Efficacy and retrievability of root canal filling using calcium silicate-based and epoxy resin-based root canal sealers with matched obturation techniques.

This study aimed to compare the efficiency of root canal filling procedures and the retrievability of the filling material with various sealers. Forty-three patients assigned to endodontic treatment with (i) continuous wave of condensation technique (CTW) with AH-plus (ii) single-cone technique (SCT) with EndoSeal MTA. The spent time, voids entrapping and postoperative symptoms were evaluated. To evaluate the retrievability, mandibular premolar (n = 60) were divided into four groups: AH-plus/CTW, EndoSeal MTA/SCT, MTA Fillapex/SCT and EndoSequence BC Sealer/SCT. The time required removing the filled materials and remnant score were examined. EndoSeal MTA/SCT showed significantly shorter time of filling procedure. The number of void did not show significant differences between two techniques. No patients showed clinical signs during the follow-up periods. There were no significant differences between group AH-plus and EndoSeal MTA for remnant score. A certain calcium silicate-based sealer with SCT may give similar clinical efficiencies as much as continuous-wave technique using AH-plus sealer.

Elastic limits in torsion of reciprocating nickel-titanium instruments.

INTRODUCTION: Reciprocating angle and torsional load at the superelastic limit were investigated for nickel-titanium (NiTi) instruments used with reciprocating movements. METHODS: Two reciprocating NiTi instruments (Reciproc R25 [VDW, Munich, Germany] and WaveOne Primary [Dentsply Maillefer, Ballaigues, Switzerland]) and ProTaper F2 (Dentsply Maillefer) were tested for 2 torsional conditions using a custom-designed testing device. Rotational angles were applied, and generated torque values were recorded. The first test condition fixed the files at 5 mm and repetitively rotated them with gradually increasing angles up to 250° (n = 10). The second test subjected the files to a single continuous rotation until fracture (n = 10). The superelastic limits of the instruments were determined from their torque-rotation curves. Statistical analysis was performed (Kruskal-Wallis) at a 95% significance level. The tested specimens were examined under a scanning electron microscope. RESULTS: It was found that the angle at the superelastic limit was higher for R25 and Primary files than the ProTaper file (P < .05). Repetitive torsional loading with a gradually increasing rotational angle reduced the torsional resistance compared with the single rotation motion. At the 5-mm fixation level all files had superelastic limit angles higher than the 170° set in the dedicated reciprocating motor. The scanning electron microscopic analysis showed features of torsional failure. CONCLUSIONS: Under the conditions of this study, the 170° set angle of dedicated motors for reciprocating file systems is safe at the 5-mm level. Reuse of reciprocating systems, even with the movements within the elastic limit, may cause deterioration of the instruments.