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.

Facial profile parameters and their relative influence on bilabial prominence and the perceptions of facial profile attractiveness: A novel approach

Objective

To evaluate the relative importance of bilabial prominence in relation to other facial profile parameters in a normal population.

Methods

Profile stimulus images of 38 individuals (28 female and 10 male; ages 19-25 years) were shown to an unrelated group of first-year students (n = 42; ages 18-24 years). The images were individually viewed on a 17-inch monitor. The observers received standardized instructions before viewing. A six-question questionnaire was completed using a Likert-type scale. The responses were analyzed by ordered logistic regression to identify associations between profile characteristics and observer preferences. The Bayesian Information Criterion was used to select variables that explained observer preferences most accurately.

Results

Nasal, bilabial, and chin prominences; the nasofrontal angle; and lip curls had the greatest effect on overall profile attractiveness perceptions. The lip-chin-throat angle and upper lip curl had the greatest effect on forehead prominence perceptions. The bilabial prominence, nasolabial angle (particularly the lower component), and mentolabial angle had the greatest effect on nasal prominence perceptions. The bilabial prominence, nasolabial angle, chin prominence, and submental length had the greatest effect on lip prominence perceptions. The bilabial prominence, nasolabial angle, mentolabial angle, and submental length had the greatest effect on chin prominence perceptions.

Conclusions

More prominent lips, within normal limits, may be considered more attractive in the profile view. Profile parameters have a greater influence on their neighboring aesthetic units but indirectly influence related profile parameters, endorsing the importance of achieving an aesthetic balance between relative prominences of all aesthetic units of the facial profile.