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Objective To investigate the effects of food hardness on chewing behavior in children compared with adults. Materials and methods Healthy children (3–17 years) were equally divided into five groups based on their dental eruption stages. Each participant ate soft and hard viscoelastic test food models (3 each), while the three-dimensional jaw movements and electromyographic (EMG) activity of the bilateral masseter muscles were recorded. The data from the children were compared with a control group of healthy adults (18–35 years). The data were analyzed with nonparametric tests. Results There was no significant difference in the number of chewing cycles and the duration of the chewing sequence between children groups and adults. Children with primary dentition (3–5 years) showed shorter lateral jaw movement and higher muscle activity at the end of the chewing sequence, compared with adults. Further, children’s age-groups (3–14 years) failed to adapt their jaw muscle activity to food hardness. However, at the late-permanent dentition stage (15–17 years), children were capable of performing adult-like chewing behavior. Conclusions Overall, it seems that children as young as 3-year-old are quite competent in performing basic chewing function similar to adults. Yet, there are differences in the anticipation or adaption of jaw muscle activity and jaw kinematics to food hardness. Clinical relevance The study may have clinical implication in the diagnosis and management of children with chewing impairment associated with dental malocclusions and other orofacial dysfunctions.

The aim of this study was to determine the reliability and validity of a new test food for the clinical assessment of masticatory performance. The test food had two overlapping acidic/basic halves. Ten dentate subjects chewed one unit for 10–100 cycles. One subject chewed ten units for the same number of cycles. Differences in the L*, a* and b* colour axes were determined before and after chewing by ANOVA. Colour guides were created based on the values of these axes and matched with the number of cycles. The reliability of the guides was evaluated using 30 images, where three examiners indicated the number of cycles in which the colour closest to that of a chewed material was found. The data were contrasted with the real values of the guides to determine the validity (Kappa coefficients). The equivalence of the guides with the median particle size (X50) was determined using equidimensional curves. The test food progressively changed from green to pink during chewing. As the number of cycles increased, the a* values increased and the b* values decreased (p 0.8 for the intra-examiner and inter-examiner reliability and the validity comparisons. The a* and X50 values were inversely proportional to each other, and the b* values showed a direct relationship with the X50 values. The L* values did not show correspondence. The new test food showed high reliability and validity for the assessment of masticatory performance through clinical colour guides matched with the number of cycles and X50.

The purpose of this study was to clarify the inter-measurement variation of the masticatory performance test. Forty healthy adults were divided into group A (10 males and 10 females), who did not chew the test food before experiment, and group B (10 males and 10 females) who chewed the test food before the experiment. Subjects were asked to chew a gummy jelly for 20 s on the habitual chewing side, and the amount of glucose extraction was measured. The test was repeated three times with an interval of 1 min in both groups (Group A: A1, A2, A3; Group B: B1, B2, B3). In both groups A and B, the difference between the measured values was compared and the reliability between measurements was investigated. In group A, the value of A1 was small, and a statistically significant difference was observed between A1 and other measured values. In group B, the three measured values were similar and no significant difference was observed among the measured values. The intraclass correlation coefficient (ICC) values for determining inter-measurement reliability in group A were 0.758 for A1–A2–A3, 0.708 for A1–A2, and 0.901 for A2–A3. The ICCs in group B were 0.924 for B1–B2–B3, 0.945 for B1–B2, and 0.926 for B2–B3. Based on these results, it can be suggested that high reliability between the measurements can be obtained if the subjects are accustomed to chewing the test food before the experiment, and that the measured values were similar whether it was performed two or three times. Consequently, one measurement was sufficient if subjects were accustomed to chewing the test food before the experiment.

