[Influence of the mandibular second premolar extraction on the angulation of the mandibular third molar].

Objective: To compare the angular changes in the developing mandibular third molars in the mandibular second premolar extraction and non-extraction cases and to determine whether the mandibular second premolar extraction causes favorable rotational changes in the angulations of the developing mandibular third molars and benefits its later eruption.

Methods: Pretreatment and posttreatment panoramic radiographs were taken from 45 subjects who had been treated by the extraction of the mandibular second premolars and 48 subjects who had been treated without extraction. The horizontal reference plane was used to measure and compare the changes in the angulations of the developing mandibular third molars.

Results: The mean uprighting of the mandibular third molars seen in the extraction group was (5.9±2.5) degrees on the right side and (8.0±3.4) degrees on the left side following treatment. For the nonextraction group the mean uprighting was (1.8±2.4) degrees on the right side and (1.5±2.1) degrees on the left side. There was a statistically significant difference between the groups (P<0.05).

Conclusion: Mandibular second premolar extraction might be a helpful procedure on the angulations of the developing mandibular third molars.