Soft tissue profile response in extraction versus non-extraction orthodontic treatment.

OBJECTIVE: To compare changes occurring in the soft tissue profile with orthodontic treatment in extraction versus nonextraction cases, and to determine the hard and soft tissue parameters that show significant correlations to understand the factors influencing the response to tooth movement. STUDY DESIGN: Quasi-experimental. PLACE AND DURATION OF STUDY: Dental Section, The Aga Khan University Hospital, Karachi, from 2005 to 2008. METHODOLOGY: Pre- and post-treatment lateral cephalographs of 34 subjects were assessed. For half of the patients (n=17), treatment included the extraction of 4 premolars, whereas the other half were treated by the non-extraction approach. Incisal and soft tissue effects of treatment were analyzed and compared between both groups using the independent sample t-test to assess the degree of change with orthodontic treatment. Pearson's correlation test was used to determine correlation. RESULTS: The extraction group finished with a statistically significant reduction in upper and lower lip procumbency (p=0.004 and 0.021), while the non-extraction group finished with a slight increase in lower lip procumbency (p=0.009) due to significant increase in IMPA (p=0.046). Although the premolar extraction group showed greater soft tissue changes with treatment, post-treatment comparisons showed that both groups finished within the same soft tissue parameters. Pearson's correlation revealed statistically significant correlations between the upper and lower lips and upper and lower incisors (p < 0.01). CONCLUSION: The effects of the two types of orthodontic treatment on the facial soft tissues were very similar, indicating that treatment, involving the extraction of premolars, does not have a detrimental effect on facial aesthetics provided the decision to extract is on sound basis and the mechanics are controlled.