Etiology of Cleft Lip Lower Lip Deformity: Use of an Objective Analysis to Measure Severity

Abstract

Objective: Measure lower lip thickness and eversion in patients with cleft lip and palate (CLP) and maxillary hypoplasia. The specific aims were to (1) compare lower lip thickness/eversion in patients with CLP to noncleft controls with maxillary hypoplasia, (2) determine differences between patients with unilateral CLP (UCLP) and bilateral CLP (BCLP), and (3) document changes in the lower lip that occur with Le Fort I advancement. Design: Retrospective case–control study. Setting: Tertiary care center. Patients/Participants: Patients with available pre- and postoperative CT scans and 2D lateral photographs who had a Le Fort I advancement between 2009 and 2017. There were 32 patients with CLP (17 females; mean age 17.7 ± 1.9 years) and 33 noncleft controls (21 females; mean age 18.8 ± 2.6 years). Main Outcome Measures: Lower lip thickness and eversion. Results: Patients with CLP and maxillary hypoplasia have a significantly thicker lower lip ( P = .019) and outward rotation of the vermilion border ( P = .003) compared to noncleft controls. The lower lip was significantly thicker in patients with BCLP than in those with UCLP ( P = .035). Lower lip thickness and rotation did not change after maxillary advancement. Conclusions: Patients with CLP and maxillary hypoplasia have a thicker and more everted lower lip than noncleft controls. Patients with BCLP have a significantly thicker lower lip than those with UCLP. Strain of the lower lip musculature appears to be an important contributor to the development of the cleft lip lower lip deformity.