Changes in facial profile during orthodontic treatment with extraction of four first premolars

Soft-tissue profiles were examined in 160 orthodontic patients treated with removal of four first premolars. Records of 10- to 30-year-old patients were selected at random from five sources: patients treated by Charles H. Tweed on file at the Tweed Foundation, patients treated with the Begg technique by the Kesling-Rocke group, patients from two practices with pretorqued, preangulated edgewise appliances, and patients with premolars enucleated at an early age. The mean changes for the total sample included an increase of 5.2 degrees in the nasolabial angle, and retraction of the upper and lower lips 3.4 and 3.6 mm to the E line, respectively. For different measurements, between 5% and 25% of the sample had values indicating more protrusive lips after treatment. In comparisons among groups, the Tweed patients generally exhibited the greatest lower lip retraction. When profile changes were compared to values representing normal (or "ideal") facial esthetics, it was evident that extraction of four first premolars generally did not result in a "dished-in" profile. Approximately 10% to 15% of cases could be defined as excessively flat after treatment. Eighty percent to 90% of patients treated by extraction of four first premolars had soft-tissue measurements that suggested the profile was improved by treatment or remained satisfactory throughout treatment.