Smile Analysis

Anatomy of the Smile.
The upper and lower lips frame the display zone of the smile. Within this framework, the components of the smile are the teeth and the gingival scaffold. The soft-tissue determinants of the display zone are lip thickness, intercommissure width, interlabial gap, smile index (width/height), and gingival architecture. Although the commissures of the lips form the lateral borders of the smile, the eye can perceive inner and outer commissures, as delineated by the innermost and outermost confluences, respectively, of the vermillion of the lips at the corners of the mouth. The inner commissure is formed by the mucosa overlying the buccinator muscle where it inserts with the orbicularis oris muscle fibers at the modiolus.