Maximum Occlusal Force and Physical Performance in the Oldest Old: The Tokyo Oldest Old Survey on Total Health

Association among handgrip strength, body mass index and decline in cognitive function among the elderly women

Background

The association between handgrip strength combined with body mass index (BMI) and cognitive impairment has not been thoroughly examined. We aimed to investigate whether the relationship between handgrip strength and risk of cognitive impairment is altered by the presence of obesity in older women.

Methods

A total of 544 older women aged over 65 years without cognitive impairment from the Korean Longitudinal Study of Aging (KLoSA) were included in the study. Handgrip strength was classified in a binary manner (weak or strong) or in tertiles and obesity was defined as a BMI ≥ 25 kg/m², in accordance with the Asia-Pacific World Health Organization criteria. Incident cognitive impairment was defined as a Korean Mini-mental State Examination (K-MMSE) score of less than 24 after eight years of follow-up.

Results

Strong handgrip strength was associated with reduced likelihood of developing cognitive impairment compared to weak handgrip strength in obese women (adjusted odds ratio, aOR 0.23, 95% confidence interval, CI 0.08–0.66). The highest tertile of handgrip strength was associated with reduced risk of incident cognitive impairment (aOR 0.16, 95% CI 0.04–0.70), compared to the lowest tertile of handgrip strength in obese women, with a significant linear trend (p for trend = 0.016). Furthermore, the highest tertile of handgrip strength was significantly associated with smaller decline in K-MMSE scores compared to the lowest tertile of handgrip strength in obese women (p value = 0.009). There was no association between handgrip strength and incident cognitive impairment in non-obese women.

Conclusions

Strong handgrip strength was associated with reduced risk of cognitive impairment among obese women, but not in non-obese women. Handgrip strength may be a simple and useful marker for predicting future cognitive impairment among obese women.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0918-9) contains supplementary material, which is available to authorized users.

Bite Force Evaluation in Complete Denture Wearer with Different Denture Base Materials: A Randomized Controlled Clinical Trial

AIM

The aim of this study is to evaluate the maximum bite force (MBF) with different denture base materials in completely edentulous patients.

MATERIALS AND METHODS

MBF was evaluated in randomly selected 100 completely edentulous patients. Patients were selected from the Outpatient Clinic, College of Dentistry, Aljouf University, Saudi Arabia. The patients were randomly divided into two equal groups: Group I (control group): Patient received a conventional heat-cured acrylic complete denture (Vertex™ Regular, Vertex-Dental B.V., The Netherlands) and Group II (experimental group): Patient received a thermoplastic complete denture (Vertex™ ThermoSens, Vertex-Dental B.V., The Netherlands). MBF measurements were taken at the time of new denture placement and after 6 months of denture use. Statistics were analyzed using independent t-test to compare the MBF measurements between both groups.

RESULTS

At the time of denture placement, there was no significant difference in bite force measurements between both groups. Bite force is increasing considerably after 6 months of denture use, and it was higher than MBF recorded at the time of new prosthesis placement in the same group. The MBF values were considerably higher in patients with a thermoplastic denture than patients with conventional acrylic denture with statistically significant difference after 6 months of denture use.

CONCLUSION

After 6 months of denture use, patients with a thermoplastic denture have a higher biting force than patients with a conventional acrylic denture. Therefore, it could be considered a treatment plan option according to the ridge nature and quality to solve the problem of diminished bite force in old age patients.

Relationship between masticatory function and frailty in community-dwelling Japanese elderly

BACKGROUND

Frailty likely results in impaired functioning, and frail individuals requiring long-term care have recently attracted the attention of researchers. In the oral health field, the number of elderly individuals who require intervention for retaining occlusion has been increasing, as has the number of remaining teeth and required prosthetic treatment. Additionally, the number of elderly with reduced masticatory function has also been increasing, and frailty is a suspected factor.

AIMS

The aim of this study is to clarify the relationship between frailty and masticatory function decline.

DESIGN

A cross-sectional study.

METHODS

A total of 747 participants (total mean age 73.6 ± 5.8 years old) underwent a comprehensive examination at the Tokyo Metropolitan Institute of Gerontology. Three masticatory functions were evaluated: maximum occlusal force, mixing ability, and self-reported chewing ability. Frailty was determined using all 25 questions of the Basic checklist developed by the Japanese Ministry of Health, Labour and Welfare, following the method reported by Satake et al. RESULTS: Binomial logistic analysis clarified the relationship between frailty and evaluation of each of the three masticatory functions. Significant correlations of pre-frailty or frailty with maximum occlusal force, mixing ability, and subjective chewing ability were observed.

CONCLUSION

All three masticatory functions (maximum occlusal force, mixing ability, and self-reported chewing ability) were associated with pre-frailty or frailty in community-dwelling Japanese elderly.

Oral hypofunction in the older population: Position paper of the Japanese Society of Gerodontology in 2016

BACKGROUND

There is growing international interest in identifying the effects of ageing on oral health and on appropriate strategies for managing oral disorders. The Japanese Society of Gerodontology (JSG), as the official representative of researchers and clinicians interested in geriatric dentistry in Japan, makes several recommendations on the concept of "oral hypofunction."

