Relationship between Changes of Nasal Length and Upper Lip Height during Smile

Depressor septi nasi is an important muscle in the nose and upper lip dynamics.1-4 Hypertrophy of this muscle leads to a deformity during smiling presented by depression of nasal tip, shortening of upper lip, and a horizontal crease in upper lip.4 Rhino-gingivolabial syndrome was defined as depression of nasal tip, shortening of upper lip, and gingival show. This syndrome was attributed to the hypertrophy of the depressor septi nasi muscle.5 In cases with depressor septi nasi hypertrophy, varied combinations of smiling deformity components are encountered. This raises the question about coincidence of hyperactivity of different parts of this muscle.5 Some cases have isolated nasal lengthening, some have isolated upper labial shortening, and some cases presented the combination. If there is a relationship between nasal lengthening and upper lip shortening, resection of depressor septi nasi (DSN) in patients with DSN hypertrophy during rhinoplasty may affect upper lip changes during smile. In this study, nasal length and upper lip changes during smile are studied.5 The results of this study can help predict changes of the upper lip during smile following manipulation of DSN.