A Randomised Controlled Trial to Assess the Alveolar Bone Height Distal to Lower Second Molar Following Either Coronectomy or Extraction of the Adjacent Impacted Lower Third Molar

A coronectomy is often chosen over complete extraction of a lower third molar when the tooth appears to be in close proximity to the inferior dental (ID) canal, as assessed on a plain radiograph or a cone beam computer tomograph (CBCT). Following a coronectomy, the roots of the third molar may migrate in a coronal direction. This effect, along with the bone-preserving technique of a coronectomy over extraction, may provide increased bone height distal to the lower second molars, when compared to extraction. Partially erupted lower third molars, specifically those with mesio-angular impactions, are commonly associated with reduced bone height distal to lower second molars, and cause damage to the periodontal support of these neighboring teeth. It is assumed that maintenance of the impacted third molars or extraction of these teeth may compromise the periodontal status of the lower second molars. This study will investigate if coronectomy improves the bone levels, and therefore the periodontal status, of lower second molars, and may propose an indication for a coronectomy regardless of the proximity of the tooth to the ID canal.

Coronectomies were first proposed as a treatment option just over thirty years ago, but there are very few long-term studies on the procedure reported in the literature. To the best of the investigator's knowledge, this will be the first randomised controlled trial comparing the bone height distal to the lower second molar following a coronectomy or extraction of the lower third molar.