We evaluate the impact of patient cost sharing on the use of dentures and subjective chewing ability exploiting a sharp reduction in the coinsurance rate, the percentage of costs born by the user, from 30% to 10% at the age of 70 with a regression discontinuity design. Using data from the Japanese Study of Aging and Retirement (JSTAR), we find that the utilization rate of dentures increases from approximately 50% to 63% around the threshold, implying that the extensive margin elasticity of denture usage with respect to the coinsurance rate is about -0.41. In addition, we find this jump is almost entirely due to the change in the rate among women. On the other hand, we do not find a significant improvement in self-reported chewing ability, although chewing ability may not be the only social benefit from dentures. Our empirical findings are also confirmed by complementary analysis with randomization tests.