Three Dimensional Analysis of Normal Smiles in Korean

Kang, Young Seok; Bae, Yong Chan; Hwang, So Min

Abstract

Smile reconstruction through restorating the movement of the upper and lower lips and the nasolabial fold for facial paralysis, is the one of the most important fields of plastic and reconstructive surgery. It is necessary to understand and analyze the normal smile in planning the surgery for facial paralysis. Fifty volunteers(25 men and 25 women) have been measured using 6-mm digital video camera with various computer programs to get the most spontaneous smile. Stop frames from the cycle of smile were captured in frontal, both lateral, and inferior views and the differences between resting and maximum smiling states were compared. Each subject had ten points marked on the lips and nasolabial creases. The distance and angle between each point of two states were measured and converted into x, y and z components in three dimensional space. Averages of each component were calculated. Average movement, average angle on coronal plane, and average posterior angle were 13.7 mm, 52.2 degrees, and 48.9 degrees at commissure, 10.5 mm, 56.3 degrees, and 31.4 degrees at nasolabial fold, 7.3 mm, 88.1 degrees, and 33.3 degrees at center of upper lip, 10.1 mm, 57.2 degrees, and 30.9 degrees at mid-lateral upper lip, 5.9 mm, -87.5 degrees, and 66.9 degrees at the center of lower lip, and 6.7 mm, -12.7 degrees, and 61.5 degrees at mid-lateral lower lip respectively. This study was tried to define the basis of smile in reconstruction of facial paralysis and to suggest the objective method of assessing preoperative state and postoperative result. Further studies should be followed to establish the standardized useful data for smile reconstruction.