Relationship between body mass index and masticatory factors evaluated with a wearable device

Normative Values of the Repetitive Saliva Swallow Test and Clinical Factors Affecting the Test Scores in Healthy Adults

The Repetitive Saliva Swallow Test (RSST) is a screening test for oropharyngeal dysphagia during which the subject is asked to perform as many empty swallows as possible in 30 s. Previous validation studies found a cutoff value of 3 > swallows as pathological. The aims of this study were to establish the normative values of the RSST and to examine the effect of clinical factors on RSST scores in healthy adults. A cross-sectional study of 280 adults. An equal number of females and males were recruited for each decade of life, ages 20 to 90 years. Patients reporting swallowing difficulties, history of neurologic disorders, or head and neck surgery or radiation were excluded. Data collected included RSST scores, number and type of comorbidities, number of prescribed medications, body mass index, smoking habits, and self-assessment xerostomia questionnaire. The mean RSST score for the entire cohort was 7.01 ± 2.86. Males had a higher RSST score (7.6 ± 3.04 compared to 6.47 ± 2.56, p = 0.001). Age showed an inverse correlation with RSST scores (Pearson's Correlation Coefficient (PCC) = -0.463, p < 0.0001), as well as body mass index, BMI (PCC = -0.2, p < 0.0001), number of co-morbidities (PCC=-0.344, p < 0.0001) and number of prescribed medications (PCC= -0.425, p < 0.0001). Self-reported amount of saliva positively correlated (PCC = 1.05, p = 0.04) with RSST scores. A multivariate logistic regression analysis was performed. Age, sex, BMI, and number of prescribed medications were found as significant independent factors on RSST scores. RSST scores in healthy adults decline with age and are lower in females, individuals taking multiple medications and with higher BMI. Mean RSST for all age groups did not fall beneath the previously established pathological cut-off.

Increased Waist Circumference after One-Year Is Associated with Poor Chewing Status

BACKGROUND

This study aimed to investigate the relationship between an increase in waist circumference (WC) after 1 year and self-reported chewing status in 10,870 Japanese adults who had received health checkups. Subsequently, 8068 participants were included in the final analysis.

METHODS

We defined an increase in WC ≥ 5 cm after 1 year as an unhealthy increase; in total, 613 (7.5%) respondents met this criterion. Chewing status was evaluated using a self-reported questionnaire at baseline; 1080 (13%) respondents were diagnosed with poor chewing status.

RESULTS

After adjusting for age, gender, WC, body mass index (BMI), and chewing status, an increase in WC ≥ 5 cm was found to be positively associated with gender (females: odds ratios [ORs]: 1.206; 95% confidence intervals [CIs]: 1.008-1.443), WC (ORs: 0.967; 95% CIs: 0.954-0.981), BMI (≥25 kg/m2; ORs: 2.194; 95% CIs: 1.715-2.808), and chewing status (poor; ORs: 1.356; 95% CIs: 1.084-1.697).

CONCLUSIONS

These findings suggest that increased WC after 1 year was associated with self-reported poor chewing status in Japanese adults.

Factors Related to Masticatory Rhythm in Patients with Oral Tumors

Background: Older adults who have undergone surgery for oral tumors are at increased risk of impaired masticatory rhythm. This study investigated the correlations between masticatory rhythm, objective masticatory performance, and subjective masticatory performance as well as factors related to masticatory rhythm. Methods: The participants were 44 adults (24 men, 20 women; age range 42~90 years old) who had undergone maxillectomy, mandibulectomy, or glossectomy and were rehabilitated with a maxillofacial prosthesis. The number of functional contact teeth pairs was confirmed by intraoral examination. Chewing rate, cycle duration, coefficient of variation (CV) for cycle duration (reflecting the stability of masticatory rhythm), and mixing ability were measured simultaneously using a mastication movement rhythm tracking device during gum chewing. Maximum occlusal force was measured using the dental prescale system. Patients' perception of chewing ability was rated using a questionnaire. Results: The Spearman's rank correlation test revealed that mixing ability, patient-rated masticatory scores, cycle duration, CV for cycle duration, and maximum occlusal force showed significant correlations with chewing rate. Multiple linear regression analysis identified mixing ability and the CV for cycle duration as significant predictors of masticatory rhythm. Conclusions: Factors associated with a faster chewing rate were higher mixing ability and masticatory scores, greater maximum occlusal force, shorter cycle duration, and smaller CV for cycle duration. Stable masticatory rhythm and mixing ability are significant predictors of chewing rate. Poor masticatory performance and unstable masticatory rhythm can result in slower chewing and thus a higher risk of inadequate dietary intake.

