Chewing ability and quality of life among the elderly residing in a rural community in Japan

Kinematics of the jaw following total temporomandibular joint replacement surgery

Total temporomandibular joint (TMJ) replacement surgery aims to improve mandibular function, reduce pain and enhance quality of life in patients suffering from end-stage TMJ disorders. Traditional post-operative jaw evaluation is carried out using measurement of maximum interincisal opening distance; however, this can correlate poorly to joint function. The present study aimed to evaluate three-dimensional (3D) jaw motion during border movements and chewing in unilateral total TMJ replacement patients and healthy controls. Motion analysis experiments were performed on six unilateral total TMJ replacement patients and ten age-matched healthy controls. Subject-specific motion tracking plates worn by each participant were registered to CT scans of each participant's skull and mandible to enable anatomical mandibular kinematics measurement using an optoelectronic system. Participants performed 15 repetitions of maximal opening, protrusion, lateral excursions, and chewing cycles. Total TMJ replacement patients had significantly smaller incisal displacements at maximum mouth opening relative to the controls (median difference: 7.1 mm, p = 0.002) and decreased anterior translation of the prosthetic condyle (median difference: 10.5 mm, p = 0.002). When TMJ replacement subjects chewed using their contralateral molars, there was a significant increase in inferior condylar translation of the non-working condyle (median difference: 9.7 mm, p = 0.016). This study found that unilateral total TMJ replacement surgery was associated with mouth opening capacity within the range of healthy individuals, but reduced anterior movement of the prosthetic condyle and restricted protrusion and lateral excursions. The results provide future direction for prosthetic TMJ design to enhance postsurgical implant functionality and improve long-term clinical outcomes for prosthesis recipients.

Subjective Wellbeing and Related Factors of Older Adults Nine and a Half Years after the Great East Japan Earthquake: A Cross-Sectional Study in the Coastal Area of Soma City

This study examined older adults’ subjective wellbeing and related factors in the coastal area of Soma City nine and a half years after the Great East Japan Earthquake (GEJE). Data were collected from 65- to 84-year-old residents and 1297 participants via a questionnaire from October to November 2020. The participants were divided into two groups: housing complexes and non-housing complexes. The dependent variable was subjective wellbeing assessed via Lawton’s Philadelphia Geriatric Center Morale Scale (PGCMS). Using multivariate regression analysis, the factors most strongly related to a low PGCMS score for both groups were poor health conditions, difficulties resting while asleep, poor financial wellbeing, inability to chew certain foods, and fear of solitary death. The GEJE experience was further distinguished in the housing complex group by the loss of an important non-family individual; for the other group, important factors were female gender, junior high school education level or lower, limited social networks, and deterioration of a family member’s health. Older adults’ subjective wellbeing in Soma City was low after nine and a half years following the GEJE. For disaster victims and their families in both groups, it is crucial to implement measures such as long-term, continuous physical and mental health support.

Development and validation of a chewing function questionnaire for Chinese older adults

OBJECTIVES

To develop and validate a questionnaire for assessing chewing function of Chinese older adults.

METHODS

The chewing function questionnaire was validated on older adults recruited from a dental hospital, an elderly home and three community centers in Hong Kong. The participants were asked to indicate their ability to chew on each of the 20 selected food items and to self-rate their overall chewing ability. Chewing function was objectively assessed by asking the participant to chew a color-changeable gum for 90 s. The color of the chewed gum was assessed using a colorimeter. Participant's maximum bite force was also measured by an electronic detector.

RESULTS

A total of 211 elders participated in this study. Ten out of the 20 food items were selected to create the final unidimensional chewing function questionnaire (CFQ). The overall Cronbach's alpha value for the CFQ was 0.912. The weighted kappa value of each food item ranged from 0.6 to 1. In general, participants with larger color change of the chewed gum had significantly higher median rank of the CFQ total score and of the score of each food item (p < 0.01). The CFQ total score was correlated with the color change of the chewed gum as measured by colorimeter (p < 0.001), the maximum bite force (p < 0.001) and self-rated chewing ability (p < 0.001).

CONCLUSION

The new unidimensional chewing function questionnaire is a valid and reliable questionnaire for assessing self-rated chewing ability of Chinese older adults.

CLINICAL SIGNIFICANCE

The newly developed self-reported questionnaire can be used to assess the chewing function of Chinese older adults and dentists can use the information obtained to discuss with their patients regarding the need for oral function rehabilitation, such as the treatment need for fixed or removable dental prosthesis.

Improvements in oral functions of elderly after simple oral exercise

Purpose: Conventional oral exercises in previous studies are considered impractical for continuous use in the elderly because of the extended duration needed for effective outcomes. Therefore, in the present study, a simple oral exercise (SOE) was developed to reduce performance time, focusing on improvements in mastication, salivation, and swallowing functions. The aim of this study was to determine the short-term effects of the SOE with respect to improving mastication, salivation, and swallowing function in elderly subjects ≥65 years of age.

