Early root migration after a mandibular third molar coronectomy

Purpose: This prospective cohort study aimed to assess early root migration after a coronectomy of the mandibular third molar at 2 and 6 months after surgery. Methods: We included all patients treated with a coronectomy of an impacted mandibular third molar. The primary outcome measure was the extent of postoperative root migration after 2 and 6 months. Migration was measured as the distance between the root complex and a fixed point on the inferior alveolar canal. The secondary aim was to identify factors (age, impaction pattern, and patient sex) that affected the extent of root migration. Results: One hundred and sixty-five coronectomies were performed in 141 patients (96 females and 45 males; mean age 33.1 years, SD 16.0). The 2-month checkup was completed by 121 patients that received 141 coronectomies. The 6-month check-up was completed by 73 patients that received 80 coronectomies. The mean root migrations were 3.30 mm (SD 2.53 mm) at 2 months and 5.27 mm (SD 3.14 mm) at 6 months. In the 2–6-month interval, the mean root migration was 2.58 mm (SD 2.07 mm). The extents of migration were similar during the 0–2-month interval and the 2–6-month interval (p = 0.529). Younger age was associated with greater root migration, and females experienced significantly greater migrations than males (p = 0.002). Conclusion: Roots migrated more rapidly in the first two postoperative months, compared to the 2–6-month interval. Age was negatively correlated with the extent of root migration, and females showed significantly greater migrations than males.