Background: Maximum bite force (MBF) is a common and useful index of masticatory function; it correlates with physical strength in elderly people. Palpation of stiffness in the masseter muscle during forceful biting has been considered to be associated with MBF. However, this assessment method relies on subjective judgments; no study has verified the relationship between MBF and quantitative measurements of masseter muscle stiffness (MMS). Objective:We aimed to verify the association between masseter muscle myotonometric assessment results and MBF. Methods: In total, 117 community-dwelling >65-year-old individuals from the Tokyo metropolitan area were assessed. MMS on the dominant side during forceful biting was measured with a MyotonPRO device. Masseter muscle thickness (MMT) during rest and forceful biting was measured with an ultrasonic diagnostic apparatus, and the difference in MMT (DMMT) between the rest and forceful biting conditions was determined. MBF data were obtained with a pressure-sensitive sheet and an associated device. To determine the independent variables affecting MBF and MMS, multivariate linear regression analyses with adjustments for age, sex and number of teeth were performed. Results:The multivariate analysis revealed that MBF correlated with the number of teeth (β = .489, P < .001) and MMS (β = .259, P = .003) (R 2 = .433). MMS correlated with MBF (β = .308, P = .003) and DMMT (β = .430, P < .001) (R 2 = .326). Conclusion:Masseter muscle stiffness possibly reflects a force generated by the masseter muscle during forceful biting. Therefore, MMS is effective to assess tooth loss as well as an index of masseter muscle strength when evaluating MBF. K E Y W O R D Sbite force, masseter muscle, muscle stiffness, myotonometric assessment, occlusal force | 751 HARA et Al.

<b><i>Introduction:</i></b> The aim of this study was to determine the associations of time spent away from bed with whole-body muscle mass and swallowing function in older adults with low activities of daily living (ADL). <b><i>Methods:</i></b> This cross-sectional study was conducted at Tokyo Medical and Dental University and included adults over 65 years of age who underwent a medical intervention at their residence. Data regarding age, sex, body height and weight, activity status, medical history, time spent away from bed, and Functional Oral Intake Scale (FOIS) were collected. We calculated the body mass index, Charlson Comorbidity Index, whole-body muscle mass, the appendicular skeletal muscle mass index (ASMI), and the trunk muscle mass index (TMI). According to the time spent away from bed, the subjects were grouped as follows: &#x3c;4 but ≥0 h (S), &#x3c;6 but ≥4 h (M), and ≥6 h (L). These variables were analyzed using the one-way analysis of variance, the Kruskal-Wallis test, and the χ² test, then differences among the three groups were examined. To adjust for confounding factors, we performed multiple regression analysis with ASMI and TMI as the dependent variables and ordinal logistic regression analysis with FOIS as the objective variable. <b><i>Results:</i></b> Ninety subjects (male: <i>n</i> = 42; female: <i>n</i> = 48; mean age = 82.9 ± 8.8 years, and groups S: <i>n</i> = 23; M: <i>n</i> = 30; L: <i>n</i> = 37) were analyzed. Group L had a significantly higher ASMI, TMI, and FOIS score than groups S and M, while group M had a significantly higher ASMI and FOIS score than group S. After adjusting for confounding factors, the significant explanatory factors for ASMI were sex, activity status, time spent away from bed, and TMI. The factors for TMI were activity status, time spent away from bed, ASMI, and FOIS. The factors for FOIS were time spent away from bed and TMI. <b><i>Conclusion:</i></b> Spending 4 or more hours away from the bed is related to appendicular skeletal muscle mass and FOIS, while spending 6 or more hours is related to appendicular skeletal muscle mass, trunk muscle mass, and FOIS in this population. These findings highlight factors that can prevent a decline in swallowing function in the daily life of older adults with low ADL who have difficulty performing exercises to preserve swallowing function.

<b><i>Introduction:</i></b> The aim of this study was to clarify the relationship among swallowing function, activity, and quality of life (QOL) in older adults with low activities of daily living (ADL). <b><i>Materials and Methods:</i></b> We conducted a cross-sectional study. In total, 271 Japanese adults aged over 65 years who underwent medical intervention at their residence (male: <i>n</i> = 107; female: <i>n</i> = 164; mean age = 84.6 ± 8.3 years) participated. We collected data regarding age, sex, body mass index (BMI), residence (their house/nursing home), activity status, consciousness level (eye response), history of aspiration pneumonia, other medical history, number of medication types, frequency of going out, and time spent away from bed. We judged consciousness level (eye response) using the Glasgow Coma Scale (GCS), calculated the Charlson comorbidity index, measured QOL using the short version of the Quality of Life Questionnaire for Dementia (short QOL-D), and assessed swallowing function using the Functional Oral Intake Scale (FOIS). To examine the relationship between scores for the FOIS and the other variables, we used the Spearman rank correlation coefficient and ordinal logistic regression analysis. <b><i>Results:</i></b> The FOIS was strongly correlated with BMI (ρ = 0.47), activity status (ρ = −0.60), GCS (ρ = −0.41), time spent away from bed (ρ = 0.56), scores for the short QOL-D (ρ = 0.40), weakly correlated with history of aspiration pneumonia (ρ = −0.27), and frequency of going out (ρ = 0.39). Results for the ordinal logistic regression analysis showed that the FOIS was associated with activity status, frequency of going out, time spent away from bed, and scores for the short QOL-D. <b><i>Conclusion:</i></b> The swallowing function of older adults with low ADL was related to their QOL and activities, such as time spent away from bed and home. Thus, in rehabilitation programs for swallowing function in older adults, not only functional but also psychological approaches may prove effective.