Relationships of physical constitution with occlusal force and masticatory performance in adults with natural dentition

This study aimed to clarify whether physical constitution affects masticatory function. A total of 251 healthy adults with completely natural dentition participated in this study. Height, weight, and body mass index (BMI) were used as parameters representing physical constitution, and the amount of glucose eluted from chewed gummy jelly and maximum occlusal force was used as parameter representing masticatory function. Handgrip strength was also measured. After comparing each parameter between male and female participants, the relationship between physical constitution and masticatory function was investigated in the combined (male and female) group, the male group, and the female group. The relationship between handgrip strength and masticatory function was also investigated. Stepwise multiple linear regression analysis was performed with masticatory function as the dependent variable and physical constitution as independent variable. The mean values of each parameter were significantly greater in the male group than in the female group. Regarding the relationship between physical constitution and occlusal force, the occlusal force tended to increase as the parameter value representing physical constitution increased, and a significant correlation was observed for all parameters. For masticatory performance, a significant correlation was observed in all parameters in the combined group, but no significant correlations were observed in the male group and in the female group. Multiple linear regression analysis showed that weight was significantly associated with occlusal force. Though occlusal force may be affected by physical constitution, masticatory performance is not easily affected by physical constitution.

Chewing and Swallowing Patterns for Different Food Textures in Healthy Subjects

Aims

This study aimed to determine the patterns of chewing and swallowing in healthy subjects with different food textures.

Methods

This cross-sectional study included 75 subjects who were asked to video record themselves while chewing different food samples of varying textures, including sweet and salty food. The food samples were coco jelly, gummy jelly, biscuit, potato crisp, and roasted nuts. A texture profile analysis test was used to measure the hardness, gumminess, and chewiness of the food samples. Chewing patterns were investigated by measuring the chewing cycle prior to the first swallow (CS1), the chewing cycle until the last swallow (CS2), and the accumulation of chewing time from the first chewing to the last swallowing (STi). Swallowing patterns were evaluated by calculating the swallowing threshold, which is the chewing time/duration prior to the first swallow (STh). The number of swallows for each food sample was also recorded.

Results

There was a statistically significant difference in the CS2 of potato crisps, as well as the STi of coco jelly, gummy jelly, and biscuits between male and female subjects. A significant positive correlation was found between hardness and STh. There was a significant negative correlation between gumminess and all chewing and swallowing parameters, as well as chewiness and CS1. This study also found s significant positive correlation between dental pain, CS1, CS2, and STh of gummy jelly, as well as dental pain and CS1 of biscuits.

Conclusions

Females require longer chewing time for harder foods. Food hardness is positively related to the chewing duration prior to the first swallow (swallowing threshold/STh). Food chewiness has a negative correlation with the chewing cycle prior to the first swallow (CS1). Food gumminess is inversely related to all the chewing and swallowing parameters. Dental pain is associated with an increased chewing cycle and swallowing time of hard foods.

Masticatory Behavior Change with a Wearable Chewing Counter: A Randomized Controlled Trial

Because a relationship has been reported between masticatory behavior, obesity, and postprandial blood glucose, it is recommended to chew well and take a longer time to eat. The purpose of this study was to examine the possibility of changing masticatory behavior using a small ear-hung wearable chewing counter, which can monitor masticatory behavior without disturbing daily meals. In total, 235 healthy volunteers participated in a 4-wk randomized controlled trial and were divided into 3 groups. All participants were instructed about the importance of mastication at the first visit. During the intervention, group B used the chewing counter without an algorithm during each meal (notification of the number of chews after meal), and group C used the chewing counter with a masticatory behavior change algorithm (setting a target value and displaying the number of chews in real time). Group A was set as the control group. The number of chews and the meal time when consuming 1 rice ball (100 g) were measured before and after the intervention using the chewing counter, and the rate of change in these values was evaluated. Participants also provided a subjective evaluation of their changes in masticatory behavior. The number of chews and the meal time of 1 rice ball increased significantly in groups B and C compared with before the intervention, and the rate of change was significantly higher in group C than in group A and group B. In addition, the subjective evaluation of the change in the number of chews was highest in group C. Self-monitoring of masticatory behavior by providing a target value and the degree of achievement for the number of chews using a wearable chewing counter with a behavioral change algorithm could promote effective change in masticatory behavior and lead to an increased number of chews. (Trial ID: UMIN000034476).

Association Between the Number of Remaining Teeth and Body Mass Index in Japanese Inpatients with Schizophrenia

Purpose

There is little evidence regarding the effects of dental status on body mass index (BMI) in inpatients with schizophrenia. Thus, we performed a cross-sectional study to explore the associations between the number of remaining teeth and BMI in Japanese inpatients with schizophrenia.

Patients and Methods

We performed multiple regression analysis to assess the effects of potential predictors (age, sex, number of remaining teeth, number of antipsychotics prescribed, chlorpromazine equivalent dose, and antipsychotic type) on BMI in 212 inpatients with schizophrenia. We then compared the number of remaining teeth between inpatients with schizophrenia and the Japanese general population (3283 individuals) from the Japan Dental Diseases Survey 2016, using an analysis of covariance with age and sex as covariates.

Results

Multiple regression analysis showed that the number of remaining teeth and the number of antipsychotics prescribed were significantly correlated with BMI (standardized regression coefficient = 0.201 and 0.235, respectively). In the analysis of covariance, inpatients with schizophrenia had significantly fewer remaining teeth compared with the Japanese general population (mean 14.8 [standard deviation: 10.9] vs mean 23.0 [standard deviation: 8.1]).

Conclusion

These results suggested that tooth loss and antipsychotic polypharmacy affect BMI in inpatients with schizophrenia, and that inpatients with schizophrenia lose more teeth compared with the general population.