A recent review assessed the success rates of miniscrews used as temporary anchorage devices. Factors ranging from screw size to time of loading can affect such success and help define guidelines for their selection and application.
The study involved a Medline search that identified 734 articles, of which 14 matched all of their criteria. Based on a review of the 14 articles, the authors concluded that the recorded average success rate was approximately 83%. There was no difference related to sex, and older patients had a higher success rate. The maxilla had a higher success rate than the mandible, and there was no difference in the success rate between miniscrews that were immediately loaded versus those that had a delayed healing period. Miniscrews that were less than 8 mm in length and less than 1.2 mm in diameter had lower success rates and should be avoided. There was no advantage to performing a surgical flap prior to screw placement. This assessment study concluded that there are specific characteristics related to miniscrew placement that can affect success rates.
(Source: Crismani AG, Bertl MH, Celar AG, et al. Miniscrews in orthodontic treatment: review and analysis of published clinical trials. American Journal of Orthodontics and Dentofacial Orthopedics. January 2010, Volume 137, Issue 1, pages 108 to 113)