Patients and methods: The study included 84 subjects, all of whom performed the SOE 2 times per day for 1 week. Masticatory performance was assessed using the mixing ability index (MAI). Unstimulated saliva and the degree of moisture of the tongue/buccal mucosa were evaluated, and the repetitive saliva swallowing test was performed. On the basis of each of these four measurements, subjects were dichotomized into two groups with high (good) and low (poor) conditions. The same evaluations were conducted before and immediately after intervention, as well as after 1 week of intervention. A subjective evaluation with questionnaires was performed after 1 week of intervention. The changes were analyzed using repeated-measures ANOVA, Cochran’s Q test, and McNemar’s test.

Results: The mean MAI increased by 6% immediately after the intervention, and by 16% in the poor-chewing group. Similarly, the amount of unstimulated saliva increased by 0.1 ml/min immediately after the SOE, and by 29% in the poor-salivation group. The degree of tongue moisture increased by 3% and was maintained. In the poor-swallowing group, 25% and 40% of the subjects were upgraded to the good-swallowing group immediately after intervention, as well as after 1 week of intervention, respectively. The subjects experienced less discomfort as their oral function improved.

Conclusion: The SOE was effective in immediately improving oral functions, and improvement was maintained for 1 week.

Individuality of masticatory performance and of masticatory muscle temporal parameters

OBJECTIVE

Mammalian mastication serves to improve intra-oral food reduction. Insufficient food reduction creates potential swallowing problems, whereas over-reduction may accelerate tooth wear and increase feeding time. Either extreme has consequences. The study's objectives were: (1) to study the relationship between food reduction, number of chews in a sequence, and chewing rate, (2) to study how controlling the number of chews and chewing rate variability affects food reduction, and (3) to assess how dentoskeletal morphological and electromyographical (EMG) characteristics impact food reduction.

DESIGN

Twenty-three healthy, fully-dentate adults chewed a standardized test food under three conditions: (1) no control, (2) number of chews controlled, and (3) number of chews and chewing rate controlled. EMG activity was sampled from masseter and temporalis muscles bilaterally. Demographic, occlusal contact area in maximum intercuspation, and cephalometric data were obtained.

RESULTS

In uncontrolled conditions, food reduction and bout duration varied more than expected across subjects. Subjects with poor reduction under controlled conditions were those with poor reduction under uncontrolled conditions. Only occlusal contact area correlated with chewing performance under uncontrolled conditions. Chewing cycle duration, EMG burst duration, and EMG peak onset latency increased when the number of chews was restricted. EMG amplitude, a surrogate for bite force, increased in tasks controlling the number of chews and chewing rate. Chewing rate variability was difficult to diminish below individual-specific levels.

CONCLUSIONS

Results: provided evidence that bite force, chewing rate, chewing performance and chewing bout duration reflected individual preferences. Future work will determine whether similar findings occur among other mammals.

Occlusal loading during biting from an experimental and simulation point of view

OBJECTIVES

Occlusal loading during clenching and biting is achieved by the action of the masticatory system, and forms the basis for the evaluation of the functional performance of prosthodontic and maxillofacial components. This review provides an overview of (i) current bite force measurement techniques and their limitations and (ii) the use of computational modelling to predict bite force. A brief simulation study highlighting the challenges of current computational dental models is also presented.

METHODS

Appropriate studies were used to highlight the development and current bite force measurement methodologies and state-of-the-art simulation for computing bite forces using biomechanical models.

RESULTS

While a number of strategies have been developed to measure occlusal forces in three-dimensions, the use of strain-gauges, piezo-electric sensors and pressure sheets remain the most widespread. In addition to experimental-based measurement techniques, bite force may be also estimated using computational models of the masticatory system. Simulations of different bite force models clearly show that the use of three-dimensional force measurements enriches the evaluation of masticatory functional performance.

SIGNIFICANCE

Hence, combining computational modelling with three-dimensional force measurement techniques can significantly improve the evaluation of masticatory system and the functional performance of prosthodontic components.

Psychological stress-relieving effects of chewing - Relationship between masticatory function-related factors and stress-relieving effects

PURPOSE

The objective of the present study was to investigate the relationship between masticatory function-related factors (masticatory performance, occlusal contact area, maximum bite force, number of chewing strokes, and muscle activity) and the stress-relieving effects of chewing.

METHODS

A total of 28 healthy male subjects were instructed to rest or chew for 10min after 30min of stress loading with arithmetic calculations. Their stress state was assessed by measuring salivary cortisol levels. Saliva was collected at three time points: before stress loading, immediately after stress loading, and 10min after stress loading. Compared to resting, chewing produced a significantly greater reduction in the rate of change in salivary cortisol levels 10min after stress loading.

RESULTS

A negative correlation was observed between the rate of decrease in salivary cortisol levels and the number of chewing strokes. No significant correlation was observed between the rate of decrease in salivary cortisol levels and other measurement items.

CONCLUSION

In healthy dentulous people, the number of chewing strokes has been shown to be a masticatory function-related factor that affects stress relief from chewing, suggesting the possibility that more appropriate chewing would produce a greater effect psychological stress relief.

