Lower Masticatory Performance Is a Risk for the Development of the Metabolic Syndrome: The Suita Study

Regular Smoking Accelerates the Decline in Masticatory Performance in Japanese Men: The Suita Study

BACKGROUND

Smoking is presumed to cause a decline in masticatory performance by worsening the intraoral environment in various ways. However, no longitudinal study has examined the relationship between smoking and masticatory performance.

OBJECTIVES

To clarify how smoking affects future decline in masticatory performance through a 5-year follow-up study of a general urban population.

METHODS

The study participants were 494 men (mean age at baseline: 65.8 years) who participated in baseline and follow-up dental examinations in the Suita Study. The masticatory performance of the participants was evaluated using a test gummy jelly. The rate of change in masticatory performance during the follow-up period was calculated by subtracting the masticatory performance at baseline from the masticatory performance at follow-up and dividing this by the masticatory performance at baseline. Logistic regression analysis was performed, with the presence or absence of a decline in masticatory performance as the objective variable and age at baseline, number of functional teeth, periodontal status, salivary flow rate, maximum bite force, smoking status, utilisation of dental services, and follow-up years as the explanatory variables.

RESULTS

The rate of change in masticatory performance during the follow-up period was significantly higher in smokers than in non-smokers. Logistic regression analysis showed that age, maximum bite force, and smoking were significant explanatory variables for a decline in masticatory performance.

CONCLUSION

A 5-year follow-up study showed that smoking causes a decline in masticatory performance in men, even after adjusting for confounding factors.

Chewing habits and masticatory performance are associated with obesity in 9- to 10-year-old children: A cross-sectional study from the Osaka MELON Study

OBJECTIVES

This study aimed to examine the relationships of masticatory performance and chewing habits with obesity in Japanese elementary school children.

METHODS

The participants were 1,403 children aged 9-10 years in Osaka City. Chewing habits were assessed via questionnaires, and masticatory performance was measured using a color-changeable chewing gum. Obesity was determined by the percentage of overweight based on height and weight. Multivariate logistic regression analyses were conducted to calculate odds ratios for obesity, using chewing habits and masticatory performance as explanatory variables, adjusted for sex, DMFT index, and Hellman dental developmental stage.

RESULTS

Logistic regression analysis showed significant associations between obesity and sex, eating fast, and lower masticatory performance in all participants (OR=1.54, 1.73, 1.50; 95 %CI=1.08-2.17, 1.23-2.44, 1.05-2.15, respectively). In boys, eating fast, eating with mouth full, and lower masticatory performance were significantly associated with obesity (OR=1.84, 1.59, 1.63; 95 %CI=1.16-2.92, 1.03-2.46, 1.02-2.59, respectively). No variable was significantly associated in girls. When eating fast and lower masticatory performance were combined, it was significantly associated with obesity, with the strongest odds ratio observed in boys exhibiting both behaviors (OR=3.00, 95 %CI=1.49-6.07).

CONCLUSIONS

In 9- to 10-year-old children, eating fast, eating with mouth full, and lower masticatory performance were linked to obesity, particularly in boys. Furthermore, the association with obesity was higher when eating fast and lower masticatory performance were combined.

CLINICAL SIGNIFICANCE

To prevent obesity in schoolchildren, approaching the problem not only from the habitual aspect of eating fast, but also from the functional aspect of lower masticatory performance is necessary.

Elucidation of Factors Affecting Anterior Occlusion in Primary Dentition Based on the Japan Environment and Children's Study

Background/Objectives: Malocclusion in primary dentition affects permanent dentition. However, the factors contributing to malocclusion in the oral cavities of children have not been fully elucidated. We hypothesized that environmental factors affect malocclusion in the primary dentition of the Japanese population and aimed to identify factors associated with anterior occlusion in primary dentition. Methods: The study involved 3793 parent-child pairs from the Miyagi Regional Centre as part of a supplementary survey to the Japan Environment and Children's Study, a cohort study. A questionnaire assessing oral development and environmental factors was administered to parent-child pairs who consented to participate. Parents assessed anterior occlusion when their children were 3.5 years old. Results: The maxillary primary central incisors tended to erupt earlier in the open bite group. Significantly more children in this group were breastfed until 1 year and drank ionic beverages at 1.5 years. In addition, thumb sucking or pacifier use was significantly common at 2 years of age. A correlation was observed between the mother's body mass index (BMI) before and after pregnancy and anterior occlusion. Conclusions: In the open bite group, the occlusion status of the anterior teeth at 3.5 years of age showed distinctive results influenced by the eruption period of the primary anterior teeth, oral habits, intake of sweetened beverages, and maternal BMI. These findings suggest that parental observation could be useful for screening children for malocclusion until the eruption of permanent dentition.

