RESUMO
OBJECTIVE: The aim of this study was to examine the influence of various insertion sites on the failure rates of orthodontic miniscrews. PATIENTS AND METHODS: 76 orthodontic miniscrews were inserted in 59 patients: 20 in the buccal and 18 in the palatal side of the maxilla, and 38 in the buccal side of the mandible. We attempted to insert all the screws at a minimum depth of at least 5 mm. RESULTS: The total failure rate was 18.4% on average (n = 14). Orthodontic miniscrews in the palatal side of the maxilla failed at a significantly higher rate than miniscrews in the buccal side of the mandible (p < 0.001); they also failed at a significantly higher failure rate during the first 3 months after insertion than did miniscrews in the buccal side of the maxilla (p = 0.003) or mandible (p < 0.001). We also observed a significant correlation between failure rate and screw length, with the shorter miniscrews showing significantly higher failure rates (r = -0.743; r2 = 0.552; p < 0.001). CONCLUSIONS: Insertion site seems to affect the failure rates of orthodontic miniscrews. To ensure that orthodontic miniscrews have adequate stability in the palatal side of the maxilla, the insertion depth should exceed 5 mm.