Coronectomy with adjunctive guided bone regeneration (GBR) involved the least root migration, reported by a study carried out by Yiu Yan Leung; Faculty of Dentistry, The University of Hong Kong. As the affected mandibular third molars extraction close to the inferior alveolar nerve (IAN) may result in neurologic damage and coronectomy is used as an alternative surgical approach. However, this surgical approach was greatly influenced by root migration.

Therefore, Dr Yiu Yan Leung proposed a randomized split-mouth clinical analysis to assess the incidents of root migration and surgical morbidities related to adjunctive GBR along with or without coronectomy. The coronectomy with adjunctive GBR (study group) given to the one side and coronectomy alone (control group) on the other side of the lower third molars. Afterwards, a two years follow-up was done and involved examination of surgical morbidities, adjacent second molar periodontal regeneration root migration, and root exposure rate.

A total of 48 patients were selected. No root exposure was seen during the review period. Both groups exhibited statistically similar extent of infection and pain rate at all time-points. The study group showed less root migration after 3 months; with only 1mm migration in 2 years. Also, no difference was seen in the periodontal attachment regeneration between the groups. This explains the adjunctive GBR is an efficient approach to reduce the root migration rates during the mandibular third molar surgery.