Association between tongue and lip functions and masticatory performance in young dentate adults

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.

Factors associated with masticatory performance in community-dwelling older adults: A cross-sectional study

BACKGROUND

Decreased masticatory performance leads to deterioration of overall health among older adults. However, maintaining and improving masticatory performance in ways other than maintenance of natural teeth and appropriate prosthodontic treatment remains unclear. If the factors related to the mixing and shearing abilities for masticatory performance are clarified, it may be possible to maintain and improve the masticatory performance of older adults. We aimed to clarify the association among mixing ability, shearing ability, and masticatory performance-related factors.

METHODS

Of the 707 community-dwelling older adults in Kusatsu Town, Japan, 344 who had been treated for any dental defects were enrolled in this study. Masticatory performance was evaluated on the basis of mixing ability and shearing ability. The number of natural teeth and artificial teeth, occlusal force, tongue pressure, and oral diadochokinesis /ta/ were measured as masticatory performance-related factors. Their relationship with mixing ability, shearing ability, and masticatory performance-related factors was examined by means of Spearman rank correlation coefficient and path analysis.

RESULTS

Among masticatory performance-related factors, the number of natural teeth, occlusal force, and tongue pressure were directly associated with both mixing ability and shearing ability. Moreover, mixing ability was also directly associated with shearing ability.

CONCLUSIONS

Tongue pressure, which can be improved by means of training, is a masticatory performance-related factor associated with both mixing and shearing abilities.

PRACTICAL IMPLICATIONS

Training for tongue pressure after proper prosthetic treatment may provide an effective means of maintaining and improving masticatory performance in older adults.

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.

Improvement of physical and oral function in community-dwelling older people after a 3-month long-term care prevention program including physical exercise, oral health instruction, and nutritional guidance

Objective

There is limited evidence about the most appropriate way to improve physical and oral function in older people. The aim of this study was to clarify the effectiveness of a long-term care prevention program combining physical exercise, oral health instruction, and nutritional guidance among community-dwelling older people.

Materials and methods

We included 43 older people aged at least 65 years (seven men and 23 women; mean age 75.3 years) in Bungotakada City, Japan. The 3-month program involved a weekly intervention. Physical and oral function was investigated on the first day of the program (i.e., baseline) and at the end of the program (i.e., after 3 months). Physical function was examined using measures such as handgrip strength, timed up-and-go test, and one-leg standing time with eyes open. An oral diadochokinesis test was used to assess oral function.

Results

Mean maximum handgrip strength increased significantly in older people aged ≤74 years (younger participants) and those aged ≥75 years (older participants) after 3 months compared with the baseline. The timed up-and-go test duration was significantly lower in older participants after the program. Repetition of the monosyllables pa and ka and the repetitive saliva swallowing test was significantly improved in both groups. The dysphagia risk assessment for the community-dwelling elderly score was significantly lower in younger participants after 3 months.

Conclusion

Participation in a 3-month program combining physical exercise, oral health instruction, and nutritional guidance may contribute to improvement or maintenance of oral and physical function in older people.

Association between tongue and lip motor functions and mixing ability in complete denture wearers

BACKGROUND

Masticatory performance of elderly complete denture wearers is low, which may lead to restriction on intakes of several foods such as fresh fruit or raw vegetables.

AIM

The aim of this study was to investigate the relationship between tongue motor function, lip motor function, and mixing ability in complete denture wearers.

MATERIALS AND METHODS

Participants comprised 54 complete denture wearers with a mean age of 77.1 years. Maximum tongue pressure and oral diadochokinesis were measured to evaluate tongue and lip motor functions. A color-changeable, chewing gum was used to evaluate mixing ability. The relationship between tongue and lip motor functions and mixing ability was assessed using stepwise multiple regression analysis.

RESULTS

The stepwise multiple regression analysis identified maximum tongue pressure, the number of repetitions of the syllable "ka", and gender as significant predictors for mixing ability among complete denture wearers.