AIMS

This study proposes diagnostic criteria and management strategies to reduce the risk of oral hypofunction among older people.

CONCEPTUAL FRAMEWORK

We define oral hypofunction as a presentation of 7 oral signs or symptoms: oral uncleanness; oral dryness; decline in occlusal force; decline in motor function of tongue and lips; decline in tongue pressure; decline in chewing function; and decline in swallowing function. The criteria of each symptom were determined based on the data of previous studies, and oral hypofunction was diagnosed if the criteria for 3 or more signs or symptoms were met.

CONCLUSIONS

We recommend that more evidence should be gathered from clinical studies and trials to clarify our diagnostic criteria and management strategies.

Age-related declines in the swallowing muscle strength of men and women aged 20-89 years: A cross-sectional study on tongue pressure and jaw-opening force in 980 subjects

Swallowing muscle strength weakens with aging. Although numerous studies have investigated tongue pressure (TP) changes with age, studies on jaw-opening force (JOF), an indicator of suprahyoid muscle strength, are lacking. We investigated differences between age-related declines in TP and JOF in a cross-sectional study of 980 healthy and independent participants (379 men, 601 women) without dysphagia. Hand grip strength (HGS), TP, and JOF were compared among decade-based age groups in multiple comparison analyses with post-hoc tests and effect size calculated. Participants were divided into adult (20 s-50 s) and elderly groups (60 s-80 s); within each group, Pearson correlations between age and muscle strength indices were evaluated. TP started to significantly decline in the 60 s and 50 s for men and women (p < .01, medium effect size and p < .05, small effect size, respectively); HGS also declined at these ages (men: p < .01, women: p < .01, medium effect size). JOF started to significantly decline in men in their 80 s (p < .01, large effect size), but remained unchanged in women. In the elderly group, all measurements declined with age more sharply in men (HGS: r = -0.56, TP: r = -0.63, JOF: r = -0.13) than in women (HGS: r = -0.38, TP: r = -0.49, JOF: r = -0.003). TP declined more steeply than did JOF. Thus, the age related-decline in TP was similar to that of the HGS, but not the JOF. The results reveal that different patterns exist in the age-related decline in swallowing muscle strength, and suggest that maintenance of JOF might contribute to safe swallowing in healthy elderly individuals.

The relationship between masseter muscle thickness and appendicular skeletal muscle mass in Japanese community-dwelling elders: A cross-sectional study

PURPOSE OF THE STUDY

Sarcopenia has been identified as a health hazard in elderly people. Although the association between sarcopenia and a decrease in masticatory function has been reported, the mechanism underlying this association has not been widely reported. Therefore, in order to elucidate the relationship between sarcopenia and masticatory function, we examined whether the masseter muscle thickness (MMT), which is a factor influencing masticatory function, in community-dwelling elders is associated with the appendicular skeletal muscle index (SMI), a diagnostic criterion for sarcopenia.

MATERIALS AND METHODS

MMT was measured in 774 community-dwelling elders aged 65 years or older at resting state via ultrasonography, and SMI was measured with the bioelectrical impedance method. The relationships were investigated by calculating Pearson's correlation coefficients. Multiple regression analyses adjusted for age and sex, SMI, and oral-related items were performed to determine the association between these factors.

RESULTS

There was a significant correlation between the MMT and the SMI. The multiple regression analysis indicated that SMI was significantly associated with a decrease in MMT.

CONCLUSIONS

The reduction in whole-body skeletal muscle mass in sarcopenia may be involved in the reduction in MMT. Prevention of sarcopenia may be an important factor for maintaining masticatory function in the elderly.

Association of handgrip strength with various oral functions in 82- to 84-year-old community-dwelling Japanese

OBJECTIVE

The purpose of this study was to elucidate the associations between muscle strength and several oral functions in a large cohort of community-dwelling, 82- to 84-year-old community-dwelling Japanese people.

BACKGROUND DATA DISCUSSING THE PRESENT STATUS OF THE FIELD

Several studies have examined the relationships between physical performance and oral functions. However, no studies have investigated the associations of muscle strength with various objectively evaluated oral functional parameters in a large cohort of very old adults.

MATERIALS AND METHODS

This study included 809 community-dwelling Japanese people (407 men and 402 women) aged 82-84 years. The oral functions examined were the maximal occlusal force, masticatory performance, stimulated salivary flow rate, repetitive saliva-swallowing test (RSST) score, tongue pressure and mouth-opening distance. Handgrip strength was measured, and its correlations with oral functions were assessed. Multiple linear and logistic regression analyses were performed to investigate the relationships between oral functions and handgrip strength.

RESULTS

Multivariate analysis revealed that handgrip strength was correlated with not only the maximal occlusal force, masticatory performance and tongue pressure but also the RSST score and mouth-opening distance after adjustment for sex, number of teeth, use of removable denture, periodontal condition, instrumental activities of daily living, body mass index. When we examine the elderly people whose handgrip strength is declining, we should predict that their various oral functions may be declining.

