Critical tooth number without subjective dysphagia.

Aim: To assess the critical tooth number (CTN) required for prevention of subjective dysphagia caused by oral impairments and to evaluate the relationship between this CTN and mortality.

Methods: The baseline study was performed with residents aged 40-89years (n=5,643; 2224 men and 3419 women) in Miyako Islands, Okinawa, in 1987. Dental examinations were performed by dentists, and subjective dysphagia was asked. We recorded the cause and year of death of participants who died during the next 15years.

Results: The average functional tooth number of participants with and without subjective dysphagia declined with age in both sexes. The CTN for each respective age group (40s, 50s, 60s, 70s and 80s) not including the denture group were 20.0, 17.5, 14.0, 11.8 and 10.1 in men and 19.0, 14.7, 12.7, 9.5 and 4.0 in women. These CTN were significant factors of 15-year mortality in both sexes (P<0.05). The hazard ratios were 0.72 (95% confidence interval=0.55-0.93) in men and 0.71 (0.51-0.99) in women.

Conclusion:   In aged people, the minimum number of functional teeth needed to avoid subjective dysphagia might not be as high as in young people.