Proportions in the upper lip-lower lip-chin area of the lower face as determined by photogrammetric method.

This study is concentrated on the lower face profile, the emphasis being given to the lips and chin area which have been analysed by various proportions. A sample consisted of 110 subjects (52 males and 58 females) with good soft tissue profile, dental class I and Caucasian type. All the records were taken in the natural head position (NHP) and all measurements were performed using the computer and by the same operator. Using the photographs of the facial profile, seven vertical measurements were taken and seven indices used to determine the relationships between measurements of the lower third of the face, lower lip, chin and upper lip. Almost all the vertical profile measurements were greater in males than in females. The only variables with no gender differences were lower (Li-Sto) and upper vermilion heights (Ls-Sto). The largest portion of the lower face was occupied by the chin and the smallest by the lower lip height in both genders. All indices were greater in females except (IND7) representing chin/lower third of the face proportion, which was greater in males. Some acknowledged aesthetic guidelines must be followed when determining orthodontic plan for optimal aesthetics. The proportional relationships found in our sample are a valuable contribution and might serve as a template for vertical facial analysis of the lower face in this patient population.