An index used to assess the outcome of orthodontic treatment based on an evaluation of the pre- and post-treatment study models. A score is assigned to various occlusal traits that make up a malocclusion; these are then weighted and summated to obtain a total that represents the extent of deviation from normal alignment and occlusion; a low score indicates a low level of irregularity. The difference between the pre- and post-treatment scores represents the degree of improvement.
Richmond S., Shaw W. C., Roberts C. T., Andrews M. The PAR Index (Peer Assessment Rating): methods to determine outcome of orthodontic treatment in terms of improvement and standards. Eur J Orthod 1992;14(3):180–87.