Guided bone regeneration to reduce root migration after coronectomy of lower third molar: a randomized clinical trial

Root migration occurs after most third molar coronectomy and a portion may be exposed in the oral cavity. This study compared the root migration rate, surgical morbidities after third molar coronectomy with or without adjunctive guided bone regeneration (GBR).

A split-mouth randomized clinical trial was conducted on patients with bilateral lower third molars close to the inferior alveolar nerve. One side of the lower third molars was randomized to receive coronectomy with adjunctive GBR (study group) and the other side received coronectomy alone (control group). The cases were followed up for 2 years. Root migration, root exposure rate, surgical morbidities, and adjacent second molar periodontal regeneration were analyzed.

Forty-eight subjects (19 males, 29 females) with a mean age of 2.6 years (SD 5.8 years) were recruited. There was no root exposure in the review period. There were no statistical differences in pain and infection rate between the two groups at all time-points. The root migration was significantly less in the study group than the control group from 3 months onwards, and migrated only 1 mm (SD 1.3 mm) in 2 years (versus 3.5 mm (S.D.1.9 mm) in the control group). There were no differences in the periodontal attachment regeneration between the two groups.

Root migration in coronectomy with adjunctive GBR was less when compared with coronectomy alone, and with similar surgical morbidities and periodontal regeneration of adjacent second molars.

Minimal root migration occurred in coronectomy with adjunctive GBR. The chance of long-term (3 years or more) root exposure and the need of subsequent second operation to remove the exposed root would be reduced.