The removal of impacted third molars (M3s) is the most common surgical procedure in dentistry. While the removal of symptomatic M3s is not in dispute the is controversy as to whether asymptomatic third molars should be extracted to avoid future problems and complications, which may be both more difficult and more costly to treat in older patients; or whether asymptomatic M3s should be left in situ. Current UK guidance (NICE; SIGN 2000) does not recommend prophylactic extraction of asymptomatic M3s, However, The American Association of Oral and Maxillofacial Surgeons (AAOMS) and the American Academy of Pediatric Dentistry have both advocated for the removal of asymptomatic M3s if future pathologic features are likely.

The aim of this review was to assess whether young adults who elect to retain their asymptomatic M3s have a risk of undergoing one or more third molar (M3) extractions in the future.

Methods

Searches were conducted in PubMed, Google Scholar, and the Cochrane Central Register of Controlled Trials. All 5 reviewers carried out study selection independently. English language prospective studies with 50+ participants with at least 1 asymptomatic M3, and a minimum follow up period of 12 months were considered. The number of M3s (or subjects) removed during the follow-up period was divided by the total number of M3s (or subjects) To estimate the cumulative incidence rate of M3 removal. Annual incidence rate was estimated by dividing the cumulative incidence rate by the total number of follow-up years.

Results

• 7 studies involving 2028 patients were included.
• Sample sizes range from 70-821 patients.
• 4723 M3s were present at baseline.
• Follow up periods ranged from 1 to 18 years.
• 1286 M3s were extracted.
• Cumulative incidence for M3 extraction varied from 5 to 64% and was associated with the follow-up duration.
• The mean annual extraction rate was 3% (range 1-9%)

Conclusions

The authors concluded

When counseling patients regarding their options for managing asymptomatic, disease- free M3s, clinicians should review the risks and benefits of extraction and retention. The discussion should include providing an estimate of the risk of M3 removal over time if the M3s are retained. Given the increased complication rate for M3 extraction with increasing age, it might be more prudent to extract M3s at a relatively younger patient age.

Commentary

Three databases have been searched for this review but only English language studies have been included which may exclude some relevant studies. While only prospective studies have been included no quality assessment of the individual studies has been conducted and no information on dropouts is reported. The authors note that life table analysis could not be conducted, as sufficient information was not reported in the original studies. While this review does provide one estimate of the incidence of extraction in asymptomatic third molars the quality of the available data means that this estimate should be treated with caution and there is a need for more high quality studies that provide data to enable time to event analysis to be conducted to give more accurate age related risks of M3 extraction.  The 2012 Cochrane review by Mettes et al  did not identify any RCTs  and they concluded

Insufficient evidence was found to support or refute routine prophylactic removal of asymptomatic impacted wisdom teeth in adults. A single trial comparing removal versus retention found no evidence of a difference on late lower incisor crowding at 5 years, however no other relevant outcomes were measured.

Watchful monitoring of asymptomatic third molar teeth may be a more prudent strategy.

Links

Gary F. Bouloux, Kamal F. Busaidy, O. Ross Beirne, , Sung-Kiang Chuang, Thomas B. Dodson. What is the Risk of Future Extraction of Asymptomatic Third Molars? A Systematic Review . Journal of Oral & Maxillofacial Surgery – In Press

Mettes TDIRKG, Ghaeminia H, Nienhuijs MEL, Perry J, van der Sanden WJM, Plasschaert A. Surgical removal versus retention for the management of asymptomatic impacted wisdom teeth. Cochrane Database of Systematic Reviews 2012, Issue 6. Art. No.: CD003879. DOI: 10.1002/14651858.CD003879.pub3.

SIGN 43. Management of Unerupted and Impacted Third Molar Teeth – March 2000

 NICE – Guidance on the extraction of wisdom teeth 2000