Objectives Following chewing a solid food, the median particle size, X50, is determined after N chewing cycles, by curve-fitting of the particle size distribution. Reduction of X50 with N is traditionally followed from N ≥ 15–20 cycles when using the artificial test food Optosil®, because of initially unreliable values of X50. The aims of the study were (i) to enable testing at small N-values by using initial particles of appropriate size, shape and amount, and (ii) to compare measures of chewing ability, i.e. chewing efficiency (N needed to halve the initial particle size, N(1/2-Xo)) and chewing performance (X50 at a particular N-value, X50,N). Design 8 subjects with a natural dentition chewed 4 types of samples of Optosil particles: (1) 8 cubes of 8 mm, border size relative to bin size (traditional test), (2) 9 half-cubes of 9.6 mm, mid-size; similar sample volume, (3) 4 half-cubes of 9.6 mm, and 2 half-cubes of 9.6 mm; reduced particle number and sample volume. All samples were tested with 4 N-values. Curve-fitting with a 2nd order polynomial function yielded log(X50)-log(N) relationships, after which N(1/2-Xo) and X50,N were obtained. Conclusions Reliable X50-values are obtained for all N-values when using half-cubes with a mid-size relative to bin sizes. By using 2 or 4 half-cubes, determination of N(1/2-Xo) or X50,N needs less chewing cycles than traditionally. Chewing efficiency is preferable over chewing performance because of a comparison of inter-subject chewing ability at the same stage of food comminution and constant intra-subject and inter-subject ratios between and within samples respectively.

Objective To develop reference data for young men/women on the variability of parameters used for the evaluation of masticatory function with an artificial test food. Methods Subjects included were...

Objective: To investigate the effect of sudden deprivation of sensory inputs from the periodontium on jaw kinematics and time-varying activation profile of the masseter muscle. Methods: Fourteen (age range: 22-26 years; four men) healthy and natural dentate volunteers participated in a single experimental session. During the experiment, the participants were asked eat six hard visco-elastic test food models, three each before and after an anesthetic intervention. The movements of the jaw in three dimensions and electromyographic (EMG) activity of the masseter muscle on the chewing side were recorded. Results: The results of the study showed no significant differences in the number of chewing cycles (P=0.233) and the duration of chewing sequence (P=0.198) due to sudden deprivation of sensory inputs from the periodontium. However, there was a significant increase in the jaw opening velocity (P=0.030) and a significant increase in the duration of occlusal phase (P=0.004) during the anesthetized condition. The EMG activity of the jaw closing phase was significantly higher during the control condition (116.5 arbitrary units (AU)) than anesthetized condition (93.9 AU). The temporal profile of the masseter muscle showed a biphasic increase in the excitatory muscle drive in the control condition but this increase was virtually absent during the anesthetized condition. Conclusion: Sudden deprivation of sensory inputs from the periodontium affects the jaw kinematics and jaw muscle activity, with a clear difference in the time-varying activation profile of the masseter muscle. The activation profile of the masseter muscle show that periodontal mechanoreceptors contribute to approximately twenty percent of the EMG activity during the jaw closing phase.

The objective was to study masticatory function of 8 to 10-year-old children with Down syndrome (DS) through the evaluation of maximum occlusal force and masticatory performance (via medium particle size) and compare it to that of children of the same age without DS.A convenience sample of eight, 8-10-year-old children with DS were included in this cross-sectional study. The study had ethical approval and parents provided informed consent. Exclusion criteria were large carious lesions, dental pain or previous orthodontic/orthopedic treatment. Masticatory performance was evaluated with an artificial test food (Optosil Comfort®) after 20 cycles and at swallowing threshold. The chewed material was collected, dried and sieved. The material on each sieve was weighed; the weights were used to calculate medium particle size. Maximum occlusal force (1st permanent molars) was determined using the GM10 Nagano Keiki Co.™ portable transducer. The number of cycles until swallowing threshold, cycle and sequence durations were also compared. The data for the reference group (n = 32) came from a previous study in children of the same age. Descriptive statistics as well as comparisons with Mann-Whitney tests and simple and multiple regression analysis were performed. Cutoff was set at p≤.05.Medium particle size is larger by 44% after 20 chewing cycles and 75% at swallowing threshold (p.05) in children with DS. Median maximum occlusal force was 254 kN in DS children and 499 kN in children without the syndrome (p.001). 48% of the variance in maximum occlusal force is explained by having DS. There were also significant differences in sequence and cycle durations. All significant differences had large effect sizes (˃1). Although the children with DS chewed more cycles before swallowing threshold the difference was not significant.Children with DS have approximately 50% of the masticatory performance and maximum occlusal force of children of the same age without DS. These findings can be associated to the feeding problems reported in children with DS.

