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Background: Sleep on the first night in a sleep laboratory is characterized by a lower sleep quality and frequency of rhythmic masticatory muscle activity (RMMA) than that on the second night in moderate to severe sleep bruxism (SB) patients. Objective: The aims of this study was to clarify the physiological factors contributing to the first night effect on oromotor activity during sleep and investigate whether physiological factors involved in the first night effect differed between rhythmic and non‐rhythmic oromotor activities. Methods: Polysomnographic data collected on two consecutive nights from 15 moderate to severe SB subjects (F 7: M 8; age: 23.2 ± 1.3 [mean ± SD] years) were retrospectively analysed. Sleep variables, RMMA and non‐specific masticatory muscle activity (NSMA) were scored in relation to episode types (i.e. phasic or tonic and cluster or isolated), sleep architecture and transient arousals. The relationships between nightly differences in oromotor and sleep variables were assessed. The distribution of oromotor events, arousals, cortical electroencephalographic power, RR intervals and heart rate variability were examined in relation to sleep cycle changes. These variables were compared between the first and second nights and between RMMA and NSMA. Results: Sleep variables showed a lower sleep quality on Night 1 than on Night 2. In comparisons with Night 1, the RMMA index increased by 18.8% (p <.001, the Wilcoxon signed‐rank test) on Night 2, while the NSMA index decreased by 17.9% (p =.041). Changes in the RMMA index did not correlate with those in sleep variables, while changes in the NSMA index correlated with those in arousal‐related variables (p <.001, Spearman's rank correlation). An increase in the RMMA index on Night 2 was found for the cluster type and stage N1 related to sleep cyclic fluctuations in cortical and cardiac activities. In contrast, the decrease in the NSMA index was associated with increases in the isolated type and the occurrence of stage N2 and wakefulness regardless of the sleep cycle. Conclusion: Discrepancies in first night effect on the occurrence of RMMA and NSMA represent unique sleep‐related processes in the genesis of oromotor phenotypes in SB subjects. [ABSTRACT FROM AUTHOR]

Background: Frailty increases the risk of negative health‐related events, such as falls, disability, hospitalizations, and death. Although the association between oral health and physical frailty is well established, the relationship between oral health and psychological frailty has not yet been investigated. Therefore, we conducted a cross‐sectional study to examine the association between maximal occlusal force and psychological frailty in Japanese community‐dwelling older adults. Methods: Psychological frailty was defined as a World Health Organization‐5 scale (WHO‐5) score of <13, cognitive and functional status was defined as a Japanese version of the Montreal Cognitive Assessment (MoCA‐J) score of <23, and psychological robustness was defined as a WHO‐5 score of ≥13 and a MoCA‐J score of ≥23. We used a cross‐sectional study design to measure maximal occlusal force in 1810 participants, and examined the following factors relevant to psychological frailty: educational level, financial status, living situation, history of chronic diseases, handgrip strength, and instrumental activities of daily living. We used propensity score matching to match the psychological frailty and psychological robustness groups according to demographic and confounding factors. This process, resulted in 344 participants, of whom 172 were in the psychological frailty group and 172 were in the psychological robustness group. In the matched cohort, differences between groups with and without psychological frailty were compared using generalized estimating equations for maximal occlusal force after adjusting for the number of teeth. Results: After controlling for potential confounding factors of frailty, the psychological frailty group showed lower maximal occlusal force compared with the psychological robustness group (unstandardized regression coefficients = −72.7, 95% confidence interval: −126.3 to −19.1). Conclusions: Maximal occlusal force was associated with a reduced prevalence of psychological frailty among Japanese community‐dwelling older adults participating in our study. [ABSTRACT FROM AUTHOR]

