Differences in oral hypofunction prevalence and category measures across age groups and sex in Japan: a pilot study

Objectives The deterioration of oral function to a state of oral hypofunction (OHF) has been associated with malnutrition and frailty. This cross-sectional pilot study investigated for differences in OHF prevalence and its category measures across age groups and sex, as well as their associations with physical function. Methods A total of 155 healthy adults (median age: 55 years, range: 22–89 years) participated in this study after providing informed consent. The cohort was age and sex matched. Seven oral function measures based on the concept of OHF were assessed: oral hygiene (Hygiene), oral dryness, maximum occlusal force (MOF), lip-tongue motor function (LTMF), maximum tongue pressure (MTP), masticatory function, and swallowing function. Hand grip strength (HGS) was also measured. The participants were divided into the young (20–39 years), middle (40–64 years), and old (≥ 65 years) age groups for linear regression analysis of differences in oral and physical function. Differences in OHF prevalence were tested by the chi-square test. Results The prevalence of OHF was significantly higher in the old group than in the young and middle groups. Such OHF measures as Hygiene, MTP, LTMF, and MOF were significantly worse in the old group as well. The measures of Hygiene and LTMF showed a moderate correlation with age in the multiple regression model (standardized partial regression coefficient, β = 0.24 and − 0.19, respectively). HGS was significantly associated with MTP (β = 0.58, p < 0.001) and LTMF (β = 0.38, p = 0.002) in both male and female participants. Conclusions Our findings suggest that OHF prevalence increases with age, especially after 65 years old. However, the pathological route may vary among OHF categories.