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Published on: May 31, 2017
Survival analyses of surgical miniscrews as orthodontic anchorage
Nita Viwattanatipa1, Sukalya Thanakitcharu, Akasith Uttraravichien
1Department of Orthodontics, Faculty of Dentistry, Mahidol University, Bangkok, Thailand. Nitaviw@hotmail.com
Introduction:
The objectives of this study were to determine the survival rate of titanium surgical miniscrews and the clinical parameters that posed the highest risks for failure.
Methods:
Ninety-seven titanium surgical miniscrews (diameter, 1.2 mm; length, 8-12 mm) were placed in the maxilla of 49 patients, at either a high level (nonkeratinized area) or a medium level (mucogingival junction), with the 1-stage or the 2-stage surgical technique. Survival time, event of each screw (survival or failure), and 7 clinical parameters were gathered for survival analysis. Age and latency factors were analyzed with t tests.
Results:
The cumulative survival rates were 85% at 6 months and 57% at 1 year. The Kaplan-Meier log rank test indicated significant differences in 3 explanatory variables: surgical stage, level of placement, and tissue response. Cox proportional hazards regression indicated that the 2-stage surgical procedure had a higher risk than the 1 stage. Placement at the high level had a greater risk than placement at the medium level. Inflammatory hypertrophy tissue reaction showed a higher risk than normal or mild inflammation. The t test showed that age and latency period were not significant.
Conclusions:
Titanium surgical miniscrews can be satisfactorily used as orthodontic anchorage. Controlling some aspects of the surgical protocol could reduce the failure rate.