Effect of frontal facial type and sex on preferred chin projection.
OBJECTIVE
To investigate the effects of frontal facial type (FFT) and sex on preferred chin projection (CP) in three-dimensional (3D) facial images.


METHODS
Six 3D facial images were acquired using a 3D facial scanner (euryprosopic [Eury-FFT], mesoprosopic [Meso-FFT], and leptoprosopic [Lepto-FFT] for each sex). After normal CP in each 3D facial image was set to 10° of the facial profile angle (glabella-subnasale-pogonion), CPs were morphed by gradations of 2° from normal (moderately protrusive [6°], slightly protrusive [8°], slightly retrusive [12°], and moderately retrusive [14°]). Seventy-five dental students (48 men and 27 women) were asked to rate the CPs (6°, 8°, 10°, 12°, and 14°) from the most to least preferred in each 3D image. Statistical analyses included the Kolmogorov-Smirnov test, Kruskal-Wallis test, and Bonferroni correction.


RESULTS
No significant difference was observed in the distribution of preferred CP in the same FFT between male and female evaluators. In Meso-FFT, the normal CP was the most preferred without any sex difference. However, in Eury-FFT, the slightly protrusive CP was favored in male 3D images, but the normal CP was preferred in female 3D images. In Lepto-FFT, the normal CP was favored in male 3D images, whereas the slightly retrusive CP was favored in female 3D images. The mean preferred CP angle differed significantly according to FFT (Eury-FFT: male, 8.7°, female, 9.9°; Meso-FFT: male, 9.8°, female, 10.7°; Lepto-FFT: male, 10.8°, female, 11.4°;p< 0.001).


CONCLUSIONS
Our findings might serve as guidelines for setting the preferred CP according to FFT and sex.
Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, Korea.; Dental Research Institute, Seoul National University, Seoul, Korea.
Jin-Young
JY
Choi
Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, Korea.
Taeyun
T
Kim
Department of Oral and Maxillofacial Surgery, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
Hyung-Mo
HM
Kim
Private Practice, Busan, Korea.
Sang-Hoon
SH
Lee
Private Practice, Pohang, Korea.
Il-Sik
IS
Cho
Dental Research Institute, Seoul National University, Seoul, Korea.; Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Korea.
Seung-Hak
SH
Baek
Chin projection; Frontal facial type; Sex; Three-dimensional facial images