Relationship between masticatory performance using a gummy jelly and masticatory movement

Pilot study on the relationship between oral function or subjective symptoms and appetite

OBJECTIVE

This pilot study evaluated the relationships between appetite and oral function, and between appetite and the subjective symptoms of decreased oral function.

METHODS

Seventy-one adult dental clinic patients (22 males, 66.0 ± 14.0 years) participated in this study. A Council on Nutrition Appetite Questionnaire score of ≤28 indicated anorexia, and the Mini Nutritional Assessment Short-form, body mass index and skeletal muscle mass index were used to define subject characteristics. Seven oral function tests and seven subjective symptoms related to oral function were evaluated. The relationship between subject characteristics, oral function tests, subjective symptoms and anorexia was analysed using the chi-square test and univariate and multivariate logistic regression.

RESULT

There were significant differences between the normal appetite group and the anorexia group for the 10-item Eating Assessment Tool (EAT-10) survey and the question 'Food remains in the oral cavity after eating' (p < .05). Univariate logistic regression found significant differences in the items of masticatory function, the EAT-10 survey and the question 'Food remains in the oral cavity after eating'. Multivariate logistic regression revealed significant differences in masticatory function (AOR 4.35; 95% CI: 1.03-18.35; p = .045) and EAT-10 (AOR 6.27; 95% CI: 1.40-24.02; p = .016).

CONCLUSION

This pilot study investigated the influence of factors related to oral function on appetite. Relationships were found among poor masticatory function, poor swallowing function and anorexia.

Relationship between texture perception and oral function: A preliminary study in young, healthy adults

BACKGROUND

Oral frailty, characterised by reduced oral function, is associated with systemic health issues in older adults. Although the criteria for diminished oral function often focus on motor and secretory abilities, texture perception also plays a crucial role in health due to its impact on food intake and palatability.

OBJECTIVE

This study aimed to explore the relationship between thickness discrimination ability (TDA) and oral motor and secretory functions in healthy young individuals.

METHODS

Twenty-eight adults were assessed for texture perception using eight concentrations of aqueous xanthan gum solutions to determine TDA scores. Measurements of occlusal force, masticatory performance, tongue pressure, stimulated salivary flow rate and tongue-lip motor function were conducted. Spearman's correlation analysis was used to evaluate the relationship between TDA scores and oral functions. Participants were divided into high-sensitivity and low-sensitivity groups based on their TDA scores to compare oral function test results.

RESULTS

The TDA scores varied among the participants, with higher scores correlating with higher masticatory performance (r = 0.41, p < .05). Masticatory performance in the high-sensitivity group was significantly higher than in the low-sensitivity group (211.9 ± 59.2 mg/dL vs. 157.9 ± 43.0 mg/dL, p = .013), with no significant differences in other oral functions.

CONCLUSION

Masticatory performance was correlated with TDA, suggesting a link between the selection function of mastication and thickness discrimination. These findings highlight the potential relevance of texture perception in oral function and indicate the need for further exploration, particularly in older adults with declining oral health.

Associations of sex, age, and number of remaining teeth with performance on oral hypofunction tests

INTRODUCTION

Oral hypofunction comprises seven aspects of oral condition, including oral hygiene, oral dryness, bite strength, tongue-lip motor function, tongue pressure, masticatory function, and swallowing function. Each of these seven has a single diagnostic criterion; however, the use of a single indicator without consideration of sex, age, or other factors is controversial. The purpose of this study was to evaluate the association between the oral hypofunction test and sex, age, and number of remaining teeth.

METHODS

The study was conducted at 12 facilities by the members of the Japanese Society of Geriatric Dentistry during April to December 2019. The participants comprised 181 healthy older adults aged 65 years and over (56.9% female; age range 65-95 years) who regularly visited these facilities. All tests of oral function and oral status available in Japan were performed on the participants, and the association between these tests and sex, age, and number of remaining teeth was examined.

RESULTS

Sex differences were observed in masticatory function, bite force, lip closure force, jaw-opening force, oral diadochokinesis "ka," and tongue coating index (p < .05). In men, age was weakly (r = 0.20-0.40) associated with masticatory function, jaw-opening force, maximum tongue pressure, oral diadochokinesis, and swallowing function. In women, the number of remaining teeth, masticatory function, jaw-opening force, and oral diadochokinesis "ta" and "ka" was also weakly associated with age.

CONCLUSIONS

Performance on the oral hypofunction test differs by sex, age, and number of remaining teeth. This means that the current single criterion for evaluation requires caution in its interpretation.

Reliability between the two-colour chewing gum and the gummy-jelly tests used for the assessment of masticatory performance

OBJECTIVE

This study aimed to evaluate the reliability of two methods used to assess masticatory performance and attempt to correlate them to achieve interchangeability between the methods.

METHODS

Twelve healthy dentate volunteers (men = 6, women = 6; mean age = 28.3 ± 4.1) with no known dental or medical pathologies were requested to participate in this study. Each participant completed three masticatory performance assessments, including two two-colour mixing-ability tests using chewing-gums (CG: gum#1 and gum#2) and the gummy-jelly (GJ) test. For each method, participants created five samples each (total = 15 measurements per participant, gum#1 = 5, gum#2 = 5, GJ = 5). For the gum#1 and gum#2 methods, the predetermined chewing cycles were fixed at 10, 15, 20, 25 and 30 cycles, and for the GJ method, the time duration was fixed at 10, 15, 20, 25 and 30 s. The parameter measures were submitted to Z-score transformation, and Bland-Altman plots were generated to graphically compare the differences between two techniques against their means. Additionally, mountain plot was used to assess the cumulative distribution of measurement error between the methods.

RESULTS

A total of 180 measurements were recorded. There were significant correlations between the number of chewing cycles/chewing time and masticatory performance using the gum#1 (r = -.753; p < .001), gum#2 (r = -.838; p < .001) and GJ (r = .730). When all tests were considered together for each method, significant correlations were found (p < .001). A descriptive range of mean values aiming to produce reference value ranges for predictive purposes was achieved considering the interchangeably among the methods [CG = GJ (VoH-mg = dL): 10 cycle = 10 s: 0.329 = 110; 15 cycles = 15 s: 0.177 = 164; 20 cycles = 20 s: 0.130 = 205; 25 cycles = 25 s: 0.086 = 200; 30 cycles = 30 s: 0.077 = 267].

CONCLUSION

The strong correlations and high consistency between the two masticatory performance methods found in this study conclude that the two assessment methods are reliable and interchangeable. Further evaluations are warranted to arrive at a conversion formula for translation of the results between the two methods.

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.

Effect of Periodontal Treatment on Reducing Chronic Inflammation in Systemically Healthy Patients With Periodontal Disease

BACKGROUND

We determined the effects and an accurate marker of periodontal treatment on serum interleukin (IL)-6 and high-sensitivity C-reactive protein (HsCRP) levels in systemically healthy individuals with periodontal disease.

METHODS

This multicenter study included systemically healthy individuals with periodontal disease who received initial periodontal treatment and had no periodontal treatment history. Periodontal parameters, including periodontal inflamed surface area, masticatory efficiency, and periodontal disease classification; serum IL-6 and HsCRP levels; and serum immunoglobulin (Ig)G titers against periodontal pathogens were evaluated at baseline and after treatment. Subjects were classified as low or high responders (group) based on periodontal inflamed surface area changes.

RESULTS

There were 153 participants. Only periodontal inflamed surface area changes were markedly different between low and high responders. Periodontal treatment (time point) decreased both serum IL-6 and HsCRP levels. The interaction between group and time point was remarkable only for serum IL-6 levels. Changes in serum immunoglobulin (Ig)G titers against periodontal pathogens were not associated with IL-6 changes in high responders. We analyzed the indirect effect of serum anti-Porphyromonas gingivalis type 2 IgG titer changes using mediation analysis and found no significance. However, the direct effect of group (low or high responder) on IL-6 changes was considerable.

