Clinical factors correlated with the success rate of miniscrews in orthodontic treatment

Miniscrews offer a reliable alternative for anchorage during orthodontic treatment, particularly for non-cooperative patients or periodontal patients with alveolar bone loss. The study aims at assessing the correlation of various clinical indicators with the success or failure of miniscrews used for anchorage during orthodontic treatment. Thirty-four consecutive patients with a cumulative total of 82 miniscrews implanted participated in the study. Generalized Estimating Equations were used to assess the correlation of various factors with success rates. The miniscrew was considered the unit of analysis clustered within site and within patient. The overall success rate of miniscrews was 90.2%. For every additional miniscrew used in a patient's oral cavity, the success rate was reduced by 67%. Retromandibular triangle and palatal placement and in movable mucosa resulted in lower success rate. The miniscrew length and diameter were found to correlate with success rates. Orthodontic force applied on miniscrews for uprighting purposes showed a lower success rate than that used for retraction. This study revealed that miniscrews present high success rates. The number of miniscrews used per patient, the miniscrew site placement, the soft tissue type of placement, the miniscrew length and diameter as well as the orthodontic force applied on the miniscrew showed significant correlation with success rates. International Journal of Oral Science (2012) 4, 38-44; doi:10.1038/ijos.2012.1; published online 12 January 2012