Kinematics of "Adaptive Motion" under Constant Torque Values.

INTRODUCTION: To demonstrate the unknown kinematics of complex adaptive motion with respect to disclosed values, the aim of this study was (1) to analyze the adaptive motion and (2) to compare the effects of constant torque values on kinematics. METHODS: A new endodontic motor (Aseptico AEU-28SYB Elements; SybronEndo, Orange, CA) and 8:1 contra-angle handpiece were used for analysis. A pilot test was conducted for synchronizing the external experimental stress on the shaft of the target object and the built-in torque sensor of the motor source. A load setup was developed by attaching universal precision weights to the shaft of the of the target object. The groups were adaptive motion with no load (TFA-0), adaptive motion with a 100-gcm constant load (TFA-100), and adaptive motion with a 200-gcm constant load (TFA-200). The peak-to-peak-based phase identification method was used to analyze the kinematics. Student t and Mann-Whitney U tests were used where applicable (α = 0.05). RESULTS: A noteworthy observation was the inconsistent kinematics of TFA-100 compared with the kinematics of TFA-0 and TFA-200. TFA-100 presented mixed-phased kinematics, which consisted of both a quaternary phase (n = 33) similar to that of TFA-200 and a dual phase (n = 17) similar to that of TFA-0. The sequence of these quaternary and dual phases of TFA-100 was arbitrarily changing. The kinematic parameters of dual-phase intermittent motion of TFA-0 and TFA-100 and quaternary-phase reciprocating motion of TFA-100 and TFA-200 revealed significant differences (P < .05). CONCLUSIONS: The main conclusions of the present study are the kinematics of adaptive motion was demonstrated, and the 100-gcm load is not sufficient for predictable and constant operation in the reciprocating mode.

Scanning electron microscopic evaluation of the efficacy of 5% ethylenediaminetetraacetic acid for smear layer removal.

The purpose of the study was to evaluate the smear layer removal efficacy of novel Saver® irrigating solution including 5% EDTA and to compare the 17% EDTA as the most used counterpart. Forty-four single-rooted teeth were divided into four groups, were instrumented, and irrigated. The smear treatment groups were as follows: sterile distilled water; 5.25% sodium hypochlorite; Saver®; 17% EDTA. The root samples were blinded. The micrographic images of root samples were collected by scanning electron microscope. The percentages of open dentin tubules were quantified using an image analysis software on micrographs. Two-way ANOVA followed by Tukey's multiple comparisons was used (p < .05). The 17% EDTA showed the highest percentages of open dentin tubules than the other treatments (p < .01). The mean percentages of open dentin tubules of 17% EDTA revealed statistically highly significant differences than Saver® treatment in all root regions (p < .01). Dentin tubules were covered by dense smear layer in distilled water irrigation whereas, the tubular pattern of dentin structure was not observed in hypochlorite irrigation. The commercial Saver® product presented to be less cleaning property on the smear layer than 17% EDTA and failed to show any improvement in the removal of smear layer compared with its tested counterpart.