CONCLUSION

Handgrip strength was related to various oral functions after adjustment for the number of teeth in this population of community-dwelling 82- to 84-year-old Japanese.

Relationship between occlusal force and falls among community-dwelling elderly in Japan: a cross-sectional correlative study

BACKGROUND

Falls may cause serious health conditions among older population. Fall-related physical factors are thought to be associated with occlusal conditions. However, few studies examined the relationship between occlusal force and falls. To identify the association between occlusal force and falls among community-dwelling elderly individuals in Japan, public health nurses conducted a cross-sectional descriptive study.

METHODS

We performed extensive physical assessments of five items: maximum occlusal force, handgrip strength, maximal knee extensor strength, one-leg standing time with eyes open and body sway. We also conducted a questionnaire survey concerning the participants' demographic characteristics, health status and fall experience during the past year. Mean scores and standard deviations were calculated for age and the total points of the index of activities of daily living. Associations were examined using Mann-Whitney tests and logistic regression.

RESULTS

We examined 159 community-dwelling people aged ≥65 years, who were independent and active, including 38 participants (24.5%) with experience of falls in the past year. Maximum occlusal force had significant correlation with handgrip strength, maximal knee extensor strength, and one-leg standing time and body sway (P < .05, respectively). We found weak associations between participants with and without a history of falls in terms of the five physical measurements. Logistic regression analysis showed that fall experience was significantly associated with maximum occlusal force (P = 0.004).

CONCLUSIONS

This is the first study, led by public health nursing researchers, to examine the associations between maximum occlusal force and falls among community-dwelling elderly in Japan. The results showed that maximum occlusal force was significantly related to the other four extensive physical assessments, and might also suggest that maximum occlusal force assessment by public health nurses could contribute to more sophisticated and precise prediction of fall risks among the community-dwelling elderly. The latest occlusal force measurement device is non-invasive and easy to use. Public health nurses can introduce it at periodical community health checkup assembly events, which might contribute to raising awareness among community-dwelling elderly individuals and public health nurses about fall prevention and prediction.

Gender difference in the effects of interleukin-6 on grip strength - a systematic review and meta-analysis

Background

Aging sarcopenia characterized by low muscle mass with low muscle strength affects men and women differently. The contribution of interleukin-6 (IL-6) to sarcopenia has been suggested based on a negative correlation between plasma IL-6 and muscle function described by some studies. However, no consensus regarding clinically relevant cut-off criteria has been reached. Another question arises whether pooling male and female data is an accurate way to determine the predictive value of IL-6 in sarcopenia. The present meta-analysis was designed to assess: (1) whether plasma IL-6 in aged populations in fact correlates negatively to muscle strength; (2) whether such a correlation exists both in men and in women; and (3) whether plasma IL-6 shows a gender difference in old age.

Methods

We applied the preferred reporting items for systematic review and meta-analysis protocols (PRISMA). We searched PubMed and Embase for papers that reported data on individuals over 65 without inflammatory diseases. We extracted either separate male and female data on plasma IL-6 along with at least one muscle parameter or correlation coefficient between plasma IL-6 and these parameters. Random effect models calculated with DerSimonian and Laird weighting methods were applied to analyze correlation coefficients and gender difference in plasma IL-6. Egger’s test was used to assess the small study effect.

Results

Twenty articles out of 468 records identified were suitable for analyses. Plasma IL-6 correlates negatively with grip strength in mixed populations and also separately in men [− 0.25 with 95% confidence interval (CI): − 0.48, − 0.02] and in women (− 0.14 with 95% CI: − 0.24, − 0.03). However, contrary to expectations, men with better muscle condition have higher plasma IL-6 than women of similar age with worse muscle condition (plasma IL-6 male–female difference: 0.25 pg/mL with 95% CI: 0.15, 0.35).

Conclusion

This is the first study to demonstrate that a higher predictive IL-6 cut-off level should be determined for aging sarcopenia in men than in women.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0798-z) contains supplementary material, which is available to authorized users.

Satisfaction with dietary life affects oral health-related quality of life and subjective well-being in very elderly people

Age-related deterioration in physical and oral health reduces healthy life expectancy and is thus an important problem for very elderly people. We investigated the effects of satisfaction with dietary life (SDL) in everyday life on oral health-related quality of life (OHRQoL) and subjective well-being and examined associations between these factors. We evaluated 426 elders aged 85 years or older. All participants completed a questionnaire that inquired about age, gender, drinking status, body mass index, cognitive function, disability, and comorbidities, among other covariates. Oral, physical, and mental health conditions were also examined. Associations of questionnaire results for SDL with items on subjective well-being (Philadelphia Geriatric Center Morale Scale [PGC] and World Health Organization-5 [WHO-5]) and OHRQoL (Geriatric Oral Health Assessment Index [GOHAI]) were confirmed with multiple logistic regression analysis. In a multivariate model adjusted for various confounders, participants with self-reported "enjoyable" SDL had significantly lower risks for having the lowest scores on the GOHAI, PGC, and WHO-5 (odds ratio [OR] = 0.460, 95% confidence interval [CI] = 0.277-0.762; OR = 0.589, 95% CI = 0.348-0.996; and OR = 0.452, 95% CI = 0.263-0.775, respectively). These associations remained after further adjustment for number of teeth.

