International comparisons of professional assessments in orthodontics: Part 1--Treatment need.

An international survey has been undertaken to assess variation in professional assessment of orthodontic treatment need. Ninety-seven orthodontists from nine countries examined a standard sample of 240 dental study casts to judge the need for orthodontic treatment in terms of dental health, dental esthetics, and deviation from normal. Participants also indicated their assessment of treatment complexity and whether they would recommend treatment. Practitioners' subjective assessments were found to be only moderately reliable overall. Of the cases examined, 76% [corrected] obtained a consensus of 80% or greater on the need for treatment. Logistic regression equations were derived to explain the observed variation in treatment decisions. It was found that occlusal traits from the dental casts were highly predictive of the treatment decision, and that the practitioners' country of origin and payment methods are important influences on prescribing behavior. The treatment decisions were predicted with an accuracy of 84% by using occlusal score values for the dental esthetics, the degree of upper arch crowding, the presence of crossbite, the anterior overbite, and the buccal segment sagittal relationship. It is suggested that these traits may form the basis for an internationally validated index of treatment need for use in clinical audit and orthodontic research.