Ectopic third mandibular molar: evaluation of surgical practices and meta-analysis

To identify the preferred surgical approach (intra- or extra-oral) to remove an ectopic third mandibular molar (ETMM) according on its location and presence of an associated cyst or cutaneous fistula, and to determine the indications for a graft or osteosynthesis.

A surgical practice questionnaire was distributed to oral and maxillo-facial surgeons attending a National Congress of the French Society of Stomatology, Maxillo-facial and Oral Surgery. A systematic review of the literature and meta-analysis was carried on Pubmed, Cochrane, Embase and ScienceDirect databases using the MeSH terms: "Ectopic teeth", "Third molar", "Mandibular". One hundred and forty-three surgeons answered the questionnaire and the meta-analysis included 66 articles.

From the questionnaire, the preferred surgical approach was intra-oral except when the ETMM was in the condyle, when it was extra-oral (69.5%; p < 0.001). In the meta-analysis, an extra-oral approach was only indicated when a cutaneous fistula was present (90% vs. 35.9%; p = 0.002), irrespective of ETMM location. In the questionnaire and meta-analysis, the presence of a cyst did not change the approach (p < 0.05). The indications for a graft or osteosynthesis were a condylar location (p < 0.001), while a cutaneous fistula decreased the indication (p = 0.04) and a cyst (p = 0.009) was only associated with a graft.

The preferential approach was intra-oral, except when the ETMM was condylar or a cutaneous fistula was present when an extra-oral approach was preferred. Osteosynthesis or a graft were more likely when the ETMM was in the condyle.

This study will help to orientate surgeons vis-à-vis ETMM treatment.