Purpose: The purposes of this study were to examine the incidence of buccal mucosal lesions and identify factors affecting this complication caused by an interradicular miniscrew used as orthodontic anchorage. Materials and Methods: Data from patients who used the Aarhus screw as orthodontic anchorage in the authors' practice from May 2003 to December 2008 were collected. The factors related to buccal injury during the use of miniscrews were evaluated using the Rank or Fisher exact test. Results were considered significant at P .05. Results: In all, 136 Aarhus screws in 54 patients were examined. The overall incidence of buccal lesions caused by interradicular miniscrews was 11.8%. The incidences of trauma were 10.4% in men and 12.5% in women, 9.5% in the maxilla and 12.8% in the mandible, 15.0% in patients with a high mandibular plane angle and 9.2% in patients with an average angle, and 28.1% with a miniscrew insertion angle between 10 and 30 degrees, 8.6% with an insertion angle between 30 and 60 degrees, and 4.4% with an insertion angle between 60 and 80 degrees. There were statistically significant differences according to site of placement (P = .00) and occlusogingival position (P = .00). Conclusions: Interradicular miniscrews may be associated with damage to the buccal mucosa. For buccal mucosal lesions caused by interradicular miniscrews, site of placement and occlusogingival position are the major risk factors, and the angle of placement and the mandibular plane angle are secondary risk factors. The patient's sex and the arch in which the screw is placed (maxilla versus mandible) have little effect. Keywords: anchorage, buccal mucosal lesion, mandibular plane angle, miniscrew, molars