Relationship between Body Fat and Masticatory Function

Neuromuscular control of masticatory muscles in people with intellectual disability, middle-aged adults and older adults

BACKGROUND

Motor control issues are common for people with intellectual disabilities (PWID), resulting in difficulties with basic activities of daily living, including eating. Mastication, which is crucial for digestion and overall health, is poorly understood in this population. PWID shows frailty similar to older people, highlighting the importance of comparing masticatory motor control with older adults. This study compared the neuromuscular control of the masticatory muscles in middle-aged, PWID and older adults.

METHODS

A cross-sectional analytical design was used. During the mastication task of a carrot piece (2 cm in diameter and weighing 0.5 g), surface electromyography was used to record muscle activity patterns from the right and left masseter and temporalis muscles. Principal component analysis (PCA) was used to assess neuromuscular control. A z-score normalisation of the first component's variance from PCA to identify those individuals with altered neuromuscular control. A mixed ANOVA was performed to assess the interaction between principal components, groups and body composition.

RESULTS

Thirty PWIDs (aged 35-55 years), middle-aged adults and 32 older adults were recruited. PWID and older adults showed decreased neuromuscular control of the masticatory muscles compared to middle-aged control adults (P < 0.05). PWID had the highest proportion of individuals with altered neuromuscular control of the masticatory muscle (53%) compared to older adults (19%) and middle-aged adults (0%) (P < 0.05).

CONCLUSIONS

Our results indicate that PWID and older adults have reduced neuromuscular control compared to middle-aged adults. Notably, a significant proportion of the PWID showed altered masticatory muscle control compared to older adults. Further research is needed to explore the potential benefits of masticatory muscle training for PWID.

Chewing and its influence on swallowing, gastrointestinal and nutrition-related factors: a systematic review

The study aimed to evaluate the hypothesis that chewing is a mechanical and physiological contributor to swallowing, physiologic/pathologic processes of the gastrointestinal tract (GIT), and nutrition-related factors. A search strategy was applied to three different databases to investigate if chewing function in adults affects the swallowing, physiologic/pathologic processes of the GIT, and nutrition-related factors compared to controls with no exposure. The included studies were evaluated for methodological quality and risk of bias and certainty of evidence. The results showed 71 eligible studies. Overall, the results showed that 46 studies supported the hypothesis while 25 refuted it. However, the GRADE analysis showed low to very low certainty of the evidence to support the hypothesis that chewing is an important contributor in the swallowing process, and physiologic/pathologic processes in the GIT. The GRADE analysis also showed a moderate to very low certainty of the evidence to suggest that chewing function contributes to nutrition-related parameters. The overall results of the current study showed that a majority (64.7%) of the studies (46 out of 71) supported the hypothesis. However, robust studies with proper design, adequate sample size, and well-defined outcome parameters are needed to establish conclusive evidence.

The association between masticatory ability and lower Timed Up & Go Test performance among community-dwelling Japanese aging men and women: The Toon Health Study

Objectives

Few studies examined the association between deterioration of masticatory ability assessed by objective marker and physical function. Therefore, we examined the association between salivary flow rate which is one of the objective and surrogate marker of masticatory ability and lower Timed Up & Go (TUG) performance which is one of major measurement of physical function among aging Japanese.

Methods

This cross-sectional study enrolled 464 Japanese aged 60-84 years old. Participants chewed tasteless and odorless gum for 5 min, calculated stimulated salivary flow rate (g/min) during all chews. The 3 m TUG was conducted, and 75th percentile value (6.8 s for men and 7.0 s for women) or higher was defined as lower TUG performance. Logistic regression analysis was used to examine the association between stimulated salivary flow rate and lower TUG performance.

Results

We found that the stimulated salivary flow rate tended to be negatively associated with the TUG time. We also observed significant negative association between stimulated salivary flow rate and lower TUG performance; the multivariable-adjusted OR (95% confidence interval, CIs) of lower TUG performance for the highest quartile of stimulated salivary flow rate compared with the lowest quartile was 0.34 (0.16-0.69, P for trend = 0.02). Further adjusting for BMI, the association was attenuated but remaind significant; the OR (95% CIs) in highest quartile was 0.37 (0.18-0.76, P for trend = 0.04).

Conclusions

Higher stimulated salivary flow, which means well masticatory ability, was inversely associated with lower TUG performance in the aging Japanese population.

The impact of poor dental status and removable dental prosthesis quality on body composition, masticatory performance and oral health-related quality of life: a cross-sectional study in older adults

Background

To determine the impact of dental status, types, and quality of dental prostheses on body composition, masticatory performance and oral health-related quality of life (OHRQoL). Potential associations between body composition, masticatory performance and OHRQoL were also investigated.

