Tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism.

BACKGROUND: Coordination among lip, cheek and tongue movements during swallowing in patients with mandibular prognathism remains unclear. OBJECTIVES: This study aimed to identify the temporal sequences of tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism and compared characteristics with those of healthy volunteers. METHODS: Seven patients with mandibular prognathism (mandibular prognathism group) and 25 healthy volunteers with individual normal occlusion (control group) were recruited. Tongue pressures and masseter, orbicularis oris, mentalis and supra- and infrahyoid muscle activities while swallowing gel were measured simultaneously using a sensor sheet system with five measurement points and surface electromyography, respectively. Onset time, offset time and durations of tongue pressure and muscle activities were analysed. RESULTS: In the mandibular prognathism group, tongue pressure was often produced first in more peripheral parts of the palate. Offset of tongue pressure in the posteromedian and peripheral parts of the palate and maxillofacial muscle activities except for orbicularis oris were delayed. Duration of tongue pressure in the anteromedian part of the palate was significantly shorter and durations of masseter, mentalis and suprahyoid muscle activities were significantly longer. Times to onset of orbicularis oris and suprahyoid muscle activities based on first onset of tongue pressure were significantly shorter. CONCLUSION: These results suggest that patients with mandibular prognathism may exhibit specific patterns of tongue pressure production and maxillofacial muscle activities during swallowing.

Decreased oral function in Japanese inpatients with schizophrenia.

AIM: Oral function in patients with schizophrenia has not been well-characterized. To address this, we performed a cross-sectional study of oral function in Japanese inpatients with schizophrenia. METHODS: We measured oral function, including occlusal force, tongue-lip motor function, tongue pressure, and masticatory function in 130 Japanese inpatients with schizophrenia. We then compared the frequency of clinical signs of oral hypofunction among 63 non-elderly and 67 elderly inpatients with schizophrenia, as well as data from 98 elderly control participants from a previous Japanese study. RESULTS: The frequency of reduced occlusal force was significantly higher in the elderly inpatients (76.2%) than in the non-elderly inpatients (43.9%) and elderly controls (43.9%). The frequency of decreased tongue-lip motor function in non-elderly inpatients (96.8%) and elderly inpatients (97.0%) was significantly higher than that in elderly controls (56.1%). The frequency of decreased tongue pressure in non-elderly inpatients (66.1%) and elderly inpatients (80.7%) was significantly higher than that in elderly controls (43.9%). Finally, the frequency of decreased masticatory function was highest in elderly inpatients (76.5%), followed by non-elderly inpatients (54.8%) and elderly controls (15.3%). CONCLUSION: Oral function was decreased in both non-elderly and elderly Japanese inpatients with schizophrenia compared with elderly controls.

Quantitative evaluation of swallowing function in Parkinson's disease using tongue pressure measurement: a mini-review.

Dysphagia is a common symptom of Parkinson's disease (PD) associated with aspiration pneumonia, choking, malnutrition, and a decreased quality of life, and is a leading cause of death among patients with PD. Tongue dysfunction in patients with PD affects the oral phase of swallowing, including the formation and propulsion of a bolus into the pharynx. Assessing tongue pressure, generated between the tongue and palate, is a method that quantitatively measures tongue function and is related to dysphagia in PD. Two assessment methods are used to measure tongue pressure: tongue strength and tongue pressure during swallowing. Previous studies measuring tongue pressure in PD have reported decreased tongue strength and pressure during swallowing, as well as a prolonged tongue pressure rise time, which are symptoms associated with PD severity and dysphagia. In this mini-review, we present a method for measuring tongue pressure and discuss its relationship with dysphagia in PD. We also describe limitations and future perspectives in tongue pressure measurement research.

Relationship between maximal isometric tongue pressure and limit of fracture force of gels in tongue squeezing.

