A comparison of the effect of extraction and non-extraction orthodontic treatment on third molar angulation

Abstract

Third molars often become impacted because of lack of space for their eruption. Extraction of first premolars and their influence on third molars impaction and eruption has been of concern to dental profession. The aim of this study was to determine the relationship between the changes of third molar angulation and the first premolar extraction in orthodontic treatment. Material & methods: This study was carried out on pretreatment and posttreatment panoramic and cephalometric radiographs of 70 subjects. Thirty-five subjects with mean age of 16.31.8 years treated with extraction of four first premolars (Extraction group) and the other thirty-five subjects with mean age of 16.92.6 years treated without extraction (Non-Extraction group) were studied. Upper third molar angulation was measured as angles between the occlusal surface of the tooth and occlusal plan and between occlusal surface and palatal plan also lower third molar angulation was measured as angles between the occlusal surface of tooth and occusal plan and between occlusal surface and mandibular plan in cephalometric radiographs. The angles between the occlusal plan and long axis of upper and lower third molar were measured in panoramic radiographs. Changes in third molar angulations from pretreatment to posttreatment for two groups were compared with non-parametric analysis. Results: statistical analysis revealed an improvement in third molar angulation in both groups but The changes of third molar angulation between two groups were not statistically significant. Conclusion: Extraction of first premolars during orthodontic treatments does not influence impacted third molar angulation.