Self-assessment of dental conditions: validity of a questionnaire.

In order to determine the validity of dental data obtained from a questionnaire, 100 subjects randomly selected from 2383 respondents were examined clinically. The quality of dental status was ordered in four groups for the number of missing and replaced teeth and for denture status. For the number of missing and replaced teeth, the observed agreement between the clinical diagnosis and the questionnaire answers was 65% for both the maxilla and the mandible, and the agreement estimated by Kappa was 0.52. However, the disagreement was not randomly distributed, since reporting of better dental status than the actual one was much more common than reporting of poorer status. Regarding denture status, the agreement between self-assessment and clinical diagnosis was good; all removable dentures in situ at the clinical examination were reported by the subjects as some kind of denture, although not always the correct type. The results of the study indicate that the use of self-assessment might be reasonable when measuring denture status, and that self-assessment of the number of missing and replaced teeth is a biased estimate of the clinical diagnosis. Thus appropriate action should be taken when using this type of data.