RESUMO

Stripping perforation is a possible complication in instrumentation of C-shaped canals. This study evaluated the minimum thickness of the root canal wall in C-shaped teeth after instrumentation. Twelve extracted C-shaped mandibular second molars (four teeth of type I, II and III each) were examined by CBCT (voxel size 90 µm) before and after instrumentation with WOG primary file. Micro-CT scans (voxel size 30 µm) were obtained after instrumentation. Percentage of canal wall area touched by the file and minimum thickness of dentine were measured and compared between CBCT and micro-CT. In type I C-shape canals, less than 10% of the canal wall area was touched by the instrument. In ten teeth, the shortest distance to root surface was from the instrumented area; no perforations occurred. CBCT and micro-CT measurements were in good agreement in ten cases; in two teeth, micro-CT revealed considerably shorter distance to root surface. The two shortest distances were 0.27 and 0.41 mm.

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RESUMO

Objetivo: Evaluar ex vivo, mediante reconstrucción tridimensional con tomografía computarizada de haz cónico, la presencia de vacíos, el volumen y la adaptación de la obturación a las paredes de conductos con reabsorciones dentinarias internas simuladas empleando gutapercha inyectable o cono único de gutapercha más sellador biocerámico. Materiales y métodos: Se utilizaron 10 incisivos centrales superiores humanos extraídos, en cada uno de los cuales se talló una reabsorción artificial para su obturación. La muestra fue sometida, de manera sucesiva, a dos condiciones experimentales diferentes: grupo 1, gutapercha inyectable con sistema EQ-V Master; grupo 2, cono de gutapercha más sellador biocerámico BioRoot RCS. Luego, se realizaron tomografías computarizadas de haz cónico y se hizo el estudio tridimensional. A continuación, se utilizó un programa para identificar los vacíos en la obturación y analizar cuantitativamente el volumen y la superficie cubierta por la obturación en los tercios coronario, medio (ampolla) y apical. Los datos fueron evaluados con la prueba de Wilcoxon (P<0,05). Resultados: El volumen de obturación y la superficie dentinaria en contacto con la obturación fueron similares para las dos técnicas empleadas. Las diferencias entre ambos grupos no fueron estadísticamente significativas (P>0,05). Conclusión: Aunque se observaron vacíos con ambas técnicas (en contacto con la superficie dentinaria cuando se empleó gutapercha inyectable, y en el interior de la obturación cuando se usó cono único de gutapercha más sellador BioRoot RCS), las dos rellenaron adecuadamente las reabsorciones simuladas (AU)

Aim: Ex vivo, tridimensional evaluation with cone beam computed tomography (CBCT), of the presence of voids, the obturation volume and adaption to the root canal walls with simulated internal root resorption, using injected gutta-percha or bioceramic sealer with single gutta-percha cone. Materials and methods: Ten maxillary extracted central human incisors were used and artificial internal root resorption was created in each one. For the root canal obturation, each tooth was subjected to two different experimental conditions successively, conforming two matched groups: Group I: EQ-V Master injected thermo plasticized gutta-percha system. Group II: gutta- percha point plus BioRoot RCS bioceramic sealer. First, the root canals were filled with injected gutta-percha and then, with the bioceramic sealer. Then the teeth were scanned with CBCT and subsequently a digital three-dimensional reconstruction was performed. The presence of voids, obturation volumne and the dentin wall surface covered by the filling material was quantitative analyzed through a software; at the coronal, middle (blister) and apical thirds. The data was analyzed by using Wilcoxon test (P<0.05). Results: The filling material volume and the dentin wall surface covered by it, was similar in both root canal obturation techniques. There was no significant difference between both groups (P>0.05). Conclusion: Although voids were observed in both groups (when the injected thermo plasticized gutta-percha system was used the voids were at the external surface and when BioRoot RCS + gutta-percha cone was used the voids were into the filling material), the obturation of simulated root canal resorption cavities was similar with both obturation techniques (AU)

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