Influence of orthodontic premolar extraction therapy on the eruption of the third molars: A systematic review of the literature.

Background: Through a systematic literature review, the authors assess the effect of premolar extractions on third-molar (M3) eruption considering eruption rate, retromolar space, and molar angulation.
Types of Studies Reviewed: The authors performed a systematic search using MEDLINE and Web of Science databases up through April 2017 to identify quality studies available comparing M3 eruption between a group with premolar extraction and a group without premolar extraction.
Results: Twelve comparative retrospective cohort studies met all the inclusion criteria. The authors found in 5 studies comparing the rate of M3 eruption that there were significantly higher results in the group with extractions. They found in 5 studies comparing the evolution of the retromolar space significantly higher results in the group with extractions. Lastly, concerning the uprighting of the M3 during treatment, the authors found only 2 studies showing significant differences between the 2 groups, each time in favor of the group with extractions.
Conclusions and Practical Implications: The dental literature on premolar extraction related to the eruption of the M3 is composed of average-quality retrospective studies. Premolar extraction significantly improves the chances of M3 eruption, but the level of evidence of comparative retrospective cohort studies is low. Clinicians must continue to rely on their judgment regarding premolar extraction on a case-by-case basis until the evidence is stronger. Retrospective studies with standardized protocols and more detailed methodologies are required to obtain higher levels of evidence.
(Copyright © 2017 American Dental Association. Published by Elsevier Inc. All rights reserved.)