Vertical facial and dental arch dimensional changes in extraction vs. non-extraction orthodontic treatment.

OBJECTIVE To compare the vertical facial and dental arch dimensional changes occurring with extraction and nonextraction orthodontic treatments. STUDY DESIGN Cross-sectional comparative study. PLACE AND DURATION OF STUDY The Aga Khan University Hospital, Karachi during the period 2003 to 2005. METHODOLOGY Data were collected using records of patients who visited the study setting during the study period. Pre- and post-treatment lateral cephalographs and study casts of 81 orthodontic patients (41=non-extraction and 40=premolar extractions) were taken. Variables used for evaluating vertical dimension were Frankfort mandibular plane angle (FMA), facial height (N-Me), facial height ratio (N-ANS/ANS-Me), soft tissue facial height (G' to Me'), soft tissue facial height ratio (G'-Sn'/zn'-Me'), upper first molar to palatal plane and lower first molar to mandibular plane distance, posterior facial height to anterior facial height ratio (PFH/AFH) and Y-axis. Intercanine, interpremolar and intermolar widths and arch depths were also measured. To evaluate the pre-treatment and posttreatment comparison within each group, paired t-tests were used. For pre- and posttreatment comparisons between the extraction and non-extraction groups, independent sample t-tests were used. RESULTS The mean age was 15.8+/-1.5 years for non-extraction and 15.4+/-1.2 years for the extraction group. There was no significant difference in the vertical dimensional changes between extraction and non-extraction treatments as it increased in both groups. When comparing posttreatment arch dimensions, there was an increase in the maxillary intermolar width in the non-extraction group while the intermolar widths and arch depths decreased in the extraction group in both arches. CONCLUSION Vertical dimensional changes showed no significant difference between extraction and non-extraction groups. Intermolar widths and arch depths decreased in both arches in the extraction group while the maxillary intermolar width increased in the non-extraction group.