Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/joor.13208

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Language：English   Publishing type：Research paper (scientific journal)  

To provide appropriate foods for elderly people with eating difficulties, it is necessary to take account of the ability of compensatory mastication such as tongue squeezing. However, the biomechanics of tongue squeezing is still unclear. The aim of present study is to investigate the effect of the initial mechanical properties of gels on the change in tongue pressure production during squeezing and swallowing. As test sample, nine kinds of gels with three fracture force and three fracture strain were prepared. Tongue pressure during squeezing and swallowing gels was measured by using an ultra-thin tongue pressure sensor with five measuring points attached on the hard palate in seven healthy participants, and analyzed at four phases; Initial squeeze, Middle squeeze, Last squeeze, and Swallowing. The maximal magnitude of tongue pressure was increased for gels with higher fracture force at most measuring points and was decreased for gels with higher fracture strain at some measuring points on the median line during Initial and Middle squeezing. However, no influence by fracture force and strain was found in magnitude during Last squeezing and Swallowing. The duration of tongue pressure increased for gels with higher force at most measuring points during Middle squeezing, although no influence by strain was found during each phase. The results clearly show how the initial fracture properties of gels influence on tongue pressure production during each phase of food oral processing, which clarified one aspect of squeezing with tongue, as the compensatory mastication.

DOI： 10.1111/jtxs.12593

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: In recent years, the chewing frequency, i.e., the number of chewing cycles, has decreased owing to changes in dietary habits. Although these changes may be related to complete body health, there is no evidence-based tool to measure the dietary habits. We developed a small ear-hung wearable device for monitoring mastication behavior. The device, worn on the ear pinna, allows the counting of the number of chewing cycles, and data are collected on a smartphone via Bluetooth. In this study, the reliability of the novel device was verified. METHODS: A total of 22 healthy volunteers participated in the study. During measurement, the subjects wore the novel wearable device on their right ear pinna and were asked to chew gum, gummy jellies, and rice balls. The number of chewing cycles was counted by the device. A mandibular kinesiograph (MKG) was also recorded, and the chewing activity was recorded as a video. The accuracy, precision, and recall of the ear-hung device were calculated by comparing the data obtained from the MKG and the video recording. Additionally, the factors affecting reliability were examined. RESULTS: The accuracy, precision, and recall of the novel device were 101.6 ± 13.6%, 85.3 ± 11.0%, and 84.5 ± 9.5%, respectively. Although the accuracy was not affected by any factor, precision and recall of the novel device for women were significantly worse than that for men, and were greatest when the subjects were chewing gum. CONCLUSIONS: Our findings suggest that the newly developed ear-hung wearable device for counting the number of chewing cycles was sufficiently reliable.

DOI： 10.2186/jpr.JPR_D_20_00032

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Language：English   Publishing type：Research paper (scientific journal)  

Mastication is a physiological process whereby food is comminuted and mixed with saliva to form a swallowable bolus; it is also the initial process for retronasal aroma that is released from foods to receptors in the nose. However, the influence of mastication state on retronasal aroma is poorly understood. The purpose of this study was to investigate the relationship between aroma concentration and factors related to mastication state. The study design was an analytical observational study. Twelve male volunteers (age, 26.5 ± 2.7 years) were recruited and divided into five and seven participants in the low and high masticatory performance groups, respectively. The stimulated salivary flow rate was measured while participants chewed paraffin wax. First, an odor sensor was placed in the nostril, and the aroma concentration was measured over time as participants chewed an orange-flavored gummy jelly standardized for masticatory performance assessment until swallowing; chewing strokes were counted to determine swallowing thresholds. Next, participants were instructed to chew the gummy jelly for a certain number of strokes (i.e., 50 or 100% of swallowing thresholds, as well as 30 strokes) and expectorate the jelly without swallowing. The surface area of comminuted jelly at 30 chewing strokes was defined as masticatory performance. Maximum and slope of aroma concentration, surface area, number of chewing strokes, and stimulated salivary flow rate were compared between low and high masticatory performance groups. Statistical significance was set at α = 0.05. At 30 chewing strokes, the maximum aroma concentration and the slope were significantly greater in the high masticatory performance group than in the low masticatory performance group. There was a positive correlation between the maximum aroma concentration and the number of chewing strokes with aroma release in both groups. No significant correlation was found between the maximum aroma concentration and the stimulated salivary flow rate. However, multiple regression analysis (with aroma concentration as a dependent variable) showed that the increase in surface area, the number of chewing strokes, and the stimulated salivary flow rate were significant explanatory variables. The results suggested that retronasal aroma was influenced by mastication state and salivary flow rate during chewing.