CONCLUSIONS

Periodontal treatment effectively decreased serum IL-6 levels, independent of periodontal pathogen infection, in systemically healthy individuals with periodontal disease.

Association between Masticatory Performance, Nutritional Intake, and Frailty in Japanese Older Adults

The older adult population in Japan is expected to increase. Therefore, long-term care and frailty prevention are important. However, the relationship between masticatory performance, nutritional intake, and frailty remains unclear. This cross-sectional study aimed to examine energy, protein, and vitamin D intake and its association with frailty and masticatory performance in older adults. Patients between January 2022 and January 2023 were recruited and divided into robust and frail groups. Masticatory performance, nutrition, frailty, and other data, such as age and sex, were evaluated through onsite measurements and a questionnaire. Logistic regression analysis was conducted with frailty as a dependent variable and masticatory performance as an independent variable, adjusting for age, sex, skeletal muscle mass, living alone, energy intake, protein-energy ratio, and vitamin D intake. No significant differences were observed between the groups regarding age or sex. The robust group showed significantly better results for protein-energy ratio, vitamin D intake, and subjective and objective masticatory performance than the frail group. Logistic regression analysis revealed a significant correlation between skeletal muscle mass, protein-energy ratio, and objective masticatory performance with frailty. Masticatory performance was associated with frailty, independent of the intake of nutrients such as energy, protein, and vitamin D.

Effect of mandibular bilateral distal extension denture design on masticatory performance

PURPOSE

Removable partial dentures have a wide range of applications as missing tooth prostheses, and the denture design can be quite diverse. However, the factors affecting masticatory function remain unclear. We investigated the effect of denture design, especially the use of indirect retainers and major connectors, on masticatory function in patients with mandibular bilateral distal extension dentures.

METHODS

Fifty-three patients with mandibular Kennedy Class I and Eichner classification B occlusal support were included in this study. Masticatory performance (MP) was assessed using gummy jelly. For the dentures, the type of major connector (bar or apron), presence or absence of indirect retainers, number of rests, and number of artificial teeth were evaluated. The number of functional teeth and occlusal support, Eichner classification, maxillary denture usage, mandibular residual ridge height, and duration of denture use were also evaluated. The factors influencing on the MP were evaluated using the Mann-Whitney U test, Spearman's correlation coefficient, and logistic regression analysis.

RESULTS

MP was significantly higher when the major connector was bar-type or when there was an indirect retainer than with an apron-type or no indirect retainer. MP was positively correlated with the number of functional teeth, occlusal support, and number of rests. Logistic regression analysis revealed that the number of functional teeth and the presence or absence of an indirect retainer were factors that significantly influenced the MP.

CONCLUSIONS

An indirect retainer setting is useful for achieving good masticatory performance in mandibular bilateral distal extension dentures.

Factors related to masticatory performance in patients with removable dentures for jaw defects following oral tumor surgery

Purpose In the treatment of oral tumors, extensive jaw defects due to surgical resection can reduce masticatory performance. Herein, we aimed to clarify the factors related to masticatory performance in patients with jaw defects.Methods In total, 76 patients (42 male and 34 female) underwent prosthetic treatment with a removable denture for a jaw defect following oral tumor surgery. Data on history of radiation therapy, period of time since surgery, period of use of the present denture, number of remaining teeth, and site of the jaw defect were collected. Masticatory performance was evaluated using test gummy jelly. In addition, maximum bite force, tongue pressure, tongue-lip motor function (oral diadochokinesis /pa/, /ta/, /ka/), and oral dryness were evaluated. Logistic regression analysis was performed with lower masticatory performance scores as the dependent variable. Since multicollinearity was suspected between the oral diadochokinesis /ta/ and /ka/ syllables, two logistic regression analyses were conducted: Model 1 with the /ta/ syllable as an explanatory variable, and Model 2 with the /ka/ syllable as an explanatory variable.Results In Model 1, a history of radiation therapy, maximum bite force, number of remaining teeth, tongue pressure, and oral diadochokinesis /ta/ were significant explanatory variables. In Model 2, a history of radiation therapy, maximum bite force, number of remaining teeth, and tongue pressure were significant explanatory variables.Conclusions A history of radiation therapy, maximum bite force, tongue pressure, number of remaining teeth, and motor function of the proglossis are related to decreased masticatory performance in patients with jaw defects.

Evaluation of masticatory performance by motion capture analysis of jaw movement

BACKGROUND

The assessment of masticatory performance (MP) is conducted in hospitals, but is difficult to perform in nursing facilities that lack specialists in dysphagia. To select the appropriate food textures in nursing practice, a simple method of evaluating the MP should be developed.

OBJECTIVE

The purpose of this study was to investigate motion parameters that influence MP by motion capture analysis of maxillofacial movement on chewing gummy jelly in healthy adults.

METHODS

The subjects were 50 healthy adults. The state of chewing gummy jelly was photographed using a high-speed camera. Simultaneously, we evaluated the amount of glucose extracted (AGE) obtained with gummy jelly as a reference value for MP. The subjects were divided into two groups: normal and low masticatory groups (NG and LG, respectively) based on the AGE. The cycle of mastication was classified into three phases: closing phase (CP), transition phase (TP) and opening phase (OP) through motion capture analysis of the video photographed. Parameters of jaw movement and their associations with the AGE were examined.

RESULTS

The transition phase rate (TR) and opening phase rate (OR) were correlated with the AGE. Furthermore, the TR in the NG was significantly higher than in the LG, whereas the OR was significantly lower than in the LG. The age, TR and opening velocity were significant independent variables.

CONCLUSION

Motion capture technology facilitated the analysis of jaw movement. The results suggested that MP can be evaluated by analysing the TP and OP rates.

Effect of sitting posture with and without sole-ground contact on chewing stability and masticatory performance

PURPOSE

To verify the effect of sitting posture with and without sole-ground contact on chewing stability and masticatory performance.

METHODS

Thirty healthy subjects were evaluated. The Conformat was used to analyze the center of sitting pressure (COSP), and the three-dimensional motion analysis system was used to analyze changes in head and trunk postures while subjects remained in a sitting position with and without sole-ground contact. The parameters of masticatory performance and movement were calculated as follows. For evaluating masticatory performance, the amount of glucose extraction (AGE) during chewing of a gummy jelly was measured. For evaluating masticatory movements, the movement of the mandibular incisal point was recorded using the Motion Visi-Trainer V1, and parameters of the stabilities of movement path and rhythm were calculated.

RESULTS

Head and trunk sway values and the displacement of COSP were significantly smaller with sole-ground contact than those without sole-ground contact. The masticatory movement path with sole-ground contact showed less variation in the opening distance and more stable movement path compared to those without sole-ground contact. The AGE was significantly greater with sole-ground contact than that without sole-ground contact.

CONCLUSION

Sitting posture with and without sole-ground contact affects chewing stability and masticatory performance.

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.

Kinematic Features of Mandibular Movement during Mastication in Geriatric Individuals Who Are Provided with a Dysphagia Diet at Long-Term Care Facilities

Providing a normal diet to a care recipient who is unable to form an adequate bolus may cause suffocation or aspiration pneumonia. We investigated whether differences in kinematic data of mandibular movements during mastication can be used as an indicator of the need for a dysphagia diet in the elderly in long-term care facilities. We included 63 participants who were provided with solid food in two long-term care facilities. The primary outcome variable was the kinematic data on mandibular movement during cracker chewing. The analysis results were compared between the normal and dysphagia diet groups. Logistic regression analysis and receiver operating characteristic curve analyses were performed. Significant differences were observed in the masticatory time, cycle frequency, total change amount, number of linear motions, and circular motion frequency between the normal and modified diet groups. The odds ratio for the circular motion frequency was -0.307, and the calculated cutoff value was 63%, with a sensitivity of 71.4%, a specificity of 73.5%, and an area under the curve of 0.714. Thus, these characteristics may be useful for detecting care recipients who need to be provided with a dysphagia diet. Moreover, the circular motion frequency could be used as a screening test to identify people who need a dysphagia diet.

