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 non-extraction 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.