Relationship of aging, skeletal muscle mass, and tooth loss with masseter muscle thickness

Background

Previous studies have reported a relationship between masseter muscle thickness and tooth loss or limb muscle thickness. However, it is not yet known whether masseter muscle thickness is related to appendicular skeletal muscle mass, and grip strength. The purpose of this study was to determine which of the two variables—tooth loss or appendicular skeletal muscle mass index—is more strongly related to masseter muscle thickness, and to identify a suitable indicator of decreasing masseter muscle thickness in healthy elderly individuals.

Methods

Grip strength, walking speed, body weight, skeletal muscle mass index, tooth loss, and masseter muscle thickness at rest and during contraction were determined in 97 community-dwelling elderly individuals aged ≥65 years (men: 44, women: 53). Masseter muscle thickness was chosen as the dependent variable, while age, skeletal muscle mass index, body weight, grip strength, and tooth loss were chosen as the independent variables. Multiple regression analysis was conducted using the stepwise regression method.

Results

In men, grip strength was the only independent predictor of masseter muscle thickness at rest. Tooth loss and grip strength were independent predictor of masseter muscle thickness during contraction. In women, tooth loss was the independent predictor of masseter muscle thickness both at rest and during contraction, while grip strength and body weight were the independent predictor of masseter muscle thickness at rest only.

Conclusions

We confirmed that in healthy elderly individuals, tooth loss has a stronger relationship with masseter muscle thickness than aging and skeletal muscle mass index do. Masseter muscle thickness in both elderly men and women is also associated with grip strength, suggesting that grip strength can be used as an indicator of masseter muscle thickness in this population.

A 5-year longitudinal study of association of maximum bite force with development of frailty in community-dwelling older adults

To determine whether maximum bite force (MBF), an objective measure of oral function, is associated with development of frailty in community-dwelling older adults. This prospective cohort study included community-dwelling Japanese adults aged 75 years at baseline (n = 322). Baseline MBF was measured using an electronic recording device (Occlusal Force-Meter GM10). Follow-up examinations, including physical fitness and anthropometric evaluation and structured questionnaires, were administered annually over a 5-year period to determine the incidence of frailty, which was defined by the presence of 3 or more of the following 5 components derived from the Cardiovascular Health Study: low level of mobility, low physical activity level, weakness, shrinking and poor endurance and energy. Adjusted hazard ratios (HRs) of incidence of frailty according to sex-stratified tertiles of baseline MBF were calculated using Cox proportional hazards regression models. During the follow-up, 49 participants (15.2%) developed frailty. Participants in the lower tertile of MBF exhibited a significantly greater risk of frailty than those in the upper tertile. After adjustment for sex, depression, diabetes and Eichner index, the adjusted HRs for frailty in the upper through lower tertiles of MBF were 1.00 (reference), 1.27 (95% confidence interval [CI]: 0.50-3.20) and 2.78 (95% CI: 1.15-6.72), respectively (P for trend = .01). Poor oral function, as indicated by low MBF, increases the risk of development of frailty among elderly men and women.

Dentition status and frailty in community-dwelling older adults: A 5-year prospective cohort study

AIM

To examine the longitudinal association between dentition status and incidence of frailty in older adults.

METHODS

The present prospective cohort study included community-dwelling Japanese adults aged 75 years at baseline (n = 322). Dental examinations, biochemical blood examinations, physical performance and anthropometric measurements, and structured questionnaires were carried out at baseline. The presence of ≥20 teeth with nine or more occluding pairs of teeth was defined as functional dentition. Annual follow-up examinations, including physical performance, anthropometric measurements and structured questionnaires, were carried out over a 5-year period to determine the incidence of frailty, defined as three or more of the following five components derived from the Cardiovascular Health Study: weight loss, weakness, slowness, poor energy and low physical activity level. Adjusted hazard ratios of frailty incidence according to dentition status were calculated from Cox proportional hazards regression analyses.

RESULTS

At baseline, 118 participants (36.6%) were defined as having functional dentition. During the follow up, 48 participants (14.9%) developed frailty. The adjusted hazard ratio for frailty in participants with functional dentition was 0.50 (95% confidence interval 0.25-0.98) compared with participants without functional dentition, after adjusting for sex, income, education, smoking status, body mass index, serum biomarkers and comorbidities.

CONCLUSIONS

Functional dentition was significantly associated with a lower risk of frailty defined by the Cardiovascular Health Study frailty index in older Japanese adults. These results suggest that maintaining healthy and functional dentition into later life is important for frailty prevention. Geriatr Gerontol Int 2018; 18: 256-262.