Use of an occlusal ramp for rehabilitation after a mandibulectomy and its effects on mastication

STATEMENT OF PROBLEM

Patients with a mandibular defect can develop mandibular deviation, resulting in a loss of or reduction in occlusal contact and ultimately loss of function. The occlusal ramp is a prosthesis used to help restore the masticatory function of such patients and is used particularly in the maxillofacial rehabilitation of patients with masticatory dysfunction resulting from mandibular deviation. The occlusal ramp is usually attached to a mandibular denture or worn as an independent device placed on the palate corresponding to the mandible that produces the offset. However, evidence of the effects of its use is sparse.

PURPOSE

The purpose of this clinical study was to investigate the effects of occlusal ramp use in functional rehabilitation.

MATERIALS AND METHODS

This study included 10 patients who had received mandibulectomies (5 men and 5 women; mean age 76.7 years, range 67 to 90 years) with deviation of the mandible. An occlusal ramp was fabricated for each participant as part of their maxillofacial prosthetic treatment. Masticatory performance was evaluated before and after the treatment by measuring glucose extraction while masticating a piece of gummy jelly. The Wilcoxon signed-rank test was used for statistical analysis (α=.05).

RESULTS

The median masticatory performance score, represented as glucose concentration (mg/dL), was 82.45 before treatment and 115.45 after treatment, with an overall improvement of 33.00. Scores differed significantly before and after treatment (P=.005). Masticatory performance for each participant improved in the range of 17.7 to 103.3, highlighting the role that the occlusal ramp played in mastication, although with differing effects in each participant.

CONCLUSIONS

Masticatory performance in participants with mandibular deviation after a mandibulectomy was significantly improved with an occlusal ramp. This suggests the effectiveness of using occlusal ramps in maxillofacial prosthetic treatment for the recovery of masticatory function in patients with mandibular deviation.

Oral Health-Related Quality of Life Changes after Clinical Remounting of Existing Dentures

The clinical remount is an accurate and efficient way to reset the occlusion of delivered removable dentures if major occlusal correction is required. Although previous studies have reported that clinical remounting of existing dentures enhances patients’ oral function, little subjective feedback is available. This retrospective study reports short-term changes in oral-health-related quality of life (OHRQoL) and masticatory function after clinical remounting of existing dentures. Three time points were defined: before adjustment (T0), immediately after adjustment (T1), and 1 week after adjustment (T2). The medical records of seven patients were analyzed. The mean age of participants was 77.71 years, and the mean service period of their prostheses was 9.43 months. The mean scores of the OHIP-EDENT-J questionnaire at the respective time points were 35, 21.14, and 22.14. The mean readings of masticatory function at the respective time points were 76.71, 89.29, and 111.86. Significant differences in the OHIP-EDENT-J were found between T0 and T1, and T0 and T2; and in masticatory function between T1 and T2, and T0 and T2. The results indicated that after rebalancing of the occlusion of the existing dentures, the patient-reported OHRQoL was improved immediately and maintained at least for a short time, and masticatory function was enhanced over a 1-week period.

Relationship between Knowledge and Attitude toward Oral Function in Middle-Aged and Older Adults

Oral hypofunction is the stage at which recovery can be expected with proper diagnosis, management, and motivation before oral dysfunction occurs. The knowledge and attitude toward oral function can influence the maintenance and improvement of oral function. However, whether middle-aged and older adults with declining oral function have knowledge of their oral function and how this knowledge and their attitude affect their oral function are unclear. Therefore, we aimed to examine (1) the relationship between knowledge and attitude toward oral function and hypofunction in individuals with suspected oral hypofunction and (2) changes in knowledge and attitude toward oral function through evaluation and education. Participants aged ≥50 years were enrolled during their first community dental clinic visit. A questionnaire assessment of knowledge and attitudes before and after oral function evaluation was performed. The oral function was initially assessed with seven criteria: oral hygiene; oral dryness; occlusal force; tongue pressure; tongue-lip motor, masticatory, and swallowing function. Associations between knowledge and attitudes and their changes were statistically analyzed. Fifty-nine participants (93.7%) were unaware of “oral hypofunction.” Associations between knowledge and attitudes and their changes in the negative to positive response groups, from 86.4% and 61.0% to 6.8% and 25.4%, respectively, after oral function evaluation, indicated that participants understood their oral function and the need for training. Middle-aged and older individuals with poor knowledge and attitudes were more likely to have a worse oral function; however, their knowledge and attitudes toward oral function could be improved through oral function assessment and education.

Decline in Oral Function and Its Management

With the renewed focus on eating abilities in the ageing population, new concepts referred to as oral frailty and oral hypofunction have been introduced in Japan. We aimed to provide an overview of (i) the evaluation and management of oral function in ageing populations according to oral frailty and oral hypofunction and (ii) recent scientific evidence of the associations of poor oral function with physical function and nutritional status. Both oral frailty and oral hypofunction are multidimensional concepts that describe poor oral function. In epidemiologic and/or clinical settings, they are defined as the accumulation of factors leading to poor oral status. Oral hypofunction is a core component of oral frailty. To date, there are no systematic strategies for addressing oral frailty or oral hypofunction. Nevertheless, recent randomised controlled trials revealed that several components of oral function can be improved through appropriate training. On the other hand, multiple observational studies published in recent years have demonstrated that oral frailty and oral hypofunction are associated with physical function (gait performance, frailty, and sarcopenia) and nutritional status (low protein intake, poor dietary diversity, and malnutrition) in community-dwelling older adults. Moreover, studies have reported a significant association between insufficient participation in social networks and poor oral function. However, most of the studies conducted to date have utilised a cross-sectional design, which does not permit assessment of the temporal association between comprehensive oral function and general health. Maintaining good oral function may be key to longevity. However, evidence is limited thus far, and comprehensive oral function has not been studied in detail; thus, additional high-quality studies are needed.

A Study for Determining the Inclination of the Occlusal Plane from the Mandibular Functional Trajectory

Background

During the fabrication of prostheses, the putative occlusal plane is generally determined based on morphological criteria such as Camper's plane. There is a possibility that morphological indexes deviate from their original positions over time. The current study investigated whether functional indexes could be used to determine occlusal planes instead of morphological indexes.

Objectives

The objectives of the present study were to investigate the relationship between the maxillary occlusal plane and mandibular functional trajectory and to consider a method for reconstructing a lost occlusal plane based on functional trajectories.

Methods

Thirteen healthy dentulous individuals were recruited for the study. Using a jaw motion tracking device with 6-degrees of freedom, the trajectories of the mandibular first molar and incisor during masticatory movement or tapping movements were measured.

Results

The closing angle of the mandibular first molar to the maxillary occlusal plane was converged and averaged 74.1° just below the intercuspal position, which is the terminal position of masticatory movement. This angle was positively correlated with the closing angle of the incisal point during tapping movement. The regression equation obtained was y = 0.37x + 45.99, where x was the closing angle of tapping movement and y was the closing angle of masticatory movement.

Conclusions

It was suggested that when determining lost occlusal plane, the occlusal plane can be derived using the closing angle of the incisal point during tapping movement.

Masticatory dysfunction in patients with diabetic neuropathy: A cross-sectional study

Introduction

Chewing well is essential for successful diet therapy and control of blood glucose level in patients with diabetes. In addition, long-term hyperglycemia is a risk factor for microvascular complications, which are the main cause of morbidity and mortality in these patients. Hence, it is plausible that masticatory disorder may be relevant to diabetic microvascular complications which is caused by long-term hyperglycemia. The aim of this study was to investigate whether masticatory disorders are relevant to diabetic microvascular complications.