Comparison of masticatory efficiency according to Angle's classification of malocclusion

Objective

The objective of this study was to investigate the differences in masticatory efficiency among patients with different Angle's classes of malocclusion and to assess the correlation between masticatory efficiency and the occlusal contact area.

Methods

The mixing ability index (MAI) was calculated for measuring masticatory efficiency of 61 adult patients according to Angle's classifications of malocclusion. The study included 25, 15, and 21 patients with Angle's Class I, II, and III malocclusions, respectively. Silicone interocclusal recording material was used to measure the occlusal contact area.

Results

Both the MAI and occlusal contact area showed the highest average values in the Class I malocclusion group, followed by the Class II and Class III malocclusion groups. No significant difference was observed in the MAI values between the Class I and Class II malocclusion groups (p > 0.05), whereas a significant difference was observed between the Class I and Class III malocclusion groups (p < 0.01) and between the Class II and Class III malocclusion groups (p < 0.05). A weak positive correlation was also observed between the MAI and occlusal contact area (p < 0.01, r² = 0.13).

Conclusions

The results of this study indicated that masticatory efficiency was the highest in patients with Angle's Class I malocclusion, followed by those with Angle's Class II and Angle's Class III malocclusions. Moreover, a weak positive correlation was observed between masticatory efficiency and the occlusal contact area.

Assessing Health-Related Quality of Life among Older People in Rural Bangladesh

The purpose of this study was to review instruments of health-related quality of life (HRQoL) to identify an instrument appropriate for elderly people in rural Bangladesh. In addition, it hypothesizes that it is important to include physical, psychological, social, spiritual, economic, and environmental dimensions when assessing HRQoL in this group. Sixteen generic instruments found through PubMed were reviewed with regard to content and construct. None of the reviewed instruments fully met the criteria required in the intended context. In-depth interviews were conducted with 11 elderly people in rural Bangladesh to explore the dimensions of HRQoL they considered important. Content analysis of the interview transcripts supported the hypothesis that all six dimensions were important. Suggestions for a new HRQoL instrument appropriate for elderly people in rural Bangladesh are presented.

EMG Activity of Masseter Muscles in the Elderly According to Rheological Properties of Solid Food

Objective

To assess the impact of aging on masticatory muscle function according to changes in hardness of solid food.

Methods

Each of fifteen healthy elderly and young people were selected. Subjects were asked to consume cooked rice, which was processed using the guidelines of the Universal Design Foods concept for elderly people (Japan Care Food Conference 2012). The properties of each cooked rice were categorized as grade 1, 2, 3 and 4 (5×10³, 2×10⁴, 5×10⁴, and 5×10⁵ N/m²) respectively. Surface electromyography (sEMG) was used to measure masseter activity from food ingestion to swallowing of test foods. The raw data was normalized by the ratio of sEMG activity to maximal voluntary contraction and compared among subjects. The data was divided according to each sequence of mastication and then calculated within the parameters of EMG activities.

Results

Intraoral tongue pressure was significantly higher in the young than in the elderly (p<0.05). Maximal value of average amplitude of the sequence in whole mastication showed significant positive correlation with hardness of food in both young and elderly groups (p<0.05). In a comparisons between groups, the maximal value of average amplitude of the sequence in whole mastication and peak amplitude in whole mastication showed that mastication in the elderly requires a higher percentage of maximal muscle activity than in the young, even with soft foods (p<0.05).

Conclusion

sEMG data of the masseter can provide valuable information to aid in the selection of foods according to hardness for the elderly. The results also support the necessity of specialized food preparation or products for the elderly.

Chronic Powder Diet After Weaning Induces Sleep, Behavioral, Neuroanatomical, and Neurophysiological Changes in Mice

The purpose of this study is to clarify the effects of chronic powder diet feeding on sleep patterns and other physiological/anatomical changes in mice. C57BL/6 male mice were divided into two groups from weaning: a group fed with solid food (SD) and a group fed with powder food (PD), and sleep and physiological and anatomical changes were compared between the groups. PD exhibited less cranial bone structure development and a significant weight gain. Furthermore, these PD mice showed reduced number of neurogenesis in the hippocampus. Sleep analysis showed that PD induced attenuated diurnal sleep/wake rhythm, characterized by increased sleep during active period and decreased sleep during rest period. With food deprivation (FD), PD showed less enhancement of wake/locomotor activity compared to SD, indicating reduced food-seeking behavior during FD. These results suggest that powder feeding in mice results in a cluster of detrimental symptoms caused by abnormal energy metabolism and anatomical/neurological changes.