DISCUSSION

The elderly edentulous individuals mainly used tongue motor function in oral motor functions for mixing color-changeable chewing gums, which might be ascribable to wearing complete dentures.

CONCLUSIONS

Under the limited conditions of this study, factors relating to tongue motor function, tongue pressure and the number of repetitions of the syllable "/ka"/ significantly contributed to the mixing ability of complete denture wearers. It was suggested that tongue motor function had positive effect on the mixing ability of complete denture wearers.

Association between echo intensity of the tongue and its thickness and function in elderly subjects

BACKGROUND

The tongue plays an important role during the oropharyngeal phase of swallowing. Each part of the tongue has a different function during swallowing. Ageing causes changes in muscle quantity and quality. Qualitative changes, such as an increase in intramuscular adipose tissue, can be determined by the echo intensity (EI) of the tongue on ultrasonography (US).

OBJECTIVE

To clarify the relationship between EI and thickness and function of the tongue.

METHODS

Ninety-four healthy elderly individuals (30 male, 64 female) aged >65 years (mean 71.10 ± 4.13 years) were enrolled. Tongue thickness (TT) and EI were determined by US. Tongue function was evaluated by measurement of tongue pressure and oral diadochokinesis (OD). Multiple regression analysis was used to identify the factor with the strongest influence on EI of the tongue.

RESULTS

The mean thickness of the middle of the tongue was 40.42 ± 4.24 mm and that of the base was 23.35 ± 3.32 mm; the respective EI values were 46.54 ± 9.33 and 49.33 ± 9.83. The average OD rates for /ta/ and /ka/ were 5.73 ± 1.09 and 5.40 ± 1.00 times/s, respectively. Multiple regression analysis for EI showed that /ta/ (β = -2.518, P = 0.042) and thickness of the middle of the tongue (β = -1.278, P < 0.001) were significant independent variables. Similarly, the EI at the base of the tongue showed that /ka/ (β = -4.038, P = 0.021) and base of TT (β = -0.913, P = 0.004) were significant independent variables.

CONCLUSION

EI may be an indicator of TT and OD in both the middle and base of the tongue. Ultrasound is beneficial for evaluating TT and function.

Positive Effects of "Textured Lunches" Gatherings and Oral Exercises Combined with Physical Exercises on Oral and Physical Function in Older Individuals: A Cluster Randomized Controlled Trial

OBJECTIVES

Proper nutrition and physical exercises are essential to prevent frailty in older adults. Proper masticatory performance and oral function may influence on physical activities as well since the mouth is the entrance of nutrition and digestion. Thus, the present study aimed to test the combined program of specially devised lunch gatherings containing textured foods with oral and physical exercises on the improvement of oral and physical function in community-dwelling older adults.

DESIGN

A Cluster randomized controlled trial; Setting and Participants: Eighty-six community-dwelling older adults in Daito city, Japan, were randomly assigned into control (n = 43) or intervention (n = 43) groups.

INTERVENTION

The control group performed the physical exercise regimen only. The intervention group participated in a 12-week physical and oral exercise program and ate a so-called "munchy lunch" that introduced textured foods with proper nutrients together after performing the physical exercise twice a week following brief dietary instruction at the intervention onset. Physical training and lunch gatherings were held at local public centers.

MEASUREMENTS

The differences in measured variables for physical and oral function between baseline and 12 weeks of intervention were statistically tested.

RESULTS

Oral function as measured by tongue pressure increased significantly in the intervention group (p=0.031), but not in the control group. Physical properties and activities, including body fat percentage and results of the timed up and go test, decreased more significantly in the intervention group than in controls (p<0.05).

CONCLUSIONS

Our findings suggest that a combined program of textured lunch gatherings with oral and physical exercises may improve physical and oral function as a preventative approach for frailty in community-dwelling older adults.