Methods

This cross-sectional study included 172 patients with type 2 diabetes who underwent educational hospitalization in the Department of Endocrinology and Diabetic Medicine, Hiroshima University Hospital, from April 2016 to March 2020. Masticatory efficiency was determined quantitatively by using the GLUCO SENSOR GS-Ⅱ. Multivariable linear regression models were constructed to examine which factors were related to masticatory efficiency. Statistical significance was defined as a two-sided p value of < 0.05.

Results

According to the bivariable analysis, masticatory efficiency was significantly correlated with duration of diabetes (p = 0. 049), number of remaining teeth (p < 0.0001), the number of moving teeth (p = 0.007) and condition of diabetic neuropathy (p < 0.0001). Moreover, the number of remaining teeth (p < 0.0001) and diabetic neuropathy (p = 0.007) remained significantly correlated with masticatory efficiency in the multivariable analysis.

Conclusions

For the first time, we demonstrated that patients with type 2 diabetes who developed diabetic neuropathy had significantly reduced masticatory efficiency. Effective mastication is an important factor in successful diet therapy for diabetes. To prevent the progression of diabetic complications, especially in patients with diabetic neuropathy, it may be necessary to combine individualized therapies from dentists and nutritionists with consideration for the level of masticatory dysfunction.

A Cross-Sectional Study on the Relationship between Oral Function and Sarcopenia in Japanese Patients with Regular Dental Maintenance

We aimed to clarify the relationship between oral function assessments regarding oral hypofunction and sarcopenia in patients who had completed treatment for organic dental problems, including oral pain, removable denture fit, and tooth loss. This cross-sectional study included 269 patients aged ≥65 years (mean age 74.9 ± 6.50 years, 133 men, 136 women) who visited a dental clinic between June 2019 and March 2021. We evaluated oral function and sarcopenia and analyzed their relationship using the Jonckheere–Terpstra test, Mantel–Haenszel trend test, and Poisson regression analysis. We diagnosed 132 (49.07%) patients with oral hypofunction, 30 (11.2%) with sarcopenia, and 24 (8.9%) with severe sarcopenia. The number of oral hypofunction items (prevalence rate ratio [PRR] = 1.39, 95%Wald = 0.11 to 0.56) was significantly associated with sarcopenia. For each of the items, tongue-lip motor function [ta] (PRR = 0.80, 95%Wald = −0.44 to −0.02)] [ka] (PRR = 0.76, 95%Wald = −0.53 to −0.03) and tongue pressure (PRR = 0.95, 95%Wald = −0.09 to −0.02) showed a significant association with sarcopenia. However, no significant association was found for other variables. Dentists should not only treat organic dental problems but also consider the relationship between oral function and sarcopenia.

Oral function and nutritional status in non-acute hospitalised elders

Introduction

Malnutrition and risk of malnutrition continues to be a common finding in elders, yet its association with oral function in hospitalised patients remains unclear.

Material and methods

Patients aged 70 years or over who had been hospitalised for non‐acute rehabilitation were recruited. Nutritional risk was screened using the Mini‐Nutritional Assessment Short Form (MNA‐SF) and Nutritional Risk Screening (NRS) scores. Malnutrition was assessed according to the Global Leadership Initiative on Malnutrition (GLIM) criteria. All participants underwent the oral hypofunction test battery, evaluating oral hygiene, oral dryness, occlusal force, tongue‐lip motor function, tongue pressure, masticatory and swallowing function. Statistical analyses comprised Mann‐Whitney or Kruskal‐Wallis tests. Bivariate associations between categorical variables were tested using the Pearson chi‐square test; for continuous variables, the Spearman correlation was calculated. A P‐value < .05 was considered statistically significant.

Results

Sixty patients aged a mean 82.5 ± 7.0 years participated. Some 88.3% were diagnosed with oral hypofunction, and this was more common in older patients (P = .020). Analysing the 7 oral hypofunction tests as an interval variable (NiOF) revealed additional correlations with number of teeth (ρ = 0.477) as well as the nutritional risk, evaluated by the MNA‐SF (ρ = −0.284) and NRS (ρ = 0.317) scores. NiOF scores were higher among denture wearers (P = .003). GLIM did not confirm the correlation with NiOF. Biomarkers such as serum albumin and CRP were not associated with the NiOF score.

Conclusion

In this sample, the association between oral function and nutritional state is more obvious in nutritional risk scores than in the malnutrition diagnosis by GLIM.

Reference value of masticatory performance by measuring the amount of glucose extraction from chewing gummy jelly

PURPOSE

The purpose of this study was to determine a reference value for masticatory performance (MP) by measuring the amount of glucose extracted(AGE) from chewing gummy jelly.

METHODS

A total of 237 young adults (young group, 20-39 years), 147 middle-aged adults (middle-aged group, 40-59 years), and 177 older adults (old group, 60-87 years) participated in this study. All participants had natural dentition, excluding the third molars. AGE was measured when the participant chewed gummy jelly and used as a parameter of MP. AGE was compared among the three groups. Next, AGE in each group was compared between the habitual chewing side and non-habitual chewing side, and between males and females. The correlation between age and AGE was also investigated.

RESULTS

AGE in the young, middle, and old groups were similar, and no significant differences were observed. AGE was significantly higher in the habitual chewing side compared to the non-habitual chewing side, and in males than that in females. No significant correlations were found between age and AGE. AGE in the habitual chewing side of all ages was 221.9 ± 34.4 mg/dL for males and 206.0 ± 28.7 mg/dL for females. The mean-2SD (standard deviation) value representing the reference value of healthy adults was 153.1 mg/dL for males and 148.6 mg/dL for females, which was close to 150 mg/dL.

CONCLUSION

It was concluded that the reference value of masticatory performance as measured by the amount of glucose extraction after chewing gummy jelly was 150 mg/dL.

Effects of food particle loss on the evaluation of masticatory ability using image analysis

PURPOSE

To examine how particle loss affects the evaluation of masticatory ability using the image analysis method.

METHODS

The subjects were divided into two groups:Y-group (healthy young adults: 10 male, 10 female; mean age 27.6 ± 1.9 years), and D-group (denture wearing older adults: 13 male, 9 female; mean age, 75.1 ± 5.3 years). Raw carrots, peanuts, and a combined test food from 5 daily food materials (mixed foods) were selected as test foods. Images of the boluses were captured and processed after the subjects freely masticated the test foods until the point of swallowing or completed half strokes of total chewing cycles. The median particle size (X₅₀) was calculated from the data for each particle. We compared X₅₀ calculated from all particles obtained from the masticatory bolus (as X_50N) with the X₅₀ of only selectively larger particles (as X_50R).

RESULTS

Significant correlations were observed between X_50N and X_50R (p < 0.01) determined in almost all masticatory conditions. In particular, for particle sizes of 2 mm or more, the correlation coefficient between X_50N and X_50R was notably strong (r > 0.75).

CONCLUSION

The method of analyzing only larger particles makes it possible to evaluate masticatory ability without losing the characteristics of the original particle size distribution of the entire bolus. This finding can be applied for the evaluation of masticatory ability, especially among older adults who have difficulty retrieving the total amount of test food due to decreased activities of daily living.

Oral function is associated with the body and muscle mass indices of middle-aged dental patients

Objectives

Undernutrition is associated with frailty, one of the common reasons for seeking long‐term care. In older adults, nutritional status is known to be associated with oral function; however, it is not yet known if there is a similar association in middle‐aged adults. The present study determined the association between nutritional status and oral function in middle‐aged adults.

