Is there a difference between the primary stability of anodized and non-anodized mini-screws subjected to repeated cycles of autoclave sterilization?

Abstract

Objective: To determine if autoclave sterilization has any deleterious effects on the clinical stability of anodized versus non-anodized mini-screws. Materials and Methods: Thirty anodized and thirty non-anodized Aarhus System mini-screws (American Orthodontics, Sheboygan, WI) were utilized. Each group was divided into three test groups. In each group, mini-screws that were sterilized once using a steam autoclave (Statim 5000, SciCan USA, Canonsburg, Pa) served as the control group (n=10). The other two test groups involved mini-screws that were subjected to a repeated cycles of sterilization for five (n=10) and ten (n=10) times. All sixty mini-screws were inserted at a 90 ° angle into custom-designed synthetic blocks that simulated the average mandible of a healthy adult. The maximum insertion torque and the lateral displacement at 0.025, 0.05, 0.1, 0.25, 0.5, and 1 mm were recorded for each sample and subjected to statistical testing. A two-way ANOVA, and a three-way mixed ANOVA were used for statistical analyses. Results: Maximum insertion torque values displayed significant differences between the anodized and non-anodized groups (p<0.001) as well as the sterilization cycles (p<0.001). No significant group and cycle interaction was observed. No significant differences were found between the groups and sterilization cycles in the evaluation of the lateral displacement test. However, there was a significant group/cycle/displacement interaction (p<0.001). Conclusion: Surface treatment of mini-screws with anodization produced differences when compared to standard surface mini-screws following autoclave sterilization. The differences between the two types of mini-screws did not indicate a potential stability concern.