Association of feeding behavior with jaw bone metabolism and tongue pressure

In recent decades, the eating habits of children and adolescents have undergone many changes due to the diversification of lifestyles worldwide. Reduced masticatory function in growing animals results in changes in the mandible, including a decrease in bone mass. However, the influence of different eating behaviors on jaw bone metabolism (e.g., the palatal palate) during the growth period is not fully understood. In addition, recent clinical studies reported that masticatory performance is positively related to tongue pressure in adults, but no consensus has been reached regarding whether tongue pressure is related to masticatory performance in children. This review summarizes current findings related to these issues, focusing on the influence of different feeding behaviors on jaw bone metabolism, including the development of tongue pressure. Consumption of a soft diet had a negative impact on jaw bone metabolism in the maxilla and mandible of rats; however, mastication of a hard diet recovered the collapsed equilibrium of bone turnover caused by a soft diet during growth. Tongue pressure is closely associated with an increase in masticatory performance in children. Peak maximum tongue pressure is reached earlier in women than in men. Before reaching adulthood, women require intervention to increase their peak tongue pressure.

Validation of a purpose-built chewing gum and smartphone application to evaluate chewing efficiency

OBJECTIVES

To validate a purpose-built two-coloured chewing gum (Hue-Check Gum^® ), and to test the accuracy of a custom-built smartphone application for a colour-mixing ability test to assess chewing function.

METHODS

Fully dentate participants (28D-group) and edentulous participants with implant overdentures (IOD-group) were recruited. They chewed a Hue-Check Gum^® for 5, 10, 20, 30 and 50 chewing cycles, respectively. Maximum voluntary bite force (MBF) was assessed with a digital gauge. The specimens were analysed according to their colour mixture (variance of hue, VOH) with a validated software (VOH_scan) and a newly developed smartphone application (VOH_app).

RESULTS

Participants segregated by dental state were significantly different regarding the number of occluding pairs of teeth, age and MBF. VOH_scan showed a negative logarithmic association with the number of chewing cycles, and VOH could be predicted from chewing cycles, MBF and gender. The clearest discrimination between the IOD and the 28D groups was observed for n = 20 chewing cycles; at this point, VOH was distinguishably different with a P-value < 0.0001. The VOH_app was a very good predictor for VOH_scan with 0.80 < pseudo-R²  < 0.83, depending on light exposure and measuring distance. There was, however, a systematic error in the accuracy of the app for inadequately chewed specimens.

CONCLUSIONS

The use of the two-coloured chewing gum would provide a fast, simple and inexpensive method for the assessment of masticatory performance, which could be used in geriatric wards or in private practices without the requirement of specialised equipment or trained staff.

Factors Influencing the Changes in Masticatory Performance: The Suita Study

Introduction:

Although previous studies have identified various factors related to masticatory performance, which factors affect longitudinal changes in masticatory performance have not been clarified.

Objectives:

We aimed to clarify factors involved in changes to masticatory performance and construct models from factors related to masticatory performance in a longitudinal study of a general urban population in Japan.

Methods:

A total of 1,005 Japanese subjects (411 men, 594 women; mean age at baseline, 65.7 ± 7.7 years; mean follow-up period, 5.0 ± 0.9 years) were included in the Suita study. These subjects participated in dental checkups both at baseline (June 2008–December 2011) and at follow-up (June 2013–January 2017). The number of functional teeth and occlusal support areas was recorded and the latter assessed using the Eichner index. Subjects’ periodontal status was evaluated based on the Community Periodontal Index. Masticatory performance was determined using test gummy jelly. Factors affecting masticatory performance at follow-up and the degree of their effect were investigated by multiple linear regression analysis.

Results:

In multiple linear regression analysis with masticatory performance at follow-up as the dependent variable, baseline age, masticatory performance, number of functional teeth, and maximum bite force were significant independent variables. The results of multiple linear regression analyses by occlusal support at baseline identified only maximum bite force at baseline in subjects who were Eichner A and baseline age, masticatory performance, and number of functional teeth in subjects who were Eichner B as significant independent variables concerning masticatory performance at follow-up.

