FESEM evaluation of smear layer removal using different irrigant activation methods (EndoActivator, EndoVac, PUI and LAI). An in vitro study.

OBJECTIVES: This study was to compare the efficacy of EndoActivator, EndoVac, PUI, and LAI methods in removing the smear layer from root canals. MATERIALS AND METHODS: Eighty single-rooted mandibular premolars were decoronated to a standardized length of 15 mm. Specimens were shaped to ProTaper F4 (Dentsply Maillefer) and irrigated with 5.25% NaOCl at 37 °C. Teeth were divided into six groups (two control groups [n = 10] and four test groups [n = 15]) according to the final irrigation activation/delivering technique (sonic irrigation [EndoActivator], passive ultrasonic irrigation [PUI], negative apical pressure [EndoVac], and laser activated irrigation [LAI]). Root canals were then split longitudinally and observed with field emission scanning electron microscopy to evaluate the presence of smear layer at 1, 3, 5, and 8 mm from the apex. Scores were analyzed by Kruskal-Wallis and Mann-Whitney U tests. RESULTS: The EndoActivator was significantly more efficient than PUI, LAI, and control groups in removing the smear layer at 3, 5, and 8 mm from the apex. The EndoVac System removed statistically significantly more smear layer than all groups at 1 mm from the apex. At 5 mm from the apex, EndoActivator and EndoVac removed more smear layer than LAI and control groups. At 5 and 8 mm from the apex, PUI and EndoVac did not differ statistically, but both performed statistically better than the control groups. CONCLUSION: In our study, none of the activation/delivery systems completely removed the smear layer from the root canal walls; nevertheless, EV and EA showed, respectively, statistically significant better results at 1, 3, 5, and 8 mm and 3, 5, and 8 mm from the apex.

Accuracy of an electronic apex locator in the retreatment of teeth obturated with plastic or cross-linked gutta-percha carrier-based materials: an ex vivo study.

INTRODUCTION: This ex vivo study evaluated the accuracy of the Root ZX electronic apex locator (EAL) (J Morita Corp, Kyoto, Japan) in determining the working length during retreatment of canals sealed with 2 different carrier-based obturating materials (ProTaper Obturator [Dentsply Maillefer, Ballaigues, Switzerland] and GuttaCore [Dentsply Maillefer]) and also evaluated whether they influenced its accuracy differently. METHODS: Fifty extracted single-rooted human teeth with sound apices were selected for the study. We measured canals with the direct visual technique using a #10 K-file and shaped them with ProTaper Universal instruments (Dentsply Maillefer) up to this predetermined length. After instrumentation, we determined the canal length again using the visual technique (direct length [DL]). This value was considered the "reference point." Specimens were then placed in a tooth holder (Pro-Train; Simit Dental, Mantova, Italy), and the canal length was electronically measured (electronic length 1 [EL1]). Specimens were then obturated with ProTaper Obturators (group 1, n = 25) and GuttaCore (group 2, n = 25). Seven days later, a new electronic length was determined (electronic length 2 [EL2]) during retreatment procedures in the presence of the obturating material. EL1 and EL2 values were compared with DL using the Bland and Altman method. The different influences of the tested materials on the accuracy of the EAL were calculated with repeated measures analysis of variance. RESULTS: Both EL1 and EL2 values provided a statistically significant overestimation of the actual canal length (DL [P < .05]), with the EL2 values higher from DL. The 2 different materials did not influence the accuracy of the EAL differently (P = .486). CONCLUSIONS: The measurements obtained with the EAL tested during orthograde retreatments can lead clinicians to overinstrumentation and consequent overfilling of the endodontic space.

Smear layer removal and canal cleanliness using different irrigation systems (EndoActivator, EndoVac, and passive ultrasonic irrigation): field emission scanning electron microscopic evaluation in an in vitro study.

INTRODUCTION: The purpose of this study was to evaluate the effectiveness of different irrigating methods in removing the smear layer at 1, 3, 5, and 8 mm from the apex of endodontic canals. METHODS: Sixty-five extracted single-rooted human mandibular premolars were decoronated to a standardized length of 16 mm. Specimens were shaped to ProTaper F4 (Dentsply Maillefer, Ballaigues, Switzerland) and irrigated with 5.25% NaOCl at 37°C. Teeth were divided into 5 groups (2 control groups [n = 10] and 3 test groups [n = 15]) according to the final irrigant activation/delivering technique (ie, sonic irrigation, passive ultrasonic irrigation [PUI], or apical negative pressure). Root canals were then split longitudinally and observed by field emission scanning electron microscopy. The presence of debris and a smear layer at 1, 3, 5, and 8 mm from the apex was evaluated. Scores were analyzed by Kruskal-Wallis and Mann-Whitney U tests. RESULTS: The EndoActivator System (Dentsply Tulsa Dental Specialties, Tulsa, OK) was significantly more efficient than PUI and the control groups in removing the smear layer at 3, 5, and 8 mm from the apex. The EndoVac System (Discus Dental, Culver City, CA) removed statistically significantly more smear layer than all groups at 1, 3, 5, and 8 mm from the apex. At 5 and 8 mm from the apex, PUI and the EndoVac did not differ statistically significantly, but both performed statistically better than the control groups. CONCLUSIONS: In our study, none of the activation/delivery systems completely removed the smear layer from the endodontic dentine walls; nevertheless, the EndoActivator and EndoVac showed the best results at 3, 5, and 8 mm (EndoActivator) and 1, 3, 5, and 8 mm (EndoVac) from the apex.