Relationship Between Self-Rated Masticatory Ability and Independent Life in Community-Dwelling Older Adults

Objective: The aim of the present study was to elucidate the influence of self-rated masticatory ability on independent living in community-dwelling older adults. Method: A total of 1,377 subjects aged 65 and over who lived in Kumamoto City, Japan were participated in a survey to investigate critical factors for self-reliance in older adults. In this study, we defined independent life in older adults as self-perceived adequate health without long-term care certification. Logistic regression analysis was used to assess self-perceived masticatory ability in relation to the independent life. Results: The population with adequate self-rated masticatory ability included a significantly higher proportion of subjects with good self-perceived health without long-term care (72.7%) than the remaining subjects (27.3%). A logistic regression analysis revealed that there was significant relationship between subjective adequate mastication and living a self-reliant healthy life (p < .001). Conclusion: Our results showed that satisfactory masticatory function was positively related to a self-reliant life with subjective healthy conditions in community-dwelling older adults, which was associated with an extended active life expectancy.

Accessible Transportation, Geographic Elevation, and Masticatory Ability Among Elderly Residents of a Rural Area

Given that public transportation networks are often worse in rural areas than in urban areas, rural residents who do not drive can find it difficult to access health-promoting goods, services, and resources related to masticatory ability. Moreover, geographical location, assessed by elevation, could modify this association. The aim of this study was to test whether the association between access to transportation and masticatory ability varied by elevation. Data were collected from a cross-sectional study conducted in Mizuho and Iwami counties, Japan. Objective masticatory ability was evaluated using a test gummy jelly and elevation was estimated by the geographic information systems according to the participant’s address. After excluding subjects with missing data, 672 subjects (Mizuho = 401 and Iwami = 271) were analyzed. After adjustment for potential confounders, being a driver was not significantly associated with masticatory ability among elderly people living at low elevation (≤313 m) in Mizuho county. However, after the same adjustment, being a driver remained significantly associated with increased masticatory ability among elderly at high elevations. Similar findings were observed in Iwami county. Accessible transportation was significantly associated with increased mastication ability in elderly people living at high elevations, but not in those living at low elevations.

Volitional chewing with a conscious effort alters and facilitates swallowing during feeding sequence

The key objective of mastication is to form a food bolus suitable for smooth swallowing. However, chewing is usually performed without a conscious effort. Poor bolus formation can cause pharyngeal residue and suffocation in elderly individuals with reduced swallowing function. Therefore, chewing with a conscious effort may help the bolus to more easily pass the pharynx. This study aimed to clarify the impact of mastication with a conscious effort on the feeding sequence. Subjects included 25 dentulous volunteers who were informed and provided written consent. Lateral videofluoroscopy was performed during the feeding of solid agar jelly under two conditions: chewing naturally in their usual manner (without volition) and chewing with a conscious effort (with volition). Temporal evaluation was performed for mastication, stage II transport (STII), swallow onset and oropharyngeal transit time. Moreover, bolus volume at swallow onset and subjective evaluation of swallowing easiness were measured. Volitional chewing with a conscious effort lengthened the duration of the chewing sequence before and after STII and delayed the swallow onset despite the fact that the bolus volume in the vallecula and hypopharynx (HYP) had significantly increased. Furthermore, with volition, the bolus transit time from swallow onset in the oral cavity, upper oropharynx and HYP was reduced, and subjective evaluation of swallowing easiness demonstrated significant improvement. These results suggest that volitional chewing with a conscious effort can alter bolus transport and swallowing, resulting in easier swallowing.

Masticatory deficiency as a risk factor for cognitive dysfunction

Several studies have demonstrated that chewing helps to maintain cognitive functions in brain regions including the hippocampus, a central nervous system (CNS) region vital for memory and learning. Epidemiological studies suggest that masticatory deficiency is associated with development of dementia, which is related to spatial memory deficits especially in older animals. The purpose of this paper is to review recent work on the effects of masticatory impairment on cognitive functions both in experimental animals and humans. We show that several mechanisms may be involved in the cognitive deficits associated with masticatory deficiency. The epidemiological data suggest a positive correlation between masticatory deficit and Alzheimer's disease. It may be concluded that chewing has important implications for the mechanisms underlying certain cognitive abilities.

Relationship between masticatory performance and heart rate variability: a pilot study

OBJECTIVE

Little information is available on how impaired masticatory performance relates to heart-rate variability (HRV). The aim of this study was to investigate the relationship between HRV indices and masticatory performance.

MATERIALS AND METHODS

Sixty-five subjects (19 men and 46 women, 66.1 ± 9.9 years old) who had received periodontal maintenance care at the Clinic of Preventive Dentistry of Okayama University Hospital were selected for the study. All subjects completed written questionnaires, a chewing (colour-changing gum) test for masticatory performance and measurement of occlusal force and HRV as well as oral examination.

RESULTS

The high sympathetic activity (LF ≥ 49.6) group showed a significantly lower level of masticatory performance (a* value) than the low sympathetic activity group (p < 0.05). There were also significant correlations of masticatory performance with LF and LF/HF (p < 0.05).

CONCLUSION

These findings suggest that there is relationship between masticatory performance and HRV indices and impaired masticatory performance may be a risk factor for inducing high sympathetic activity.

