Smile Esthetics and Rotated Maxillary Lateral Incisors

Although tooth rotations are a common orthodontic problem, little research has addressed how lay observers perceive these rotations. Consequently, the aim of this study is to determine laypersons' esthetic perceptions of changes in the rotation of the maxillary lateral incisors.

An intraoral digital scan of a female adult's dentition was manipulated with ClinCheck software to create four smile conditions: (A) no rotation either maxillary lateral incisor, (B) 20° mesial-out rotation of both, (C) 30° mesial-out rotation, and (D) 40° mesial-out rotation. Each condition was shown with frontal and three-quarter view images. A panel of laypeople (age 18-30, no dental training) rated the attractiveness of each smile using a 100 mm visual analog scale (VAS; 0 = least esthetic, 100 = most esthetic). The score for each condition was recorded. A mixed-model two-way ANOVA (gender × rotation) with repeated measures was used to analyze the data.

No-rotation smiles were rated significantly more attractive than any smiles with rotated lateral incisors (p  < 0.05). Smiles with a 40° rotation received the lowest esthetic scores and were significantly less attractive than the others (p  < 0.001). Laypersons did not significantly distinguish between 20° and 30° rotations (p  > 0.05). There was no significant difference in ratings between male and female panelists (p = 0.104). No interaction effect between panelist gender and rotation level was observed.

Laypeople preferred the smile with no rotation of the lateral incisors. They could not perceive a notable esthetic difference between 20° and 30° rotations. However, a 40° rotation was perceived as substantially less esthetic. Panelist gender did not affect esthetic ratings.