BACKGROUND: There is no clear objective indicator for selecting soft foods that are required for food bolus formation in older people with impaired oral function. OBJECTIVE: This study aimed to investigate the relationship between maximal isometric tongue pressure (MITP) and the mechanical properties of gels that can be crushed by the tongue. METHODS: This study included 65 healthy participants aged 22-96 (young group; 15 males, 15 females; older dentate group; 7 males, 8 females; older edentulous group; 10 males, 10 females). MITP was measured by the balloon-probe device. Agar gel with 10 different kinds of fracture force from 10N to 100N was used. The limit of fracture force of gels (LFFG) that were crushed by the tongue was measured by the up-and-down method. In the older edentulous group, two items were measured with and without dentures. Spearman's rank correlation coefficient was used to evaluate the relationship between MITP and LFFG in each group (p < .05). RESULTS: There were positive correlations between MITP and LFFG in all groups (overall groups: rs = .66, young group: rs = .46, older dentate group: rs = .61, older edentulous group with dentures: rs = .60, older edentulous group without dentures: rs = .47). CONCLUSION: MITP and LFFG were positively correlated in young, older dentate and older edentulous groups, suggesting that MITP has the potential to be an objective indicator of the range of mechanical properties of soft food that can be crushed by the tongue.

Developing tongue coating status assessment using image recognition with deep learning.

PURPOSE: To build an image recognition network to evaluate tongue coating status. METHODS: Two image recognition networks were built: one for tongue detection and another for tongue coating classification. Digital tongue photographs were used to develop both networks; images from 251 (178 women, 74.7±6.6 years) and 144 older adults (83 women, 73.8±7.3 years) who volunteered to participate were used for the tongue detection network and coating classification network, respectively. The learning objective of the tongue detection network is to extract a rectangular region that includes the tongue. You-Only-Look-Once (YOLO) v2 was used as the detection network, and transfer learning was performed using ResNet-50. The accuracy was evaluated by calculating the intersection over the union. For tongue coating classification, the rectangular area including the tongue was divided into a grid of 7×7. Five experienced panelists scored the tongue coating in each area using one of five grades, and the tongue coating index (TCI) was calculated. Transfer learning for tongue coating grades was performed using ResNet-18, and the TCI was calculated. Agreement between the panelists and network for the tongue coating grades in each area and TCI was evaluated using the kappa coefficient and intraclass correlation, respectively. RESULTS: The tongue detection network recognized the tongue with a high intersection over union (0.885±0.081). The tongue coating classification network showed high agreement with tongue coating grades and TCI, with a kappa coefficient of 0.826 and an intraclass correlation coefficient of 0.807, respectively. CONCLUSIONS: Image recognition enables simple and detailed assessment of tongue coating status.

The impact of residual ridge morphology on the masticatory performance of complete denture wearers.

Statement of the problem: Morphology of the residual ridge (RR) is expected to influence the masticatory performance (MP) of complete denture (CD) patients, but considerable details of this relationship are unknown. Purpose: We aimed to investigate the association between the objective MP and RR morphology of CD wearers and other contributory factors affecting their MP. Materials and methods: Sixty-five patients with well-fitting upper and lower CDs with no complaints of pain were enrolled. The objective MP was measured using test gummy jelly and a fully automated measuring device. The RR form was divided into U-type, V-type, I-intermediate, and F-Flat, then combinations of upper and lower RR forms (combined RR) were classified. The height was measured using CD's denture basal surface replicas, while occlusal contact of CDs was assessed using a tooth contact analysis system. The relationship between surveyed factors and MP was evaluated using Spearman's rank correlation, Kruskal-Wallis test, generalized linear regression, and analysis of covariance. Results: Participants with F-F and V-F combined RR forms had the lowest MP, while those with U-U and U-I forms had the highest MP, regardless of RR height. Participants with low RR height had the lowest MP, and those with high RR height had the highest MP, regardless of RR form. The analysis of covariance revealed that mandibular RR height, combined RR forms, and total occlusal contact area significantly affected the MP. Conclusions: Our findings confirmed that the mandibular RR height, RR form combinations, and occlusal contact influence the MP of CD wearers.ClinicalImplications:The MP of CD wearers varied, depending on the height and form of the RR, as well as the occlusal contact area of the CDs. The results of this manuscript show that the morphology of the denture bearing area and the occlusion of the CDs are essential factors in predicting the treatment outcome of CD wearers. This allows the clinician to fabricate a complete denture with the denture basal surfaces adjusted and occlusion provided according to the patient. CD patients can be educated on how to chew to improve MP based on their own RR morphology.

