An Evaluation of the Effect of the Guide Socket on the Primary Stability of the Miniscrew in a Polyurethane Cortical Bone Model

Only a few studies in the literature have evaluated the effect of pilot drilling to create a guide socket on the primary stability of miniscrews. The aim of this study was to evaluate the effect of creating a guide socket during miniscrew insertion on the primary stability of the miniscrew in an in vitro polyurethane (PU) cortical bone model. PU blocks with a density of 0.96 g/cm³ were used for in vitro cortical bone modelling, and 1.8 × 8 mm self-drilling mushroom-head titanium miniscrews were used. A 1 mm diameter surgical fissure drill was used to create the guide sockets in the study groups. A total of 45 miniscrews were included in this study in the no-guide, 2 mm guide, and 4 mm guide groups. The insertion torque values for the miniscrews in the 4 mm guide socket group were significantly lower than in the other groups, and the removal torque values for the miniscrews in the 2 mm guide socket group were significantly higher than in the other groups (<i>p</i> < 0.01). This study demonstrated that a 0.96 g/cm³ PU block can be used for in vitro cortical bone modelling and that the creation of a 2 mm guide socket increases the primary stability of the 1.8 × 8 mm mushroom-head miniscrew.