Evaluation of different instrumentation techiniques in the marginal apical seal

The biomechanical preparation and sealing of the root canal system are directly related to the success of the endodontic therapy. Objectives: The aim of this study was to evaluate in vitro the influence of different instrumentation techniques on the apical seal, by means of apical microleakage. Methods: Thirty-two human canines were divided into 3 groups; group 1: manual instrumentation with the Step-Back techinique, group 2: manual instrumentation using the Crown-Down techinique and group 3: rotary instrumentation with the Profile System taper 0.4 (apical third) and taper 0.6 (medium and cervical thirds). The apical limit was standardized at a # 40. Two ml of 1% sodium hypochlorite at each instrument change and a final irrigation with 1 ml of 17% EDTA for 5 min were used. Posterior irrigation with 5 ml of distilled and deionized water was performed. The root canals were filled with an epoxy-resin based cement (Sealer 26) using the lateral condensation technique. The external root surface was impermeabilized with cyanoacrylate, except the 2 apical mm. Two teeth were used as positive and negative controls. The teeth were immersed in India ink for 96 h and submitted to diafanization for microleakage visualization. The average microleakage for group 1 was 0.72 ± 0.67 mm, for group 2, 0.31 ± 0.25 mm and group 3, 0.40 ± 0.54 mm. Results: The results showed no significant statistical difference (p>0.05) between the techniques. Conclusions: We can conclude that the apical microleakage was not influenced by the instrumentation techniques.