Background: During sleep, limb and jaw muscle motor activity can be quantified by electromyography (EMG). The frequency of periodic limb activity during sleep increases with age in both the general and clinical research populations. The literature is controversial regarding stability, over age, of the frequency of rhythmic masticatory muscle activity (RMMA), which is one biomarker of sleep bruxism (SB). Objectives: The purpose of this retrospective sleep laboratory study was to assess if any change in RMMA frequency occurs over age in the general population (GP) and two clinical research (CR) samples. Methods: RMMA signals from polysomnography (PSG) recordings of 465 individuals, irrespective of SB awareness, were analysed. The sample comprised 164 individuals from the GP of Sao Paulo, and 301 individuals from Montreal and Osaka CR samples. Data were divided into two subgroups, younger (15–39) and older (40–80) participants. RMMA was classified as low frequency (<2 events/h) or high (≥2 events/h). Pearson correlation (R) and B (slope) analyses were performed with power estimations. Results: In the GP sample, no significant change over age was noted in the RMMA index/year. In the CR samples, a significant reduction was observed in the RMMA index/year (−0.05) with age (R2 =.042; p <.001; 3.5 to 1.5 RMMA/h from 20 to 60 years old). Conclusions: In the GP, the RMMA index remained stable over age. In the CR samples, a significant, reduction was observed. Prospective studies with multiple home sleep recordings, in both general and clinical research populations, are needed before extrapolating from the present findings. [ABSTRACT FROM AUTHOR]

Aim: This large epidemiological survey of older people examined oral hypofunction and the relationship between oral hypofunction and frailty. Methods: Participants were community‐dwelling adults aged 65–85 years in Japan. The oral function evaluation included seven items (oral hygiene, oral dryness, occlusal force, tongue–lip motor function, tongue pressure, masticatory function and swallowing function), and oral hypofunction was defined as having abnormalities in at least three of these items. The frailty status was classified into three categories (robust, pre‐frail and frail) according to the total Kihon Checklist score. We analyzed 978 subjects with complete data. The relationship between oral function and frailty status was analyzed using multivariate multinomial logistic regression analyses. Results: Approximately 60% of the older adults had oral hypofunction. The multivariate odds ratios (ORs) for a pre‐frail or frail status were significantly higher for older people with reduced occlusal force, reduced tongue–lip motor function and deteriorated swallowing function than in those without deterioration of those items. Of the oral function items, swallowing function was most strongly associated with the frailty status, and the ORs (95% confidence interval [CI]) for deteriorated swallowing function in pre‐frail and frail patients were 6.4 (3.9–10.8) and 10.2 (5.4–19.1), respectively. Those with oral hypofunction had significantly higher adjusted ORs for pre‐frail (OR 1.4, 95% CI 1.1–2.0) and frail (OR 2.1, 95% CI 1.2–3.5) statuses. Conclusion: Many community‐dwelling older people have reduced oral function or oral hypofunction, which is significantly associated with frailty in older people. Geriatr Gerontol Int 2020; 20: 917–926. [ABSTRACT FROM AUTHOR]

In 2016, the Japanese Society of Gerodontology (JSG) proposed the concept of "oral hypofunction (OHF)," and recommended two initial criteria for reduced occlusal force (ROF): <200 N of maximum occlusal force (MOF) and < 20 remaining teeth. However, the JSG stated that these criteria need to be reviewed by accumulating further evidence. To examine the validity and equivalence of the two criteria for ROF in the diagnostic criteria for OHF by using the incidence of functional disability as the outcome. This study enrolled 815 community‐dwelling Japanese individuals ≥ 70 years. They underwent examinations for physical, mental and social functions; MOF; and number of teeth at baseline. The incidence of functional disability (a condition that requires at least partial assistance with daily activities) based on the first certification of long‐term care insurance was followed up. The Cox proportional hazard model revealed that MOF < 200 N (hazard ratio [HR], 1.33; 95% confidence interval [CI], 1.04‐1.72) and < 20 teeth (HR, 1.40; 95% CI, 1.07‐1.84) were significantly associated with increased risk of functional disability. Receiver operating characteristic curve analyses revealed that the optimal cut‐off values of MOF and number of teeth that best predicted incident functional disability were 264.6 N and 19 teeth, respectively. Twelve teeth were the optimal threshold that best predicted < 200 N of MOF. The two criteria for ROF in the diagnostic criteria for OHF had some degree of validity. However, further studies are needed to develop appropriate and reliable criteria for a decision of ROF. [ABSTRACT FROM AUTHOR]