The drug burden of anticholinergics and sedatives and influence on outcomes in the community-living oldest old: The Tokyo Oldest Old survey on Total Health (TOOTH) survey

AIM

The objective of this study was to assess the burdens of anticholinergic and sedative drugs in community-living individuals of 85 years of age or older.

METHODS

The Tokyo Oldest Old survey on Total Health (TOOTH) is a cohort study designed to assess the physical, mental, and oral health of the community-living oldest old. We investigated the relationships between the anticholinergic/sedative burden and physical/cognitive outcomes. The drug burden was assessed by the Drug Burden Index (DBI). Relationships between the DBI score and the physical/cognitive outcomes were evaluated by multivariate regression. The age-related changes (baseline to 3-year follow-up) of these outcomes were also investigated.

RESULTS

At baseline, the data of 306 subjects were subjected to a cross-sectional analysis. The Instrumental Activities of Daily Living and Mini Mental State Examination scores were found to be significantly associated with the DBI score. After 3 years, the Activities of Daily Living score was significantly associated with the DBI score in 176 subjects. Changes in these outcome measures were small during the 3-year follow-up period and were not associated with the DBI scores at baseline.

DISCUSSION

DBI in the community-living oldest old were evaluated. Our findings suggest that anticholinergic and sedative drugs may influence the physical and cognitive function in the oldest old. Additional studies should be performed to investigate the relationships between the change of the physical/cognitive functions and the DBI score over a long-term observation period.

Perceived swallowing problems and mortality risk in very elderly people ≥85 years old: Results of the Tokyo Oldest Old Survey on Total Health study

OBJECTIVE

The aim of this study was to clarify whether perceived swallowing problems affect the life expectancy of very elderly individuals.

BACKGROUND

In an ageing society, oral function affects health status. In particular, a decline in swallowing function may increase the risk of various diseases, morbidity and malnutrition.

MATERIALS AND METHODS

We evaluated 526 elderly individuals aged ≥85 years. All participants completed a questionnaire and underwent oral, physical and mental health examinations. The comprehensive oral health assessment comprised a face-to-face interview that included a questionnaire on swallowing function. We estimated hazard ratios and 95% confidence intervals using the Cox proportional hazards model, adjusting for potential confounders between perceived swallowing problems and all-cause mortality over a 3-year period.

RESULTS

Over a 3-year follow-up period, 88 of 526 participants died and 68 participants complained of perceived swallowing problems. Perceived swallowing problems had statistically significant associations with physical status and function and nutrition. In the univariate analysis, perceived swallowing problems had statistically significant associations with an approximately 1.9-fold higher risk of all-cause mortality during the 3-year period (HR: 1.89, 95% CI: 1.14-3.14). In the multivariate analysis, the statistically significant association between perceived swallowing problems and all-cause mortality remained after adjusting for various confounding factors (HR: 1.73, 95% CI: 1.03-2.92).

CONCLUSION

Perceived swallowing disorders should be verified by a clinical examination, as they are associated with other health outcomes and increased all-cause mortality.

Relationship Between Frailty and Oral Function in Community-Dwelling Elderly Adults

OBJECTIVES

To determine the standard values of and age-related changes in objective oral function of healthy older people; compare oral function of robust, prefrail, and frail older people; and determine the association between oral function and frailty.

DESIGN

Cross-sectional analysis.

SETTING

General community.

PARTICIPANTS

Elderly adults (≥65) from the Obu Study of Health Promotion for the Elderly were included and assigned to the robust, prefrail, and frail groups (N = 4,720).

MEASUREMENTS

Each participant underwent detailed physical testing to assess frailty. The frailty phenotype was defined according to the presence of limitations in three or more of the following five domains: mobility, strength, endurance, physical activity, and nutrition. The numbers of present teeth and functional teeth were counted, and occlusal force, masseter muscle thickness, and oral diadochokinesis (ODK) rate were measured, along with sociodemographic and functional status, comorbidities, and blood chemistry.

RESULTS

The number of present teeth, occlusal force, masseter muscle thickness, and ODK rate decreased with age. The frail group had significantly fewer present teeth (women aged ≥70), lower occlusal force (women aged ≥70; men aged ≥80), lower masseter muscle thickness, and lower ODK rate than the robust group. Multivariate analysis indicated that age, Geriatric Depression Scale score, skeletal muscle mass index, Mini-Mental State Examination score, hypertension, diabetes mellitus, albumin and triglyceride levels, and oral function were significantly associated with frailty.

CONCLUSION

Age-related differences in oral function were found in older adults. Moreover, frail older individuals had significantly poorer oral function than prefrail and robust individuals. The risk of frailty was associated with lower occlusal force, masseter muscle thickness, and ODK rate.

Association between maximum occlusal force and 3-year all-cause mortality in community-dwelling elderly people

BACKGROUND

Among the very elderly, poor oral health reduces life expectancy. In this study, differences in the magnitude of the maximum occlusal force (MOF) in the very elderly were examined in terms of effects on all-cause mortality in a 3-year follow-up.