Material and methods

This cross‐sectional study was conducted in 117 outpatients aged 40–64 years who underwent dental check‐up at a private dental clinic. Factors associated with oral function, including oral moisture, number of teeth present, oral diadochokinesis, tongue pressure, lip‐seal strength, and masticatory performance, were evaluated. Body mass index (BMI), fat‐free mass index (FFMI), and skeletal muscle mass index (SMI) were analyzed as nutritional statuses. Pearson's correlation analysis was conducted to determine the correlation between nutritional statuses and other variables. Multiple linear regression analysis was performed, with adjustment for age and sex, using BMI, FFMI, or SMI as response variables and oral moisture, maximum tongue pressure, lip‐seal strength, oral diadochokinetic rate, and masticatory performance as explanatory variables.

Results

All nutritional statuses showed significant correlation with maximum tongue pressure and lip‐seal strength. Multiple linear regression analysis revealed that BMI was associated with maximum tongue pressure and lip‐seal strength, whereas FFMI and SMI showed significant association with sex, maximum tongue pressure, and lip‐seal strength.

Conclusions

In middle‐aged outpatients at a regional dental clinic, lip‐seal strength and tongue pressure were positively associated with BMI, FFMI, and SMI.

Differences in the factors associated with tongue pressure between children with class I and Class II malocclusions

Background

The relationship between tongue pressure and masticatory performance during the mixed dentition period in cases of Class II malocclusion has not been clarified. The aim of this study was to determine differences in tongue pressure-related factors, including maxillofacial morphology and masticatory performance, between Class I and Class II malocclusions during the mixed dentition period.

Methods

A total of 56 children with Class I malocclusion (12 boys, 16 girls) or Class II malocclusion (16 boys, 12 girls) with mixed dentition were included in the present study. Height, body weight, hand grip strength, maximum occlusal force, maximum tongue pressure, masticatory performance, and the number of decayed, missing, and filled teeth were measured in all participants. Their lateral cephalograms were also evaluated. The means of all measurements were compared between Class I and Class II malocclusions. Pearson’s correlation coefficients were used to determine associations between maximum tongue pressure and other variables for each type of malocclusion.

Results

The maximum tongue pressure, hand grip strength, and maximum occlusal force in the Class II malocclusion group were significantly lower than those in the Class I malocclusion group (all, p < 0.05). The maximum tongue pressure was significantly positively correlated with hand grip strength, maximum occlusal force, masticatory performance, and SNB (sella, nasion, B point) angle in the Class I group (all, p < 0.05), and with height, body weight, and labial inclination of the central incisors in the Class II group (all, p < 0.05).

Conclusions

The maxillofacial morphometric factors associated with tongue pressure were clearly different between cases of Class I and Class II malocclusion with mixed dentition. Masticatory performance and tongue pressure were significantly positively correlated in cases of Class I malocclusion, but not in cases of Class II malocclusion.

Masticatory movements and food textures in older patients with eating difficulties

Objectives

To investigate whether masticatory movements in older patients with eating difficulties were associated with oral motor function, physical function, and appropriate food textures.

Background

There are few reports on the association between masticatory movements and food textures in older patients with eating difficulties.

Materials and Methods

This cross‐sectional study involved outpatients at a clinic that specialised in eating and swallowing rehabilitation. Masticatory movements were evaluated as normal or abnormal masticatory path patterns. Oral and physical functions were assessed in terms of oral and physical status, muscle strength and motor skills. The appropriate food texture was determined based on fibreoptic endoscopic evaluation of swallowing and a video fluoroscopic swallowing study. The associations between food texture and masticatory organ, muscle strength and motor skills were analysed.

Results

A total of 126 outpatients (75 men and 51 women; mean age, 78.2 years; SD, 9.6 years) were included in the analysis. 68 participants (54.0%) showed abnormal masticatory movements. Masticatory movement was associated with masticatory performance (odds ratio [OR] = 0.99, 95% confidence interval [CI] = 0.98‐0.99), oral diadochokinesis (OR = 0.55, CI = 0.35‐0.86) and stepping test (OR = 0.92, CI = 0.86‐0.97). Masticatory movement (OR = 2.94, CI = 1.23‐7.01) and the number of natural teeth (OR = 0.94, CI = 0.89‐0.99) were associated with normal food.

Conclusion

Masticatory movements in older patients with eating difficulties may be associated with appropriate food textures whilst being influenced by individual differences in systemic motor control. Masticatory movements may be as important as teeth to enjoy eating.

Stability of masticatory movements after placement of implant-supported denture

The purpose of this study was to clarify the stability of masticatory movement after placement of implant-supported denture. Fourteen patients (patient group) with mandibular implants denture and maxillary complete denture and 30 dentate adults (control group) were asked to chew a boiled fishpaste, and the masticatory movement was recorded using MKG. For the 10 cycles beginning with the 5th cycle of mastication, the parameters representing the stability of masticatory movement were calculated. Data collected at 1, 3, 6, 9 months and 1, 2, 3 years after insertion of implants denture were compared between sessions and also between the patient and control groups. The mean and standard deviation of the values in the patient group at 1 month after insertion of implants denture were large, but gradually decreased 6 to 9 months after insertion of implants denture. Each parameter maintained almost the same value from 1 to 3 years. The parameter values of the patient group were significantly larger than those of control group from 1 to 9 months after insertion of implants denture, but 1 year after insertion of implants denture, there was no significant difference between the two groups in 5 out of 7 parameters. From these results, it was suggested that a certain duration, about 9 months to 1 year, was necessary for patients with implants denture to adapt to the new masticatory function and that the timing of functional evaluation should be set to 1 year after insertion of implants denture.

Effect of an Oral Frailty Measures Program on Community-Dwelling Elderly People: A Cluster-Randomized Controlled Trial

INTRODUCTION

Oral frailty describes a trivial decline in the oral function and is considered to be related to frailty. Thus, effective management of oral frailty could prevent or ameliorate physical frailty and the need for care. However, there is a lack of consensus regarding specific interventions for oral frailty. In this cluster-randomized controlled trial, we investigated the effects of a newly developed oral frailty measures program mentored by dentists and dental hygienists for elderly people in a clinical setting.

METHODS

Of 3,296 participants included in a field survey, 219 who regularly visited dental clinics and met at least 3 of the following 6 criteria for oral frailty were considered eligible: <20 natural teeth, decreased chewing ability, decreased articulatory oral-motor skills, decreased tongue pressure, and substantial subjective difficulties in eating and swallowing. After applying the inclusion and exclusion criteria, we studied 51 patients in the intervention group (14 men and 37 women; mean age, 78.6 years) and 32 patients in the control group (7 men and 25 women; mean age, 78.0 years). We implemented a 12-week oral frailty measures program only for the intervention group. The program included preparatory oral exercises, mouth-opening training, tongue pressure training, prosodic training, and masticatory training. Primary outcome measures were the chewing ability score, articulatory oral motor skill for /ta/, tongue pressure, subjective difficulty in eating tough foods, and subjective difficulty in swallowing. We compared baseline characteristics using the Mann-Whitney U and χ2 tests for continuous and categorical variables, respectively. A repeated-measures two-way ANOVA was used to determine the efficacy of independent intervention variables, following the Wilcoxon signed-rank test. The groups (intervention/control) and time (baseline/week 12) were the independent variables. Oral frailty measures were the dependent variables.

RESULTS

Baseline characteristics and assessment results were similar between groups. We observed significant improvements in the intervention group in terms of articulatory oral motor skill for /ta/ and tongue pressure (p < 0.001). No improvements were observed in the control group.

DISCUSSION/CONCLUSION

Our results suggest that our oral frailty measures program effectively alleviates oral frailty. Future studies are needed to clarify the impact on preventing physical frailty and improving the nutritional status.

