Ten years shift of adult dentition by percentile observation

Objectives: The purpose of this study was to evaluate dental caries and dentition of an adult population over a ten-year period. The percentile curves of present and sound teeth were examined by cohort analysis. Methods: Dental examination was conducted by two calibrated dentists in 1992 and 2002. The number of sound and present teeth were recorded (excluding third molars). Subjects of this study were male bank employees in the Yokohama area. 3,198 subjects (20 to 64 years old) were examined in 1992, and 1,935 subjects were examined in 2002. The percentile curves for present and sound teeth were produced using Osada's method (1999). The data were serialized by the number of present and sound teeth in the baseline data and were classified into quartiles. Results: Due to national health insurance, patients received dental treatments in the company's dental clinic and in community clinics. During the ten years of observation, the number of present teeth increased with dental visits and dental health education. The 50th and 90th percentile curves of present teeth in 2002 increased after 55 years of age. But subjects who were in the high-risk group (below 75th percentile) for tooth loss at the first examination tended to be in the same group at the end of the ten years. Conclusion: These results suggest that percentile observation of adult dentition is useful for dental education. The patients can find out individual oral health status in comparison with the general population.