The lips have the function of articulation and concealing the teeth and also play a crucial role in facial expression. A beautiful pair of lips not only helps convey emotion on speaking but also is a representation of sexiness. Because the lips also play a role in balancing the nose and chin, there are a set of evaluation references of the golden ratio about lip esthetics in the field of plastic surgery. Regarding lip thickness, the upper lip should be slightly thinner than the lower lip, and the upper/lower lip ratio is approximately 1:1.5 (oriental standard)–1:2 (Western standard); taking into account the whole face proportion, the thickness of the upper lip should be less than one-third of that of the philtrum (distance from the bottom of the columella to the upper lip margin), and the thickness of the lower lip is less than one-fourth of the distance from the lip margin to the chin bottom. As for the lip shape, the upper lip should be slightly more projected than the lower lip from lateral profile, with the central lip bead at the highest point and extending to both sides like Cupid’s bow, while the lower margin of the upper lip slightly exposes the tooth crevice (no wider than 0.2 cm) and forms the natural M shape with the tooth border (M-shaped lip); the lower lip is slightly extroverted, with the center mildly depressed to complement the upper lip procheilon (ideally M shape at the upper lip and V shape at the lower lip), thus forming the sexiest and most attractive lip shape.
Lip plasty may be divided into the following methods based on patients’ requirements and the surgical objective: