Introduction. The mandibular third molar is, by far, the most frequently impacted tooth because of lack of retromolar space. In some orthodontics treatments, premolars are extracted allowing mesial drifting of the third molar, suggesting a concomitant increase in eruption space. Objectives. The purpose of this systematic review was to compare the information available about the effects of premolar extraction and nonextraction treatments in the angular changes and eruption in the mandibular third molar. Materials and methods. A literature search was conducted to identify clinical trials that assessed premolar extraction and nonextraction cases and its effects in third mandibular molar impaction. Electronic databases (PubMed) and hand-searched were searched. Results. Finally, eighteen articles met the initial inclusion criteria. From these, twelve show that there were significant difference in the angulation or eruption of the third mandibular molar between the extraction and nonextraction groups, however the six remaining didn’t find significant differences. Conclusions. The third mandibular molar behavior is not much predictable. In the literature, there isn’t a generalized consensus about the effect of the premolar extractions in the angulation or eruption of the third mandibular molar. Further studies are necessary to obtain conclusive results.
(Rev Esp Ortod. 2009;39(4):321-325)