Validity of the self-reported number of natural teeth in Japanese adults

The aims of this research were to assess the validity of self-reporting of the number of teeth by comparing the number with that obtained through clinical dental examinations, and to investigate factors affecting the discordance between the two measures.

Self-administered questionnaires and dental examinations were conducted among 1152 dentate community residents in Japan. The validity of the patients' reports of the number of teeth was assessed by comparing the self-reported number with that determined at the clinical examination. Factors affecting the absolute value of the difference between the self-reported number of teeth and the number at clinical examination were investigated using a multivariate analysis.

Overall, 47.5% of participants had perfect agreement in their self-report with the clinical examination. There was a slight tendency toward underestimation of the number of natural teeth by self-reporting. Pearson's correlation coefficient was 0.80, and the intraclass correlation coefficient was 0.78 for all patients. Decayed, filled, sound teeth, and fixed prosthetic pontics were significantly associated with the absolute value of the difference between self-reports and clinical examinations.

Patients' reported number of remaining teeth, the data for which were collected via the questionnaire, provided reasonably valid data on the actual number of teeth within a population group.