Accurate predictions of orthodontic market changes are serious concerns for the specialist. For instance, in addition to increases in the provision of orthodontic services by general dentists, recent decades have witnessed progressive increments in the supply of specialist manpower. The impact of such changes, however, together with fluctuations in the overall economy has yet to be subjected to systematic evaluation. In order to address some of these concerns, random 25% annual samples of the referral base of one orthodontic specialist was investigated over a 24-year period in order to test the following null hypothesis: That no significant changes occurred in the referral base of the orthodontic practitioner over the 24-year period. The need for orthodontic services for this 1156 case sample was then assayed by computation of the Dental Aesthetic Index (DAI), based on the consensus that this index comprises the most appropriate summary of service need. This index and its component parameters were subjectedto multivariate and univariate statistical analyses. (Abstract shortened by UMI.)