Decreased masticatory performance leads to deterioration of overall health among older adults. However, maintaining and improving masticatory performance in ways other than maintenance of natural teeth and appropriate prosthodontic treatment remains unclear. If the factors related to the mixing and shearing abilities for masticatory performance are clarified, it may be possible to maintain and improve the masticatory performance of older adults. We aimed to clarify the association among mixing ability, shearing ability, and masticatory performance-related factors. Of the 707 community-dwelling older adults in Kusatsu Town, Japan, 344 who had been treated for any dental defects were enrolled in this study. Masticatory performance was evaluated on the basis of mixing ability and shearing ability. The number of natural teeth and artificial teeth, occlusal force, tongue pressure, and oral diadochokinesis /ta/ were measured as masticatory performance-related factors. Their relationship with mixing ability, shearing ability, and masticatory performance-related factors was examined by means of Spearman rank correlation coefficient and path analysis. Among masticatory performance-related factors, the number of natural teeth, occlusal force, and tongue pressure were directly associated with both mixing ability and shearing ability. Moreover, mixing ability was also directly associated with shearing ability. Tongue pressure, which can be improved by means of training, is a masticatory performance-related factor associated with both mixing and shearing abilities. Training for tongue pressure after proper prosthetic treatment may provide an effective means of maintaining and improving masticatory performance in older adults. [ABSTRACT FROM AUTHOR]

Highlights • Oral motor functions were correlated with MMSE as cognitive function. • Tongue pressure and oral diadochokinesis were significantly associated with MMSE. • Diminished tongue pressure and oral diadochokinesis may lead to cognitive decline. Abstract Background Diminished oral motor function is considered to be a factor influencing cognitive decline, but this association has not been clarified. The aim of the present study was to clarify the association between cognitive and oral motor function in older people with either from normal cognitive function or mild cognitive decline. Methods A cross-sectional study was conducted across 1118 older people (445 men, 673 women) aged ≥70 years (mean age, 77.0 ± 4.7 years) who lived in a city of Tokyo Metropolis, Japan. Cognitive function was assessed using the Mini-Mental State Examination (MMSE). Older people who had an MMSE score of 23 points or lower were excluded. To investigate the relationship between cognitive and oral motor function, Pearson's correlation, multiple linear regression, and path analysis were performed. Results Pearson's correlation revealed that, among the oral motor functions assessed, masticatory performance, occlusal force, and tongue pressure were correlated with MMSE score. Multiple linear regression showed that tongue pressure and oral diadochokinesis (ODK) were significantly associated with MMSE score. Path analysis revealed that decreases in tongue pressure and in ODK were directly associated with decreases in MMSE score. Decreases in tongue pressure were also indirectly associated with decreases in MMSE score via decreases in ODK. Conclusions Among the oral motor functions assessed, tongue pressure and ODK were associated with cognitive function in older people ranging from those with normal cognitive function to those with mild cognitive decline. Diminished tongue pressure and ODK might thus lead to cognitive decline. [ABSTRACT FROM AUTHOR]

