Improving dental health status indicators for evaluation.

Central to the evaluation of any dental health programme is the dental status of the population it serves. The DMFT index has been widely used to indicate dental status in evaluations, however, there are a number of characteristics of the DMFT index which undermine its value in evaluating programmes. The aim of this study was to compare DMFT, five utility weighted versions of this index, and single measures of caries experience, in order to determine their relative validity. The indices were investigated in terms of two criteria: 1) the percentage of variance explained by a set of antecedent and behavioural variables in a series of multiple regression analyses; and 2) percentage changes in the indices following re-examination of the population after five years. Results show that the variance explained by the different composite indices ranged between 29% and 46%, while it varied between 16% and 49% for the single measures. The size of percentage changes after five years ranged between 0% and 4.5%), and indicated that utility weighted indices were generally not more sensitive than the DMFT, but that some single measures were. Where composite indices are required, a full quality adjusted tooth years (QATY) approach, rather than utility weighting the DMFT index, may be required to improve the validity of dental health status indicators. Single rather than composite measures also provide valid information for evaluating dental programmes.