METHODS

We evaluated 489 community-living elderly individuals aged 85 years or older. MOF was measured using an occlusal force measuring device, and participants were classified into three groups according to gender- and dental status-sensitive tertiles. Demographic variables, cognitive, physical function, psychological status, oral health, comorbidity, and blood chemistry factors were assessed. One-way analyses of variance, χ (2) tests, and the Kruskal-Wallis test were used for statistical analyses. The relationship between MOF tertiles and 3-year all-cause mortality was examined using a multivariate Cox model analysis after adjusting for confounding factors.

RESULTS

MOF tertiles were significantly associated with cognitive impairment, number of teeth, limitations on chewable foods, handgrip strength, timed up-and-go test, and diabetes mellitus. During the follow-up period, 74 subjects died. Subjects with the highest MOF had a significantly lower mortality rate than other groups (log rank P  =  0.031). In the univariate Cox model, MOF tertiles were independently associated with a lower risk of death (HR = 0.69, 95 % CI = 0.51-0.91). Even after adjusting for various confounders in the multivariate Cox model (Model 1), MOF was independently associated with a lower risk of death (HR = 0.67, 95 % CI = 0.50-0.91). In model 2, we added handgrip strength as a confounder and found that the HR for MOF was attenuated (HR = 0.73, 95 % CI = 0.54-0.99), but still statistically significant.

CONCLUSIONS

In a cohort of the very elderly, MOF was independently associated with all-cause mortality after adjusting for various health issues. Moreover, this independent association remained after a further adjustment for handgrip strength; however, the HR was attenuated. This suggests that MOF and handgrip strength may share a common mechanism of a general decrease in muscle strength, possibly sarcopenia, which is a significant cause of mortality in the very old.

Maximum bite force at age 70 years predicts all-cause mortality during the following 13 years in Japanese men

There is limited information on the impact of oral function on mortality among older adults. The aim of this prospective cohort study was to examine whether an objective measure of oral function, maximum bite force (MBF), is associated with mortality in older adults during a 13-year follow-up period. Five hundred and fifty-nine community-dwelling Japanese (282 men and 277 women) aged 70 years at baseline were included in the study. Medical and dental examinations and a questionnaire survey were conducted at baseline. Maximum bite force was measured using an electronic recording device (Occlusal Force-Meter GM10). Follow-up investigation to ascertain vital status was conducted 13 years after baseline examinations. Survival rates among MBF tertiles were compared using Cox proportional hazards regression models stratified by sex. There were a total of 111 deaths (82 events for men and 29 for women). Univariable analysis revealed that male participants in the lower MBF tertile had increased risk of all-cause mortality [hazard ratio (HR) = 1·94, 95% confidence interval (CI) = 1·13-3·34] compared with those in the upper MBF tertile. This association remained significant after adjustment for confounders (adjusted HR = 1·84, 95% CI = 1·07-3·19). Conversely, no association between MBF and all-cause mortality was observed in female participants. Maximum bite force was independently associated with all-cause mortality in older Japanese male adults. These data provide additional evidence for the association between oral function and geriatric health.

Association of Occlusal Force with Cognition in Independent Older Japanese People

Recent longitudinal studies have shown the influence of multiple tooth loss on cognitive impairment, and earlier studies suggested that periodontal disease was related to cognitive decline. Tooth loss is associated with reduced masticatory function, which may affect stimulation of the central nervous system and dietary intake. Although some studies have reported a relationship between chewing ability and cognitive function, no studies have examined this area in terms of objective oral function. The aim of this study was to examine the association of occlusal force with cognitive decline in the preclinical stage among older people with higher-level functional capacity. This cross-sectional study for community-dwelling older people living in urban and rural areas in Japan examined 994 persons in the 70-y group (age range, 69–71 y) and 968 persons in the 80-y group (age range, 79–81 y). Retention of higher-level competence was defined according to the Tokyo Metropolitan Institute of Gerontology Index of Competence. Cognitive function was measured with the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Oral status and function were assessed by the number of remaining teeth, periodontal pocket depth, and maximal occlusal force. Associations between the MoCA-J score and occlusal force were examined by bivariate and multivariate analysis. Approximately one-half of the participants retained higher-level functional capacity and were included in the analysis. Multiple regression analysis showed that occlusal force was significantly related to cognitive function after controlling for possible predictors including age, sex, socioeconomic status, medical condition, and handgrip strength. The number of remaining teeth and periodontal pocket depth were not significantly associated with cognitive function. Among community-dwelling older people with retained competence, maximal occlusal force was positively associated with their cognitive function. These results suggest that oral function might be a predictor for preclinical cognitive decline.

Knowledge Transfer Statement: Multiple regression analysis showed that occlusal force was significantly related to cognition after controlling for possible predictors including handgrip strength as an indicator of general muscle strength, suggesting the independence of oral function. The number of remaining teeth did not have this association. The majority of older people have lost teeth and have received prosthodontic treatment, and their occlusal force is determined not only by the number of remaining teeth but also by prosthetic rehabilitation. These results can be used by clinicians focusing on prevention of tooth loss among the entire population, as well as to encourage partially edentulous and fully edentulous patients to restore their oral function with prostheses in order to eliminate a possible risk factor for cognitive impairment.

