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.

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.

Effect of fracture properties of gels on tongue pressure during different phases of squeezing and swallowing.

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.

Reliability of a novel wearable device to measure chewing frequency.

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.

Differentiation of Feeding Behaviors Based on Masseter and Supra-Hyoid Muscle Activity.

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.

Estimation of pharyngeal residue after swallowing by retronasal aroma.

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.

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.

Coordination of tongue pressure production, hyoid movement, and suprahyoid muscle activity during squeezing of gels.

OBJECTIVE: The aim of this study was to evaluate tongue movement and its biomechanical effects during squeezing, one of the oral strategies for processing soft foods, by tongue pressure sensors, videofluorography, and surface electromyography. DESIGN: Fifteen healthy men (mean age, 31.0 ± 4.1 years) without dysphagia were recruited. A 0.1-mm-thick pressure sensor sheet with five measuring points, videofluorography, and surface electromyography were used for synchronous measurements of tongue pressure, hyoid movement, and suprahyoid muscles activity, respectively, while squeezing 5 mL of gels. Amplitude, duration, area, and their sequential order during initial squeezing were analyzed. Differences in hyoid position at the onset, peak, and offset of hyoid movement were also analyzed. RESULTS: At the beginning of initial squeezing, tongue pressure at the middle area of the hard palate, hyoid movement, and suprahyoid muscle activity appeared simultaneously, followed by tongue pressure at the anterior area and then at the posterior area. When the hyoid was in an elevated position, the amplitude of suprahyoid muscle activity and tongue pressure peaked. At the end of initial squeezing, the hyoid position at the offset of hyoid excursion was superior to that at the onset. All evaluation items of tongue pressure, hyoid movement, and suprahyoid muscle activity were modulated according to the texture of gels. CONCLUSIONS: During initial squeezing, tongue pressure, hyoid movement, and suprahyoid muscle activity were coordinated while being modulated by the food texture. At the end of initial squeezing, the hyoid was maintained in an elevated position, which might be beneficial for subsequent squeezing.

Evaluation of hyoid movement during swallowing using a bend sensor.

BACKGROUND: Movement of the hyoid and laryngeal complex is critical for preventing aspiration, as well as smooth bolus passage through the pharynx. We have developed a non-invasive system for measuring laryngeal movement during swallowing with a bend sensor and have already reported the time coordination between the signal waveform from the sensor and hyoid movement. OBJECTIVE: The aim of this study was to clarify the quantitative association between the output value of the sensor and hyoid movement during swallowing. METHODS: A small bend sensor was fixed on the skin surface along the midline of the neck of 13 healthy men (mean age, 30.8 ± 4.5 years). Laryngeal and hyoid movements during swallowing of 5 mL of water were recorded synchronously by the bend sensor and videofluorography. The relationship between the bend sensor output value (LM value) and hyoid position (x- and y-axis displacements) by videofluorography from the onset to the offset of the signal waveform was analysed for all tasks and for each task using Pearson's correlation coefficients. RESULTS: There was a positive correlation between the LM value and hyoid position for all tasks (x-axis displacement: r = .647, y-axis displacement: r = .233). In particular, there was a moderate to high correlation between the LM value and x-axis displacement for each task (.453 ≤ r ≤ .934). CONCLUSION: The LM value can be a quantitative parameter of anterior hyoid movement during swallowing that might be associated with bolus flow and upper oesophageal sphincter opening.