Pinhole preparation for self-threading pins.

The force required to remove self-threading retention pins from dentin when the holes were drilled with two different methods was determined. The two methods employed to drill the holes were (1) using a conventional slow-speed contra-angle handpiece and (2) using a 10-to-1 gear reduction contra-angle handpiece attached to a conventional slow-speed handpiece. Also determined were the number of drills broken in the process of drilling the holes. Results demonstrated no difference in the retention of pins placed in holes drilled using these two methods. Two drills were broken in the process of drilling well over 100 holes, and both breaks occurred with the gear-reduced handpiece. Either of the two methods tested is acceptable, but we recommended using a conventional slow-speed contra-angle handpiece because of the ease of producing the holes.