Prevalence of anatomical alar band

Abstract

연세대학교 치과대학 구강생물학교실, 3 연세대학교 치과대학 교정학교실Purpose: Due to the presence of various muscles around lips, variety of facial expression can be made and changes from aging process such as wrinkles can develop on the facial skin by the action of multiple muscles. In animals, skin and muscles are developed in the entire body. On contrast, they are well developed only in the face and just one is present in the neck and the palm. Alar band was defined as outer wrinkle formed by zygomaticus minor muscle, which is common in Koreans. This study aimed to investigate clinical prevalence of alar band. Materials & Methods: Subjects were chosen from 780 new patients who visited private clinic in Gyeonggi province for orthodontic treatment. Presence of alar band was examined from the smile extraoral photos. Correlation among skeletal form, lip protrusion, gender, and age were evaluated. Results: Prevalence of alar band was higher in women (27.9%) than in men (18.5%) with statistical significance (p<0.05). With respect to age, prevalence of alar band was 19.4% in age 0-9 y, 16.9% in age 10-19 y, 31.2% in age 20-29 y, 39.5% in age 30-39, 56.5% in age 40-49. Prevalence was gradually increased from patients in their 20s to patients in their 40s and statistical significance was found (p<0.001). Concerning SN_NP, prevalence was 26.2% in normodivergent facial type, 22.0% in hyperdivergent facial type, and 32.2% in hypodivergent facial type. Hypodivergent facial group had higher prevalence but statistical significance was not observed. Statistically significant difference was not found regarding upper lip. However, prevalence of the alar band was 26% in patients with normal lower lip, 14.7% in patients with pretruded lower lip, and 33.3% in retruded lower lip. The prevalence was higher in patients with retruded lower lip with statistical significance (p< 0.05). Conclusions: 27.8% on previous anatomical study and this study showed 27.8% prevalence of alar band in clinical smile photographs. Clinical photograph study showed that alar band was more prominent in women, older people, and people with retruded lips with statistical significance. This will provide valuable diagnostic information for esthetic consideration. (J Korean Acad Esthet Dent 2015;24(1):4-12)