Methods

This cross-sectional study included 110 older adults who received prosthodontic treatment at the Dental Faculty Clinics at Chulalongkorn University. Participants were categorized according to their dental prostheses: complete denture (CD), removable partial denture (RPD) and fixed partial denture (FPD). Retention and stability of the RPD and CD were evaluated using the CU-modified Kapur and the modified NHANES III criteria to classify denture quality into acceptable and unacceptable. Dental status including posterior occluding pairs and number of remaining natural teeth were assessed intraorally. Dependent variables were body composition, masticatory performance and OHRQoL. Body composition, including muscle mass (kg), bone mass (kg), basal metabolic rate (kcal) and visceral fat (%) were determined through a bioelectrical impedance analysis. Masticatory performance was assessed using a multiple sieve method of peanut mastication. OHRQoL was assessed using the validated Thai version of Oral Impacts on Daily Performances (Thai-OIDP) index. After adjusting for covariates, including age and sex, the associations between oral and dental prosthesis status and body composition, masticatory performance as well as OIDP score were analyzed using multivariable linear and negative binomial regression analyses. Spearman’s correlation was used to determine the potential associations between body composition, masticatory performance and OHRQoL.

Results

The presence of fewer natural teeth or wearing an unacceptable removable denture were factors associated with lower bone mass, muscle mass and basal metabolic rate, and with a higher visceral fat. Similar dental and removable denture status were also associated with larger peanut particle size and higher OIDP score. Masticatory performance and OHRQoL variables were moderately correlated (Spearman's rho = 0.44). However, body composition was not correlated with masticatory performance or OHRQoL.

Conclusions

In individuals wearing dental prostheses, factors such as severity of tooth loss, types, and quality of dental prostheses, particularly retention and stability, negatively impacted not only masticatory function and OHRQoL, but also their overall body composition and health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02103-7.

Evaluation of Stomatognathic System Parameters After Bariatric Surgery

PURPOSE

The present study aimed to evaluate electromyographic activity, bite strength, and masticatory muscle thickness in women without obesity and with severe obesity elected for bariatric surgery. Also, patients with obesity underwent bariatric surgery and were re-evaluated 3 and 6 months after surgery to analyze the influence of bariatric surgery outcomes on the stomatognathic system, a functional anatomical system comprising teeth, jaw, and associated soft tissues.

MATERIAL AND METHODS

Thirty-seven women were enrolled in the study. Twenty-one women with class II and III obesity according to the body mass index (BMI) and eligible for bariatric surgery composed the obesity pre-surgery group (Ob). Sixteen women with a normal weight according to BMI composed the non-obesity group (NOb). Afterward, the patients from the Ob group were followed up for 3 and 6 months after undergoing Roux-en-Y gastric bypass. Anthropometry, body composition, and parameters of the stomatognathic system were evaluated.

RESULTS

The stomatognathic system of the Ob group had less muscle activity and bite strength, but the thickness of masseter and temporal muscles was larger than the NOb group. We also observed a significant change in the muscular activity and bit strength of the stomatognathic system post-bariatric surgery.

CONCLUSION

Evaluating the stomatognathic system indicated that women with clinically severe obesity have less masticatory efficiency than non-obese. Also, we found a positive influence of bariatric surgery in masticatory activity after 3 and 6 months. Thus, monitoring the parameters of the stomatognathic system could be important in the indication and outcomes of bariatric surgery.

Poor Masticatory Capacity and Blood Biomarkers of Elevated Cardiovascular Disease Risk in the Community: The Paris Prospective Study III

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Masticatory rhythm 3 months after treatment with unilateral implant-supported fixed partial prosthesis: A clinical study

STATEMENT OF PROBLEM

Whether treatment with an implant-supported fixed partial prosthesis (ISFPP) affects the masticatory rhythm in patients with unilateral posterior missing teeth is unclear.

PURPOSE

The purpose of this prospective clinical study was to determine the change in masticatory rhythm in participants with unilateral posterior missing teeth 3 months after treatment with an ISFPP and to assess whether treatment influenced the stability of the masticatory rhythm.

MATERIAL AND METHODS

Thirty participants (mean age 59 years; 17 women) with unilateral posterior missing teeth were treated with 1-, 2-, or 3-unit ISFPPs. Ten healthy individuals (mean age 36 years; 8 women) with a complete natural dentition were included in a control group. In this prospective study, each participant performed 3 masticatory assays (freestyle, unilateral right, and unilateral left) at baseline and at the 3-month follow-up. Each assay comprised 5 trials of 20 cycles masticating pieces of silicone placed in a latex bag. The time needed to complete the 20 masticatory cycles per trial was measured, and the mean masticatory frequency was calculated for each assay. Coefficients of variation were then calculated from the 5 mean values of the masticatory trials. Differences in the data at 3 months and baseline were analyzed by using the Wilcoxon or paired t tests. The control and treated groups were compared by analysis of variance or Mann-Whitney U tests (α=.05).