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.

Masticatory Performance Test Using a Gummy Jelly for Older People with Low Masticatory Ability.

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

Retronasal aroma dynamics related to the swallowing threshold.

BACKGROUND: The state of food comminution caused by chewing is an important factor triggering the swallowing reflex. However, the impact of retronasal aroma released from comminuted food to the nose upon swallowing during food intake is poorly understood. OBJECTIVE: The present study investigated the relationship between aroma concentration and swallowing threshold while chewing a standardised test food. METHODS: Twenty healthy participants took part in this study. Concentration of retronasal aroma was measured over time through the nostrils using an odour sensor. The aroma concentration was measured while chewing an orange-flavoured gummy jelly until swallowing, and the number of chewing strokes was measured to determine the swallowing threshold. Next, the aroma concentration was measured while chewing the gummy jelly for 30 strokes, and 100% and 200% of swallowing threshold without swallowing. The surface area increase in the expectorated gummy jelly pieces was calculated using image analysis and defined as masticatory performance at 30 strokes. RESULTS: The average number of chewing strokes until the swallowing threshold was 45.1 ± 14.2. Higher masticatory performance was associated with a smaller number of chewing strokes at swallowing threshold, and a greater increase in surface area at the swallowing threshold. The number of chewing strokes and the aroma concentration were similar between the swallowing threshold and at the maximum aroma concentration while chewing at 200% of the swallowing threshold. CONCLUSION: The findings suggested that the swallowing threshold might be influenced by retronasal aroma concentration as well as the state of food comminution.

Features of Masticatory Behaviors in Older Adults with Oral Hypofunction: A Cross-Sectional Study.

Although many studies have shown the relationships between oral function and nutrition and health, few reports have investigated the masticatory behaviors of older people. This study aimed to clarify the relationships between oral function and the masticatory behaviors and features of masticatory behaviors with oral hypofunction. A total of 98 community-dwelling independent older adults participated. Seven oral conditions related to oral hypofunction were examined, and the masticatory behaviors when consuming a rice ball were measured. The participants were divided into two groups according to the criteria for oral hypofunction, and the masticatory behaviors were compared. Furthermore, the relationship between masticatory performance and the number of chews was investigated. The chewing rate of the oral hypofunction group was slower than that of the no oral hypofunction group, but there was no difference in the number of chews and chewing time. The decreased tongue-lip motor function group showed a slower chewing rate, and the decreased tongue pressure group showed a smaller number of chews and shorter chewing time. No significant correlation was observed between masticatory performance and behavior. In conclusion, older adults with oral hypofunction chewed slowly due to decreased dexterity, while, even if oral and masticatory function decreased, no compensatory increase in the number of chews was observed.

Noninvasive Evaluation of the Biomechanical Accommodations to Bolus Volume during Human Swallowing.

