Objective:

  To determine if repeated sterilization has deleterious effects on the clinical stability of mini-screws.

 Materials and Methods:

 Thirty each of the following mini-screws were tested: Aarhus (American Orthodontics, Sheboygan, Wisc), VectorTAS (Ormco Corporation, Orange, Calif), Dual-Top (RMO, Denver, Colo), and Ortho Anchor (KLS Martin, Jacksonville, Fla). Controls were sterilized once using a steam autoclave (Statim 5000, SciCan USA, Canonsburg, Pa). Each group of mini-screws was divided into three groups: the control (n  =  10) and two test groups (n  =  10, each). Test groups were cycled five and 10 times respectively. All screws were inserted into custom-designed synthetic blocks that simulated mandibular bone. Maximum insertion torque and lateral displacement force data were recorded and subjected to statistical testing. Two-way analysis of variance (ANOVA) and three-way mixed ANOVA were used for statistical analyses for maximum insertion torque data and lateral displacement force data, respectively. Level of significance was established at P < .05.

 Results:

 Insertion torque values displayed significant differences between both of the groups and sterilization cycles (P < .05). Significant differences were observed between American Aarhus mini-screws and both RMO and KLS Martin mini-screws. Ormco Vector mini-screws also differed significantly from the KLS Martin mini-screws in this comparison (P < .05). For lateral displacement, there was a significant main effect of groups, F(1,36)  =  14.5 (P < .05). Significant differences were observed between American Aarhus mini-screws and all three of the other groups (P < .05).

 Conclusions:

  The examined groups displayed statistical differences of variable quality that may not affect their clinical stability.

 Source: The Angel Orthodontists

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