Comparison of two sonic handpieces during the preparation of simulated root canals.

The objective of this study was to assess and compare two sonic handpieces during the preparation of simulated root canals. A total of 60 simulated canals in clear resin blocks of various angles and positions of curvature were prepared using Shaper files activated either by an MM1500 Sonic Air or an MM1400 Mecasonic handpiece. Each handpiece was used to prepare 30 canals using an identical preparation procedure which involved a linear filing motion and an anticurvature technique in curved canals. The efficacy of the handpieces was determined for straight and curved canals separately and included an assessment of loss of canal length, weight loss from the blocks, smoothness of canal walls, transportation and overall shape of the prepared canals. Canals were prepared rapidly and effectively by both handpieces. Overall, the MM1500 handpiece was associated with significantly less distance loss (P < 0.05) and significantly more loss of weight (P < 0.01). Only four prepared canals (8%) had hour-glass shapes displaying zips and elbows, each handpiece created two. Only two canals (4%) had danger zones, both were created by the MM1400 handpiece. There was little difference between the handpieces in terms of the smoothness of canal walls, the direction and amount of transportation or the overall shape of canals. Under the conditions of this study, the new MM1400 Mecasonic handpiece performed as well as the established MM1500 Sonic Air.