Development of supernumerary premolars in an orthodontic population.

Seven cases exhibiting supernumerary premolar development were detected during a 2-year period during the routine care of approximately 1,100 orthodontic patients. This 0.64% prevalence is more than twice as high as has been previously reported and represents an occurrence rate of 1 per 157 patients. This report describes the summary data for the cases detected and briefly reviews the available literature.