Design Systematic review and critical appraisal of relevant reviews.

Methods Computerised databases (Medline and Embase), the Index to Dental Literature, and the references of articles were searched to identify relevant reviews.

Main outcome measures Pathologies associated with impacted third molars and outcomes following surgical removal of third molars.

Results Twelve published reviews were assessed. Major methodological problems in these include that authors did not describe review methods such as literature search strategy and criteria for inclusion of primary studies. Reviews with similar aims included different sets of primary studies as evidence. Details of primary studies quoted were seldom sufficient for readers to judge the reliability of the evidence. With the exception of two reviews with poorer quality, the reviews concluded that there is a lack of evidence to support the prophylactic removal of impacted third molars. Two decision analyses also concluded that, on average, patients' long-term wellbeing is maximised if extraction is confined to those impacted third molars with pathology.

Conclusions In the absence of good evidence to support prophylactic removal, there appears to be little justification for the removal of pathology-free impacted third molars.