The effect of anterior tooth retraction on lip position of orthodontically treated adult Indonesians.

This study was conducted to determine upper and lower lip changes after orthodontic treatment of bimaxillary dental protrusion in adult Indonesians. Pretreatment and posttreatment cephalograms of 40 patients (6 males and 34 females) who required extraction of 4 premolars, were traced, superimposed, and measured. The changes of anterior tooth position (measured as the horizontal distance from the incisal tip to a constructed vertical through sella) were correlated with changes in the upper and lower lip positions with the Pearson correlation method. Significant positive correlation was found between changes of the maxillary and mandibular incisors with the changes in both the upper lip (r(U1) = 0.39, P <.05; r(L1) = 0.44, P <.01) and the lower lip (r(U1) = 0.44, P <.01; r(L1) = 0.51, P <.01) positions. By using stepwise multiple regression, it was found that for every millimeter of mandibular incisor retraction, 0.4 mm of upper lip retraction and 0.6 mm of lower lip retraction were produced. This study concluded that, for this Indonesian sample, a strong correlation exists between mandibular anterior tooth retraction and the position of both lips.