Chewing Well Modulates Pharyngeal Bolus Transit During Swallowing in Healthy Participants

Mastication is controlled by central pattern generator in the brainstem and can be modulated by volition. The aim of this study was to investigate the effect of chewing well on swallowing. Twenty-six healthy participants were instructed to eat 8, 12, and/or 16 g of steamed rice with barium sulphate under the following two conditions: chewing freely task (CF; chewing naturally in their usual manner) and chewing well task (CW; chewing the food with a request to "chew well"). We evaluated bolus transport and swallowing movement using videofluoroscopy and electromyography of the masseter, suprahyoid and thyrohyoid muscles. The chewing time and pharyngeal transit time (PTT) at the first swallow showed high reproducibility in both CF and CW. PTT for CW was significantly shorter and longer than CF in 12 and 16 g, respectively. In 12 g, CW increased the pharyngeal bolus velocity and decreased thyrohyoid EMG activity during swallowing compared with CF. In 16 g, the difference between CW and CF in the estimated swallowed bolus volume was positively correlated with that in upper esophageal sphincter transit duration. We speculate that CW modulates PTT during swallowing depending on the mouthful volume.

Impact of Masticatory Performance and the Tongue-Lip Motor Function on Incident Adverse Health Events in Patients with Metabolic Disease

AIM

The present study aimed to determine whether decreased masticatory performance and tongue-lip motor function are associated with an increased incidence of adverse health events in patients with metabolic disease.

METHODS

One thousand patients with metabolic diseases including diabetes, dyslipidemia, hypertension, and hyperuricemia were recruited. Masticatory performance was assessed using a gummy jelly test, wherein glucose elution from chewed gummy jelly was measured. The tongue-lip motor function was measured using repeatedly pronounced syllables per second. Their association with the incidence of adverse health events (a composite of all-cause death, cardiovascular disease, bone fracture, malignant neoplasm, pneumonia, and dementia) was investigated using the generalized propensity score (GPS) method.

RESULTS

During a median follow-up period of 36.6 (interquartile range, 35.0-37.7) months, adverse health events were observed in 191 patients. The GPS adjusted dose-response function demonstrated that masticatory performance was inversely associated with the incidence of adverse health events. The 3-year incidence rate was 22.8% (95% confidence interval, 19.0-26.4%) for the lower quartile versus 13.6% (10.5-16.7%) for the upper quartile (P＜0.001). Similarly, the tongue-lip motor function was inversely associated with the incidence of adverse health events, with a 3-year incidence rate of 23.6% (20.0-27.0%) for the lower quartile versus 13.2% (10.4-15.9%) for the upper quartile (P＜0.001).

CONCLUSIONS

Decreased masticatory performance and tongue-lip motor function were associated with an increased incidence of adverse health events in patients with metabolic disease.

Factors related to subjective evaluation of difficulty in chewing among community-dwelling older adults

AIM

Awareness of difficulty chewing may limit the diversity of food intake in older adults. However, few studies have clarified which factors are related to subjective difficulty in chewing. The aim was to identify factors related to subjective difficulty in chewing in 70- and 80-year-old Japanese older adults.

METHODS

A total of 1680 participants (792 men, 888 women) were surveyed. Difficulty in chewing was assessed with questionnaires regarding food intake, such as rice, apples, beef, and hard rice crackers. The participants were classified into two groups, the "with difficulty" group (participants who answered "cannot eat," "can eat with difficulty," and "can eat if small") and the "without difficulty" group (participants who answered "can eat without problems"), according to their answers to questionnaires for each food. A logistic regression analysis with subjective difficulty in chewing as the dependent variable was performed for each food.

