This study aimed to subjectively and objectively assess masticatory function and identify related factors in older adults. From July 2017 to September 2018, we enrolled 115 healthy participants aged between 65 and 86 years. They underwent oral examination, and their stimulated salivary secretion rate and masseter muscle tone and biomechanical properties were assessed. Masticatory performance with two-colored chewing wax was objectively evaluated using the mixing ability index (MAI). Key food intake ability (KFIA) was subjectively assessed using a questionnaire. The MAI score was significantly associated with the number of remaining teeth (r = 0.524, p < 0.001) and the tone (r = -0.222, p = 0.017), elasticity (r = -0.242, p = 0.009), and dynamic stiffness (r = -0.265, p = 0.004) of the masseter muscles. In contrast, the KFIA score was only significantly associated with the number of remaining teeth (r = 0.450, p < 0.001). A weak association between the MAI and KFIA scores was observed (r = 0.304, p = 0.001). A combination of objective and subjective methods should be used to accurately assess masticatory function in older adults. In addition to physical factors such as the number of remaining teeth, properties of the masticatory muscles should be evaluated to improve the masticatory function of older adults. In addition to dental problems, various maxillofacial and oral factors must be considered when establishing management strategies for the improvement of masticatory function in older adults.

Maeng YJ, et al. J Periodontal Implant Sci. 2016 Feb;46(1):10-21. https://doi.org/10.5051/jpis.2016.46.1.10

The oral biofilm structure or composition can affect the penetration of remineralizing agents. Therefore, this study evaluated the remineralizing efficacy of fluoride using a pH-cycling model with oral microcosm biofilms. Artificial carious lesions were formed in 80 bovine incisors. The pH-cycling conditions with or without oral microcosm biofilms were applied to 40 specimens each. The pH-cycling scheme was repeated for 12 days. Fluorescence loss (ΔF,%) of early carious lesions was measured for all specimens using a quantitative light-induced fluorescence-digital camera, before and after fluoride application. Biofilms on specimens were further analyzed for red fluorescence intensity (red/green ratios) and colony-forming unit counts. The effects of pH-cycling conditions and treatments on changes in ΔF (ΔΔF) and the effects of interactions between factors were analyzed using two-way analysis of variance. The fluoride-treated group with oral biofilms had an approximately 0.89-fold lower ΔΔF than the fluoride-treated group without oral biofilms (p < 0.0001). When oral biofilms were absent, the fluoride-treated group showed a 1.31-fold greater ΔΔF compared to that in the distilled water-treated group (p < 0.0001). When oral biofilms were present, the fluoride-treated group showed a 1.14-fold greater ΔΔF compared to that in the distilled water-treated group; however, this difference was not statistically significant. There was a significant difference in fluoride remineralizing efficacy based on the presence of biofilms on early carious lesions. Therefore, fluoride remineralization assessment in the absence of oral biofilms could lead to an overestimation of efficacy. Fluoride application might not have a robust remineralization effect on early carious lesions in the presence of a mature biofilm on the tooth surface.

Most previous studies addressing dysphagia examined individuals who already had diseases causing dysphagia and did not pay much attention to oral health conditions as a risk factor. This pilot study investigated 62 healthy adults aged 65 years or older who were living independently in the community, performed basic activities of daily living independently, and had no history of a causative disease of dysphagia to identify the factors associated with dysphagia risk, especially oral health. The Dysphagia Risk Assessment Scale was used to screen the patients for dysphagia. Hyposalivation was diagnosed by evaluating the unstimulated salivary flow rate, and orofacial muscle strength (anterior tongue elevation, buccinator muscle, and lip strength) was quantitatively measured using the Iowa Oral Performance Instrument. To analyze the factors associated with dysphagia risk, the Mann–Whitney test, Kruskal–Wallis test, and multiple logistic regression analyses were conducted. In the final regression model adjusted for sociodemographic characteristics, the oral health-related factors independently associated with dysphagia risk were buccinator muscle strength, hyposalivation, and subjective masticatory discomfort (p < 0.05). Therefore, our findings suggest that weak buccinator muscle strength, hyposalivation, and subjective masticatory discomfort are valuable indicators for the early detection of dysphagia in older, healthy, independent, community-dwelling adults.

While appropriate nutrient intake is important for older adults, various oral problems cause decreased masticatory function. This cross-sectional study aimed to identify the factors associated with decreased masticatory performance in older adults. Oral examinations were performed on 80 participants (mean age: 75.10 ± 5.64 years) to determine the number of functional tooth units (FTUs). Symptoms of periodontal and temporomandibular diseases were evaluated via a questionnaire. The tone, elasticity, and dynamic stiffness of the masseter muscle were measured using the Myoton^® PRO device. The mixing ability test was used to assess the masticatory performance, and the mixing ability index (MAI) was calculated. The analysis of covariance test was performed to adjust for confounding factors, and multiple logistic regression analysis was performed to identify the risk factors affecting MAI. A lower MAI was significantly associated with higher tone (p = 0.006) and lower elasticity (p = 0.013). The number of FTUs (adjusted odds ratio (OR) = 0.724, p = 0.029), tone (adjusted OR = 1.215, p = 0.016), and elasticity (adjusted OR = 4.789, p = 0.038) were independently associated with the MAI. Muscle function training and prosthetic treatments may help increase masticatory performance in older adults, which would improve overall health.