Factors Influencing the Changes in Masticatory Performance: The Suita Study.

Abstract

Although previous studies have identified various factors related to masticatory performance, which factors affect longitudinal changes in masticatory performance have not been clarified. We aimed to clarify factors involved in changes to masticatory performance and construct models from factors related to masticatory performance in a longitudinal study of a general urban population in Japan. A total of 1,005 Japanese subjects (411 men, 594 women; mean age at baseline, 65.7 ± 7.7 years; mean follow-up period, 5.0 ± 0.9 years) were included in the Suita study. These subjects participated in dental checkups both at baseline (June 2008-December 2011) and at follow-up (June 2013-January 2017). The number of functional teeth and occlusal support areas was recorded and the latter assessed using the Eichner index. Subjects' periodontal status was evaluated based on the Community Periodontal Index. Masticatory performance was determined using test gummy jelly. Factors affecting masticatory performance at follow-up and the degree of their effect were investigated by multiple linear regression analysis. In multiple linear regression analysis with masticatory performance at follow-up as the dependent variable, baseline age, masticatory performance, number of functional teeth, and maximum bite force were significant independent variables. The results of multiple linear regression analyses by occlusal support at baseline identified only maximum bite force at baseline in subjects who were Eichner A and baseline age, masticatory performance, and number of functional teeth in subjects who were Eichner B as significant independent variables concerning masticatory performance at follow-up. Our study showed a relationship between longitudinal changes in masticatory performance and age, number of functional teeth, and maximum bite force and furthermore showed that the effects of these factors vary according to the residual number of occlusal support areas. Patients and clinicians should recognize the importance of objective and quantitative assessment for chewing efficiency and understand that various factors are related to longitudinal changes in masticatory performance. The results of this study can provide basic data for preventing or improving the decline in masticatory performance for elderly people with varying numbers of occlusal support areas.