Kinematics of a novel reciprocating endodontic handpiece.

AIM: To analyse the kinematics of the Reciproc Direct® contra-angle reciprocating device with different motor sources. 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 (α = 0.05). RESULTS: For the brushless micro-motor, median engaging angle was 186.5 ° at 10 000 rpm and 188.0 ° at 15 000 rpm which were significantly different than median engaging angles at 20 000 (188.5 °) and 25 000 (189.3 °) 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.

Odontoblast-like cell numbers and reparative dentine thickness after direct pulp capping with platelet-rich plasma and enamel matrix derivative: a histomorphometric evaluation.

AIM: To collect quantitative information about the numbers of odontoblast-like cells and reparative dentine thickness after direct pulp capping with platelet-rich plasma (PRP) and enamel matrix derivative (EMD). METHODOLOGY: The experiment was conducted on 36 Wistar albino rats and a total of 144 incisor teeth. Calcium hydroxide, mineral trioxide aggregate, PRP and EMD were applied as direct capping agents on the pulps of 96 incisors (n = 24). Positive and negative control groups were created on the remaining 48 incisors. The teeth were extracted on the 7th and 28th days. After routine histological preparation, cross-sections were stained with haematoxylin and eosin. The numbers of the odontoblast-like cells were measured histomorphometrically on day 7 and day 28. The thickness of the reparative dentine was also measured. The number of odontoblast-like cells was also measured beneath the dentine bridge. The normal distribution of all data was tested with the Mann-Whitney U test. The statistical differences between groups were analysed using the Kruskal-Wallis test. RESULTS: The mean number of odontoblast-like cells increased between day 7 and 28 following pulp exposure (P > 0.01) in all groups except for the EMD group (P < 0.01), when compared with both the experimental and negative control groups (P < 0.01). Reparative dentine formation was observed in all groups of teeth (P > 0.01). CONCLUSIONS: Reparative dentine formation was observed, but with no significant difference between the groups. Odontoblast-like cells were observed in association with the outcome of pulps capped with PRP and EMD. PRP and EMD are possible capping agents that influence the thickness of reparative dentine formation.