Conclusion:

Our study showed a relationship between longitudinal changes in masticatory performance and age, number of functional teeth, and maximum bite force and furthermore showed that the effects of these factors vary according to the residual number of occlusal support areas.

Knowledge Transfer Statement:

Patients and clinicians should recognize the importance of objective and quantitative assessment for chewing efficiency and understand that various factors are related to longitudinal changes in masticatory performance. The results of this study can provide basic data for preventing or improving the decline in masticatory performance for elderly people with varying numbers of occlusal support areas.

Oral hypofunction in the older population: Position paper of the Japanese Society of Gerodontology in 2016

BACKGROUND

There is growing international interest in identifying the effects of ageing on oral health and on appropriate strategies for managing oral disorders. The Japanese Society of Gerodontology (JSG), as the official representative of researchers and clinicians interested in geriatric dentistry in Japan, makes several recommendations on the concept of "oral hypofunction."

AIMS

This study proposes diagnostic criteria and management strategies to reduce the risk of oral hypofunction among older people.

CONCEPTUAL FRAMEWORK

We define oral hypofunction as a presentation of 7 oral signs or symptoms: oral uncleanness; oral dryness; decline in occlusal force; decline in motor function of tongue and lips; decline in tongue pressure; decline in chewing function; and decline in swallowing function. The criteria of each symptom were determined based on the data of previous studies, and oral hypofunction was diagnosed if the criteria for 3 or more signs or symptoms were met.

CONCLUSIONS

We recommend that more evidence should be gathered from clinical studies and trials to clarify our diagnostic criteria and management strategies.

Comparison of masticatory performance and tongue pressure between children and young adults

The aims of the present study were to evaluate whether there are significant differences in masticatory performance by gender and dental stage. We also determined the factors directly associated with the masticatory performance in children, and those directly associated with masticatory performance in young adults. The study included 180 subjects, ranging in age from 6 to 12 years or 20 to 33 years. The subjects were divided into three groups according to the Hellman developmental stage (III A, III B, or VA); the groups were the subdivided according to gender. The body mass index (BMI), maximum tongue pressure, and sum of decayed, missing, and filled teeth (DMFT) were determined in all subjects. To investigate masticatory performance, the total number and maximum projected area of chewed particles of the jelly materials were measured. Masticatory performance had the highest values at Stage VA in both males and females. Regarding the maximum tongue pressure in females, Stage III B had the highest value of all stages. Multiple regression analysis showed that masticatory performance was associated with DMFT index, maximum tongue pressure, and BMI in children. Among young adults, masticatory performance was associated with DMFT index and maximum tongue pressure. Better masticatory performance is directly associated with better dental status, a higher BMI, and tongue pressure in schoolchildren. Additionally, masticatory performance was well-correlated with tongue pressure in young adults, although maximum tongue pressure reached its peak before Stage VA in females. We suggest that females need training with respect to tongue pressure, by the mixed dentition stage.

Reliability of a two-colour chewing gum test to assess masticatory performance in complete denture wearers

The aim of this study was to test the reliability of a method to measure the masticatory performance of complete denture wearers employing a colour-mixing ability test and assessment by visual and electronic colourimetric analysis. A sample of 75 subjects was selected from patients who received new conventional complete dentures. Masticatory tests were performed using a two-colour chewing gum that was masticated for 5, 10, 20, 30 and 50 chewing cycles, performed in a random order. The mixing level of the two colours of the chewed gum was assessed visually by two independent raters based on a 5-point ordinal scale. The specimens were flattened into a 1-mm-width wafer, scanned and saved as a two-sided digital image. Each pair of images was submitted to an electronic colourimetric analysis to assess the level of colour mixture, measured by the circular variance of hue (VOH). Overall inter- and intra-rater agreements in visual analysis were 64% and 68%, respectively (almost 99% of scores ranged within ±1 point), whilst overall weighted kappa was >0.80. A proportional increase in the level of mixture occurred with increased number of chewing cycles (P < .001). Similarly, VOH and the visual analysis were highly correlated (r = -.89; P < .001). Bland-Altman plots revealed excellent agreement and extremely low systematic error between duplicated VOH measures. It was concluded that the two-colour chewing gum test is a reliable method to assess the masticatory performance in complete denture wearers using both visual and electronic colourimetric analyses.

