Article: Coronectomy of Mandibular Third Molar Four Years of Follow Up of 130 Cases
The problem of inferior alveolar nerve involvement during the removal of lower third molars is a clinical and, more recently, medicolegal issue. Because the results of damage to the inferior alveolar nerve are unpredictable in that many cases do recover but some do not, it is preferable to carry out a technique that may reduce the possibility of this involvement. The technique of coronectomy, partial odontectomy, or deliberate root retention, is one such technique. The best technique for partial odontectomy involves sectioning of the tooth at a 45 degree angle (as measured bucco-lingually) followed by further reduction to reduce the remaining fragments 3 mm below the crestal bone level. The distance of 3 mm has been validated by animal studies to allow bone formation over the retained root fragments. Primary closure is indicated to reduce the risk of postoperative infection. The technique of coronectomy seems to be a safe and straightforward technique with few complications or potential complications. In Pogrel’s series, there has only been one case of mild, transient (5 days) lingual paresthesia, presumably caused by the lingual retraction, but no other cases of lingual nerve involvement were reported. Other studies, however, have suggested a higher rate of transient lingual paresthesias from the use of the lingual retractor but not permanent cases of lingual nerve involvement. There does not seem to be any need to treat the exposed pulp of the tooth, and root treatment actually seems to be contraindicated. Animal studies have shown that vital roots remain vital with minimal degenerative changes.
Coronectomy was associated with a low incidence of complications in terms of IANIs (0–9.5%), lingual nerve injury (0–2%), postoperative pain (1.1–41.9%) and swelling (4.6%), dry socket symptoms (2–12%), infection rate (1–9.5%) and pulp disease (0.9%)
Coronectomy is a viable technique in those cases where removal of an impacted third molar might put the inferior alveolar nerve at considerable risk of damage. Infection, tooth mobility, and horizontally impacted teeth adjacent to the nerve are contraindications for this technique.
