2001 Volume 51 Issue 3 Pages 248-257
Several reports indicated that selection bias due to non-participation if targeted subjects were only participants in dental examination with a low response rate. Consequently, in the fourth survey of dental disease in Niigata Prefecture, the conventional search procedure which targeted only participants in a dental examination was changed to a procedure distributes the questionnaire to all subjects of the survey before dental examination. This paper evaluate this new method by comparing the response rate of participants in a dental examination to the questionnaire response rate and the characteristics of participants in the dental examination to those of non- participants by questionnaire. We selected 23 areas by allocating 1-2 areas to each prefectural health center. Total subjects of this survey were 3,561 people living in these areas excluding individuals 0 years old. The response rate of the dental examination was low (35.3%) with large differences in age and sex. The response rate of the questionnaire was high (83.2%) with small differences in age and sex. Self-estimated numbers of present teeth of participants in dental examinaion were higher than those of non-participants among 60-79-year-olds indicating that numbers of remaining teeth in the elderly was over-estimated when the subjects targeted consisted only of participants in dental examination when the response rate of dental examination was low as in this survey. Comparison of questionnaire responses between participants in the dental examination and non-participants showed that participants had more subjective oral symptoms, visited dental clinics earlier and had undergone scaling more often than non-participants. In conclusion, the new method adopted in this survey was considered useful for describing the community health picture correctly.
