The validation of the Peer Assessment Rating index for malocclusion severity and treatment difficulty.

The Peer Assessment Rating (PAR) index is a British occlusal index that measures the severity of dental malocclusion and has been used in several investigations that have evaluated the effectiveness of orthodontic treatment provision in Europe. As part of its development, the PAR index was validated for malocclusion severity, by using the opinions of a panel of 74 dentists and orthodontists. The present investigation was carried out to validate the PAR index, by using the opinion of an American panel of orthodontists. Eleven orthodontists examined a sample of 200 sets of study casts and rated them for malocclusion severity and perceived treatment difficulty. Multiple regression techniques were used to evaluate the predictive power of the components of malocclusion on the panel's scores. Weightings were calculated from the partial regression coefficients and, when these weightings were applied to the PAR index, the association between the panel's opinion and the PAR index scores was increased.