SOFT-TISSUE FACIAL PROFILE CHANGES AFTER ORTHODONTIC TREATMENT WITH 4PREMOLARS 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 lo wer lips moved back an average of 3.4 and 3.8 mm to the E line respect ively; 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 la biomental angle after treatment was almost null (0.1-degrees). The mea n change in the nasolabial angle after treatment showed an increase of 3.7-degrees. There was an important individual variability for both a ngular measurements. (3) The mean upper and lower lip protrusion relat ive to the Sn-Pg' line decreased 2.4 and 3.1 mm respectively. (4) The sulcus superior depth measured following Holdaway showed an average de crease 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 Sulcu s inferior to the H line increased an average of 0.8 mm. (5) When comp aring these changes to acceptable esthetic values for the variables us ed, we observed that only 12% of patients in our sample finished treat ment with a clearly more flattened facial profile. (6) To avoid unesth etic soft tissue profile changes, extraction of premolars should not b e performed, if possible, when the pretreatment cephalogram shows any of the following characteristics: Nasolabial angle greater-than-or-equ al-to 110-degrees, Ls to Sn-Pg' line less-than-or-equal-to 3 mm, Li to Sn-Pg' line less-than-or-equal-to 2 mm, Ss to H line less-than-or-equ al-to 3 mm, Li to H line less-than-or-equal-to 0 mm.