Coronectomy of lower third molars with and without guided bony regeneration: a pilot study

This pilot study for a split-mouth, randomised, clinical trial compared the incidence of postoperative complications, root migration, and adjacent second molar periodontal attachment after coronectomy of the lower third molars with or without guided bony regeneration. Six patients (three men and three women, mean (range) age 27 (21-44) years), each with bilateral lower third molars in close proximity to the inferior alveolar nerve, were recruited. One third molar of each patient was randomised to be treated by coronectomy with guided bony regeneration, and the other side coronectomy alone. All subjects were reviewed for 12 months. No neurosensory deficit was noted in either group. We found no significant differences between the two groups in postoperative morbidity. Mean (SD) root migration after coronectomy with guided bony regeneration at postoperative 2 weeks, 3 months, 6 months, and 12 months were 0.14 (0.34), 0.56 (0.68), 0.63 (0.83), and 0.63 (0.83) mm, respectively. These were significantly less than the results in the control group from postoperative 3 months onwards (3 months p=0.01, 6 months p=0.004, and 12 months p=0.003). There was a trend towards reduced periodontal depth at the adjacent second molar in the study group compared with that in the control group, but not significantly so. These results show that coronectomy of lower third molars with guided bony regeneration has low morbidity and seems to reduce root migration. A full-scale randomised clinical trial will show the effect on root migration and periodontal attachment of the adjacent second molar.