Bolus volume is very important in the biomechanics of swallowing. By noninvasively characterizing swallow responses to volume challenges, we can gain more knowledge on swallowing and evaluate swallowing behavior easily. This study aimed to evaluate the impact of bolus volume on the biomechanical characteristics of oropharyngeal swallowing events with a noninvasive sensing system. Fifteen healthy male subjects were recruited and instructed to swallow 5, 10, and 15 ml of water. The sensing system consisted of a tongue pressure sensor sheet, bend sensor, surface electrodes, and a microphone. They were used to monitor tongue pressure, hyoid activity, surface EMG of swallowing-related muscles, and swallowing sound, respectively. In addition to the onset, the peak time and offset of the above four structures, certain characteristics, such as the duration, peak value, and interval of the structure motions, were measured during the different drinking tasks. The coordination between the hyoid movement and tongue pressure was also assessed. Although no sequence of the structural events changed with volume, most of the timings of the structural events were significantly delayed, except for certain hyoid activities. The swallowing volume did not affect the active durations of the monitored structures, the peak values, or intervals of tongue pressure and supra- and infrahyoid muscle activity, but certain hyoid kinetic phases were prolonged when a larger volume was swallowed. Additionally, sequential coordination between hyoid movement and tongue pressure was confirmed among the three volumes. These findings suggest that oropharyngeal structural movements change in response to bolus volume to facilitate safe swallowing. The noninvasive and quantitative measurements taken with the sensing system provide essential information for understanding normal oropharyngeal swallowing.

The effects of tongue elevation using a weighted plastic bottle on the tongue pressure and activity of suprahyoid muscles.

BACKGROUND: A rise in tongue pressure coincides with an increase in the suprahyoid muscle activity. OBJECTIVES: The aim was to investigate the effects of holding a weighted plastic bottle on tongue pressure and the suprahyoid muscle activity. METHODS: Eighteen participants (8 men and 10 women; mean age 42 ± 16 years) participated in this study. All participants had no history of speech, language, hearing or swallowing disorders and no tooth loss, and they did not require dentures. Healthy participants held gauzes connected with a plastic bottle with increasing resistive loads of 0 g, 250 g, 500 g and 750 g, between their palate and tongue. The maximum tongue pressure and average tongue pressure were measured during a 5 s hold. The average tongue pressure was defined as the mean tongue pressure data in each task. The suprahyoid muscle activity was measured using the electromyogram (EMG). The root mean square of the EMG signals measured while lifting different loads and while performing the head lifting exercises was compared. All variables were examined using the Friedman's test and Wilcoxon signed-rank test. RESULTS: The maximum tongue pressure (p < .05) and average tongue pressure values (p < .05) increased gradually in the anterior-median region with increasing resistive loads, and the root mean square amplitudes for 250 g, 500 g and 750 g were not significant compared with head lifting exercises. CONCLUSION: These results indicated that plastic bottle holding could be a potential strength training tool for the tongue and the suprahyoid muscles.

Effects of Tongue-Strengthening Exercise on Tongue Strength and Effortful Swallowing Pressure in Young Healthy Adults: A Pilot Study.

PURPOSE: The purpose of this study was to investigate the effects of tongue-strengthening exercise (TSE) on tongue strength and effortful swallowing pressure in young healthy adults. METHOD: Thirteen young healthy volunteers (six men, seven women; M age = 20.5 ± 0.5 years) performed 8 weeks of isometric TSE 3 days per week. A tongue pressure measurement device was used to measure maximum isometric tongue pressure (MITP) and conduct the TSE, and a tactile sensor system attached to the hard palate was used to measure effortful swallowing pressure. MITP and effortful swallowing pressure were measured at baseline, after 4 and 8 weeks of training, and at 4 and 8 weeks after the last training session to examine the detraining effects. RESULTS: The results indicated that both MITP and effortful swallowing pressure increased significantly from baseline to 8 weeks after training. Although the improved MITP significantly decreased at 4 and 8 weeks after training cessation, no detraining effect was observed for effortful swallowing pressure. CONCLUSIONS: TSE is an effective method for increasing tongue pressure in wide tongue-palate contact areas during effortful swallow. The effortful swallowing pressure gained with TSE appears to be maintained for at least eight nontraining weeks.

