Premolar and Additional First Molar Extraction Effects on Soft Tissue

Abstract

To determine the effects of premolar and additional first molar extractions (AFMEs) on soft tissue changes after four premolar extractions in high Angle Class II division 1 patients. Thirty-three AFME patients, 24 of who had maxillary-only AFME and 9 of who had all-four AFME, were studied by cephalometric analysis and compared with 43 patients treated with four premolar-only extractions (PRMEs) as a control group. Lateral cephalograms taken at four time points-pretreatment, before AFME, posttreatment, and retention-were utilized for statistical analysis by Student's t-test. AFME significantly contributed to the maxillary incisor retraction and subsequent soft tissue change as measured by the Z-angle and lower lip E line. In addition, the bivariate correlation analysis revealed that the soft tissue changes correlated more with maxillary incisor retraction than with mandibular incisor retraction in both the AFME and PRME groups. This finding suggests that, in Class II patients, the lower lip position is most affected by reduction of maxillary incisor proclination. The AFME approach is useful to improve profiles in severe high Angle Class II division 1 patients who are borderline between PRME treatment and a premolar extraction plus orthognathic surgery approach.