Soft tissue facial profile changes after orthodontic treatment with four premolars extracted

A study on the changes occurring in the soft tissue facial profile in a sample of 16 orthodontic female patients treated with extraction of four premolars led to the following observations: (1) The upper and lower lips moved back an average of 3.4 and 3.8 mm to the E line respectively; Sulcus superior and Sulcus inferior moved back an average of 1.6 and 2.3 mm to the E line respectively. (2) The mean change in the labiomental angle after treatment was almost null (0.1 degree). The mean change in the nasolabial angle after treatment showed an increase of 3.7 degrees. There was an important individual variability for both angular measurements. (3) The mean upper and lower lip protrusion relative to the Sn-Pg' line decreased 2.4 and 3.1 mm respectively. (4) The sulcus superior depth measured following Holdaway showed an average decrease of 0.9 mm. The mean changes of the integumental profile of the face relative to the H line after treatment showed that the lower lip moved back an average of 1.4 mm; the distance from Sulcus superior to the H line decreased an average of 2.4 mm, and the distance from Sulcus inferior to the H line increased an average of 0.8 mm. (5) When comparing these changes to acceptable esthetic values for the variables used, we observed that only 12% of patients in our sample finished treatment with a clearly more flattened facial profile. (6) To avoid unesthetic soft tissue profile changes, extraction of premolars should not be performed, if possible, when the pretreatment cephalogram shows any of the following characteristics: Nasolabial angle > or = 110 degrees, Ls to Sn-Pg' line < or = 3 mm, Li to Sn-Pg' line < or = 2 mm, Ss to H line < or = 3 mm, Li to H line < or = 0 mm.