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The effectiveness of the tongue right positioner (TRP) use on oral and swallowing functions remains unclear. To investigate the effects of TRP use on tongue function in patients with dysphagia. This interventional study included eight participants with dysphagia who visited a university dental hospital. The measurement variables included tongue pressure (TP) as the primary outcome and lip and tongue movements, peak nasal inspiratory flow, and changes in the tongue and suprahyoid muscle regions on ultrasonography as the secondary outcomes. Each participant was asked to use a TRP for at least 8 h every night for 2 months. The measurement variables before and after the intervention were compared using the paired t test and Wilcoxon signed-rank test. TP after intervention (31.5 ± 13.1 kPa) was significantly higher than that before intervention (23.0 ± 13.4 kPa), while other measurement variables did not significantly improve. Numerous exercises have been suggested to improve TP; however, most require patients’ adherence to instructions. In contrast, although participants did not perform active exercises, most participants in this study observed an improved TP. Our findings show that TRP can greatly improve TP after 2 months of usage.Trial registration number: University Hospital Medical Information Network Clinical Trials Registry (UMIN000040253, date of first registration: 27/04/2020).

Background Although age‐related changes in muscle quality influence muscle strength, the relationship between masseter muscle (MM) quality and maximum biting force (MBF) has never been studied. Objective The aims of the study were to verify the relationship among MM quality, MBF, and the displacement of the MM while biting forcefully (MMD) and to clarify the age‐related decline in MBF in healthy elderly persons. Methods Seventy‐four healthy community‐dwelling individuals (mean age, >65 years) from Tokyo metropolis were recruited. The thickness (index of muscle quantity), echo intensity (index of muscle quality) and displacement of the MM while biting forcefully (MMT, MMEI and MMD, respectively) were measured by ultrasonography. MBF was measured using a pressure‐sensitive sheet. Independent predictors of MBF and MMD were determined using multivariate linear regression analyses adjusted for age, sex and the number of present teeth. Results MBF was significantly correlated with the number of teeth (β = 0.577, P < .001) and MMD (β = 0.302, P = .015), but not with MMT (β = 0.019, P = .868) or MMEI (β = 0.054 P = .703). MMD was significantly correlated with MMEI (β = −0.606, P < .001), but not with MMT (β = 0.048, P = .681) or the number of teeth (β = 0.065, P = .613). Conclusions MMEI was associated with MMD, an index of MBF, regardless of tooth number. The age‐related quality change in the MM might cause a decrease in its contraction, resulting in age‐related decline in MBF.

<b><i>Introduction:</i></b> Jaw-opening force (JOF) can be a potential screening tool for dysphagia. However, confounding variables such as comorbidities or physical and oral functions that are associated with the physiology of swallowing have not previously been examined. Adjusting for these variables could reveal the relationship between JOF and dysphagia and indicate whether JOF is an independent factor associated with dysphagia. We therefore aimed to assess the efficacy of using JOF for dysphagia screening in this multi-institutional study. <b><i>Methods:</i></b> Community-dwelling older adults over the age of 65 years (<i>N</i> = 403) who visited the university dental hospitals and participated in health surveys (mean age ± standard deviation, 77.1 ± 7.0 years; range, 65–96 years) between November 2018 and January 2020 were included in this study. The JOFs of all participants were measured. The measured JOF was compared with the presence of dysphagia, which was defined using the Functional Oral Intake Scale and the Eating Assessment Tool-10. <b><i>Results:</i></b> Multiple logistic regression analysis revealed that the presence of dysphagia was independently associated with JOF, calf circumference, and dependence after adjusting for age and sex. <b><i>Discussion/Conclusion:</i></b> Decreased JOF can be a risk factor for dysphagia in older adults.

Forward head posture, an abnormality in head and trunk positioning, adversely affects suprahyoid muscle activity. Jaw-opening force, which reflects suprahyoid muscle strength, is a useful index of dysphagia. However, the relationship between forward head posture and strength and morphology of suprahyoid muscles remains unclear. This study aims to clarify the relationship between forward head posture, jaw-opening force and morphology of suprahyoid muscles.Methods: During October 2018, we enrolled older adults aged ≥65 years. The craniovertebral angle was measured, and an angle <49 was defined as forward head posture. Jaw-opening force was also measured. The geniohyoid muscle (GHM) was selected to represent the suprahyoid muscles, and its cross-sectional area and length were measured using ultrasonography. Sarcopenia was also determined based on the criteria of the 2019 Asian Working Group for Sarcopenia. Multiple regression analyses were conducted to determine the association between morphological characteristics of the suprahyoid muscle and jawopening force as well as the association between the former and forward head posture.Results: Data of 87 participants were analyzed. Sex, cross-sectional area and length of the GHM, and sarcopenia were significantly associated with jaw-opening force. In addition, sex and forward head posture were significantly associated with the length of the GHM.Conclusions: Our study demonstrated that an overextended length of suprahyoid muscles mediates the relationship between forward head posture and jaw-opening force. Forward head posture is easily visualized and can be a useful indicator of decline in suprahyoid muscle strength.