Objectives Food comminution during chewing is due to intra-oral particle selection and subsequent breakage. Under conditions of habitual chewing and a nearly complete selection, the influence of initial breakage on particle size reduction was studied in trials with a first chewing cycle (N = 1) from a sequence of randomized trials with various cycle numbers. Furthermore, relationships were examined between degree of fragmentation from breakage (r-fr), molar maximal bite force (MBF) and chewing efficiency (the number of cycles needed to half the initial particle size, N(1/2-Xo)). Design Thirty-one subjects with a natural dentition chewed samples of 2 half-cubes (9.6 × 9.6x4.8 mm) of Optosil®, using sequences with 1-7 cycles, in 2-10 randomized trials; 10 trials with one cycle. Particle size distributions by underweight, characterized by median particle size, X50, were obtained using sieving. N(1/2-Xo) was derived from the log(X50)-log(N) relationship. and r-fr from the cumulative distribution of underweight fractions of damaged particles for N = 1. MBF was determined on both sides of the jaw using a force transducer and averaged. Conclusions A strong, decreasing regression occurred in X50 at N = 1 with r-fr (R2 = 0.934, p

A test using a solid food is relevant to measure chewing ability (CA) as (a) it includes an integrated functioning of all oral structures involved, (b) an impairment of chewing a solid food causes inevitably diet restrictions, and (c) chewing efficiency (CE) can easily be defined. CE is the number of chewing cycles, N(1/2-Xo), needed to attain a particular chewing outcome (a median particle size, X 50 , which is half the initial particle size Xo) whereas chewing performance (CP) is a state of chewing outcome (X 50 ) at an arbitrary number of chewing cycles. The use of CE is preferable for CA because inter-subject ratios are constant regardless of the initial conditions of the test food. Furthermore, the inter-subject variation is two times larger for CE values than for CP ones, yielding a better inter-subject differentiation of CA. However, a determination of CP needs only one N-value, and that of CE at least two N-values for enabling an interpolation of N(1/2-Xo). Using samples of only two half-cubes (9.6 x 9.6 x 4.8 mm; limiting test load) of Optosil (an artificial test food), and detailed previous information on log(X 50 )-log(N) relationships (Liu et al., Archives of Oral Biology, 2018, 91, 63-77) as a "gold standard," a short procedure has been developed for a priori choosing two appropriate N-numbers, and the subsequent determination of a subject's CE. This procedure has been developed using results from 20 young adults (23.7 years, SD 1.1) and was validated in 10 middle-aged and older adults (52.3 years, SD 10.1), where impairments in the dentition were reflected in the CE-values. Our short procedure to determine CE will improve studies on relationships between CA and food preference, or between CA and dental factors and/or physiological factors. The first type of relationship may be of interest for food industry whereas the second type may be of interest for population studies in rapidly aging societies and for clinical studies in dentistry. Results can be compared between subjects and studies without bias by using CE rather than CP as a measure of CA.

Purpose Evaluate how clinical factors related to conventional complete denture (CCD) wearers, can influence masticatory function (MF) of totally edentulous patients before and after one-year transitioning to implant-retained mandibular overdentures (IMO). Methods Forty patients using CCD were rehabilitated with IMO and their MF was evaluated by: (i) ST_X50: theoretical aperture through which 50 % of the weight of the particles would pass; (ii) STB: distribution homogeneity of the crushed particles. The clinical parameters analyzed were: atrophy, retention, stability, facial type, anteroposterior skeletal discrepancy, and type of loading. The statistical association was tested through crude and adjusted logistic regression. Results IMO promoted improvements in the MF, irrespective of the clinical parameters. CCD wearers with poor retention had 86 % less chance of achieving a good ST_X50. STB was associated with stability, facial type, and anteroposterior discrepancy. Subjects with poor mandibular CCD stability had a 76 % lower chance of achieving a good test food homogenization, whereas brachyfacial individuals were 1.3 times more likely to have a good STB. Class II patients had an 89 % lower chance of having a good homogenization of the particles as CCD users and after transition to IMO. Conclusions CCD users with poor retention achieved an inferior ST_X50. The STB performance can be compromised by poor stability or Class II characteristics, while brachyfacial individuals achieve better homogenezation of the food bolus. Although the transition to IMO improved the masticatory function, the anteroposterior discrepancy still maintained an association with STB, as Class II individuals still presented difficulties homogenizing food.

