Comparison of numbers of remaining teeth from questionnaires and clinical examination

The purpose of this study was to compare numbers of remaining teeth from questionnaires and clinical examination and to find out whether information collected through questionnaires is sufficiently valid for use by various institutes in national level. The group studied consisted of 255 adult patients from Savonlinna, not representative of the municipal population. Numbers of remaining teeth were determined from replies to a questionnaire by the subjects and by clinical examination by two dentists. Agreement about numbers of remaining teeth as estimated by the subjects and counted by the dentists was significant when tested using Somer's D and the t-test. Correlations between estimates by subjects and counting by dentists were high (0.98 for men and 0.99 for women). Underestimation of numbers of teeth was more common than overestimation for men and women. On the basis of the results it would seem that questionnaires can give sufficiently valid data about numbers of remaining teeth if samples are large enough.