[Relationship between comprehensive quality of life and factors related to chewing and swallowing function among community-dwelling elderly individuals]

AIM

The purpose of the present study was to examine the relationship between comprehensive quality of life (QOL) and some factors regarding chewing and swallowing function among community-dwelling elderly individuals.

METHODS

The subjects were 675 independent elderly persons residing in the northern area of Miyazaki Prefecture, and we obtained the self-administered questionnaires from 545 elderly people. We used "active scale for the elderly (ASE)" and "dysphagia risk assessment for the community-dwelling elderly (DRACE)" to evaluate their comprehensive QOL and function of chewing and swallowing, respectively. Furthermore, we examined some factors such as age, gender, subjective satisfaction with diet and verbal communication.

RESULTS

The score of ASE showed a significant decline with age (p<0.01) while the DRACE score increased significantly with age (p<0.01). Pearson's correlation coefficients revealed that the ASE score was significantly related to all of the factors regarding regulation of food intake. Partial correlation coefficients adjusted for age also revealed the same tendency. From the multiple regression analysis, subjective satisfaction with verbal communication, DRACE score, age and appetite were extracted as factors influencing ASE score (adjusted R(2)=0.43, p<0.01).

CONCLUSION

Among independent elderly persons residing in the community, the comprehensive QOL was significantly related to factors such as subjective satisfaction with verbal communication, dysphagia risk, age, and appetite.

Assessment of masticatory performance, bite force, orthodontic treatment need and orofacial dysfunction in children and adolescents

OBJECTIVES

Few studies have evaluated the relationship between morphological and functional characteristics of the masticatory apparatus in young subjects. Thus, the aim of this study was to evaluate masticatory performance (MP), maximal bite force (BF), orthodontic treatment need and orofacial dysfunction in children and adolescents.

DESIGN

The sample consisted of 316 subjects of both genders, with an age range 6-16years divided into 4 groups: early mixed, intermediate mixed, late mixed and permanent dentition. MP was evaluated by the individual's ability to comminute a chewable test material in order to determine median particle size (X(50)) and distribution of particles in different sieves ("b"). BF was determined using a digital gnatodynamometer with fork strength of 10mm. Orofacial function and orthodontic treatment need were screened using the Nordic Orofacial Test-Screening (NOT-S) protocol and Index of Orthodontic Treatment Need (IOTN), respectively. The results were submitted to descriptive statistics, normality test, analysis of variance and stepwise multiple linear regression to test relationship between MP and studied independent variables.

RESULTS

Variance of X(50) and b between groups was statistically significant. But evaluation of variables that significantly contributed to MP variation showed that age, body mass index (BMI), BF and the presence of sleep bruxism were negatively related to X(50) and the NOT-S clinical exam scores showed a positive relationship with X(50).

CONCLUSION

In the studied sample, age, BMI, BF and the presence of sleep bruxism were related to better MP; but the increase in NOT-S scores was significantly related to poorer MP.

Effect of regular gum chewing on levels of anxiety, mood, and fatigue in healthy young adults

INTRODUCTION

The effect of regular gum chewing on psychological status is unknown. The purpose of this study was to examine the effect of gum chewing for fourteen days on psychological status and physical and mental fatigue in healthy young adults.

METHODS

We assigned 50 volunteers randomly to an intervention group (n = 26) and a control group (n = 24). Participants in the intervention group were requested to chew the gum twice per a day for fourteen days. The volunteers were required to complete a questionnaire related to lifestyle for baseline assessment. The State-Trait Anxiety Inventory (STAI), the Profile of Mood State (POMS), the World Health Organization Quality of Life 26, and assessment of physical and mental fatigue by visual analog scale were used at baseline, 2 weeks (after intervention), and 4 weeks (follow-up).

RESULTS

At 2 weeks, the score of state anxiety was significantly lower in the intervention group than the control group. The intervention participants' scores of depression-dejection, fatigue and confusion in POMS were better than the control group scores. Mental fatigue were also relieved after the intervention. At 4 weeks, there were no significant differences between both groups.

CONCLUSION

Fourteen days' gum chewing may improve the levels of anxiety, mood and fatigue.

Masticatory function and cognitive function

Recent studies have suggest that masticatory (chewing) function is useful for maintaining neurocognitive function in the elderly. For example, a reduced ability to masticate, such as that resulting from toothlessness or soft-diet feeding, causes learning and memory deficits in aged animals and pathologic changes in the hippocampus. In addition, occlusal disharmony impairs hippocampal memory processes via chronic stress, and induces similar hippocampal pathology. Chewing, however, rescues stress-induced suppression of long-term potentiation in the hippocampus and the stress-induced impairment of hippocampal-dependent learning. These findings strongly suggest a link between mastication and neurocognitive function.