Revisiting the link between cognitive decline and masticatory dysfunction

Age-related decline in cognitive functions and dementia are major challenges in geriatric healthcare. Accumulating evidence from clinical, epidemiological and animal research suggests that tooth loss may be a risk factor for the decline of cognitive functions. This issue highlights the role of the brain-stomatognathic axis in geriatric medicine. Whether input from the stomatognathic apparatus can affect the brain remains an open debate. By revisiting the evidence published in the past five years, we argue that the hypothesis regarding the association between cognitive decline and masticatory dysfunction should be carefully interpreted. Most of the available clinical and epidemiological studies present only cross-sectional data. With respect to the prospective studies, important confounding factors, such as nutritional and physical conditions, were not fully controlled for. Animal research has revealed that hippocampal deficits may play key roles in the observed cognitive decline. However, experimental intervention and outcome assessments may not capture the condition of human subjects. Brain neuroimaging research may be suitable for bridging the gap between clinical and animal research, potentially contributing to (a) the clarification of the brain network associated with mastication, (b) the identification of brain imaging markers for exploring the mechanisms underlying long-term changes in masticatory functions, and (c) the elucidation of interactions between mastication and other cognitive-affective processing systems. Three potential models of the brain-stomatognathic axis and relevant hypotheses are summarized, focusing on the sensory feedback mechanisms, the compensation of motor control, and cerebellar deficits. Finally, we highlight four critical aspects of study and experimental design that should be considered in future research: (a) the refinement of the considered behavioral assessments, (b) the inclusion of baseline changes in mental and physical conditions,

How fast can treatment with overdentures improve the masticatory function and OHRQoL of atrophic edentulous patients? A 1-year longitudinal clinical study

OBJECTIVES

The aim of this prospective clinical study was to evaluate the masticatory function (MF) and subjective perception of patients with poor denture-bearing tissue in relation to change and the time required to identify an improvement in these parameters after rehabilitation with mandibular overdentures (MO) by two narrow-diameter two-piece implants.

MATERIAL AND METHODS

Twenty-three edentulous patients were selected for MO installation. The masticatory function (MF) was evaluated with the masticatory performance (MP) and swallowing threshold (ST) tests. In the MP test, each volunteer was instructed to masticate a portion of Optocal (standardized artificial test food) for 40 masticatory cycles. During the swallowing threshold test, the patients were instructed to chew a new portion of Optocal cubes until they felt the desire to swallow. The MF tests were performed while complete denture (CD) wearers (baseline) and 1, 3, 6, and 12 months after MO loading. In addition, the subjective perception was assessed through the questionnaires Dental Impact on Daily Living (DIDL), Geriatric Oral Health Assessment Index (GOHAI), and Oral Health Impact Profile in Edentulous (OHIP- EDENT) at the baseline and 3, 6, and 12 months after MO loading.

RESULTS

A significant improvement in masticatory function (p < .05) was observed already in the first month of loading. Three months after MO loading, a significant improvement (p < .05) was found in the subjective perception of patients. The effect size indicates that the MO had the greatest impact on the domains related to function and comfort of all questionnaires and in relation to psychosocial domain of the GOHAI. The level of patient satisfaction increased significantly after the MO loading and reached >90% satisfied patients at 12 months.