Clinical study on mandibular fracture after marginal resection of the mandible

OBJECTIVES

Postoperative mandibular fracture (PMF) after marginal resection (MR) of the mandible remains an unresolved issue, and it has been reported that at least 10 mm of postoperative mandibular body height (PMBH) is required to prevent PMF. This study evaluated the clinical, physical, and structural risk factors for PMF in MR patients and determined appropriate preventive measures for PMF.

STUDY DESIGN

This retrospective study included 44 patients with lower gingival carcinoma who underwent MR. PMF occurred in four of these patients. Thirteen associated factors identified from medical records and radiographs were statistically analyzed.

RESULTS

Mandibular body height (MBH) preservation ratio originally evaluated as less than 0.3, more than 20 remaining teeth after surgery, and inferior alveolar canal (IAC) exposure were significant risk factors for PMF. Prostheses and number of remaining teeth were also correlated with PMF.

CONCLUSIONS

The preserved mandibular bone should be reinforced in patients with an MBH preservation ratio of less than 0.3, more than 20 remaining teeth after surgery, and intraoperative IAC exposure. Patients with prostheses are at an increased risk of PMF compared with those without because of stable occlusion and a strong occlusal force. Our novel findings provide useful reference standards for PMF prevention in MR patients.

Bite-force difference among obese adolescents in central Taiwan

BACKGROUND/PURPOSE

Maximal bite force of the jaw can cause thorough food chewing and result in good digestion. Bite force is related to the health of the masticatory muscles. Muscle force is frequently affected by obesity in adolescence, however, little is known about how obesity influences the maximum bite force and the difference between genders.

METHODS

Five hundred and seventy-seven adolescent students (292 girls and 285 boys), aged 13-16 years, from central Taiwan were recruited for a cross-sectional study in 2009. The maximum bite force, hand strength, triceps skin-fold fat thickness, serum level of testosterone, and body mass index (BMI) were measured. Dental health was evaluated based on malocclusion and dental caries.

RESULTS

Bite force in girls was highest in the obese group (32.49 ± 19.13 kg, mean ± standard deviation), whereas in boys it was higher in the overweight group (41.89 ± 19.3 kg) than in the obese group (33.21 ± 17.12 kg). The prevalence of obesity was twofold higher in boys (14.39%) than in girls (7.88%). The mean serum level of testosterone increased with BMI in girls (p = 0.0172), whereas it decreased with BMI in boys (p = 0.0014). The relationships of serum testosterone level and bite force with BMI were similar in the two gender groups.

CONCLUSION

The maximum bite force decreased in obese boys but increased in obese girls, which may be due to the sensitivity to testosterone being modulated by the fat level.

Denture wearing during sleep doubles the risk of pneumonia in the very elderly

Poor oral health and hygiene are increasingly recognized as major risk factors for pneumonia among the elderly. To identify modifiable oral health-related risk factors, we prospectively investigated associations between a constellation of oral health behaviors and incident pneumonia in the community-living very elderly (i.e., 85 years of age or older). At baseline, 524 randomly selected seniors (228 men and 296 women; mean age, 87.8 years) were examined for oral health status and oral hygiene behaviors as well as medical assessment, including blood chemistry analysis, and followed up annually until first hospitalization for or death from pneumonia. During a 3-year follow-up period, 48 events associated with pneumonia (20 deaths and 28 acute hospitalizations) were identified. Among 453 denture wearers, 186 (40.8%) who wore their dentures during sleep were at higher risk for pneumonia than those who removed their dentures at night (log rank P = 0.021). In a multivariate Cox model, both perceived swallowing difficulties and overnight denture wearing were independently associated with an approximately 2.3-fold higher risk of the incidence of pneumonia (for perceived swallowing difficulties, hazard ratio [HR], 2.31; and 95% confidence interval [CI], 1.11-4.82; and for denture wearing during sleep, HR, 2.38; and 95% CI, 1.25-4.56), which was comparable with the HR attributable to cognitive impairment (HR, 2.15; 95% CI, 1.06-4.34), history of stroke (HR, 2.46; 95% CI, 1.13-5.35), and respiratory disease (HR, 2.25; 95% CI, 1.20-4.23). In addition, those who wore dentures during sleep were more likely to have tongue and denture plaque, gum inflammation, positive culture for Candida albicans, and higher levels of circulating interleukin-6 as compared with their counterparts. This study provided empirical evidence that denture wearing during sleep is associated not only with oral inflammatory and microbial burden but also with incident pneumonia, suggesting potential implications of oral hygiene programs for pneumonia prevention in the community.

Adaptive properties of human cementum and cementum dentin junction with age

OBJECTIVES

The objective of this study was to evaluate age related changes in physical (structure/mechanical properties) and chemical (elemental/inorganic mineral content) properties of cementum layers interfacing dentin.

