9 8 0 13 7 15 2 3 6 0 14

Assessing the effect of root canal dressings and occurrence of no or slight inflammatory infiltrate were less frequent with Calen/PMCC paste (P < .05), regardless of sealer used. The dissociation of calcium hydroxide into calcium and hydroxide ions is responsible for increasing the pH of the root canal system, making it unfavorable for bacterial growth. Other properties of calcium hydroxide, such as an antiexudate action,15 dissolution of necrotic tissue residues,16 and lipid A hydrolysis,17 may contribute to apical and periapical repair.17 The high pH of the pastes used in this study as root canal dressings is dependent on the liberation of hydroxide ions, which maintain this high pH long enough to act on the microorganisms present in all of the root canal system.7 Calcium hydroxide paste, containing a viscous vehicle, such as propylene glycol 400, a component of the Calen/PMCC paste, has been shown to be effective for the maintenance of the calcium hydroxide action, allowing a slow and extended release of calcium and hydroxyl ions for 60 days.6,9 Calcium hydroxide–based pastes in an aqueous solution could theoretically dissociate and dissipate more rapidly than a propylene-glycol–based paste.9,18 This could explain the unsatisfactory results obtained with Calasept paste and AH Plus cement (P < .05) and the more favorable results with Sealapex. The antimicrobial action of the sealer is considered to be an important auxiliary factor for the complete elimination of remaining bacteria in the dentin tubules and the root canal system after biomechanical prepara-

tion and the application of a root canal dressing.6,10 The antimicrobial action of Sealapex is related to the dissociation of calcium and hydroxide ions, which is responsible for maintaining a high pH of the tissues even after hardening due to its solubility.19,20 This antimicrobial action associated with its biocompatibility13 could explain the more favorable results obtained by Sealapex when used with a calcium hydroxide dressing.

CONCLUSIONS • Sealapex showed better histopathologic results than did AH Plus (P < .05). • When compared with the results of the other groups in this study, the Calasept/AH Plus group showed the poorest histopathologic results (P < .05). • Calen/PMCC paste associated with the 2 sealers had histopathologic results that were statistically similar to those with Calasept paste and Sealapex sealer. REFERENCES 1. Tronstad L, Barnett F, Cervone F. Periapical bacterial plaque in teeth refractory to endodontic treatment. Endod Dent Traumatol 1990;6:73-7. 2. Leonardo MR, Almeida WA, Silva LAB, Utrila LS. Histopathological observations of periapical repair in teeth with radiolucent areas submitted to two different methods of root canal treatment. J Endod 1995;21:137-41. 3. Byström A, Sundqvist G. The antibacterial action of sodium hypochlorite and EDTA in 60 cases of endodontic therapy. Int Endod J 1985;18:35-40. 4. Tronstad L, Barnett F, Riso K, Slots J. Extraradicular endodontic infections. Endod Dent Traumatol 1987;3:86-90.

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5. Sundqvist G. Ecology of the root canal flora. J Endod 1992;1:427-30. 6. Leonardo MR, Almeida WA, Ito IY, Silva LAB. Radiographic and microbiological evaluation of posttreatment apical and periapical repair of dog’s teeth with experimentally induced chronic lesion. Oral Surg Oral Med Oral Pathol 1994;78:232-8. 7. Fuss Z, Rafaeloff R, Tagger M, Szajkis S. Intracanal pH changes of calcium hydroxide pastes exposed to carbon dioxide in vitro. J Endod 1996;22:362-4. 8. Alencar AHG, Leonardo MR, Silva LAB, Ito IY. Determination of the p-monochlorophenol residue in the calcium hydroxide + p-monochlorophenol combination used as an intracanal dressing in pulpless teeth of dogs with induced chronic periapical lesion. J Endod 1997;23:522-4. 9. Anthony DR, Gordon TM, del Rio CE. The effect of three vehicles on the pH of calcium hydroxide. Oral Surg Oral Med Oral Pathol 1982;54:560-5. 10. Tanomaru Filho M, Leonardo MR, Silva LAB, Utrilla LS. Effect of different root canal sealers on periapical repair of teeth with chronic periradicular periodontitis. Int Endod J 1998;31:85-9. 11. Leonardo MR, Silva LAB, Almeida WA, Utrila LS. Tissue response to an epoxy resin-based root canal sealer. Endod Dent Traumatol 1999;15:28-32. 12. Tagger M, Tagger E, Kfir A. Release of calcium and hydroxyl ions from set endodontic sealers containing calcium hydroxide. J Endod 1988;14:588-91. 13. Holland R, Souza V. Ability of a new calcium hydroxide root canal filling material to induce hard tissue formation. J Endod 1985;11:535-43.

14. Orstavik D. Weight loss of endodontic sealers, cements and pastes in water. Scand J Dent Res 1983;91:316-9. 15. Heithersay GS. Calcium hydroxide in the treatment of pulpless teeth with associated pathology. J Br Endod Soc 1975;8:74-93. 16. Hasselgren G, Olsson B, Cvek M. Effects of calcium hydroxide and sodium hypochlorite on the dissolution of necrotic porcine muscle tissue. J Endod 1988;14:125. 17. Safavi KE, Nicholls FC. Alteration of biological properties of bacterial lipopolysaccharide by calcium hydroxide treatment. J Endod 1994;20:127-9. 18. Simon ST, Bhat KS, Francis R. Effect of four vehicles on the pH of calcium hydroxide and the release of calcium ion. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;80:45964. 19. Gordon TM, Alexander JB. Influence on pH level of two calcium hydroxide root canal sealers in vitro. Oral Surg Oral Med Oral Pathol 1986;61:624-8. 20. Tronstad L, Barnett F, Flax M. Solubility and biocompatibility of calcium hydroxide-containing root canal sealers. Endod Dent Traumatol 1988;4:152-9. Reprint requests: Mario Roberto Leonardo, DDS, PhD Departamento de Endodontia Faculdade de Odontologia de Araraquara UNESP, Rua Humaitá, 1680 Araraquara, SP, Brazil 14801-903

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