Evaluation of emergency screws in nonstripped pilot holes in bone

Clinicians continue to search for a rigid internal fixation system that will remain stable in thin bone, such as that found in the lateral walls of the maxilla. Insertion of a large-diameter screw in a pilot hole has been suggested to improve screw retention. This study evaluates insertional and stripping torque of six emergency screw systems placed in nonstripped pilot holes of porcine rib (thickness < or = 2 mm). The Timesh and Synthes emergency screws did not properly fit into the nonstripped pilot holes. The Techmedica emergency screw was the most retentive. The Luhr, Wurzburg, and Steinhouser emergency screws were less retentive. The Techmedica emergency screw had the greatest stripping torque in nonstripped pilot holes, but it was not significantly greater when compared to the stripping torque of identical screws placed in 2.0-mm stripped holes. The Luhr, Wurzburg, and Steinhouser emergency screws placed in 1.5-mm pilot holes had significantly less stripping torque when compared to identical screws placed in 2.0-mm stripped holes. It appears the Luhr, Wurzberg, and Steinhouser 2.0-mm self-tapping screws have a greater stripping torque than the corresponding emergency screw when placed in 1.5-mm pilot holes.