The effect of repetitive screw hole use on the retentive strength of pretapped and self-tapped screws

Abstract

Multiple systems for internal screw fixation are presently in use in oral and maxillofacial surgery. These systems differ in screw diameter, material, and design. This study evaluated the uniaxial pullout strength of five screw systems. Two-millimeter, 2.7-mm, and 3.5-mm screws were initially evaluated for pullout strength. Pretapped and self-tapped screws were then inserted into the same hole multiple times before pullout testing. Results of pullout testing revealed no significant difference in pullout strength of pretapped and self-tapped screws of equal diameter ( P > .05). Increased screw diameter produced increased pullout strength. No significant difference in pullout strength was noted in pretapped or self-tapped screws inserted into the same hole one, two, or three times before pullout testing ( P > .05).