DOI： 10.3389/fnut.2021.623507

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Tongue motor biomechanics during swallowing was not fully elucidated due to the technical difficulty. OBJECTIVE: To evaluate the relationship between tongue motion and tongue pressure production by simultaneously measuring tongue motion and tongue pressure during water swallowing. METHODS: In 12 healthy male participants (mean age, 30.8 ± 4.2 years), tongue pressure and tongue motion trajectory during dipper- and tipper-type swallows of 3 mL of water were measured using a sensor sheet system equipped with five sensing points and an electromagnetic articulography, respectively. The temporal correlation between motion of anterior/posterior tongue and tongue pressure production during swallowing was evaluated on the synchronised waveforms. RESULTS: In the dipper-type swallow, a similar up-and-down motion pattern in vertical direction was observed among all participants before tongue pressure production. Those motion patterns were common at the anterior and posterior tongue locations with a temporal difference in some segment of tongue motion. On the other hand, tongue directly attached to hard palate with temporal synchronicity between the anterior and posterior parts. In both types of swallow, a strong temporal correlation was found between the timing of tongue-palate contact and the Onset of tongue pressure by intra-class correlation coefficients. CONCLUSION: From the simultaneous measurement of tongue motion and tongue pressure production, the tongue motion pattern during water swallowing and the temporal correlation between tongue motion and tongue pressure production were elucidated.

DOI： 10.1111/joor.13079

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Pharyngeal residue can trigger aspiration and choking after swallowing. Various studies to assess the amount of pharyngeal residue have been conducted; however, an easy and quantitative method is yet to be established. The aroma released from the pharyngeal residue is thought to be delivered from the pharynx to the nasal cavity via velopharynx by expiration, that is, retronasal pathway. OBJECTIVE: This study verified that the amount of pharyngeal residue could be estimated by aroma intensity. METHODS: Ten healthy adult subjects had tubes in from the oral cavity to the pharynx. Varying amounts of essence were dispensed into the pharynx through the tube either at rest or after swallowing the essence. Pharyngeal residue was simulated by retention essence in the pharynx without swallowing. An odour sensor was placed in the nostril, and the aroma intensity of the retained essence was measured over time. RESULTS: The aroma intensity level flattened after a certain period of time had elapsed, and a significant correlation was found between the amount of essence dispensed and the flattened aroma intensity, both at rest and after swallowing. Furthermore, to estimate in a short period of time, changes in aroma intensity over time were estimated by fitting to a decay curve. The estimated intensity at convergence, calculated from the fitted curve from 80 to 120 seconds after swallowing, was significantly correlated to the measured intensity. CONCLUSION: The amount of pharyngeal residue can be estimated in a short period of time by measuring the aroma intensity.

DOI： 10.1111/joor.12974

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Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1016/j.jpor.2019.04.010

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Language：English   Publishing type：Research paper (scientific journal)  

Older adults with disorders of mastication and swallowing are often fed soft foods such as jelly or puree. The texture of such semi-solid foods allows them to be squeezed between the tongue and palate rather than being chewed. However, it is difficult to visually identify such strategies for the oral processing of food. This study aimed to test the hypothesis that there is a difference in the sequential coordination between the masseter and supra-hyoid muscles, and to identify feeding behaviors such as chewing and squeezing using electromyography. Seventeen male subjects (mean age: 30.8 years) were recruited. Four kinds of gels were prepared (two kinds of fracture force and fracture strain) as test samples. Subjects were instructed to consume the gels in three ways: squeezing with the tongue, chewing with the teeth and eating freely until swallowing. The amount of squeezing/chewing and the consumption time was unlimited. The masseter and supra-hyoid muscle activity were recorded during the entire consumption time and videofluorography was simultaneously recorded during each ingestion. Lissajous figures were made from the electromyographic activity of the two groups of muscles during the first stroke, and a regression line was made to determine the gradient of each figure to compare squeezing and chewing using the Mann-Whitney U-test. The masseter and supra-hyoid muscles were active simultaneously during squeezing with the tongue. However, the masseter was active after the supra-hyoid during chewing. The gradient of the regression line from the Lissajous figures between the masseter and supra-hyoid muscle activity was positive during squeezing, but negative during chewing. Analysis of the ROC curve showed that the cutoff value of the gradient for differentiating feeding behaviors was 0.097, with a sensitivity of 95.3% and specificity of 98.4%. When we allocated 68 free intakes into squeezing and chewing according to this cutoff value, we could distinguish with good precision, and the accuracy, sensitivity, and specificity were 86.8, 91.1, and 66.7% respectively. These results suggest that certain aspects of muscle activity differed among oral processing methods. Lissajous analysis of muscle activity was useful for identifying ingestion behaviors.

DOI： 10.3389/fphys.2020.00618

PubMed

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Language：Japanese   Publisher：(公社)日本補綴歯科学会  

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Language：Japanese   Publisher：(一社)日本老年歯科医学会  

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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Presentation type：Symposium, workshop panel (nominated)  

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