[Assessing the influence of chin prominence on perceived facial aesthetics among three groups of observers].

Purpose: To assess the influence of chin prominence on facial aesthetics with 3D images, to investigate the cognitive boundaries of chin prominence among orthodontists, general dentists and laypeople and compare the variance of their cognitive data, in order to provide quantitative reference for selection of clinical treatment.

Methods: A 3D facial image was obtained by 3dMD. The soft tissue pogonion point was altered in 2 mm increments from -10 to 10 mm with Geomagic Wrap 2015, in order to represent retrusion and protrusion of the chin. These images were rated by orthodontists, general dentists and laypeople with VAS scores. Multivariate mixed linear regression was used to analyze the influence of gender, age and chin prominence on VAS scores, and whether there were differences among different groups with SAS 9.4 software package. ANOVA was also applied for comparison of each prominence.

Results: This study was composed of 243 subjects, including 90 orthodontists, 101 general dentists and 52 laypeople. Chin prominence had significant effect on VAS scores. VAS scores decreased by 0.8910 for each unit increase in chin retrusion and decreased by 1.0958 for each unit increase in chin protrusion（P<0.01）. Desire for treatment started when chin retrusion exceeded 6 mm in orthodontist group and layperson group, 4 mm in general dentist group, and chin protrusion reached 6 mm in all groups（VAS scores <5）. There was no significant difference in the scores among orthodontists, general dentists and laypeople with the variance of chin prominence, and there was no significant difference in gender and age.

Conclusions: Chin prominence had significant effect on facial aesthetics. Soft tissue pogonion point located on the zero meridian was considered as the most attractive. Treatment needs increased significantly when chin protrusion reached 6 mm or chin retrusion exceeded 6 mm. There was no significant difference in the assessment among orthodontists, general dentists and laypeople.