Summary: Objectives: The purpose of our cross‐sectional study was to investigate the relationship between gerotranscendence and oral health‐related quality of life (OHR‐QOL). To our knowledge, this is the first study to investigate the relationship between gerotranscendence and OHR‐QOL. Methods: Participants (total n = 1969; 70‐year‐old group, n = 999; 80‐year‐old group, n = 970) were drawn from resident lists in four areas of Japan: one urban area and one rural area in each of two geographical regions. OHR‐QOL was measured using the Geriatric Oral Health Assessment Index (GOHAI). Measurement of occlusal force was performed using pressure‐sensitive sheets. Gerotranscendence was assessed with the Japanese Gerotranscendence Scale Revised (JGS‐R). We used multiple linear regression analysis to examine the relationships among OHR‐QOL and other variables. Results: Geriatric Oral Health Assessment Index score was significantly correlated with occlusal force, number of teeth, financial status and JGS‐R score on linear regression analysis. Conclusion: Degree of gerotranscendence was significantly and independently correlated with degree of OHR‐QOL in our sample. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Masticatory muscle activity during teeth clenching is affected by occlusal pattern. However, few studies have performed simultaneous evaluation of all masticatory activities during teeth clenching under various occlusal conditions. The aim of this study was to use muscle functional magnetic resonance imaging (mfMRI) to evaluate the effects of changes in occlusal point on masticatory activity during single tooth clenching. Changes in mean proton transverse relaxation time (∆T2) as an index of activity in all masticatory muscles during left unilateral clenching at the first molar or first premolar for 1 min were examined in nine healthy volunteers. Bite force was maintained at 40% of the maximum voluntary clenching force. The ∆T2 values of the masseter and lateral pterygoid muscles were analysed separately for superficial and deep layers, and for superior and inferior heads. The ∆T2 values for the ipsilateral deep masseter were significantly lower, and for the superior head of the ipsilateral lateral pterygoid muscles were significantly higher, after left first premolar clenching compared to left first molar clenching. These results quantitatively demonstrate a significant increase in activity of the superior head of the ipsilateral lateral pterygoid muscle and a significant decrease in activity of the ipsilateral deep masseter muscle with forward displacement of the occlusal contact point during unilateral tooth clenching. [ABSTRACT FROM AUTHOR]

Due to the rapid rise of aged populations throughout the world, it is essential to elucidate the cause of taste dysfunction, because it may reduce appetite, leading to inadequate dietary intake. We aimed to compare taste detection ability between dependently and independently living geriatric individuals of nearly the same age with oral status. Forty-three elderly individuals considered to be cognitively eligible and residing in nursing homes in Japan were enrolled ( n = 43, 82·3 ± 8·5 years) and were compared with an independently living elderly group ( n = 949, 79·9 ± 0·8 years), aiming to compare taste detection ability between dependently and independently living elders of nearly the same age. Information regarding comorbidity and medication was obtained as general health status, and oral status including number of present teeth, denture usage and maximal occlusal force was also noted. In the dependently living group, 69·4%, 14·3%, 16·3% and 8·2% of participants could detect sweet, sour, salty and bitter tastes, respectively, which was significantly lower than the independently living group for each taste (97·9%, 70·8%, 89·6% and 43·8% for sweet, sour, salty and bitter tastes, respectively). The multivariate logistic regression analysis revealed that residing in nursing homes was associated with reduced sensitivity for four different tastes. The diseases and the situation of dependent elders were more likely the cause of the decreased taste sensitivity. [ABSTRACT FROM AUTHOR]

Previous studies have identified various factors related to masticatory performance. This study was aimed to investigate variations and impacts of factors related to masticatory performance among different occlusal support areas in general urban population in Japan. A total of 1875 Japanese subjects (mean age: 66·7 years) were included in the Suita study. Periodontal status was evaluated using the Community Periodontal Index (CPI). The number of functional teeth and occlusal support areas (OSA) were recorded, and the latter divided into three categories of perfect, decreased and lost OSA based on the Eichner Index. Masticatory performance was determined by means of test gummy jelly. For denture wearers, masticatory performance was measured with the dentures in place. The multiple linear regression analysis showed that, when controlling for other variables, masticatory performance was significantly associated with sex, number of functional teeth, maximum bite force and periodontal status in perfect OSA. Masticatory performance was significantly associated with number of functional teeth, maximum bite force and periodontal status in decreased OSA. In lost OSA, masticatory performance was significantly associated with maximum bite force. Maximum bite force was a factor significantly influencing masticatory performance that was common to all OSA groups. After controlling for possible confounding factors, the number of functional teeth and periodontal status were common factors in the perfect and decreased OSA groups, and only sex was significant in the perfect OSA group. These findings may help in providing dietary guidance to elderly people with tooth loss or periodontal disease. [ABSTRACT FROM AUTHOR]

