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Introduction: The maintenance of the aseptic chain associated with the knowledge and mastery of technique by the Endodontists are key factors for the success of endodontic treatment. Objective: This study aimed to evaluate, through a questionnaire, the care and cleaning, sterilization and storage methods of endodontic instruments, and the time of material disposal by endodontists from city of Caxias do Sul/ RS. Material and methods: Thirty-two endodontists participated in the study. The professionals answered a questionnaire with eight questions regarding biosecurity methods that they applied in their offices. Results: The cleaning process most adopted by most professionals was the use of brush associated or not with ultrasound. The disinfecting agent of choice by most respondents was the enzymatic detergent. All professionals performing the sterilization process by autoclave. Concerning to the disposal of manual endodontic instruments, fifteen participants reported to control the presence of twist or fracture and sixteen by the number of uses. For the rotary and reciprocating systems, most endodontists controlled the instrument replacement by the number of uses; with mean age of five uses for rotatory instruments. For the reciprocating system, different responses regarding the number of uses were reported. Conclusion: This study showed that the endodontists from Caxias do Sul/RS followed a satisfactory protocol for cleaning and sterilization of endodontic instruments. However, for the replacement of rotatory and reciprocating instruments, it was found that most professionals did not follow the manufacturers' recommendation.

This study aimed to compare the diameter of sizes 25/.06, 30/.05, 35/.04, 40/.04 and 25/.07 main gutta-percha point of MTwo®system in relation to their corresponding nickel-titanium instruments. Material and methods: For this purpose, the measurements of both the main gutta-percha points and their corresponding instruments were obtained with the aid of a caliper at the positions D1, D3 and D11. Twenty points and six instruments of each size were used. Results: Data were subjected to student t test, with a significance level of 5%. It could be observed that there was a variation in the diameter of the gutta-percha points in relation to the diameter of the instruments. At D1 and D3, size 25/.07 points had diameters significantly higher than their respective instruments. At D11, sizes 25/.06, 25/.07, 30/.05 and 35/.04 points also had significantly higher diameters. For size 40/.04 point, there were no statistically significant differences between the point and instrument diameters. Conclusion:Most of the main gutta-percha points of MTwo® system analyzed in this study showed significantly greater diameters than those of their corresponding instruments. Only the size 40/.04 points did not present significant differences in diameter compared with their corresponding instrument.

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Objective: This study aimed to analyze apical deviation occurrence after preparation with three systems: manual, rotary and reciprocating. Material and Methods: Thirty simulated curved root canals 16 mm in length and a 35 degree angle were used. Canals were divided into three experimental groups, according to the system used: manual, rotary and reciprocating. The canals in the manual group were prepared by the crowndown technique, stainless steel #30 memory files were used. In the rotary and reciprocating groups, canals were instrumented by the rotary and reciprocating systems, respectively (Wizard NavigatorTM and UniconeTM) both engine-driven. For apical deviation analysis, before and after preparation, canals were filled with Indian ink and photographed in a standard manner on a platform.Subsequently, the images were manipulated by Adobe Photoshop TM software, with superimposition of pre-and postoperative images. The occurrence of deviation was measured 1 mm and 3 mm short of the working length (WL) with the aid of a ruler tool. Data were subject to analysis of variance (ANOVA), followed by post hoc Turkey's test, with significance set at 5%. Results: The occurrence of apical deviations in the manual group was significantly higher when compared to the other groups. In all three groups, mean deviation 1 mm short of the WL was significantly greater than that 3 mm short of the WL. Conclusion: The manual technique provided a larger amount of apical deviation compared to the rotary and reciprocating systems. A high number of deviations was observed 1 mm short of the WL. Keywords: Endodontics. Root canal preparation. Computer-assisted image processing. IntroductionThe aim of mechanical instrumentation is to form a continuously tapered shape canal with the smallest apical foramen diameter and the largest cervical third diameter possible, 1 while respecting root canal anatomy, without deviations from the original trajectory, mainly in curved and thin canals.