RESULTS

After 3 months, participants treated with ISFPPs showed an increase of 8.7% in masticatory frequency during freestyle mastication (P<.001) and an 8.0% increase during unilateral mastication on the treated side (P<.01). At baseline, the coefficient of variation of masticatory frequency on the treated side was higher in the ISFPP group than in the control group during unilateral mastication (P=.033). Three months after treatment, there was a significant reduction in the coefficient of variation during unilateral mastication on the treated side of the ISFPP group (P<.001). The treatment group also reached a masticatory frequency similar to that of the control group (75 and 78 cycles per minute, respectively).

CONCLUSIONS

Treatment with ISFPPs accelerated the masticatory rhythm of individuals with unilateral posterior missing teeth, who achieve similar rhythms to those with complete natural dentitions. The stability of the masticatory rhythm was also restored, indicating an improvement in masticatory function.

The influence of malocclusion, sucking habits and dental caries in the masticatory function of preschool children

The aim of this study was to evaluate the association of malocclusion, nutritive and non-nutritive sucking habits and dental caries in the masticatory function of preschool children. A cross-sectional study was conducted with a sample of 384 children aged 3-5 years. A single examiner calibrated for oral clinical examinations performed all the evaluations (kappa > 0.82). Presence of malocclusion was recorded using Foster and Hamilton criteria. The number of masticatory units and of posterior teeth cavitated by dental caries was also recorded. The parents answered a questionnaire in the form of an interview, addressing questions about the child's nutritive and non-nutritive sucking habits. The masticatory function was evaluated using Optocal test material, and was based on the median particle size in the masticatory performance, on the swallowing threshold, and on the number of masticatory cycles during the swallowing threshold. Data analysis involved simple and multiple linear regression analyses, and the confidence level adopted was 95%. The sample consisted of 206 children in the malocclusion group and 178 in the non-malocclusion group. In the multiple regression analysis, the masticatory performance was associated with age (p = 0.025), bottle feeding (p = 0.004), presence of malocclusion (p = 0.048) and number of cavitated posterior teeth (p = 0.030). The swallowing threshold was associated with age (p = 0.025), bottle feeding (p = 0.001) and posterior malocclusion (p = 0.017). The number of masticatory cycles during the swallowing threshold was associated with the number of cavitated posterior teeth (p = 0.001). In conclusion, posterior malocclusion, bottle feeding and dental caries may interfere in the masticatory function of preschool children.

Nutritional status and masticatory function of the indigenous compared with non-indigenous people of Nayarit, Mexico

OBJECTIVE

The objective of this study was to compare the nutritional statuses and masticatory function of the non-indigenous and indigenous adult people of the state of Nayarit, Mexico.

DESIGN

Forty-two indigenous (Cora or Huichol ethnic group) and 100 non-indigenous people, all adults with natural dentition, participated in this cross-sectional study. They performed a free-style masticatory test consisting five trials of chewing silicon pieces for 20 cycles. Masticatory performance was determined by sieving the silicon particles, masticatory laterality was determined by calculating the asymmetry index, and the cycle duration was also recorded. Weight and body fat mass were measured using a portable digital weighing machine and height and body circumferences were recorded to calculate the body mass index (BMI), body fat percentage, and the waist-hip ratio. Each aspect of masticatory function and each nutritional variable were compared using T-test, analysis of variance, and Kruskal-Wallis or Mann-Whitney tests, as appropriate.

RESULTS

Body fat percentage, BMI, and waist-hip ratio were higher (P < 0.0005) in the indigenous group compared to the non-indigenous. The indigenous group had a significantly shorter stature than the non-indigenous group. Cora group had a higher BMI and higher percentage of body fat than the Huichol group (P < 0.05). No significant differences were detected between the groups for any aspect of masticatory function.

CONCLUSIONS

Indigenous people from the Nayarit, especially the Cora ethnic group, are more obese, have more total body fat, and more abdominal fat than non-indigenous people. Indigenous people show similar masticatory function.