OBJECTIVES: To investigate the association between lower extremity motor function and occlusion in older adults and to examine the possibility of dietary intake of protein mediating the association. DESIGN: Cross-sectional, population-based study. SETTING: Urban and rural area in Japan. PARTICIPANTS: Community-dwelling septuagenarians (N = 655) and octogenarians (N = 629). MEASUREMENTS: Information was collected on occlusal force, protein intake, grip strength, walking speed, sociodemographic characteristics, and medical history. Multivariable logistic regression analysis was used to investigate the association between walking speed, occlusal force, and protein intake, and structural equation modeling analysis and mediation analysis were performed to investigate the validity of the hypothesized model and identify the indirect effect of protein intake in occlusal force and walking speed. RESULTS: The proportion of participants whose walking speed was 0.8 m/s or slower (slow walking speed) was 27.7%. Logistic regression analyses showed that slower walking speed was associated with occlusal force (odds ratio = 1.57, P = .001) after adjusting for medical history, body mass index, grip strength, and protein intake. The fit of the hypothesized model that walking speed was associated with occlusal force through protein intake was good, and the indirect effect was significant. CONCLUSION: Slower walking speed was associated with lower occlusal force. Lower protein intake mediated the association between walking speed and occlusal force. Maintaining occlusal force might prevent insufficient nutrition intake and further deterioration of motor function in older people. [ABSTRACT FROM AUTHOR]

There are patients who suffer from persistent dentoalveolar pain disorder (PDAP) which is a pain of the teeth, either dentoalveolar pain or nonodontogenic toothache, and its cause has not yet been identified. An effective intervention for PDAP has not yet been established. Interventions for patients with PDAP are generally pharmacological treatments such as antidepressants, anticonvulsants, and pregabalin. However, these medicines are not always effective for patients. The pain disorder in the orofacial region including temporomandibular disorder (TMD) and PDAP was effectively treated with our original exercise therapy. However, we did observe some intractable cases of PDAP even when our original exercise therapy was used. This paper presents our findings in which Kamishoyosan improved the pain intensity in 14 out of 15 PDAP patients refractory to our original exercise therapy. [ABSTRACT FROM AUTHOR]

Purpose The present study examined the relationship between oral function, such as eating/swallowing, and life prognosis among a homebound elderly population, considering physical and mental function. Methods The participants were 511 homebound older adults aged 65 years or older living in four Japanese prefectures. Sex, age, activities of daily living ( ADL), cognitive function, underlying disease, nutritional status as Mini- Nutritional Assessment- Short Form ( MNA®- SF), swallowing function, dietary modification and occlusal status were examined at baseline. Participants were categorized into poor outcome (died or admitted to hospital or nursing home) and good outcome (still under home care) groups at 1-year follow up, and significant related baseline factors were analyzed. In addition, these groups were compared by the ADL subgroup divided into <60 (lower) and ≥60 (higher) by Barthel Index. Results In total, 473 participants were followed up (poor outcome group 177 [37.4%], good outcome group 296 [62.6%]). Sex, age, ADL, MNA®- SF, swallowing function, dietary modification and occlusal support were significantly different between these groups. Logistic regression analysis showed that sex and MNA®- SF score were significantly related to prognosis in the lower ADL group, and sex, age, Charlson Comorbidity Index and occlusal support were significantly related in the higher ADL group. Conclusions ADL was strongly correlated with life prognosis in homebound older adults. Within the higher ADL participants, occlusal support was related to this outcome. Geriatr Gerontol Int 2015; 15: 1001-1006. [ABSTRACT FROM AUTHOR]