Purpose The purpose of this study was to examine the hypothesis that in the process from food ingestion to swallowing, intentional decrease in the muscle activity during mastication would affect the number of chewing strokes, and thus the occurrence of Stage II transport (St2Tr) or the number of swallowing. Methods Twenty adults with healthy dentition were instructed to make (1) normal mastication and (2) mastication with 50% muscle activity (50% mastication), controlled by visual feedback with electromyogram. Gummy jelly was selected as a test food. The oropharynx was observed during the sequence of events from the start of mastication until swallowing using a nasal endoscope. The number of chewing strokes was calculated by rhythmical masseter muscle activity on electromyogram. Results The number of chewing strokes increased with 50% mastication. There was a particularly noticeable increase in the number of pre-St2Tr strokes. No effect on the number of additional swallows was seen as a result of 50% mastication. Conclusions The present study supported the hypothesis that intentional decrease in the muscle activity during mastication affected the number of chewing strokes and the occurrence of St2Tr. Particularly, this tendency was noticeable during the mastication before the start of St2Tr. However, our results did not support a question as to the number of swallowing.

The aim of this study was to observe the adaptation strategy of the stomatognathic system during the adaptation of complete dentures, comprising masticatory parameters and subjective measures. Our hypothesis was that with new dentures, masticatory performance would increase while the effort of the system is kept constant. Thirty-two patients received standardized new complete dentures. Masticatory performance tests were conducted with old dentures (T1), immediately after incorporation of new dentures (T2) and after an adaptation period of 3 months (T3). Patients habitually chewed the silicone-based artificial test food Optocal. The comminuted test food was analyzed and mean particle sizes (x50) were calculated. Simultaneously, surface EMGs of the anterior temporalis and masseter muscles were recorded. Specific (SMW) and total muscle work (TMW) were determined. Patients filled in the OHIP-49 questionnaire. Test conditions were compared using repeated-measures ANOVA with SPSS 22 (SPSS Inc.) Masticatory performance increased (P = 0.016) between old (x50 = 4.99 ± 0.28) and adapted new dentures (x50 = 4.80 ± 0.33). TMW deteriorated (P = 0.004) at T2 (from TMW1 = 119.77 ± 56.49 to TMW2 = 92.12 46.27), and increased again (P = 0.028) at T3 (TMW3 = 107.66 ± 44.65). OHIP scores decreased significantly in all subscales (P

Lip closing is an important motor act in food acquisition. Appropriate food capture in anticipatory and early oral stages of feeding is essential for mastication and swallowing. The aim of this study was to investigate the effect of food type and quantity on lip closing pressure during food capture with a spoon, and to identify normal lip function during food acquisition in healthy young adults. Twenty young healthy males (age range: 22-30 years) participated in this study. They were asked to eat the test food freely with a spoon. Test foods were yogurt and cream cheese, which were given in quantities of 3, 5 and 10 g in weight; 3 ml water was included as a reference. A strain gauge transducer was embedded in the spoon in advance, and lip closing pressures during food capture were measured and recorded. The Vicon motion analysis system was used to collect three-dimensional kinematic data of spoon operation. Positive pressure with lip closing during capture of adhesive food, such as cream cheese, significantly increased (P 0.001). Moreover, positive pressure significantly decreased when food quantity increased (P 0.01), irrespective of food type. Negative pressure that preceded positive pressure appeared more frequently during cream cheese intake and increased when food quantity on the spoon increased (P 0.001). These findings indicated that participants sucked or squeezed the spoon further during capture of adhesive food. Maximum mouth opening occurred predominantly during the spoon insertion period, while mouth closing occurred predominantly during the spoon withdrawal period. After mouth closing, all subsequent lip pressure events appeared in the withdrawal period. Our results may be useful for comprehending normal lip function during food acquisition in healthy young adults. They may also aid in the diagnosis and management of abnormal lip function in oral hypofunction and dysfunction, which can be examined in future studies.

Summary To test the hypothesis that treatment with orthodontic appliances disturbs masticatory and swallowing performances. Twenty-seven subjects with malocclusions requiring orthodontic treatment were included in this prospective study. The masticatory and swallowing performances were evaluated at five different times: before bracket placement (T0), immediately after archwire placement (T1), 48 h after archwire placement (T2), 30 days after archwire placement (T3) and 3 months after the initial appointment (T4). Masticatory performance was determined by the median particle sizes for the Optocal test food after 15 chewing strokes, and the swallowing thresholds were registered for both the test food and a natural food (peanuts). Pain during mastication was evaluated using a 100-mm visual analogue scale. Masticatory performance was significantly reduced at T2, at which time patients reported the highest pain values. The time spent to the first swallow was increased at T2 for the natural food but not for the test food. The values for pain, masticatory and swallowing performances at T3 and T4 were similar to those at T0. Orthodontic patient masticatory function is only reduced during the period of higher pain experience, which could also disrupt the deglutition of harder foods. However, neither mastication nor deglutition processes were disturbed by orthodontic appliances in long-term treatment.

