Factors Affecting the Clinical Success Rate of Miniscrew Implants for Orthodontic Treatment

Purpose: The purpose of this study was to evaluate the various factors that influence the success rate of miniscrew implants used as orthodontic anchorage. Materials and Methods: Potential confounding variables examined were sex, age, vertical (FMA) and sagittal (ANB) skeletal facial pattern, site of placement (labial and buccal, palatal, and retromandibular triangle), arch of placement (maxilla and mandible), placement soft tissue type, oral hygiene, diameter and length of miniscrew implants, insertion method (predrilled or drill-free), angle of placement, onset and strength of force application, and clinical purpose. The correlations between success rate and overall variables were investigated by logistic regression analysis, and the effect of each variable on the success rate was utilized by variance analysis. Results: One hundred fourteen patients were included with a total of 253 miniscrew implants. The overall success rate was 88.54% with an average loading period of 9.5 months in successful cases. Age, oral hygiene, vertical skeletal facial pattern (FMA), and general placement sites (maxillary and mandibular) presented significant differences in success rates both by logistic regression analysis and variance analysis (P .05). Conclusion: To minimize the failure of miniscrew implants, proper oral hygiene instruction and effective supervision should be given for patients, especially young ( 12 years) high-angle patients with miniscrew implants placed in the mandible. Keywords: clinical success, miniscrew implants, multiple-factor regression, orthodontic anchorage