PERMEABILIDADE DENTINÁRIA RADICULAR APÓS REMOÇÃO DE MATERIAL OBTURADOR POR DOIS MÉTODOS DIFERENTES

Abstract

Secondary infections of the root canal system are the main cause of the need for endodontic reinterventions in teeth that present post-treatment apical periodontitis. The success of these reinterventions depends, among other factors, on the penetration of irrigating solutions, medication and filling material in the dentinal tubules so the etiological agent can be controlled and, consequently, remission of signs and symptoms are achieved. The objective of this study is to determine the influence of two methods used to remove the endodontic filling material on root dentin permeability. Thirty-three human maxillary canines were decoronated, their root canals were endodontically prepared and they were randomly assigned to three experimental groups. In Group I (control), the canals were not filled, while in the other two groups, filling were performed using the vertical compaction of warm gutta-percha. After two weeks of storage, obturation of the canals in Group II were removed with the combined use of ultrasonic inserts and Reciproc R40 instruments, while in Group III the removal of the filling material was performed with the same mechanized endodontic instruments, however associated with solvent (chloroform). Eight samples from each group were immersed in 1.0% methylene blue under vacuum, transversely sectioned and observed under optical microscopy to measure dentin permeability. The three remaining roots of each group were divided in a sagittal plane and on the root dentin surface observed under scanning electron microscopy. The analysis of the results revealed higher permeability in the control group, with intermediary values for the roots where the ultrasonic tip was used and lower dye infiltration when chloroform was applied to soften gutta-percha. The photomicrographs showed open dentinal tubules in the control group, while in Groups II and III these were partial or totally obliterated. It can be concluded that chloroform promotes greater reduction of dentin permeability than the use of ultrasonic tips during the removal of endodontic filling material.