Influence of changes after orthodontic relapse on the perception of smile esthetics by orthodontics patients: a Survey study

Objectives: To evaluate the effect of possible tooth movements after orthodontic relapse on the aesthetic perception of patients receiving orthodontic treatment. Materials and Methods: Frontal and lateral smile photographs of a female and a male volunteer with a normal profile, class I occlusion and class I skeletal pattern who had previously undergone orthodontic treatment were used. Variables performed on female and male smile photographs and evaluated by 200 laypersons undergoing orthodontic treatment: median diastema, overbite change, central tooth extrusion, labio-lingual inclination of incisors, labio-lingual translation of the lateral tooth. Raters rated the overall attractiveness and acceptability of each photo using a scale from 0 to 10 (0: least attractive; 10: most attractive). Results: Statistical differences were observed between male and female raters. Female and male model attractiveness scores were affected by median diastema of 0.5 mm or greater and central tooth extrusion. It was observed that the increased overbite was more aesthetically acceptable in the male model compared to the female model. Although lingual inclinations of the incisors were preferred over labial inclinations in both models, there was a difference between the models in terms of the acceptable threshold. In the labiolingual translation of the lateral tooth, a decrease in attractiveness scores was observed with 1 mm of labial movement, except for male participants' frontal angle evaluations of the female model. While only 1.5 mm of lingual movement in the profile view affected the smile aesthetics in the male model, lingual movements in the frontal view affected the smile aesthetics in a similar way to the labial movements in the female model. Conclusions: Female evaluators were more critical than male evaluators. As a result of the evaluations, 0.5 mm median diastema and central tooth extrusion negatively affect smile aesthetics. There were differences between the male and female model in terms of overbite, labio-lingual inclination of the incisors, and the acceptable threshold of labio-lingual translation of the lateral teeth.