Effects of laterality on esthetic preferences of orthodontists, maxillofacial surgeons, and laypeople regarding the lip position and facial convexity: a psychometric clinical trial.

INTRODUCTION

There are few, controversial, and limited studies on factors associated with the perception of profile beauty. Moreover, no study has ever assessed the role of laterality in esthetic judgment. Hence, this clinical trial was conducted.

METHODS

Photographs of 6 patients (3 women) with normal lip position (Ricketts norm = 0 mm) and facial convexity (Legan-Burstone norm = 12°) were digitally manipulated to create two series of 9 gradient images each, with convexity changes of 2° and anteroposterior lip modifications of 1 mm. Half of profiles were flipped horizontally. Laypeople (n = 35), orthodontists (n = 19), and maxillofacial surgeons (n = 10) selected the esthetically acceptable images (6912 esthetic evaluations [2 parameters × 6 sets × 9 images × 64 judges]). Effects of photogrammetric stimuli and other factors on judges' zone of esthetical acceptability (ZA) and its midrange were assessed statistically (α = 0.05).

RESULTS

Orthodontists and surgeons had respectively the broadest and narrowest ZAs (p < 0.05, ANOVA). Mean midranges of surgeons, orthodontists, and laypeople were respectively 0.27 ± 1.35, 0.56 ± 1.46, and 0.41 ± 1.77 mm for males' lower lips (p = 0.710, ANOVA); 0.27 ± 1.10, - 0.44 ± 0.91, and 0.03 ± 1.56 mm for females' lower lips (p = 0.034); 10.40 ± 3.17°, 11.09 ± 2.86°, and 11.57 ± 3.84° for men's profile convexity (p = 0.246); 10.27 ± 3.20°, 11.05 ± 1.87°, and 11.13 ± 3.26° for women's profile convexity (p = 0.346). Judges' gender did not affect their esthetic perception (p > 0.1). When patients' left side of face was visible, judges' esthetic preference parameters shifted towards a less convex profile and a narrower ZA (p < 0.05).

CONCLUSION

Slightly protruded lips (for men) and slightly less convex profiles (for men/women) might be favored by all groups. Women's esthetic lip positions might differ among groups. Judges' gender might not be a determinant. Subjects' face side can influence judges' esthetic perception of facial convexity.