Purpose The purpose of this study was to clarify whether differences in masticating conditions affected masticatory path stabilities of healthy subjects and TMD patients. Methods Twenty healthy female subjects as the healthy group, and 20 female Temporomandibular Disorders (TMD) patients as the TMD group, were selected. Incisal point movement of during mastication of both masticating condition 1 (mc1; crispy bread chewed until swallowing on the free side) and masticating condition 2 (mc2; softened chewing-gum chewed for 20s on the habitual side) were recorded by MKG. As for mc1, out of all cycles during mastication only those cycles on the habitual chewing side were analyzed. As for mc2, the ten cycles from the fifth cycle were analyzed. For these analyzed sections, the indicators representing movement path stability were calculated and compared between the two groups. Results As for mc1, though the values of the indicators representing path stability were larger for the TMD group, there were cases where no significant differences were found between the two groups. As for mc2, the values were significantly larger for the TMD group (SDs; P P Conclusions From these results, it was suggested that the differences in masticating conditions affected the assessment of masticatory path stabilities of healthy subjects and TMD patients and the conditions should be considered for analyzing masticatory movement.

To elucidate the effects of water on the mechanical properties of the food bolus, the texture of the bolus was assessed. Thirteen adult subjects were instructed to chew 6 g of two test foods, a biscuit and rice cake, with and without water (2 mL). In the early, middle and late stages of mastication, subjects were instructed to spit the food bolus into a cup. Texture parameters (hardness, adhesiveness and cohesiveness) of the bolus were identified by texture profile analysis. Addition of water significantly ( p >0.001) decreased the number of chewing strokes (NCS) until swallowing for both test foods. Hardness of each of the two test food boluses decreased during mastication regardless of the presence or absence of water. Adhesiveness and cohesiveness of the biscuit bolus increased, whereas those of the rice cake bolus decreased regardless of the presence or absence of water. There were no significant differences in the three texture parameters immediately before swallowing for both food boluses with and without water, although the NCS until swallowing decreased during mastication with water. These results suggest that the presence of water and saliva accelerates bolus formation for swallowing the biscuits and rice cakes studied.

This study evaluated the relationship among malocclusion, number of occlusal pairs, masticatory performance, masticatory time and masticatory ability in completely dentate subjects. Eighty healthy subjects (mean age = 19.40 ± 4.14 years) were grouped according to malocclusion diagnosis (n = 16): Class I, Class Class II-2, Class III and Normocclusion (control). Number of occlusal pairs was determined clinically. Masticatory performance was evaluated by the sieving method, and the time used for the comminute test food was registered as the masticatory time. Masticatory ability was measured by a dichotomic self-perception questionnaire. Statistical analysis was done by one-way ANOVA, ANOVA on ranks, Chi-Square and Spearman tests. Class II-1 and III malocclusion groups presented a smaller number of occlusal pairs than Normocclusion (p < 0.0001), Class I (p < 0.001) and II-2 (p < 0.0001) malocclusion groups. Class I, and III malocclusion groups showed lower masticatory performance values compared to Normocclusion (p < 0.05) and Class II-2 (p < 0.05) malocclusion groups. There were no differences in masticatory time (p = 0.156) and ability (χ2 = 3.58/p= 0.465) among groups. Occlusal pairs were associated with malocclusion (rho = 0.444/p < 0.0001) and masticatory performance (rho = 0.393/p < 0.0001), but malocclusion was not correlated with masticatory performance (rho = 0.116/p= 0.306). In conclusion, masticatory performance and ability were not related to malocclusion, and subjects with Class I, II-1 and III malocclusions presented lower masticatory performance because of their smaller number of occlusal pairs.

