Oral animation in the decision for chin augmentation.

Oral animation, such as opening and closing the lips, smiling, or laughing, leads to muscular tension over the skin and the soft tissues of the chin. The "S"-like labiomental line presents a variable scope of curves, from a full curve, through "lazy-S", to a straight line. The different profiles of the chin thus achieved enable the plastic surgeon during preoperative planning to decide whether or not to perform chin augmentation in addition to the required rhinoplasty. Anatomical, functional, and clinical data are presented and discussed.