Long-term comparison of extraction and nonextraction alternatives in matched samples of African American patients.

African American orthodontic patients often present with morphologic characteristics that prompt the extraction of premolars. Referring dentists, however, commonly see extraction as a cause of "dished in" profiles, collapsed arches, and temporomandibular dysfunction. If true, these claims imply that African American patients are disproportionately at risk of clinical misadventure. Unfortunately, a meaningful long-term comparison of alternative treatments--be it retrospective or prospective--requires samples of patients who were equally susceptible to the two alternatives. Thus, if a retrospective study is to be free of susceptibility bias, the samples must be matched with respect to the anatomic differences that prompted the clinicians' choice of treatments. The goals of this investigation, therefore, were the following: to gather a large sample of African American expatients and to identify by means of discriminant analysis the characteristics that seem to have been important to the extraction decision, to use this knowledge to assemble subsamples of extraction and nonextraction expatients (both Class I and II) who were similar before treatment, and, finally, to recall them so that the long-term impact of the two strategies could be compared. In the end, 60 expatients--30 extraction and 30 nonextraction--were recalled, on average, nearly 8 years after the completion of treatment. In general, both treatments reduced irregularity and neither seemed to produce posterior mandibular displacement. Premolar extraction led to a modest reduction in dental and soft tissue protrusion (half the incisor retraction minus one); nonextraction, by way of contrast, produced an increase. Long term, the difference between the two treatments was about 2 mm at the upper lip and 4 mm at the lower. Excessive profile flattening was not a common finding. Our findings thus imply that the various "functional orthodontic" arguments against premolar extraction do not apply to African Americans any more than they do to whites.