Abstract: Objective: To compare the surface roughness, the degree of microleakage, and fracture resistance of veneers after using air-turbine handpiece and electric handpiece at different speeds to prepare tooth in vitro. Methods: Sixty premolars without decay were extracted and divided into 4 groups (n=15) according to the way of preparation. Air-turbine handpiece (Group A) and electric handpiece with 200,000 r/min (Group B), 50,000 r/min (Group C), and 20,000 r/min (Group D) were used to prepare tooth in vitro. White light interferometer was used to measure the surface roughness. The microleakage of the mid-longitudinal section was surveyed under a microscope after bonding veneers with resin cement and simulated for aging. The fracture resistance was measured by an electronic universal testing machine. Results: There was no significant difference on the surface roughness and fracture resistance between four groups (P>0.05). However, there was significant difference in the microleakage degree after aging test (P<0.05). Conclusion: The surface roughness and fracture resistance of veneers are not affected by the type and speed of handpieces. Electric handpiece at 200,000 r/min had the smallest average microleakage of veneers.

Key words: electric handpiece, air-turbine handpiece, veneer, surface roughness, microleakage, fracture resistance