Biomechanical evaluation of the anodic oxidized miniscrew implant

Abstract

The aim of this study was to evaluate biomechanical stability of orthodontic miniscrew which was surface treated with anodic oxidization method. In order to find out biomechanical stabilities depending on the time-points of the installation and also the biological characteristics of orthodontic miniscrew, the insertion torque, mobility and removal torque were measured by using anodic oxidized miniscrew and machined surface miniscrew. The surface form and surface roughness of each group were observed under SEM. On each side of mandibular buccal bone in 6 mature dogs, 24 self-drilling type miniscrews of 1.45 mm diameter and 7 mm length were installed respectively. Then immediate loading was applied after the installation, and the success rate, insertion torque, mobility and removal torque were measured. Beagle dogs were sacrificed, and the tissue specimens were made and histological changes were compared and observed. The obtained results were as follows: 1. The overall success rate of total 48 miniscrews was 98%. 2. There was no statistically significant difference in insertion torque. The insertion torques were 12.5 Ncm in experimental group and 12.2 Ncm in control group (P >0.05). 3. In mobility measurement, there was a statistically significant difference between the time-points of measurements (P <0.05), but there was no statistically significant difference between groups at certain time-point (P >0.05).

4. There was a statistically significant difference between groups in removal torque. The removal torques of experimental group were 4.1 Ncm in 3 weeks and 4.6 Ncm in 12 weeks, and the removal torques of control group were 2.4 Ncm in 3 weeks and 2.5 Ncm in 12 weeks (P <0.05). 5. In histological observation, anodic oxidized miniscrew group showed more mature bone adjacent to miniscrew as time passed. In this study, anodic oxidized miniscrew showed a relatively higher osseointegration ability than those of non-oxidized ones. This is thought to be helpful for the biocompatibility, and it is considered that various comparative studies will be necessary.