Changes in the soft tissue facial profile following orthodontic extractions: a geometric morphometric study

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.

Longitudinal, retrospective.

San Juan, PR and Aberdeen, UK. Fifty-eight consecutively treated children using fixed appliances with a mean age of 13.2 (+/- 2.1) years.

Extraction of the upper and lower, first or second premolars.

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.

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.

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.