Effect of chewing rate on meal intake

Fast eating has been shown to increase the risk of overweight in both children and adults. The objectives of the present study were to investigate the correlation between chewing rate and the number of chews per mouthful and to evaluate if they were associated with the weight of meal intake. Thirty healthy subjects, aged 18-24 yr, ate a test lunch at their habitual speed until they felt satiated. The activities of masseter and suprahyoid muscles were recorded to determine the number of chews and the moment of swallowing. The weight of meal intake was recorded along with body mass index (BMI), chewing rate, number of chews per mouthful, meal duration, ingestion rate, hunger, and food preference levels. The mean weight (±SD) of meal intake, chewing rate, and number of chews per mouthful were 261.4 ± 78.9 g, 94.4 ± 13.5 chews min^-1 , 19.2 ± 6.4 chews per mouthful, respectively. Chewing rate was not correlated with the number of chews per mouthful. The multivariable linear regression showed that meal intake was significantly positively associated with chewing rate, meal duration, and BMI, but inversely associated with the number of chews per mouthful (adjusted R² = 0.42). It was concluded that the number of chews was not associated with chewing rate but meal intake was explained by both reduced number of chews and increased chewing rate.

Association of mastication and factors affecting masticatory function with obesity in adults: a systematic review

Background

A substantial number of adults suffer from obesity, that is caused by the risk factor, masticatory dysfunction. The association between mastication and obesity, however, is inconclusive. This systematic review aims to provide literature regarding the association between mastication and factors affecting masticatory function, and obesity in adults.

Methods

Four electronic databases (PubMed, EMBASE, Cochrane Library, and Web of Science) were used to search for publications that met the following criteria: published between 2007 and 2016, written in English, and assessed the associations between mastication and obesity among the population aged ≥18 years. The included publications were analyzed based on the study design, main conclusions, and strength of evidence identified by the two authors who screened all the abstracts and full-text articles and, abstracted data, and performed quality assessments by using a critical appraisal tool, the Critical Appraisal Skills Programme Cohort Studies Checklists.

Results

A total of 18 articles (16 cross-sectional, 1 cohort studies, and 1 randomized controlled trial [RCT]) met our inclusion criteria and were evaluated. Poorer mastication was associated with obesity in 12 out of 16 cross-sectional studies. One cohort study showed that the obesity group displayed higher tooth loss than the normal weight group. One RCT demonstrated that gum-chewing intervention for 8 weeks significantly decreased waist circumference.

Conclusions

Most studies revealed a positive association between mastication and obesity among adults. Nonetheless, most of them are cross-sectional studies, which are insufficient to demonstrate a causal relation. Further advancement requires RCT, especially an intervention of improvement of mastication and obesity needed to confirm this association.

Electronic supplementary material

The online version of this article (10.1186/s12903-018-0525-3) contains supplementary material, which is available to authorized users.

Chewing Stimulation Reduces Appetite Ratings and Attentional Bias toward Visual Food Stimuli in Healthy-Weight Individuals

Based on the theory of incentive sensitization, the exposure to food stimuli sensitizes the brain’s reward circuits and enhances attentional bias toward food. Therefore, reducing attentional bias to food could possibly be beneficial in preventing impulsive eating. The importance of chewing has been increasingly implicated as one of the methods for reducing appetite, however, no studies to investigate the effect of chewing on attentional bias to food. In this study, we investigated whether chewing stimulation (i.e., chewing tasteless gum) reduces attentional bias to food as well as an actual feeding (i.e., ingesting a standardized meal) does. We measured reaction time, gaze direction and gaze duration to assess attentional bias toward food images in pairs of food and non-food images that were presented in a visual probe task (Experiment 1, n = 21) and/or eye-tracking task (Experiment 2, n = 20). We also measured appetite ratings using visual analog scale. In addition, we conducted a control study in which the same number of participants performed the identical tasks to Experiments 1 and 2, but the participants did not perform sham feeding with gum-chewing/actual feeding between tasks and they took a rest. Two-way ANOVA revealed that after actual feeding, subjective ratings of hunger, preoccupation with food, and desire to eat significantly decreased, whereas fullness significantly increased. Sham feeding showed the same trends, but to a lesser degree. Results of the visual probe task in Experiment 1 showed that both sham feeding and actual feeding reduced reaction time bias significantly. Eye-tracking data showed that both sham and actual feeding resulted in significant reduction in gaze direction bias, indexing initial attentional orientation. Gaze duration bias was unaffected. In both control experiments, one-way ANOVAs showed no significant differences between immediately before and after the resting state for any of the appetite ratings, reaction time bias, gaze direction bias, or gaze duration bias. In conclusion, chewing stimulation reduced subjective appetite and attentional bias to food, particularly initial attentional orientation to food. These findings suggest that chewing stimulation, even without taste, odor, or ingestion, may affect reward circuits and help prevent impulsive eating.