OBJECTIVE: To compare chewing cycle kinematics of subjects with better and poorer masticatory performance. MATERIALS AND METHODS: A cross-sectional study compared masticatory performance, based on the breakdown of the artificial test food Cuttersil®, in 30 subjects with Class I occlusion. Individuals with median particle sizes greater and lesser than the median value for the entire sample were categorized as poorer (15) and better (15) performers, respectively. While chewing Cuttersil, three-dimensional jaw movements of subjects were tracked with an optoelectric computer system. Multilevel linear modeling was used to evaluate differences in estimated cycle shape, cycle duration, and maximum excursions, as well as within-subject variation between the two groups. RESULTS: Poorer performers had a significantly longer opening duration (0.274 ± 0.225 sec vs 0.325 ± 0.270 sec) than better performers. Poorer and better performers also showed significant differences in cycle shape, including a less horizontal path of closure and more posterior jaw movement in the poorer performers. In addition, poorer performers exhibited significantly more cycle-to-cycle (within-subject) variability in chewing cycle duration, excursive movements, and lateral velocity than did better performers. CONCLUSIONS: Poorer performers lacked consistency in their chewing cycles, and their cycle shape differs from that of better performers.

Purpose The purpose of this study was to compare the muscle activity of jaw-closing muscles during chewing of a wax cube used for mixing ability test with that of peanuts used for masticatory performance test. Methods Twenty subjects with complete dentitions (mean age 24.1 years) were directed to perform a mixing ability test and a masticatory performance test. Surface electromyograms (EMGs) were recorded from the masseter and temporalis muscles on right and left sides. Muscle work, maximal voltage and duration were measured on the integrated EMG signal in each muscle. In addition, muscle work was normalized with EMG activity during maximum voluntary clenching at centric occlusion. The mean of the 2nd to 5th cycle in each parameter was employed for statistical analysis. Results Repeated measures one-way multiple analysis of variance found a significant effect of chewing test on muscle work, normalized muscle work and maximal voltage ( P P =0.07). Muscle work, normalized muscle work and maximal voltage for the mixing ability test were significantly less than for the masticatory performance test in all muscles (paired t -test, P Conclusion The results of this study suggest that muscle activity of jaw-closing muscles in the mixing ability test is less than that in the masticatory performance test using peanuts as test food.

To investigate the effects of appetitive sensations, body mass index (BMI) and physical/sensory properties of food (almonds) on masticatory indices and resultant pre-swallowing particle sizes.Twelve lean (BMI=22.2+/-0.3) and 12 obese (BMI=34.3+/-0.6) adults. After collecting appetitive ratings, electromyographic recordings were used to assess participants' microstructure of eating for five almond products (raw, dry unsalted roasted, natural sliced, roasted salted and honey roasted) under fasted and satiated conditions. Duplicate samples were masticated to the point of deglutition and then were expectorated and size sorted.No statistically significant effects of BMI were detected for any of the mastication measures. Maximum and mean bite forces were greater under the fasted condition. Sliced almonds required lower bite force than did the other almond varieties. The pre-swallowing particle sizes were significantly greater for the sliced almonds than all other varieties. Both the number of chews and mastication time were negatively correlated with particle size. There were no significant effects of almond form or flavor on particle size.These results do not support differences in masticatory performance between lean and obese individuals, nor effects of sensory properties. Instead, the physical form of foods as well as an individuals' appetitive state may have a greater influence on masticatory behavior. The health implications of these observations warrant further investigation.

Purpose: The purpose of this study was to investigate the effects of the insertion of unilateral extension base removable partial dentures (RPDs) on the elution of umami components during mastication in Kennedy Class II cases.Methods: Rishiri kelp cut into 25 mm×25 mm pieces was selected as the test food. Eight patients with unilateral molar teeth defects were instructed to masticate samples for 50 strokes each, on the edentate side with RPDs, on the edentate side without RPDs, and on the dentate side. The amount of glutamic acid extracted from the samples was determined by spectrometry; the difference between the amounts of glutamic acid in the original and chewed samples was regarded as the amount intraorally eluted. The ratios of the amounts of glutamic acid eluted intraorally to that present in the original samples were compared among the groups.Results: Bonferroni-adjusted Wilcoxon matched-pairs signed-rank tests revealed a significant difference between the ratios of the amount of glutamic acid eluted intraorally from samples chewed on the edentate side with RPDs and that from samples chewed on the edentate side without RPDs and between the ratios of the amount of glutamic acid eluted intraorally from samples chewed on the dentate side and that from samples chewed on the edentate side without RPDs (P