Occlusion and brain function: mastication as a prevention of cognitive dysfunction

Research in animals and humans has shown that mastication maintains cognitive function in the hippocampus, a brain area important for learning and memory. Reduced mastication, an epidemiological risk factor for the development of dementia in humans, attenuates spatial memory and causes hippocampal neurons to deteriorate morphologically and functionally, especially in aged animals. Active mastication rescues the stress-attenuated hippocampal memory process in animals and attenuates the perception of stress in humans by suppressing endocrinological and autonomic stress responses. Active mastication further improves the performance of sustained cognitive tasks by increasing the activation of the hippocampus and the prefrontal cortex, the brain regions that are essential for cognitive processing. Abnormal mastication caused by experimental occlusal disharmony in animals produces chronic stress, which in turn suppresses spatial learning ability. The negative correlation between mastication and corticosteroids has raised the hypothesis that the suppression of the hypothalamic-pituitary-adrenal (HPA) axis by masticatory stimulation contributes, in part, to preserving cognitive functions associated with mastication. In the present review, we examine research pertaining to the mastication-induced amelioration of deficits in cognitive function, its possible relationship with the HPA axis, and the neuronal mechanisms that may be involved in this process in the hippocampus.

Masticatory performance and chewing cycle kinematics-are they related?

OBJECTIVE

To compare chewing cycle kinematics of subjects with better and poorer masticatory performance.

MATERIALS AND METHODS

A cross-sectional study compared masticatory performance, based on the breakdown of the artificial test food Cuttersil, in 30 subjects with Class I occlusion. Individuals with median particle sizes greater and lesser than the median value for the entire sample were categorized as poorer (15) and better (15) performers, respectively. While chewing Cuttersil, three-dimensional jaw movements of subjects were tracked with an optoelectric computer system. Multilevel linear modeling was used to evaluate differences in estimated cycle shape, cycle duration, and maximum excursions, as well as within-subject variation between the two groups.

RESULTS

Poorer performers had a significantly longer opening duration (0.274 +/- 0.225 sec vs 0.325 +/- 0.270 sec) than better performers. Poorer and better performers also showed significant differences in cycle shape, including a less horizontal path of closure and more posterior jaw movement in the poorer performers. In addition, poorer performers exhibited significantly more cycle-to-cycle (within-subject) variability in chewing cycle duration, excursive movements, and lateral velocity than did better performers.

CONCLUSIONS

Poorer performers lacked consistency in their chewing cycles, and their cycle shape differs from that of better performers.

Development and evaluation of an index of eating difficulty for older southern Chinese people

The objectives of this study were to develop and evaluate the validity and reliability of a new index to assess difficulty in eating certain foods among older southern Chinese people. The Index of Eating Difficulty (IED) was developed using a Guttman scaling analysis. After two pilot studies in which subjects were asked to grade 39 typical, frequently eaten Chinese foods, 10 of the 39 foods were selected and divided into five groups based on their texture and frequency of being eaten by older people. In the main study, 1229 Chinese generally healthy subjects aged 55 years and above, attending routine health checks in the Check-up Centre of the First Affiliated Hospital of Guangxi Medical University, Nanning of Guangxi province, China were interviewed to psychometrically test the index. Content, face and criterion validity, coefficients of reproducibility and scalability and test-retest reliability were tested. For criterion validity, the index was significantly associated with three other established eating difficulty measures, namely, general eating difficulty, dissatisfaction with chewing ability and oral impact on daily performances eating scores (P < 0.001 for all tests). The coefficients of reproducibility and scalability were 0.99 and 0.89, respectively. Weighted kappa for test-retest reliability was 0.89. The present results indicate that the IED is a valid and reliable measure to be used among older southern Chinese people.

Esthetic Restorative Materials and Opposing Enamel Wear

The data obtained in this study can help practitioners with selection of the appropriate restorative materials to minimize further tooth and restoration wear, which is an important consideration during treatment planning.

Relationship between number of natural teeth in older Japanese people and health related functioning

The objective was to assess the relationship between number of functional occluding natural pairs of teeth and health related functioning in older free living Japanese people using the SF-20. The participants were 107 elderly people aged 80 years. Health related functioning was measured with the SF-20. The numbers of functional occluding natural pairs of teeth (OPs) were calculated and scored as follows: 1, for each pair of anterior teeth and premolars in occlusion. Molar functional natural occluding pairs were scored 2 for each occluding pair. The number of functional occluding pairs was assessed separately as anterior natural occluding pairs (AOPs) and posterior occluding pairs (POPs). There were significant differences in the role functioning subscale of SF-20 between those who were edentulous and those with one to nine natural teeth and 10 or more natural teeth (P = 0.030). Those with one to six AOPs had significantly higher role functioning than the zero AOPs group (P = 0.042). Those with 1-12 POPs also had significantly higher role functioning scores than the zero natural POPs group (P = 0.007). However, there were no significant relationships between number of natural teeth, OPs or AOPs, and POPs on the one hand, and all other subscales of SF-20 on the other hand. The community-dwelling 80-year-old Japanese people in this study had overall good health related functioning. The number of functional occluding pairs of natural teeth, especially POPs, was related with the role functioning subscale of SF-20 but had no significant relationships to the other dimensions of SF-20.