RESULTS

Subjective difficulty in chewing was associated with age, occlusal force, and depression for rice; age, number of remaining teeth, occlusal force, and depression for apples; number of remaining teeth, occlusal force, and depression for beef; and number of remaining teeth and occlusal force for hard rice crackers.

CONCLUSIONS

Age, number of remaining teeth, and occlusal force, as well as depression, might be related to subjective evaluation of difficulty chewing in community-dwelling Japanese older adults. Geriatr Gerontol Int 2024; 24: 327-333.

Changes in masticatory performance and the new onset of diabetes mellitus in older adults: a 5-year longitudinal study

Objective

Although masticatory performance is affected by age-related reduction in number of teeth (or treatment), the relationship between longitudinal changes in masticatory performance and diabetes mellitus is unknown. This longitudinal study investigated the association between changes in masticatory performance and new-onset diabetes mellitus among community-dwelling Japanese older adults.

Methods

The data of 214 older adults living in Ohnan Town, Shimane, Japan, who participated in two surveys conducted between 2012 and 2017 were analyzed. Diabetes mellitus was defined as a hemoglobin A1c level ≥ 6.5% or self-reported diabetes mellitus. The masticatory performance (measured by number of gummy jelly pieces collected after chewing) was evaluated by dental hygienists. Masticatory performance was categorized into two groups (high or low) based on the median in each survey; further, four groups (Group A: remained consistently high, Group B: changed from low to high, Group C: remained consistently low, Group D: changed from high to low) were used to determine longitudinal changes in masticatory performance. Logistic regression was used to analyze the association between changes in masticatory performance and new-onset diabetes mellitus.

Results

Overall, 10.3% of participants had diabetes mellitus at the follow-up survey. Multivariate analysis showed that Group D (odds ratio 8.69, 95% confidence interval 1.98-38.22) was positively associated with the development of diabetes mellitus compared with Group A after adjusting for sex, age, body mass index, alcohol consumption, physical activity, and eating speed.

Conclusions

Deteriorating masticatory performance for 5 years may cause diabetes mellitus among older adults.

Maria MT, Marito P, Takano H, Khaing AMM, Nokubi T, Ono T. Masticatory Performance Test Using a Gummy Jelly for Older People with Low Masticatory Ability

Evaluation of masticatory ability has become more important in an aging society because decreased masticatory ability has the potential to affect the general health of older people. A new masticatory performance test, intended for older people with low masticatory ability, has been developed using gummy jelly half the size of that used in the conventional masticatory performance test. This study aimed to investigate the compatibility between the new and conventional tests and the adaptation of the new test. The new test using the 8-grade visual score with half-size gummy jelly was performed among 137 removable denture wearers (mean age 75.8 ± 9.0 years) with low masticatory performance (a score of ≤4 on a conventional test). The correlation between the scores of half-size gummy jelly (VS-H) in the new test and those of full-size gummy jelly (VS) in the conventional test was evaluated. VS-H among the groups divided by VS were also compared. A strong positive correlation was detected between VS-H and VS (r_s = 0.70). In groups with VS of 0 and 1, VS-H values were widely distributed from 0 to 7. There were significant differences in VS-H between the groups with VS of 0-2 but no significant differences in VS-H between the groups with VS of 2-4. Therefore, the masticatory performance test using half-size gummy jelly is suitable for a detailed evaluation of masticatory ability in older people with low masticatory ability when their visual score of full-size gummy jelly in the conventional test is 2 or less.

Association of self-rated chewing function and oral health status with metabolic syndrome

PURPOSE

The study aimed to examine the association of self-rated chewing function, the number of teeth and periodontal status with metabolic syndrome.

METHODS

The participants were 11,119 adults aged 40-74 years who underwent specific health checkups, including an oral health examination, in 2018 in Japan. This study used the standard questions of the specific health checkups to obtain information on self-rated chewing function. A multinomial logistic regression analysis was performed with metabolic syndrome status as the dependent variable, and age, sex, lifestyle questions, self-rated chewing function, number of teeth, and periodontal status as the independent variables.

RESULTS

Number of teeth and periodontal status were significantly associated with metabolic syndrome after adjusting for confounding variables. Self-rated chewing function was significantly associated with metabolic syndrome in the crude analysis, but not after adjustment for confounding variables. Both number of teeth and periodontal status were significantly associated with self-rated chewing function.

