Kinematics of a novel reciprocating endodontic handpiece

Aim To analyse the kinematics of the Reciproc Direct (R) contra-angle reciprocating device with different motor sources.\n Methodology Reciproc Direct contra-angle (VDW GmbH, Munich, Germany) was tested with new micro-motor sources. The micro-motor groups were as follows: a brushless electric micro-motor, a brushed electric micro-motor and an air-driven micro-motor. The electric micro-motor sources were also divided into four subgroups as 10 000, 15 000, 20 000 and 25 000 rpm. The maximum air pressure of the air-driven micro-motor was adjusted to 2 and 3 kgf cm(-2). A custom target object was attached to the Reciproc Direct, and reciprocating motions were recorded with a high-speed camera at 1200 frames per second. The following kinematic parameters were calculated: duration of each reciprocating motion, engaging and disengaging angles, cycle rotational speeds, engaging and disengaging rotational speeds, net cycle angle, total cycle angle and number of cycles to complete full rotation. One-way anova was used where applicable, followed by Tukey's multiple comparison tests, to compare the kinematic values of reciprocating motion for each micro-motor/Reciproc Direct combination. The Kruskal-Wallis test followed by Dunn's multiple comparison test was used for non-normally distributed data. Statistical analysis was performed (alpha = 0.05). Results For the brushless micro-motor, median engaging angle was 186.5 degrees at 10 000 rpm and 188.0 degrees at 15 000 rpm which were significantly different than median engaging angles at 20 000 (188.5 degrees) and 25 000 (189.3 degrees) rpm (P < 0.05). For the brushless micro-motor, median cycle rotational speed was 372.5 rpm at 10 000 and 459.8 rpm at 15 000 rpm which were significantly different than median cycle rotational speed at 20 000 (576.2 rpm) and 25 000 (677.8 rpm) rpm (P < 0.05). For the brushed micro-motor, median cycle rotational speed was 293.5 rpm at 10 000 and 386.3 rpm at 15 000 rpm which were significantly different than median cycle rotational speed at 20 000 (508.9 rpm) and 25 000 (597.6 rpm) rpm (P < 0.05). Conclusions Rotational speeds were influenced significantly by motor sources even when the Reciproc Direct was used at speeds recommended by the manufacturer. This could indicate that the kinematics of the Reciproc Direct are dependent on the power of the rotating motor.C1 [Orhan, E. O.] Eskisehir Osmangazi Univ, Dept Endodont, Eskisehir, Turkey.[Irmak, O.] Eskisehir Osmangazi Univ, Dept Restorat Dent, Eskisehir, Turkey.[Ertugrul, I. F.] Pamukkale Univ, Dept Endodont, Fac Dent, Denizli, Turkey

Enhanced Removal of Enterococcus faecalis

Objective: The purpose of this study was to determine the effectiveness of laser-activated irrigation by photon-induced photoacoustic streaming (PIPS) using Er:YAG laser energy in decontaminating heavily colonized root canal systems in vitro. Materials and methods: Extracted single-rooted human teeth (n=60) were mechanically and chemically prepared, sterilized, inoculated with Enterococcus faecalis for 3 weeks, and randomly assigned to four groups (n=15): Group I (control, no decontamination), Group II (PIPS+6% NaOCl), Group III (PIPS+saline), and Group IV (6% NaOCl). PIPS settings were all preset to 50 μsec pulse, 20 mJ, 15 Hz, for an average power of 0.3 W. After decontamination, the remaining live microbes from all specimens were collected and recovered via plate counting of the colony-forming units (CFUs). Randomized root canal surfaces were examined with scanning electron microscopy and confocal laser microscopy. Mean variance and Dunnett's t test (post-hoc test) comparisons were used to compare mean scores for the three groups with the control group. Results: The CFU analysis showed the following measurements (mean±SE): Group I (control), 336.8±1.8; Group II (PIPS+NaOCl), 0.27±0.21; Group III (PIPS+saline), 225.0±21; and Group IV (NaOCl), 46.9±20.29. Group II had significantly lower CFUs than any other groups (p<0.05). Both imaging analyses confirmed levels of remaining bacteria on examined root surfaces. Conclusions: The use of the PIPS system along with NaOCl showed the most efficient eradication of the bacterial biofilm. It appears that laser-activated irrigation (LAI) utilizing PIPS may enhance the disinfection of the root canal system