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

Numerous studies have evaluated the relationship between eating behavior and obesity, however few studies have objectively assessed eating behavior. Additionally, the association of masticatory behaviors with masticatory performance remains unclear. This study aimed to verify the relationship between masticatory performance and behavior measured by a wearable masticatory counter, and BMI. 365 healthy adults participated. Mastication behaviors, i.e. number of chews and bites, chewing rate, and chewing time, were measured using wearable masticatory counter while consuming one rice ball (100 g). Masticatory performance was evaluated using testing gummy jelly. Lifestyle habits including exercise, walking, and breakfast, were surveyed by questionnaire. The correlation coefficients between masticatory behaviors and performance and BMI were analyzed. Furthermore, multiple regression analysis was performed. The number of chews showed positive correlation with chewing rate, number of bites and chewing time, but no correlation with masticatory performance. BMI had weak but significant negative correlation with number of chews, bites, chewing time, and masticatory performance, but had no correlation with chewing rate. Multiple regression analysis revealed that BMI was associated with sex, age, number of chews, bites, masticatory performance, and walking speed. In conclusion, masticatory behavior and performance were not interrelated, but both were independently associated with BMI weakly.

Impact of Masticatory Behaviors Measured With Wearable Device on Metabolic Syndrome: Cross-sectional Study.

BACKGROUND: It has been widely recognized that mastication behaviors are related to the health of the whole body and to lifestyle-related diseases. However, many studies were based on subjective questionnaires or were limited to small-scale research in the laboratory due to the lack of a device for measuring mastication behaviors during the daily meal objectively. Recently, a small wearable masticatory counter device, called bitescan (Sharp Co), for measuring masticatory behavior was developed. This wearable device is designed to assess objective masticatory behavior by being worn on the ear in daily life. OBJECTIVE: This study aimed to investigate the relation between mastication behaviors in the laboratory and in daily meals and to clarify the difference in mastication behaviors between those with metabolic syndrome (MetS) and those without (non-MetS) measured using a wearable device. METHODS: A total of 99 healthy volunteers (50 men and 49 women, mean age 36.4 [SD 11.7] years) participated in this study. The mastication behaviors (ie, number of chews and bites, number of chews per bite, and chewing rate) were measured using a wearable ear-hung device. Mastication behaviors while eating a rice ball (100 g) in the laboratory and during usual meals for an entire day were monitored, and the daily energy intake was calculated. Participants' abdominal circumference, fasting glucose concentration, blood pressure, and serum lipids were also measured. Mastication behaviors in the laboratory and during meals for 1 entire day were compared. The participants were divided into 2 groups using the Japanese criteria for MetS (positive/negative for MetS or each MetS component), and mastication behaviors were compared. RESULTS: Mastication behaviors in the laboratory and during daily meals were significantly correlated (number of chews r=0.36; P<.001; number of bites r=0.49; P<.001; number of chews per bite r=0.33; P=.001; and chewing rate r=0.51; P<.001). Although a positive correlation was observed between the number of chews during the 1-day meals and energy intake (r=0.26, P=.009), the number of chews per calorie ingested was negatively correlated with energy intake (r=-0.32, P=.002). Of the 99 participants, 8 fit the criteria for MetS and 14 for pre-MetS. The number of chews and bites for a rice ball in the pre-MetS(+) group was significantly lower than the pre-MetS(-) group (P=.02 and P=.04, respectively). Additionally, scores for the positive abdominal circumference and hypertension subgroups were also less than the counterpart groups (P=.004 and P=.01 for chews, P=.006 and P=.02 for bites, respectively). The number of chews and bites for an entire day in the hypertension subgroup were significantly lower than in the other groups (P=.02 and P=.006). Furthermore, the positive abdominal circumference and hypertension subgroups showed lower numbers of chews per calorie ingested for 1-day meals (P=.03 and P=.02, respectively). CONCLUSIONS: These results suggest a relationship between masticatory behaviors in the laboratory and those during daily meals and that masticatory behaviors are associated with MetS and MetS components. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry R000034453; https://tinyurl.com/mwzrhrua.

Compatibility of two types of gummy jelly tests for detecting decreased masticatory function.