CONCLUSION

There was no significant direct association between self-rated chewing function and metabolic syndrome. Self-rated chewing function may be an indicator of poor oral condition that links to metabolic syndrome.

Tooth Loss Related with Prevalence of Metabolic Syndrome in a General Urban Japanese Population: The Suita Study

We examined whether the number of teeth could be a surrogate marker for metabolic syndrome (MetS) risk in cross-section. A total of 3771 individuals from the general urban Japanese population (1690 men, 2081 women; mean age 67.1 ± 11.0 years) participated in this study. Participants were diagnosed with MetS with three or more components hypertension, hyperglycemia, lipid metabolism abnormality, and abnormal abdominal girth. Questionnaires were administered to determine the number of teeth, smoking status, drinking status, and past illnesses. To clarify the relationships between the number of teeth and the presence of MetS components, we divided subjects into two groups: those with less than 20 residual teeth and those with 20 or more, then statistical analyses (Mantel-Haenszel tests and logistic regression analysis) were performed. MetS were higher for those with ≤19 teeth than those with ≥20 teeth when examining all participants and women-only groups. Hyperglycemia, low HDL cholesterol, high triglycerides, and diagnosis with MetS were all significantly higher in the ≤19 teeth group for both sexes combined and for women. These results suggest that less than 20 teeth may be a surrogate marker for MetS risk, but further studies on gender differences and pathological background are needed.

The Association of Dietary Intake, Oral Health, and Blood Pressure in Older Adults: A Cross-Sectional Observational Study

Hypertension is related to impaired mastication that causes malnutrition, declining the general health of older adults. This study assessed the role of dietary intake in the relationship between oral health and blood pressure. Eight hundred ninety-four adults aged ≥65 years who independently lived in rural regions of Japan participated in this study. Hypertension was classified according to the guidelines of the Japanese Society of Hypertension. The oral condition was evaluated by analyzing the remaining teeth, occlusal force, posterior occlusal support, masticatory performance, oral moisture, and oral bacterial level. Dietary intake was assessed using a brief self-administered dietary history questionnaire. Mann-Whitney U, chi-square, Kruskal-Wallis tests, and logistic regression analyses were used to elucidate the factors related to hypertension. Normotensive, hypertensive, and history of hypertension were observed in 30.9%, 23.8%, and 45.3% of the participants, respectively. The factors significantly associated with the hypertension were age, body mass index, posterior occlusal support condition, and sodium-to-potassium ratio related to salt intake and/or vegetable intake. Participants without posterior occlusion significantly had higher risk of hypertension (odds ratio = 1.72). This study suggested that there was an association between oral health and hypertension, while the loss of occlusal support may influence nutritional intake conditions.

Association of occlusal support with type 2 diabetes: A community-based study

Occlusal support was proved to be associated with type 2 diabetes. Our aim was to investigate the association between the Eichner index and the prevalence of type 2 diabetes. We included 715 participants with oral health examinations in the Shanghai Aging Study. The occlusal support status was determined by the number of functional occlusal support areas and Eichner index classifications. Those with fasting plasma glucose ≥126 mg/dL and/or hemoglobin A1c ≥6.5% and/or current medications for type 2 diabetes with relevant medical history were diagnosed with type 2 diabetes. Multiple logistic regression models were used to analyze the relationship between occlusal support status and type 2 diabetes. The average age of 715 participants was 73.74 ± 6.49 years old. There were 84 diabetics with 1.71 occlusal supporting areas on average. Seven hundred and fifteen participants were divided into 3 groups according to Eichner classifications: Eichner group A with 4 occlusal functional areas, Eichner group B with 1-3 occlusal functional areas or 0 area with anterior occlusal contact, and Eichner group C with no functional occlusal contact. Blood glucose level was significantly lower in participants of Eichner group A compared to those in group B or C. The ordinal logistic regression showed more occlusal supporting areas were significantly associated with less type 2 diabetes cases with an Odds Ratio(OR) of 0.253(95%CI 0.108-0.594) after adjusting covariates. Participants in Eichner group A had a significantly much lower OR of 0.078 for type 2 diabetes (95%CI 0.009-0.694) compared to those in Eichner group C after adjustment. The number of functional occlusal support areas might be inversely related to the blood glucose level and the prevalence of type 2 diabetes.