Effect of class II extractions and functional appliance treatment on smile esthetics

Class II malocclusion is routinely observed in orthodontics. Its treatment usually revolves around the growth modification or the extractions of the teeth. Identifying treatment that leads to the greatest improvement can aid clinicians in providing the desired smile esthetics.

The aim of the study was to compare smile esthetics between treatment groups by measuring various smile variables and the esthetic perceptions of 3 panels of raters.

A cross-sectional study was performed on 66 patients equally divided into the functional appliance (FA) and upper first premolar extraction (UPE) groups. Eight smile variables were measured on post-treatment photographs using the Adobe Photoshop® software. Ten orthodontic residents, general dentists and laypersons performed the subjective evaluations of smiles using the visual analog scale (VAS). The Mann-Whitney U-test was applied to compare smile variables between the groups. The Kruskal-Wallis test was used to compare esthetic scores (ES) among the raters. The simple linear regression analysis, followed by the multiple linear regression analysis was applied to determine the smile variables associated with the ES values.

Statistically significant differences were found between the FA and UPE groups for the buccal corridor ratio (BCR) (p = 0.046), the visible dentition width ratio (VDWR) (p = 0.019) and the arch form index (AFI) (p < 0.001). The Kruskal-Wallis test showed significant differences in ES among the raters for the FA (p < 0.001) and UPE (p = 0.004) groups. The simple linear regression analysis showed significant associations between ES and the patient's age (p = 0.002), BCR (p = 0.020) and VDWR (p = 0.006). The multiple linear regression analysis showed that age (p = 0.008) and VDWR (p = 0.021) were significantly associated with the ES values.

The FA group had narrower buccal corridor spaces, a greater visible dentition width and a wider arch form in their smiles. The UPE group showed an increase in the buccal corridor width. Each panel rated the FA appliance group as superior.