Quantitative and perceived visual changes of the nasolabial fold following orthodontic retraction of lip protrusion

Abstract

OBJECTIVES: The objectives of this study were to evaluate the quantitative and perceived visual changes of the nasolabial fold (NLF) after maximum retraction in adults and to determine its contributing factors. MATERIALS AND METHODS: A total of 39 adult women's cone-beam computed tomography images were collected retrospectively and divided into the retraction group (age 26.9 +/- 8.80) that underwent maximum retraction following 4 premolar extraction and the control group (age 24.6 +/- 5.36) with minor changes of the incisors. Three-dimensional morphologic changes of hard and soft tissue including NLF were measured by pre- and posttreatment cone-beam computed tomography. In addition, perceived visual change of the NLF was monitored using the modified Global Aesthetic Improvement Scale. The influence of age, initial severity of NLF, and initial soft tissue thickness was evaluated. RESULTS: Anterior retraction induced significant changes of the facial soft tissue including the lips, perioral, and the NLF when compared with the controls ( P < .01). Perceived visual changes of the NLF was noted only in women younger than age 30 ( P < .05), with the odds ratio (95% confidence interval) of 2.44 (1.3461-4.4226), indicating greater possibility for improvement of NLF esthetics in young women of the retraction group when compared with the controls. CONCLUSIONS: Orthodontic retraction induced quantitative and perceived visual changes of the NLF. For adult women younger than age 30, the appearance of the NLF improved after maximum retraction despite the greater posterior change of the NLF.