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

## TL;DR

This study shows that creating a 2 mm guide socket improves the stability of miniscrews in a synthetic bone model.

## Contribution

The study introduces a new finding that a 2 mm guide socket enhances miniscrew primary stability in a polyurethane cortical bone model.

## Key findings

- A 4 mm guide socket significantly lowers insertion torque compared to other groups.
- A 2 mm guide socket significantly increases removal torque compared to other groups.
- A 0.96 g/cm3 PU block is suitable for in vitro cortical bone modeling.

## Abstract

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 (p < 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.