The functional and esthetic results of reconstructive surgery after extended total maxillectomy or extended orbital exenteration greatly depend on the quality of the orbital reconstruction. We developed dynamic eye socket reconstruction using temporalis transfer to achieve good orbital reconstruction, and examined the usefulness of our technique. Five patients (three men and two women, aged 44-72 years) who underwent extensive resection of midfacial malignancies were treated with dynamic eye socket reconstruction using temporalis transfer. In most cases, eye socket reconstruction was performed approximately 1 year after the initial surgery, and temporalis transfer was used after maturation of the eye socket. The follow-up period ranged from 16 to 120 months (average 63.8 months). Movement of the upper and lower eyelids was achieved in all cases, and definite creases at the lateral canthus were observed in two patients. A good shape in the reconstructed medial and lateral canthal areas was maintained in all patients. Our reconstruction technique is extremely effective in creating natural creases ('crow's feet') at the lateral canthus during smiling, enabling movement of the upper and lower eyelids, and maintaining a sharp palpebral morphology. [ABSTRACT FROM AUTHOR]

It is known that maximum bite force has various influences on chewing function; however, there have not been studies in which the relationships between maximum bite force and masticatory jaw movement have been clarified. The aim of this study was to investigate the effect of maximum bite force on masticatory jaw movement in subjects with normal occlusion. Thirty young adults (22 men and 8 women; mean age, 22·6 years) with good occlusion were divided into two groups based on whether they had a relatively high or low maximum bite force according to the median. The maximum bite force was determined according to the Dental Prescale System using pressure-sensitive sheets. Jaw movement during mastication of hard gummy jelly (each 5·5 g) on the preferred chewing side was recorded using a six degrees of freedom jaw movement recording system. The motion of the lower incisal point of the mandible was computed, and the mean values of 10 cycles (cycles 2-11) were calculated. A masticatory performance test was conducted using gummy jelly. Subjects with a lower maximum bite force showed increased maximum lateral amplitude, closing distance, width and closing angle; wider masticatory jaw movement; and significantly lower masticatory performance. However, no differences in the maximum vertical or maximum anteroposterior amplitudes were observed between the groups. Although other factors, such as individual morphology, may influence masticatory jaw movement, our results suggest that subjects with a lower maximum bite force show increased lateral jaw motion during mastication. [ABSTRACT FROM AUTHOR]

This study explored the influence of the thickness of silicone registration material on evaluation of the occlusal contact area and number of occlusal contact points, during increasing tooth clenching conditions in normal subjects. Twenty-four subjects with no more than one missing tooth per quadrant participated. Surface electro-myography was recorded from the masseter muscle. As a baseline measurement, intercuspal position was maintained with minimal force, and occlusal contact was recorded using blue silicone material. Occlusal contact was also recorded at 20% maximum voluntary contraction ( MVC) and 40% MVC using visual feedback. The occlusal contact area and number of occlusal contact points were analysed using five levels of thickness of silicone registration material: Level 1 (0-149 μm); Level 2 (0-89 μm); Level 3 (0-49 μm); Level 4 (0-29 μm); and Level 5 (0-4 μm). The anterior part and the left and right posterior regions of the dental arch were analysed separately. At all detection levels, the occlusal contact area significantly increased from baseline to 20% MVC and to 40% MVC in the molar area ( P < 0·05). In the anterior part, the occlusal contact area significantly increased from baseline to 20% MVC and to 40% MVC only when using Level 5. The number of occlusal contact points significantly increased from baseline to 20% MVC and to 40% MVC only when using Level 5 in the molar area ( P < 0·05). It suggested that occlusal contacts may be different at low tooth clenching intensity with potential effects on the teeth or periodontal tissues. [ABSTRACT FROM AUTHOR]