Analysis of the relevant factors associated with oral health-related quality of life in elderly denture wearers

PURPOSE

The purpose of the present study was to explore the factors related to oral health-related quality of life (OHRQoL) in elderly patients who underwent prosthetic treatment with removable dentures through several objective and subjective examinations and to analyze their interrelationships.

METHODS

The current study involved 78 denture wearers, aged 65 years or above, who underwent treatment at the clinic of prosthodontics and undertook routine checkups. The present study used eight age-matched patients with healthy dentition as controls. The following items were evaluated: OHRQoL (Oral Health Impact Profile), main occluding area, maximal occlusal force, masticatory performance, and masticatory ability. Spearman's rank correlation coefficient was used to assess the correlation between the OHIP score and each item and multiple linear regression analysis with the backward elimination method was used to analyze the factors affecting the OHIP score (α = 0.05).

RESULTS

The OHIP summary score was significantly correlated with the number of occlusal supports, number of remaining teeth, maximal occlusal force, and the masticatory ability score. The multiple regression analysis revealed that the number of occlusal supports, the number of remaining upper teeth, whether the upper main occluding area was the remaining tooth or not, and the masticatory ability score were the significant independent variables that affected the OHIP summary scores.

CONCLUSIONS

The present study verified the relationship between the OHRQoL and the occlusion of remaining teeth or the items derived from the main occluding areas. The current results suggest that retaining the maxillary first molar is a key factor in the OHRQoL.

Assessment of Age-Related Changes on Masticatory Function in a Population with Normal Dentition

This study aimed to investigate the influence of changes in age-related physiological muscular and dental factors on masticatory function. This study was conducted in 211 healthy participants divided into four different age groups: 20–45 years (Gr1); 45–60 years (Gr2); 61–70 years (Gr3); and ≥71 years (Gr4). For objective evaluation of masticatory function, the masticatory performance, bite force, posterior bite area (PBA), functional tooth units (FTUs), the number of remaining teeth, tongue pressure, masseter muscle thickness (MMT), and handgrip strength were examined. Food intake ability (FIA) and the Oral Health Impact Profile-14 score were assessed subjectively using questionnaires. A significant decrease in the number of remaining teeth, FTUs, handgrip strength, and FIA was found in Gr4, and a significant decrease in the tongue pressure, PBA, and bite force was found in those aged ≥61 years. In groups 1 and 3, an association of the PBA with masticatory performance was observed. However, there was no significant decreasing trend in the MMT with respect to masticatory performance with aging. With sufficient FTUs and posterior tooth support, although age-dependent decreases in the bite force, tongue pressure and handgrip strength were observed, masticatory performance was maintained. Establishing the PBA by improving occlusion through dental treatment is thought to be important for masticatory function.

Distribution of lip-seal strength and its relation to oral motor functions

Objectives

Lip‐seal strength, which represents the muscle strength of the lips, appears to chiefly contribute to mastication and pronunciation. However, the functional characteristics of lip‐seal strength in adults are still undefined. The present study aimed to understand not only the distribution of lip‐seal strength in adult men and women but also the effect of age on this strength and identify oral motor functions correlated with lip‐seal strength.

Materials and methods

The subjects included 339 participants (men: 170, age 39.2 ± 18.2 years; women: 169, age 43.1 ± 19.7 years). Oral motor function was evaluated for lip‐seal strength, oral diadochokinesis (ODK), tongue pressure, occlusal force, and masticatory performance. Statistical analyses included the Shapiro–Wilk, Mann–Whitney U, and Jonckheere–Terpstra tests, in addition to the Spearman's correlation analysis and curvilinear regression analysis.

Results

Lip‐seal strength did not have a normal distribution (p < 0.001). The mean ± standard deviation and median (first quartile, third quartile) of lip‐seal strength were 11.2 ± 3.4 and 10.9 (8.7, 13.2)N for the whole sample, 12.3 ± 3.4 and 11.9 (9.4, 14.4)N for men, and 10.2 ± 3.0 and 9.9 (8.0, 12.0)N for women. A significant difference was observed in lip‐seal strength between men and women (p < 0.001). Oral motor functions showed a marked correlation with lip‐seal strength, including tongue pressure, occlusal force, and masticatory performance and ODK (/pa/ and /ta/), tongue pressure, and masticatory ability in men and women, respectively. In women, lip‐seal strength declined with increase in age.

Conclusions

Lip‐seal strength was non‐normally distributed in both men and women, and lip‐seal strength was affected by age only in women. Lip‐seal strength and multiple oral motor functions were significantly correlated. Because the indicators of perioral muscle strength and performance were correlated with lip‐seal strength, lip‐seal strength may also partially reflect the condition of the perioral muscles.

Finite element simulation of fixed dental prostheses made from PMMA -Part I: Experimental investigation under quasi-static loading and chewing velocities

Material properties are of high clinical relevance, even though in vitro laboratory setups may differ from clinical conditions. Therefore, the aim of the present study was to investigate the fracture behavior of three-unit bridge restoration (Telio CAD) with different test velocities (1.0 mm/min International Organization for Standardization (ISO) standard speed/ 130 mm/s mean chewing velocity) and to provide crucial validation experiments for the upcoming Part 2 of our study, in which FEA on such temporary restorations will be conducted. Local strains were detected using digital image correlation (DIC). The material exhibited significantly different responses at different test velocities, and the forces at fracture were found to be much smaller at chewing velocity (130 mm/s) than in the quasi-static test. Overall, the results of the present study show that characteristics pertaining to material behavior can change significantly with increasing chewing velocity, and that fracture forces decrease with increasing test velocity.

Validation of masticatory function and related factors in maxillectomy patients based on the concept of "oral hypofunction": A retrospective cross-sectional study

PURPOSE

Although oral functions have been evaluated by various methods in maxillectomy patients, there exists substantial difficulty in the assessment procedures. The purpose of this study was to evaluate masticatory function, maximum occlusal force (MOF), and maximum tongue pressure (MTP) in maxillectomy patients objectively as per the "oral hypofunction" criteria, and examine the factors that correlate with masticatory function.

METHODS

This retrospective cross-sectional study included 50 maxillectomy patients with maxillofacial prostheses (23 males and 27 females, median age, 72 years; interquartile range (IQR), 63.75-77). The records of masticatory function, MOF, and MTP as per the "oral hypofunction" criteria and their profiles (age, number of occlusal supports, and maxillary defect configuration) were reviewed. The number of patients who exceeded a threshold value of "oral hypofunction" and the effects of occlusal support and defect configuration on masticatory function and MOF were calculated. Multiple regression analysis was performed to assess the associations between masticatory function and other variables.

RESULTS

The median value of masticatory function (114 mg/dL, IQR: 73-167.5) exceeded a threshold value, but not MOF (229.2 N, IQR: 110.2-419.6) and MTP (25.9 kPa, IQR: 21.4-29.0). The number of patients who exceeded each threshold value was 27 (masticatory function), 8 (MOF), and 12 (MTP), respectively. The influence of the number of occlusal supports, but not the defect configuration, was statistically significant. Multiple regression analysis revealed that MOF was independently related to masticatory function (P=0.042).

CONCLUSIONS

Within the limitations of this study, the median value of masticatory function in maxillectomy patients could exceed a threshold and MOF might be an independent predictor of masticatory function.

