Prediction of orthodontic treatment of surgically exposed unilateral maxillary impacted canine patients

Objective: To determine whether clinical variables associated with surgically exposed unilateral maxillary impacted canine cases are predictors for orthodontic treatment choices involving (1) extraction, (2) expansion, (3) extraction and expansion, or (4) nonextraction and nonexpansion. Materials and Methods: A retrospective study of records of 97 cases meeting the inclusion criteria with unilateral maxillary impacted canines from three private practices were reviewed for gender, age, molar classification, impaction location and angulation, and presence of pretreatment maxillary and mandibular casts and cephalograms. Maxillary and mandibular transverse dimensions and lower incisor crowding were obtained from occlusal cast images using custom computer software. Skeletal analysis and incisor angulation and position were obtained from digitized cephalometric tracings. Statistical comparisons were made to determine parameters orthodontists could use to develop an orthodontic treatment plan. Results: Subjects with Class II end-on molars on the nonaffected side were less likely to have extraction and/or expansion. Subjects with extraction and/or expansion had decreased lower incisor to mandibular plane, available canine space, maxillary premolars, and molar transverse dimensions and an increased mandibular incisor Irregularity Index compared with nonextraction/nonexpansion subjects. Using a multiple-variable model, available canine space was the single most important predictor of extraction and/or expansion, followed by maxillary molar transverse dimension and mandibular incisor Irregularity Index. Conclusions: Available canine space, maxillary transverse dimension at the molars, and the mandibular incisor Irregularity Index serve as indicators for extraction and/or expansion in cases involving unilateral maxillary impacted canines requiring surgical exposure. Many of these cases are treated without extraction and/or expansion. (Angle Orthod. 2012;82:723-731.)