Evaluation of the effect of the first premolars extraction in fixed orthodontic treatment patients on smile morphometric indices

Introduction:In this study, we evaluated the changes in smile morphometric indices before and after fixed orthodontic treatment with and without tooth extraction. Materials and Methods:This retrospective study was performed using photographs of 46 female patients (aged between 18 and 25 years) that were taken before and after fixed orthodontic treatment. In 26 patients (Ext), the first premolars were extracted for orthodontic purposes, and in 20 patients (Nonext), no tooth was extracted for orthodontic treatment. The photographs were analysed with smile analyzer software and morphometric smile parameters were measured. In order to compare the indicators before and after treatment, paired t-test was used. For comparing the Ext and Nonext groups, we used independent t-test. Results: We did not find any significant changes in smile morphometric indices before and after orthodontic treatment in neither group (P=0.05Zamen Sa1 ). The two groups (with or without extraction) were compared using smile analyzer software, which showed that in the pre-treatment photographs, visible maxillary dentition width (P=0.01, and in post-treatment photographs, visible maxillary dentition width (P=0.00), smile width (P=0.04), and smile height (P=0.04) differed significantly between the extraction and Nonext groups. Conclusion: Orthodontic treatment with Roth system in both groups of with or without tooth extraction does not cause any significant changes in smile morphometric indices.