Objective: To evaluate the ideal anteroposterior position of incisors in lateral smiling profiles concerning different chin prominences, and to relate these positions to nose and chin landmarks based on orthodontists' and laypersons' perceptions.
Methods: A lateral smiling profile image of a female subject was adjusted into five chin prominence series (-6, -3, 0, +3, +6 mm). For each series, the anteroposterior incisor positions were adjusted into five levels (-4, -2, 0, +2, +4 mm). Thirty-six orthodontists and 36 laypersons scored attractiveness using a visual analog scale. The maxillary incisor position (U1) relative to external nose and chin landmarks (E-line) was measured. Perception differences between orthodontists and laypersons were analyzed.
Results: In 6 and 3 mm chin retrusion, the most favored incisor positions were 2 mm retrusion and unaltered position, respectively. In the unaltered chin position, orthodontists preferred unaltered incisor, while laypersons favored 2 mm protrusion. Conversely, with 3 and 6 mm chin protrusion, the favored incisor positions were 4 mm and 2 mm protrusion, respectively, for both groups. The distance U1-E-line of the most attractive images ranged from 8.5-11.5 mm. From the regression model, the distance of 8.95 mm was recommended.
Conclusion: The preferred incisor position depended on the chin prominence. The favored incisor position tended to change in the same direction as the chin. The U1 to E-line can be the clinically useful tool for determining the proper incisor positions. The esthetic perception was similar between orthodontists and laypersons.

Keywords: Esthetics, Perception, Soft tissue