OBJECTIVE: This study aimed to verify the compatibility of masticatory performance tests using different two types of gummy jellies. BACKGROUND DATA DISCUSSING THE PRESENT STATUS OF THE FIELD: Compatibility between the glucose concentration measuring method (GC) and 10-steps visual scoring method (VS), which are masticatory performance tests for diagnosing decreased masticatory function (DMF) in oral hypofunction and the use of different types of gummy jelly, has yet to be confirmed. MATERIALS AND METHODS: The participants consisted of 134 Japanese older people (51 men and 83 women). GC, VS and the increased surface area measuring method (ISA), as an alternative analysis method for VS, were conducted to evaluate masticatory performance. Cohen's Kappa coefficient was used to verify the consistency for detecting DMF between GC and VS. Pearson's correlation coefficient was used to analyse the relationship between GC and ISA. Each masticatory performance was compared among three different groups for the number of residual teeth. Cut-off values of VS and ISA for DMF that were consistent with GC were identified. RESULTS: Glucose concentration measuring method and VS showed an excellent consistency (Kappa coefficient = 0.86). There was a high positive correlation between GC and ISA (r = .70). However, the change in masticatory performance according to the number of teeth was different between GC and VS/ISA. The cut-off values of VS and ISA were a Score of 2 and 1687 mm2 , respectively. CONCLUSION: Glucose concentration measuring method and VS/ISA remained fairly consistent for detecting DMF, which might be useful information to interconnect the various studies on masticatory performance.

Modulation of tongue motion and tongue pressure during liquid swallowing with different bolus volumes.

BACKGROUND: The tongue functions by modulating according to bolus volume when swallowing; however, associated tongue dynamics are unclear. OBJECTIVE: We aimed to clarify how tongue motion and tongue pressure change with bolus volume during swallowing. METHODS: Sixteen healthy volunteers (age 29.5 ± 3.8 years; 12 males, 4 females) were recruited. Two electromagnetic articulography markers were attached, one each on the anterior and posterior parts of the tongue, to measure motion. A sensor sheet, with five pressure-sensitive points, was attached to the hard palate to measure tongue pressure. Participants were asked to swallow 3 ml and 10 ml of water. Motion trajectory, maximum velocity, vertical displacement just before contact with the hard palate, and maximum magnitude and duration of tongue pressure were analysed. RESULTS: Tongue rotation was observed in the sagittal plane; its rate of appearance was significantly higher when swallowing 3 ml of water than when swallowing 10 ml, and the rate of rotation at posterior part was significantly higher than at the anterior part. The maximum velocity and vertical displacement were significantly greater when swallowing 10 ml of water than those when swallowing 3 ml of water. There was no significant difference in either the maximum magnitude of tongue pressure or maximum duration of tongue pressure between 3 ml and 10 ml. CONCLUSION: Bolus volume influenced the pattern of tongue motion; however, there was no difference in tongue pressure.

Clarification of the aspects of tongue-palate contacts during mastication with/without stage II transport.

BACKGROUND: During mastication, the tongue presses the bolus into the pharynx by a "squeeze-back" motion, known as stage II transport (St2Tr). However, the pressure of St2Tr tongue-palate contact has not been examined. OBJECTIVES: We aimed to clarify aspects of St2Tr occurrence and tongue-palate contact during mastication by measuring tongue pressure. METHODS: Ten healthy adults (eight men, two women, aged 26.8 ± 2.2 years) were enrolled. Tongue pressure was measured (Swallow Scan) during mastication. Sensors were placed on the palate near the incisive papilla (Ch.1), in the middle (Ch.2), at the posterior (Ch.3), and near the first molars on the habitual (Ch.H) and non-habitual (Ch.Nh) masticatory sides. Nasopharyngeal endoscopy confirmed St2Tr and swallowing. Tongue pressures were measured repeatedly, from mastication onset through the first swallow, until eight sets of data were obtained. Tongue-palate contact frequencies, integrated values of tongue pressure, and mastication times were recorded for St2Tr(+) and St2Tr(-) mastication conditions. RESULTS: St2Tr occurred in 43 of 80 trials (53.8%). St2Tr(+) exhibited the highest tongue-palate contact frequency at Ch.H; it exhibited higher contact frequencies at Ch.2, Ch.3 and Ch.H than St2Tr(-). St2Tr(+) exhibited higher tongue pressures at Ch.1, Ch.2 and Ch.H than at Ch.3; it exhibited higher tongue pressures at Ch.1 and Ch.2 than St2Tr(-). CONCLUSION: The study suggested that during St2Tr, the tongue frequently touched the palate at the central and posterior regions, as well as at its habitual masticatory side. It applies the strongest pressure at the anterior and central palate to transport the bolus to the pharynx.