Aim: The Eichner index (EI) is used to evaluate occlusal support. However, this index is based on existing natural tooth contact. This study aimed to establish whether a modified EI that included artificial teeth reflected individual oral condition of elderly people, and to clarify the relationship between this index and: (i) mental condition; (ii) physical condition; and (iii) physical function. Methods: We recruited 286 people (145 men, 141 women) aged 65-79 years. They were divided into three groups by modified EI, and then underwent assessment of oral condition. After establishing that the index was clearly related to oral condition, we investigated psychological factors (satisfaction with life, self-rated health and anxiety regarding falling), indicators of walking and balance (Timed Up & Go test [TUG] and one-leg standing balance), physical condition (higher-level functional capacity [HLFC]: instrumental activities of daily living [IADL], intellectual activity and social role; continuous walking over 15 min; and frequency of outings), and health history in the previous year (history of hospital admissions and falls). Results: Modified EI was a good indicator of occlusal condition. The index was significantly correlated in men with satisfaction with life, TUG test, one-leg standing balance, overall HLFC and HLFC-IADL, and in women with TUG test, one-leg standing balance and HLFC-Intellectual activity. Conclusion: The evaluation of occlusal support including that from artificial teeth is beneficial in the elderly as an indicator of health and oral function, in particular firm bite. Geriatr Gerontol Int 2013; 13: 539-546. [ABSTRACT FROM AUTHOR]

Aim: Mastication is an important function to maintain, not only for oral health, but also for quality of life. An easy-to-use method to evaluate the chewing ability of elderly people in any environment is necessary. Few studies have discussed the effectiveness of the masseter muscle by palpation. The purpose of this study was to clarify the availability of masseter muscle tension assessment methods by investigating its relationship with oral health status, and comparing it with other methods of assessing chewing ability. Methods: This cross-sectional study was carried out with 547 community-dwelling elderly subjects (246 men and 301 women; mean age 73.8 ± 6.2 years) who participated in a comprehensive annual geriatric health examination in 2010 at Kusatsu, Gunma, Japan. Chewing ability was evaluated by masseter muscle tension palpation, differences of masseter muscle thickness, occlusal force, self-reported chewing ability, and the number of remaining and functional teeth. Masseter muscle thickness was measured by ultrasonography. Results: Masseter muscle thickness and occlusal force showed significant differences between males and females. The strength of masseter muscle tension palpation was significantly associated with men's occlusal force, masseter muscle thickness, the number of remaining and functional teeth, and self-reported chewing ability ( P < 0.05). Female participants showed a significant association with occlusal force, masseter muscle thickness, the number of remaining teeth, and self-reported chewing ability and results of palpation ( P < 0.05). Conclusion: These results showed that the palpation of masseter muscle tension is a reliable and easy-to-use method to evaluate the chewing ability of elderly people. Geriatr Gerontol Int 2013; 13: 372-377. [ABSTRACT FROM AUTHOR]

Objectives To investigate the relationship between swallowing problems and the number of remaining teeth in healthy elderly people. Design Cross-sectional. Setting Nara, Japan. Participants Three thousand six hundred sixty-three male and female volunteers aged 65 and older who were living independently were analyzed. Measurements Swallowing problems were defined operationally using a questionnaire and the 30-mL water swallow test. Data were collected on the number of remaining teeth, maximum bite force, occlusal status, presence or absence of oral dryness, and medical history. Results The prevalence of swallowing problems was 15.1% (n = 554) in this population. A positive correlation was observed between the number of remaining teeth and maximum bite force. The number of remaining teeth was categorized according to tertiles. Multiple logistic regression analysis revealed that the adjusted odds ratios for 0 to 13 or 14 to 24 remaining teeth to 25 to 32 remaining teeth for swallowing problems were 2.04 (95% confidence interval ( CI) = 1.60-2.60) and 1.31 (95% CI = 1.02-1.70), respectively. Significant increases in these odds ratios were found in a trend test ( P < .001). Conclusion Tooth loss is associated with swallowing problems. Having fewer teeth inhibits masticatory ability, which disturbs the execution of smooth swallowing. Preventive measures against tooth loss at a younger age may be effective at reducing the risk of laryngeal penetration and aspiration at an older age. [ABSTRACT FROM AUTHOR]