METHODS

Human mandibular molars (N=43) were collected and sorted by age (younger=19-39, middle=40-60, older=61-81 years). The structures of primary and secondary cementum (PC, SC) types were evaluated using light and atomic force microscopy (AFM) techniques. Chemical composition of cementum layers were characterized through gravimetric analysis by estimating ash weight and concentrations of Ca, Mn, and Zn trace elements in the analytes through inductively coupled plasma mass spectroscopy. The hardness of PC and SC was determined using microindentation and site-specific reduced elastic modulus properties were determined using nanoindentation techniques.

RESULTS

PC contained fibrous 1-3 µm wide hygroscopic radial PDL-inserts. SC illustrated PC-like structure adjacent to a multilayered architecture composing of regions that contained mineral dominant lamellae. The width of the cementum dentin junction (CDJ) decreased as measured from the cementum enamel junction (CEJ) to the tooth apex (49-21 µm), and significantly decreased with age (44-23 µm; p<0.05). The inorganic ratio defined as the ratio of post-burn to pre-burn weight increased with age within primary cementum (PC) and secondary cementum (SC). Cementum showed an increase in hardness with age (PC (0.40-0.46 GPa), SC (0.37-0.43 GPa)), while dentin showed a decreasing trend (coronal dentin (0.70-0.72 GPa); apical dentin (0.63-0.73 GPa)).

SIGNIFICANCE

The observed physicochemical changes are indicative of increased mineralization of cementum and CDJ over time. Changes in tissue properties of teeth can alter overall tooth biomechanics and in turn the entire bone-tooth complex including the periodontal ligament. This study provides baseline information about the changes in physicochemical properties of cementum with age, which can be identified as adaptive in nature.

Masseter muscle tension, chewing ability, and selected parameters of physical fitness in elderly care home residents in Lodz, Poland

BACKGROUND

Maintaining good physical fitness and oral function in old age is an important element of good quality of life. Disability-related impairment of oral function contributes to a deterioration of the diet of older people and to the reduction of their social activity.

OBJECTIVES

Investigate the association between masseter muscle tension, dental status, and physical fitness parameters.

MATERIALS AND METHODS

Two hundred fifty-nine elderly care home residents (97 men, 162 women; mean age, 75.3±8.9 years) were involved in this cross-sectional study. Their chewing ability was evaluated by masseter muscle tension palpation, differences of masseter muscle thickness, self-reported chewing ability, number of present and functional teeth, and number of posterior tooth pairs. Masseter muscle thickness was measured by ultrasonography. To assess physical fitness, hand grip strength and the timed up-and-go test were performed. Nutritional status was assessed using body mass index and body cell mass index (BCMI), calculated on the basis of electrical bioimpedance measurements. Medical records were used to collect information on systemic diseases and the number of prescribed medications. Subjects were also evaluated for their ability to perform ten activities of daily living.

RESULTS

Ninety-seven percent of the subjects suffered from systemic diseases. The three most prevalent illnesses were cardiac/circulatory 64.5%, musculoskeletal 37.3%, and endocrine/metabolic/nutritional 29.3%. Of the participants, 1.5% were underweight and more than one third (34.4%) were overweight. Malnutrition (BCMI below normal) was found in almost half (45.2%) of the subjects. Only 5.8% had a sufficient number of functional natural teeth. Statistically significant correlations were found between palpation of masseter muscle tension and perceived chewing ability, number of present teeth, number of functional teeth, number of posterior tooth pairs, timed up-and-go, hand grip strength, body mass index, BCMI, and activities of daily living. In a multivariate model, after adjusting for age, sex, and education, subjects with higher BCMI, higher hand grip strength, and more present teeth had a significantly higher chance of strong masseter muscle tension.

CONCLUSION

There is a relationship between chewing ability and physical fitness in elderly people. Efficiency of masseter muscles is related to physical fitness in the elderly. Masseter muscle tension examined by palpation can be used in public dentistry as one of the indicators of quality of life.

Assessing articulatory speed performance as a potential factor of slowed speech in older adults

PURPOSE To improve our understanding about the underlying factors of aging-related speaking rate decline, the authors sought to determine if lip and jaw speeds are physiologically constrained in older adults. METHOD Thirty-six females-10 young adults (ages 22-27 years), 9 middle-aged adults (ages 45-55 years), 10 young-old adults (65-74 years), and 7 very old adults (ages 87-95 years)-completed metronome-paced syllable repetitions while moving the lower lip or jaw to a fixed target with each repetition. Metronome paces incrementally increased from 1.4 Hz to 6.7 Hz. Lip and jaw movements were tracked using a 3-dimensional motion capture system. RESULTS Older adults' maximum percent increase in lip and jaw peak speed was comparable to or tended to be even greater than that of middle-aged and young adults. By contrast, lip and jaw stiffness, indexed by peak speed-displacement ratios, tended to decrease with age during fast and very fast repetition rates and were associated with mildly prolonged movement durations. CONCLUSIONS The findings suggest that lip and jaw speeds are not constrained in older adults. The trend of reduced stiffness during fast rates, however, suggests that fine-force regulation becomes difficult for older adults. Thus, older adults may implement reduced habitual speaking rates as a behavioral strategy to compensate for diminished articulatory control.