Evaluation of the lip during smile in normal occlusion adults

Chi, Kuk Sop; Kim, Kwang Won

Abstract

This study was performed to mark the criteria of the eathetic smile that was necessary to improve the esthetic problem in oral maxilla-facial region. The facial straight photographs of 62 adults(30 males, 32 females: 19-24 years old) in resting position and during smile were taken. The measurements and proportion of lip-teeth relationship during smile were statistically analized with photogrammetry The following results were obtained: 1. In the evaluation of the change of lips, smile line ratio was 0.93, buccal corridor ratio was 0.63, and smile symmetry ratio was 0.96. 2. The width of mouth during smile was 1.31 times of the width in the resting position and 0.48 times of face width. 3. The upper lip height during smile was 0.69 times of the height in the resting position and the lower lip height during smile was 0.93 times of the height in the resting position. 4. The mean exposed length of upper central incisor was 9.96mm, Maxillary incisor exposure was significantly correlated with the upper lip change ratio, mouth width change ratio, and buccal corridor ratio.