Life-quality indicators in elderly people are influenced by selenium status

BACKGROUND AND AIMS

Selenium is of fundamental importance to human health. Our aim was to evaluate the effect of selenium (intake and serum levels) on subjective indicators of quality of life in older people, such as self-perceived health, chewing ability and physical activity.

METHODS

The sample was a cohort of 227 elderly people (93 men and 134 women) residing in 14 nursing homes in Asturias (Spain). Mean age +/- SD was 72.9+/-7.2 y and 76.4+/-5.9 y, for men and women respectively. Information was collected in personal interviews. Dietary intake was recorded by means of a food-frequency questionnaire. Selenium was determined in serum by graphite-furnace atomic absorption spectrometry.

RESULTS

Serum selenium was associated with self-perceived health, chewing ability and physical activity in this sample. Subjects in the upper tertile of serum selenium had more than twice as much probability (Odds Ratios, 2.05 to 3.157) of reporting good health status, good chewing ability and of doing more than 60 min of exercise/day.

CONCLUSIONS

The maintenance of good serum selenium levels is important, since it may affect the self-perception of health, chewing ability, or physical activity and, consequently, the quality of life in elderly people.

Chewing ability and quality of life in an 80-year-old population

As quality of life (QOL) could be influenced by oral status in the elderly, we examined whether chewing ability or number of teeth affected QOL in 80-year olds. A cross-sectional survey included dental examination, chewing self-assessment, and a QOL questionnaire. A total of 823 people who were 80 years old participated in this study. QOL was assessed in terms of satisfaction with physical condition, meals, daily living and social interactions, and with face-scale scores. After adjustment for gender, spouse and activities of daily living, dissatisfaction with social interactions was 3.9 times more prevalent in individuals able to chew four foods or fewer than in those chewing 15. Dissatisfaction with physical condition, meals and daily living, and poor face-scale scores, were 2.7, 2.4, 3.4, and 2.4 times more prevalent, respectively, in subjects chewing four foods or fewer. The number of teeth showed little effect. In conclusion, self-assessed chewing ability but not number of teeth was associated with QOL in 80-year-old subjects.

Relationship between general health status and the change in chewing ability: a longitudinal study of the frail elderly in Japan over a 3-year period

OBJECTIVES

The aim of the present study was to identify the onset predictors of a change in chewing ability over a 3-year period in the frail elderly.

METHODS

The subjects were frail elderly people living in southern Japan. Data were collected at baseline (n = 92) and 3 years later (n = 60). The dependent variable was a change in self-rated chewing ability. The independent variables were age, gender, number of present teeth, dentition, maximum bite force (evaluated using a pressure-sensitive foil), basic activities of daily living, self-rated general health status, higher level of competence (evaluated using Tokyo Metropolitan Institute of Gerontology index), cognitive status (evaluated by revised Hasegawa Dementia Rating scale), and quality of life (evaluated using Philadelphia Geriatric Center morale scale) at baseline. To identify the most reliable predictors, bivariate analysis and multiple logistic regression analysis were performed, with the change of chewing ability as the dependent variable.

RESULTS

Bivariate analysis showed the change in chewing ability was significantly associated with general health status (p < 0.01), number of present teeth (p < 0.05) and maximum bite force (p < 0.01). Backward logistic regression analysis revealed that the most reliable predictor of a change in chewing ability at 3 years was general health status (odds ratio = 6.35, 95% CI = 1.69-23.88).

CONCLUSION

The present findings suggest that general health status at baseline produces a change in chewing ability.

Relationship between Number of Present Teeth and Nutritional Intake in Institutionalized Elderly

We conducted oral examinations and dietary surveys on a total of 141 subjects with an average age of 80 years or more-specifically, seniors (S-group) living in a health service facility for the elderly and patients with mild dementia (SD-group) living in a special nursing home for the elderly. All were assumed to have a roughly uniform diet. We investigated which factors contributed to their dietary intake, and the relationship between dietary intake and number of present teeth (PT). Factors affecting total energy of the subjects and those in the S-group were body weight and number of PT. No factors were recognized as having a relationship with total energy in the SD-group. A significant difference was found in males in the S-group in that those in the "five PT or more" group had higher levels of carbohydrates and vitamin B1) than those in the "four PT or less" group. However, significant differences were found in the SD-group in that subjects in the "five PT or more" group had higher levels of carbohydrates, calcium, iron, and vitamins A, B1, B2, and C than those in the "four PT or less" group. Significant differences were seen in both groups for female patients in the nursing home with regard to total energy, proteins, carbohydrates, iron, vitamin B1, and fiber intake. No significant differences were recognized, however, for females in the SD-group. Reductions in dietary intake should be considered from the perspective of nutritional status, which is a problem that can be resolved through dental treatment. This study found that recovery of chewing ability in seniors was essential not only to maintain nutritional status, but also to fully bring out all the functions of the foods themselves.