Efficient mastication of different types and size of food depends on fast integration of sensory information from mechanoreceptors and central control mechanisms of jaw movements and applied bite force. The neural basis underlying mastication has been studied for decades but little progress in understanding the dynamics of bite force has been made mainly due to technical limitations of bite force recorders. The aims of this study were to develop a new intraoral bite force recorder which would allow the study of natural mastication without an increase in the occlusal vertical dimension and subsequently to analyze the relation between electromyographic (EMG) activity of jaw-closing muscles, jaw movements and bite force during mastication of five different types of food. Customized force recorders based on strain gauge sensors were fitted to the upper and lower molar teeth on the preferred chewing side in fourteen healthy and dentate subjects (21-39 years), and recordings were carried out during voluntary mastication of five different kinds of food. Intraoral force recordings were successively obtained from all subjects. anova showed that impulse of bite force as well as integrated EMG was significantly influenced by food ( P < 0·05), while time-related parameters were significantly affected by chewing cycles ( P < 0·001). This study demonstrates that intraoral force recordings are feasible and can provide new information on the dynamics of human mastication with direct implications for oral rehabilitation. We also propose that the control of bite force during mastication is achieved by anticipatory adjustment and encoding of bolus characteristics. [ABSTRACT FROM AUTHOR]

Objectives To elucidate the independent relationship between masticatory and physical performance in community-living oldest old people (mean age ± standard deviation 87.8 ± 2.2, range 85-102). Design Cross-sectional analysis . Setting University research center or home-based examination. Participants Four hundred eighty-nine community-living individuals (219 men, 270 women) aged 85 and older. Measurements Maximum occlusal force ( MOF) was measured using an occlusal force measuring device. Sociodemographic and functional factors, oral health, comorbidities, blood chemistry, lower extremity performance, and handgrip strength were assessed. Blood chemistry analyses included serum albumin, C-reactive protein, interleukin ( IL)-6, and total and free testosterone. Results MOF was significantly associated with age, body mass index, and cognitive impairment in men but not in women. Comorbidities and blood chemistry were not associated with MOF except for a significant association with IL-6 concentration in women. In a multivariate model adjusted for various confounders, lower MOF was associated with greater risk for poor performance on the timed up and go ( TUG) test in men and women (men: odds ratio ( OR)=2.34, 95% confidence interval ( CI)=1.02-5.38; women: OR=2.44, 95% CI=1.12-5.33). MOF was similarly associated with performance in chair standing, one-leg standing, and handgrip strength only in men. These associations remained after adjustment for number of natural teeth. Conclusion MOF was strongly and independently associated with all measures of physical performance in men and with the TUG test in women after adjustment for various confounders, suggesting that age-related declines in masticatory and skeletal muscle functions share common mechanistic pathways in older age, particularly in men. [ABSTRACT FROM AUTHOR]

The purposes of this study were (1) to examine differences in dental status among various age groups, particularly, focusing on whether subjects retained 20 or more natural teeth, and (2) to investigate the relationship among dental status, the number and categories of functional tooth units (FTUs), and masticatory ability. A dental examination and self-administered questionnaire were conducted in a total of 2,164 residents aged 40 to 75 years who dwelt in Japan. The percentage of subjects with 20 and more natural teeth and their number of posterior teeth decreased with age. There was not much difference in the mean number of FTUs in subjects with and without 20 or more natural teeth, but those with 20 natural teeth had fewer numbers of FTUs than those with more than 20 natural teeth. The categories of the FTUs were extremely different. Subjects with 20 or more natural teeth had FTUs consisting mostly of natural to natural teeth. Subjects with 19 or fewer natural teeth had many FTUs consisting of removable prosthetic teeth. The subjective chewing ability test was significantly correlated with the number of natural teeth. Subjects could chew the higher number of test foods as the number of natural teeth increased. Not only the number of natural teeth but the categories of FTUs appear to be key factors of chewing ability. It is important to keep as many natural teeth as possible so that the person’s categories of FTUs are mainly composed of natural to natural teeth to maintain better oral function. [ABSTRACT FROM AUTHOR]