Outcome Analysis and Unexpected-Scenario Prediction in 2-Stage Orthodontic Lower Third Molar Extraction

Purpose: We propose a 2-stage orthodontic lower third molar extraction procedure to reduce iatrogenic inferior alveolar nerve injury. We tested our hypothesis that there are factors that can predict both dislodgement of the root portion and limited traction distances. Patients and Methods: Fifteen patients (mean age, 25.7 years; age range, 17 to 65 years) with 20 lower third molars were enrolled. Panoramic films and cone beam computed tomography were analyzed. Dislodgement of the root portion, traction distance, duration of the orthodontic phase, and postoperative complications were documented. The predictive factors were analyzed and discussed. Results: Three teeth had dislodgements of the root portion. The mean traction duration was 59.2 days (range, 33 to 77 days), and the mean traction distance was 2.60 mm (range, 0.27 to 5.20 mm). Root apex cortical bone indentation and root curvature were significantly associated with traction distance. Pulpitis symptoms were documented in 1 tooth, and no postoperative nerve disturbances occurred. Conclusions: Our proposed 2-stage orthodontic lower third molar extraction procedure reduced iatrogenic inferior alveolar nerve injury. Cortical bone indentation and root curvature predicted dislodgement of the root portion and limited traction distances.