Percentile Curves for Food Acceptance Response Scores in Assessing Chewing Functions in Adults

The purpose of this study was to evaluate whether percentile curves for food acceptance response scores were useful in assessing oral and occlusal conditions. We used data obtained from Chiba City Patient Surveys (males: 1,276, females: 1,381, aged 20 to 64), which were conducted in 1998 and 1999. Subjects were assigned scores of between 1 and 4 for 31 different kinds of food based on their food acceptance responses. Occlusal conditions were measured with pressure-sensitive sheets. We calculated the percentile values from 5 to 95 at intervals of five years. We divided the subjects into two groups at the twenty-fifth percentile and statistically analyzed various oral conditions in the two groups. Significant differences were found between them in the mean numbers of present, sound, and missing teeth for almost all age groups. Moreover, there were significant differences in tooth-contact area and occlusal force between the two groups. The results of multiple regression analysis revealed that the scores had a stronger correlation with occlusal conditions than number of teeth in 55-year-olds, although the effect teeth-factors had on scores was more significant in 45- to 50-year-old males. Females' scores had a stronger correlation with occlusal conditions than number of teeth in all age groups. These results indicate that the questionnaire on the acceptance of 31 different kinds of food is useful in providing a basis for oral health instruction and dental treatment aimed at improving chewing ability in adults.

Reducing within-subject variation in chewing cycle kinematics—a statistical approach

OBJECTIVES

High levels of within-subject variability have limited the use of chewing cycle kinematics in the experimental and clinical context. The purpose of this study was to validate a new strategy for reducing within-subject variability in chewing cycle kinematics, based on the 10 most representative cycles from a chewing sequence.

METHODS

This prospective study included 25 young subjects, with normal class I occlusions. An optoelectronic recording system was used to track chin movements of subjects chewing gum (2.5 g). Computer programs provided estimates for duration and movement as well as the 3D coordinates of the chin point. The total output files were further processed for selection of 10 representative cycles based on standard scores for total duration, excursive ranges in the lateral, vertical and antero-posterior directions. Multilevel modelling procedures were used to test for significant differences.

RESULTS

There were no significant differences in cycle duration or excursions between the estimates for all cycles versus the 10 most representative cycles. Cycle shapes were very similar. There were no statistically significant differences in between-subject variances. All within-subject variances were smaller when using data from the 10 most representative cycles. The reduction of variance was approximately 33% for total duration and 75% for total 3D excursion.

CONCLUSIONS

The results validate the pre-processing strategy that selects the 10 most representative cycles from a sequence without altering cycle duration, excursions or shape or affecting between-subject variation but reducing within-subject variation substantially.

Masticatory performance in 80-year-old individuals

OBJECTIVE

To evaluate the masticatory performance of elderly people at the age of 80 years.

SUBJECTS

A total of 283 individuals of 80 years of age took part in a general and dental health survey.

MAIN OUTCOME MEASURES

A dental examination including the number of remaining teeth, occlusion, prostheses, bite force recording, and a questionnaire regarding masticatory performance were recorded.

SETTING

Five municipalities (Okazaki city, Tokoname city, Tahara town, Atsumi town and Minami-chita town) in Aichi prefecture, Japan.

RESULTS

There were 20 or more teeth in 7.4% subjects, and 44.5% were edentulous. Subjects with no occlusion accounted for 77.4% of the total. Subjects with prostheses accounted for 90.8%. Maximum bite force and masticatory ability score for patients with 20 or more teeth or not wearing prostheses were higher than other groups. The non-wearing prostheses group had a low masticatory ability score.

CONCLUSION

Most of the 80-year-old individuals recovered their masticatory ability with the assistance of prostheses. Several individuals with 20 or more remaining teeth or without removable dentures present in both jaws had a high score for bite forces and masticatory abilities.

Masticatory ability in 80-year-old subjects and its relation to intake of energy, nutrients and food items

OBJECTIVE

The aim of the present study was to analyse the relationship between masticatory ability (self-assessed masticatory ability and bite force) and intake of energy, nutrients and food items in a population sample of elderly subjects.

DESIGN AND SUBJECTS

From a population sample of 80-year-old people, 160 individuals (74 men and 86 women) took part in an odontological study.

MAIN OUTCOME MEASURES

A dental examination including bite force recording, a questionnaire focusing on self-assessed masticatory ability, and a dietary interview.

SETTING

Department of Geriatric Medicine, Göteborg University, Sweden.

RESULTS

The dental status among the participants varied much (from edentulous in both jaws--22%--to more than 20 natural teeth--30%). The mean maximum bite force was higher in men (165 N) than in women (105 N). Bite force was significantly correlated to the Eichner index and to the number of teeth. One third of the subjects reported no masticatory problem, whereas 18% identified > or = 3 such problems. The intake of energy and nutrients varied much but the means were well above recommended values. The correlations between dental status and bite force on one side and dietary intake on the other side were in general weak and most often statistically non-significant. Impaired general health and reduced dentition were both associated with more masticatory problems.

CONCLUSION

The examined sample of 80-year-old subjects had a great variation in dental status, bite force and self-assessed masticatory ability, but these factors had only a minor influence on dietary selection and intake, which on average were well above recommended values.