Improvement of oral hypofunction by a comprehensive oral and physical exercise programme including textured lunch gatherings

The deterioration of oral function to a state of oral hypofunction (OHF) is reportedly associated with malnutrition and frailty. Thus, we Investigated the association of OHF with physical characteristics and function and test the effects of a programme including comprehensive oral and physical exercises and textured lunch gatherings (COPE-TeL programme) on oral and physical function in older adults with OHF. Eighty-six community-dwelling older adults were randomly assigned into control (n = 43) or intervention (n = 43) groups. The participants were further divided into OHF and normal oral function (NOF) sub-groups based on initial oral examinations. The intervention group participated in the 12-week COPE-TeL programme, while the control group performed the physical exercise regimen only. The differences in measured variables for physical and oral function between the OHF and NOF groups were statistically tested, and changes in the proportion of participants with OHF were examined. Physical function, such as hand grip strength and walking speed, was significantly lower in the OHF group at the initial assessment. The proportion of participants with OHF was 56% in the intervention group and 67% in the control group before the trial, which became significantly reduced after completing the COPE-TeL programme in the intervention group (26%, P = .002), but not in the controls (61%, P = .549). Older adults with OHF may have diminished physical function. The COPE-TeL programme of oral and physical exercises along with textured lunch gatherings may be effective for older adults with OHF.

A prediction model of masticatory performance change in 50- to 70-year-old Japanese: The Suita study

OBJECTIVES

Declines in masticatory performance might be a risk factor for worsening nutritional intake and result in general frailty. The present study constructed and investigated a method to predict the extent to which objective masticatory performance declines with age in cases with poor oral health status.

METHODS

Participants comprised 1201 participants in the Suita study with dental checkup at both baseline and follow-up (500 men and 701 women; age at baseline, 65.6 ± 7.8 years; mean follow-up, 5.1 ± 1.1 years). First, multiple linear regression analysis was performed with masticatory performance at follow-up as the dependent variable and sex as well as baseline age, number of functional teeth, maximum bite force, occlusal support, periodontal status, salivary flow rate, and masticatory performance as independent variables. Scores were assigned to each factor based on the standardized partial regression coefficient obtained from multiple linear regression analysis. Participants were divided into quintile groups (Q1-Q5) based on total scores for factors, and rates of masticatory performance change for each group were calculated and compared.

RESULTS

Mean rates of masticatory performance change in groups Q1-Q5 from the model to predict declining masticatory performance were: Q1, -9.7%; Q2, -12.7%; Q3, -18.0%; Q4, -19.9%; and Q5, -29.8%.Thus there was a trend for masticatory performance to decrease with decreasing score.

CONCLUSIONS

The model developed in this study quantitatively predicted declines in masticatory performance after approximately 5 years.

CLINICAL SIGNIFICANCE

We developed a model for predicting the extent to which masticatory performance will change over the next 5 years. This model may offer a useful tool when taking measures to prevent declines in masticatory performance with aging.

Association between masticatory ability and oral functions

Background

Mastication is the process of breaking ingested food with the teeth and mixing it with saliva to form a mass that is easy to swallow. However, few studies have reported on oral functions, such as occlusal force, tongue pressure, and mastication. The purpose of this study was to evaluate the association between masticatory function and oral functions, such as occlusal force and tongue pressure.

Material and Methods

In this study, there were 113 patients (41 men and 72 women; mean age, 68.4 ± 11.3 years) who visited dentists at the Hiroshima University Hospital, Hiroshima, Japan between April 2015 and November 2018. Masticatory function of the patients was evaluated using a masticatory ability test system. In addition, occlusal force was measured using a pressure-sensitive film and the maximum tongue pressure was measured with a tongue pressure measuring device according to a conventional method. The relationship of masticatory ability with occlusal force and tongue pressure was examined using multivariate analysis while considering patients’ age, gender, and the number of remaining teeth.

Results

Masticatory ability was significantly related to occlusal force, maximum tongue pressure, age, body mass index, the number of remaining teeth, and occlusal contact area (p< 0.05). Multiple regression analysis identified that masticatory ability was significantly associated (p< 0.05) with occlusal force and maximum tongue pressure.

Conclusions

Masticatory ability was significantly associated with occlusal force and maximum tongue pressure, indicating that the large muscle mass in the oral cavity is indispensable for improving masticatory function.

Key words:Mastication, tongue pressure, occlusion force, oral function.

Is the assumption of linear elasticity within prosthodontics valid for polymers? -An exemplary study of possible problems

As shown in previous studies within other scientific fields, the material behavior of polymethyl methacrylate (PMMA) is viscoelastic-viscoplastic. However, in dental biomaterial science it is mostly considered as linear elastic or elastic-plastic. The aim of the present study was to evaluate, whether the assumption of elastic or elastic-plastic material behavior for PMMA is a practicable simplification or a potential source of error, especially considering clinical loading conditions. Telio-CAD was tested in three-point bending tests with different test velocities to examine the material behavior at different initial loading rates. Additionally, a dynamic-mechanical-thermal-analysis at different frequencies and temperatures was used. Here, a significant influence of loading rate and temperature as well as stress relaxation and creep were observed. To describe the rate-dependency of the elastic modulus, a new model was created, from which the elastic modulus can be calculated with a given strain rate. This model was validated using linear elastic finite element analysis.

Association among kidney function, frailty, and oral function in patients with chronic kidney disease: a cross-sectional study

Background

Chronic kidney disease (CKD) involves many factors that can cause frailty and oral hypofunction. We aimed to investigate the prevalence of frailty and oral hypofunction and to examine the associations among kidney function, frailty, and oral function in adults with CKD in Japan.

Methods

This cross-sectional study was conducted at two institutions. The participants included 109 patients with CKD stages 3–5 who visited outpatient clinics or were admitted for inpatient treatment. Frailty was evaluated using the Japanese version of the Cardiovascular Health Study frailty criteria. Oral function was evaluated by assessing oral motor skills [oral diadochokinesis (ODK) rate], masticatory ability, and the repetitive saliva swallowing test. The estimated glomerular filtration rate (eGFR) was used to indicate kidney function. We examined the associations among kidney function, frailty, and oral function using binomial logistic regression analysis.

Results

In total, 31 participants (28.4%) were classified as being frail. Univariate analysis showed that age, body mass index, eGFR, and haemoglobin level were significantly associated with frailty. ODK and swallowing function were significantly associated with frailty. Multivariate analysis revealed that frailty was significantly associated with eGFR [odds ratio (OR) 0.96, 95% confidence interval (CI) 0.92–1.00, p = 0.048] and ODK rate (OR 0.68, CI 0.47–0.98, p = 0.038). However, no significant association was found between CKD severity and masticatory or swallowing function.

Conclusion

We found a high prevalence of frailty in patients with CKD and a significant association between frailty and oral motor skills, affecting the swallowing function of patients with nondialysis CKD. The high prevalence of frailty among patients with CKD suggests that routine assessment of frailty is necessary to prevent the development of severe complications. In addition, oral and kidney function should be carefully evaluated, and oral health education and interventions should be performed for patients with CKD.

The Association of Oral Function with Oral Health-Related Quality of Life in University Students: A Cross-Sectional Pilot Study

The aim of this cross-sectional study was to investigate the association between oral function and oral health-related quality of life (OHRQoL) in healthy university students. Oral functions and OHRQoL (General Oral Health Assessment Index; GOHAI) were investigated in 58 healthy university students. Oral functions, such as tongue pressure, tongue-lip motor function, occlusal force, and masticatory function, were examined. The participants were divided into two groups based on low and high GOHAI scores. Information about oral health, dental caries treatment history, insomnia, and personality and lifestyle was obtained using a self-reported questionnaire. Oral mucosal wetness scores and tongue-lip motor functions (oral diadochokinesis /ka/) were significantly decreased in the low GOHAI score group compared to the high GOHAI score group (p = 0.001 and p = 0.017, respectively). In the logistic regression model, the GOHAI score was independently associated with the oral mucosal wetness score (odds ratio (OR) = 0.622; 95% confidence interval (CI), 0.411–0.941; p = 0.025) and oral diadochokinesis /ka/ (OR = 0.376; 95% CI, 0.170–0.832; p = 0.016). Our study demonstrated the presence of low oral function in university students and suggested its association to low OHRQoL in this population.

