Objectives: The aim of this study is to test the null hypothesis that changes in soft tissue facial profile in children who undergo orthodontic treatment, using either an extraction or non-extraction technique, do not differ.
Design: Longitudinal, retrospective.
Setting and sample population: San Juan, PR and Aberdeen, UK. Fifty-eight consecutively treated children using fixed appliances with a mean age of 13.2 (+/- 2.1) years.
Experimental variable: Extraction of the upper and lower, first or second premolars.
Outcome measures: The mean pre- and post-treatment, extraction and non-extraction configurations were compared using finite-element scaling analysis (FESA), incorporating a thin-plate spline interpolation.
Results: Post-treatment the two groups differed statistically in the premaxillary region (p < 0.05) with the non-extraction group being relatively larger in that region by 25%. For the non-extraction group after treatment, localized increases in relative size in the naso-maxillary region size of 25% (p < 0.01) were present. For the extraction group after treatment, a non-significant reduction in relative size of 15% was localized in the putative bicuspid area.
Conclusion: Soft tissue facial differences in non-extraction and extraction cases prior to treatment may be accentuated following orthodontic treatments that elect non-extraction or extraction protocols. Robust diagnosis and treatment planning, incorporating the judicious use of extractions if appropriate, may yield optimal orthodontic outcomes.