Masticatory performance is associated with dietary intake [1], and declining masticatory performance has been reported to be a risk factor for dementia, frailty, and sarcopenia [2,3]. Therefore, maintaining masticatory performance is important for older adults to live a healthy life.

To date, many studies have investigated the risk factors associated with declining masticatory performance. Cross-sectional studies revealed that polypharmacy, removable denture use, missing teeth, low occlusal force, and low tongue pressure were associated with low masticatory performance [4,5]. The Suita study, which is a cohort study, reported that age, number of functional teeth, and maximum bite force at baseline were associated with changes in masticatory performance, and the effects of these factors varied according to the residual number of occlusal support areas at baseline [6]. Our study of independently living adults aged over 60 years also found that the number of teeth, occlusal force, and posterior occlusal support zones were related to masticatory performance. Although various factors may be involved in the reduction of masticatory performance, we showed that posterior occlusal support had the greatest effect on masticatory performance among these risk factors [7], [8], [9].

However, previous studies were cross-sectional or investigated the effect of baseline status on change in masticatory performance. Although changes in posterior occlusal support were expected to have the greatest influence on mastication, no studies had investigated the relationship. It was hypothesized that loss of posterior occlusal support affects masticatory performance. Therefore, this study aimed to investigate the effect of loss of posterior occlusal support on masticatory performance in the community-dwelling older population in a longitudinal study.