Textural Changes by Mastication and Proper Food Texture for Patients with Oropharyngeal Dysphagia

Bolus texture is a key factor for safe swallowing in patients with dysphagia since an improper texture may result in aspiration and/or pharyngeal residue. This article discusses swallowing bolus texture from two key aspects: the textural change of solid food by mastication and the current standardized definition of food texture in Japan. When swallowing a liquid bolus, the texture is mostly maintained from ingestion to swallow onset. For solid food, however, the food is crushed by chewing and mixed with saliva before swallowing; the texture of the ingested food is modified to an easily swallowable form at swallow onset by mastication. Understanding the mechanism of mastication and its assessment are therefore important in deciding the proper diet for dysphagic patients. As standardized criteria for classifying the texture of food and liquid are essential as well, this report also describes the Japanese Dysphagia Diet 2013 that is commonly used as the standardized index for dysphagic diets in Japan.

A Cross-Sectional Study of Age-Related Changes in Oral Function in Healthy Japanese Individuals

BACKGROUND

Oral function deterioration is related to a variety of factors, including aging, decline in activities of daily living, malnutrition, and cognitive decline. This cross-sectional study examined the effects of aging on oral function in healthy individuals.

METHODS

A retrospective study was conducted on 175 healthy, independent patients aged 40-89 years, without dementia and with ≥20 teeth, who visited a local dental clinic in Japan. Patients were compared with 92 university students aged 20-29 years. The seven criteria proposed by the Japanese Society of Gerodontology to diagnose "oral hypofunction" were observed and statistically analyzed.

RESULTS

Compared with those in the control group, the degree of tongue coating was increased in the group aged over 80 years, occlusal force was decreased in the group aged 70-79 years, tongue motor function was decreased in the groups aged 60-69 years and older, and tongue pressure was decreased in the groups aged 70-79 years and older.

CONCLUSIONS

Healthy, independent individuals maintained several oral function criteria across aging, including oral mucosal wetness, occlusal force, lip motor function, masticatory function, and swallowing function. Tongue motor function and tongue pressure decreased with aging, indicating that these may be rehabilitation targets.

Relation of dietary preference to masticatory movement and masticatory exercises in Japanese children

OBJECTIVE

Modern Japanese children have decreased masticatory function, which can be explained by the dietary change to soft foods. In earlier studies involving children with mixed dentition, masticatory exercises were shown to improve masticatory function and modify dental arch growth. Grinding type of mastication with a wide path reportedly increases lateral growth of the dental arch. This study aimed to assess the relationship between masticatory movements and dietary preference, and how masticatory exercises affected masticatory movement during Hellman's dental stages IIA to IIC (period of first molar eruption).

DESIGN

In 64 Japanese pre-school children, we measured masticatory movements with foods of five different levels of hardness and investigated the dietary preference for hard foods through a questionnaire. Participants were also required to perform masticatory exercises. Masticatory movements and dietary preference for hard foods were assessed at the start (T1), conclusion (T2), and after six months of exercises (T3). Participants were allocated to Wide and Narrow groups at T1 based on their masticatory path width.

RESULTS

Baguettes and bananas resulted in the widest and narrowest masticatory paths, respectively, at T1. Results of questionnaire indicated that those eating hard foods had a broad grinding type of masticatory path. Masticatory exercises significantly widened the masticatory path in the Narrow group demonstrating that masticatory exercises help children learn to chew with grinding strokes. Moreover, the masticatory path remained stable on assessment at T3 (six-month follow-up).

CONCLUSIONS

Masticatory exercises are effective in children who are unable to grind hard foods, affecting their dietary preferences.

Differences in comminution progress during mastication in healthy dentate and denture-wearing elderly people

PURPOSE

This study aimed to investigate the effect of removable denture prostheses on the comminution progress in elderly people.

METHODS

Twenty-two denture wearers of Eichner's classification B and C (75.1±5.3 years old) and 20 young fully dentate subjects (27.6±1.9 years old) participated in the masticatory examination, which used a combined test food from 5 daily food materials. Full masticatory cycles lasting until subjects needed to swallow and the half number of the cycles were adopted as masticatory conditions. Digital images of food particles under wet conditions were obtained for each bolus, and particles were analyzed by calculating the homogeneity and particle size indices.

RESULTS

The characteristic properties of the food particles were observed using a homogeneity index in the elderly denture group for half masticatory strokes. Their homogeneity index was significantly higher than that of the young dentate group. By contrast, no significant difference was observed in the indices for particles immediately before swallowing between two groups.

CONCLUSIONS

The comminuted particle size before swallowing in healthy denture wearers was not significantly different from that in the natural dentate group. The comminution of the first-half process in denture wearers was typical and could be one possible focus for meal property specifications in future studies.

Masticatory performance analysis using photographic image of gummy jelly

PURPOSE

Masticatory performance can be measured through elution of glucose or beta-carotene from comminuted gummy jelly. However, these methods require special devices. Additionally, occasional/unintentional swallowing or inadequate collection of comminuted particles of gummy jelly in the oral cavity may cause measurement errors. Therefore, we devised a new photographic method to estimate the increase in surface area and weight of comminuted gummy jelly. This study aimed to verify the accuracy of this method.

METHODS

Initially, fifty images depicting the comminuted pieces in a special box were prepared. Then, the increase in surface area was measured using a fully-automated method, and the weight was measured. The size and angle of each image were adjusted based on markers located at the four corners of the box. From these photographic images, the area, perimeter, color average, color deviation, side area, and amount of surface roughness for each particle was calculated, and multiple regression analysis was performed to estimate the surface area and weight. The relationship between the estimated values and the values measured with the fully-automated device and by weight were analyzed.

RESULTS

The intra-class correlation coefficient between the estimated value and the value from the fully-automated method was r = 0.956. This high correlation was also obtained under different photographic conditions. Furthermore, for determining whether 80% or less gummy jelly was collected, the sensitivity was 100% and the specificity was 91%.

CONCLUSIONS

The newly developed photographic method is valuable because it is accessible and may assist in achieving reliable evaluation of masticatory performance.

Influence of decrease in the muscle activity during mastication on occurrence of the Stage II transport

PURPOSE

The purpose of this study was to examine the hypothesis that in the process from food ingestion to swallowing, intentional decrease in the muscle activity during mastication would affect the number of chewing strokes, and thus the occurrence of Stage II transport (St2Tr) or the number of swallowing.

METHODS

Twenty adults with healthy dentition were instructed to make (1) normal mastication and (2) mastication with 50% muscle activity (50% mastication), controlled by visual feedback with electromyogram. Gummy jelly was selected as a test food. The oropharynx was observed during the sequence of events from the start of mastication until swallowing using a nasal endoscope. The number of chewing strokes was calculated by rhythmical masseter muscle activity on electromyogram.

RESULTS

The number of chewing strokes increased with 50% mastication. There was a particularly noticeable increase in the number of pre-St2Tr strokes. No effect on the number of additional swallows was seen as a result of 50% mastication.

CONCLUSIONS

The present study supported the hypothesis that intentional decrease in the muscle activity during mastication affected the number of chewing strokes and the occurrence of St2Tr. Particularly, this tendency was noticeable during the mastication before the start of St2Tr. However, our results did not support a question as to the number of swallowing.

Relationship between bite size per mouthful and dental arch size in healthy subjects

Although multiple factors influence food bite size, the relationship between food bite size per mouthful and mandible or tongue size remains poorly understood. Here, we examined the correlations between food bite size and the lower dental arch size (an indicator of tongue size) in human subjects with good oral and general health, using fish sausage and bread as test foods. Notably, bite size of both foods was significantly positively correlated with the lower dental arch size, whereas masticatory performance (measured in terms of glucose extraction from a gummy jelly) showed no dependence on bite size. Further, bite size was significantly positively correlated with the body mass index. Our findings suggest that larger bite size is associated with larger tongue size, which might be a contributory factor to obesity.