DOES THE APICAL LIMIT OF MECHANICAL PREPARATION MODIFY THE FORAMEN AND ROOT CANAL MORPHOLOGY?

Abstract

The aim of this study was to evaluate the influence of the mechanical preparation performed at three different working lengths (WL), through rotary and reciprocating kinematics, on the morphology of the apical foramen and root canal. Before and after preparation, 30 mesial roots of mandibular molars with 2 separate canals were scanned by computed microtomography and the apical foramina of the canals were photographed by stereomicroscope. Three groups were formed (n = 20) according to the WL: G-1 - foramen-1mm; G0 - foramen; and G+1 - foramen+1mm. Each group was divided into 2 subgroups (n = 10): G-1: Buchanan patency and manual foraminal debridement; G0 and G+1: rotary (Prodesign S #25/.08) and reciprocating (R25) foraminal enlargement. The area, perimeter, deviation and non-instrumented cemental wall (NICW) of the foramen were evaluated. Canal transportation and prepare centralization at 1, 3 and 5 mm from the foramen were evaluated. The ANOVA test was used for repeated measures to compare data on foraminal area and perimeter before and after preparation, and the Bonferroni test was used to identify the differences. For other variables, Kruskal-Wallis and Dunn tests were used. For all tests, a significance level of 5% was established. Regarding NICW, there were no differences between mechanized foraminal enlargements, which were similar to manual foraminal debridement. There was no difference in canal transport and centralization at 1, 3 and 5 mm from the foramen, regardless of the kinematics. Preparations performed in the foramen or 1 mm beyond with Prodesign S #25/.08 and R25 files promoted foraminal enlargements, deviations and were not able to instrument the entire cemental wall. The instruments used were able to maintain the apical anatomy of the canal.