CONCLUSION

The MO improved both the MF of the patient and their oral health-related quality of life and satisfaction regarding the prosthesis in a short time period.

Tongue strength in patients with subacute myelo-optico-neuropathy

Subacute myelo-optico-neuropathy (SMON) is a neurodegenerative disease that may be caused by overdose or prolonged oral administration of clioquinol. Recently, dysphagia has attracted attention as a complication of SMON. To investigate lingual control in SMON, we examined patients with SMON using assessments of maximum tongue pressure, compared with dysphagia-related diseases, such as sporadic inclusion body myositis (sIBM) and amyotrophic lateral sclerosis (ALS), and healthy volunteer. The mean maximum tongue pressure (P_max) in patients with SMON was 14.7 ± 5.8 kPa, while it was 33.6 ± 4.4 kPa in the controls. In contrast, the mean P_max for patients with ALS with or without bulbar involvement was 7.8 ± 2.7 kPa and 34.4 ± 5.7 kPa, respectively, while it was 29.4 ± 8.2 kPa in patients with sIBM. P_max values correlated with lower limb weakness in SMON patients. Decreases in P_max may be involved in the development of dysphagia in patients with SMON.

Association between chewing-stimulated salivary flow under the effects of atropine and mixing ability assessed using a color-changeable chewing gum

PURPOSE

To assess the time course of chewing-stimulated salivary flow after oral atropine administration, and determine the association between chewing-stimulated salivary flow and mixing ability using color-changeable chewing gum in dentate adults.

METHODS

Ten healthy dentate adults were administered 1mg oral atropine to induce mouth dryness. The subjects' chewing-stimulated salivary flow was assessed using the Saxon test. They were then asked to rinse their mouth with tap water for 15s, and to chew on color-changeable chewing gum for 60s at a constant rate of 60 cycles per min. This procedure was performed before, and at 10-min intervals for up to 120min after the atropine administration. The experiment was repeated after 1 week. Steel's test was used to compare the chewing-stimulated salivary flow rates at each time point after atropine administration with the baseline value. The effect of the stimulated salivary flow rates on the degree of color change was analyzed using linear mixed effects models, with the stimulated salivary flow rates as fixed factors and subjects as the random factor.

RESULTS

Chewing-stimulated salivary flow showed a significant decrease from 50 to 120min after oral atropine administration (P<0.05) and the amount of chewing-stimulated salivary flow had a significant effect on the color change of the color-changeable chewing gum (P<0.001).

CONCLUSIONS

We observed a decrease in stimulated salivary flow after orally administering 1mg atropine, and a positive association between mixing ability using color-changeable chewing gum and chewing-stimulated salivary flow in dentate subjects.

Assessment of masticatory performance by means of a color-changeable chewing gum

PURPOSE

Previous research determined the relevance of masticatory performance with regard to nutritional status, cognitive functions, or stress management. In addition, the measurement of masticatory efficiency contributes to the evaluation of therapeutic successes within the stomatognathic system. However, the question remains unanswered as to what extent modern techniques are able to reproduce the subtle differences in masticatory efficiency within various patient groups. The purpose of this review is to provide an extensive summary of the evaluation of masticatory performance by means of a color-changeable chewing gum with regard to its clinical relevance and applicability.

STUDY SELECTION

A general overview describing the various methods available for this task has already been published. This review focuses in depth on the research findings available on the technique of measuring masticatory performance by means of color-changeable chewing gum. Described are the mechanism and the differentiability of the color change and methods to evaluate the color changes. Subsequently, research on masticatory performance is conducted with regard to patient age groups, the impact of general diseases and the effect of prosthetic and surgical treatment.

RESULTS

The studies indicate that color-changeable chewing gum is a valid and reliable method for the evaluation of masticatory function.

CONCLUSION

Apart from other methods, in clinical practice this technique can enhance dental diagnostics as well as the assessment of therapy outcomes.