Factors Affecting Masticatory Satisfaction in Patients with Removable Partial Dentures.

(1) Background: The degree of satisfaction with dental treatment varies among patients, and the discrepancy may exist between the patient's subjective evaluation and the objective assessment. Further, the optimal methods for increasing patient satisfaction with mastication remain unclear. This study aimed to identify factors affecting masticatory satisfaction in patients with removable partial dentures. (2) Methods: A total of 132 participants (71.0 ± 9.0 years) were included. Masticatory satisfaction was assessed on a visual analog scale. An oral health survey was conducted to assess the number of functional teeth, missing tooth classification: Kennedy classification, occlusal support: Eichner classification, and removable partial dentures wearing jaw. Objective masticatory performance was assessed using gummy jelly, while subjective masticatory ability was assessed using food acceptance status and oral health-related quality of life. The associations of these factors with masticatory satisfaction were assessed. (3) Results: Masticatory satisfaction among removable partial denture wearers was not significantly associated with gender, age, denture wearing jaw, Kennedy classification, and occlusal support. The degree of masticatory satisfaction was significantly greater with higher levels of masticatory function: masticatory performance, food acceptance score, and OHIP-14 score. The OHIP-14 score was the only significant explanatory variable for masticatory satisfaction in the multiple regression analysis; the strongest associations were with the "psychological discomfort" and "physical disability" subscales (p = 0.02 and p = 0.005, respectively). (4) Conclusions: Masticatory satisfaction among removable partial denture wearers was strongly associated with oral health-related quality of life, in which the ability to eat meals comfortably with removable partial dentures is the most important determinant of masticatory satisfaction.

Effect of hard gummy candy chewing on masticatory function.

BACKGROUND: Although various training methods have been reported for improving oral function such as occlusal force, there are few reports that show the training effect of eating hard food on the oral functions. OBJECTIVE: To examine the training effects of habitually ating hard gummy candies on oral functions. METHODS: Participants of this cohort study were recruited into a training (six women, eight men; mean age 27.6 ± 3.5 years) and control group (two women, seven men; mean age 28.3 ± 4.9 years). The training group ate nine custom-developed hard gummy candies three times per week for 3 months. Training effects were evaluated by measuring the maximal occlusal force, masticatory performance, maximal tongue pressure, number of chewing cycles until swallowing the candy, duration of chewing and cycle time before training, after 1, 2 and 3 months of training, and 1 month after stopping training. The iEMG/force, which evaluates masseter muscle hypertrophy with electromyograms (EMG), was calculated. RESULTS: Masticatory performance after 1 month (p = 0.01), maximal occlusal force after 2 months (p < 0.01) and maximal tongue pressure after 3 months of training were significantly increased (p = 0.02), and the cycle time after 2 months of training (p = 0.02) was significantly decreased compared to before the intervention. Except for masticatory performance, the other effects were maintained for 1 month after stopping training. Changes in iEMG/force were not significant, but a tendency for muscle hypertrophy was observed in the training group. CONCLUSION: Habitual eating of hard gummy candies is a task-specific training that can improve overall masticatory function, including tongue pressure.