Objective:
In this study, we investigated the effect of smoking on the oral health and the cost of dental treatment in Japanese latter-stage elderly people.

Methods:
The number of subjects enrolled in this study were 931 (males: 347, females: 584) who was 75 years of age living in Tokushima City, Japan, and who was able to grasp the smoking period until the age of 75. Dental-health examination was conducted in 2015-2017. According to the questionnaire on smoking habit, the subjects were divided into two groups; the smoking group were current smokers and former smokers who quit smoking after the age of 55, and the control group were never smokers and former smokers who quit smoking before the age of 55. Statistical analysis regarding oral condition and the cost of dental treatment was performed according to gender.

Results:
The number of the smoking groups and control groups were 253:94 for males, and 573:11 for females, respectively. Among males, the number of teeth in the smoking group (18.6±8.9) was significantly lower (p=0.008, t-test) than that in the control group (21.4±7.5), and the cost of dental treatment in the smoking group (65,036±53,706 Japanese Yen/ year) was significantly higher (p=0.012, t-test) than that in the control group (48,902±52,179 Japanese Yen/ year). In addition, there is a significant problem with swallowing in the smoking group when compared to that in the control group (odds ratio=1.873; 95% CI=1.067 - 3.302). On the other hand, no significant differences were found between the two groups in females.

Conclusions:
Results from the cross-sectional survey suggested that long-term smoking affects the oral health of later-stage elderly males and also increases the cost of dental treatment.