summary Surgical correction of retrognathism may influence chewing performance and its underlying mechanisms selection and breakage of food particles. In this study we examined the hypothesis that treatment of this anomaly improves chewing performance. Furthermore, we determined to what extent this change can be attributed to selection and breakage of food particles. Eleven patients were tested before and 1–1·5 years after surgery. To determine chewing performance, eight cubes of 8 mm of a silicone rubber (Optosil®) were used as a test food. Selection and breakage were determined in one-chew experiments using three particle sizes. On average, no differences were found for chewing performance, selection or breakage. However, on an individual basis, patients with a poor chewing performance before surgery tended to improve, whereas no improvement was observed for patients with a good chewing performance. The change in chewing performance was mainly due to a change in breakage of the food particles.

We analysed the effect of three portion sizes Optocal Plus (small, medium and large) on swallowing thresholds in subjects with either conventional complete dentures or mandibular implant-retained overdentures (transmandibular and permucosal cylindric implants). Tests were carried out in 52 women and 15 men (mean age 59 years) 4 years after treatment in a randomised controlled clinical trial. The results indicated that the degree of mucosal support for the mandibular denture did not affect the number of chewing strokes, time till swallowing or swallowed particle size. Only the chewing rate differed: subjects wearing mandibular implant-retained overdentures chewed the food at a higher rate than complete-denture wearers. With larger portion sizes, subjects needed significantly more chewing strokes and time until swallowing and they would have swallowed larger particles. Men chewed their food more efficiently than women, as they used the same number of chewing strokes and time, but achieved a greater particle size reduction at the swallowing moment.

In order to find the most suitable food and chewing side for evaluating the stability of masticatory movement, three types of food with varying textures, as well as both free chewing and unilateral chewing, were utilized in analyzing the masticatory path during mastication. A piece of chewing gum, one peanut, and a slice of crispy bread were used as test foods. For 20 healthy subjects, movement of the incisal point while masticating a test food for 10 s on the free side and the habitual side was recorded. Indicators representing movement path stability were calculated and compared among the foods and between the chewing sides. Masticatory movement was most stable when masticating chewing gum, and less stable for the peanut, and most unstable for the crispy bread. There was a statistically significant difference between each pair of foods for almost all of the indicators. The indicators for peanut were approximately 1.5 times larger than those for masticating chewing gum and the indicators for crispy bread were double those for the chewing gum. When comparing free chewing with unilateral chewing, the masticatory movement of unilateral chewing was significantly more stable than that of free chewing for all test foods. From these results it was suggested that, for evaluating masticatory movement path stability, the most suitable type of food was softened chewing gum and the most suitable chewing method was unilateral chewing on the habitual chewing side.

Objective The aim of this study was to examine the validity of objective assessment of actual chewing side by measurement of electromyographic (EMG) activity of the bilateral masseter muscles upon chewing test foods. Design The sample consisted of 19 healthy, dentate individuals. The subjects were asked to chew three types of test foods (peanuts, beef jerky, and chewing gum) for 10 strokes on the right side and then on the left side, and instructed to perform maximum voluntary clenching for 3 s, three times. EMG activity from the bilateral masseter muscles was recorded. The data were collected in three different days. The root mean square EMG amplitude obtained from the maximum clenching task was used as the maximum voluntary contraction (MVC). Then, the level of amplitude against the MVC (%MVC) was calculated for the right and left sides on each stroke. The side with the larger %MVC value was judged as the chewing side, and the concordance rates (CRs) for the instructed chewing side (ICS) and the judged chewing side (JCS) were calculated. Intraclass correlation coefficients (ICCs) of the CRs were calculated to evaluate the reproducibility of the method. Results High CRs between the ICS and JCS for each test food were recognized. There were significant ICCs for beef jerky (R = 0.761, P Conclusions The results suggested that the measurement of EMG activity from the bilateral masseter muscles may be a useful method for the objective determination of the actual chewing side during mastication.

Recent research indicates that chewing behavior may influence energy intake and energy expenditure. However, little is known about the relationship between chewing behavior and body weight status. In the present study, 64 fully dentate normal-weight or overweight/obese adults were asked to consume five portions of a test food and the number of chewing cycles, chewing duration before swallowing and chewing rate were measured. Adjusting for age and gender, normal-weight participants used a higher number of chewing cycles (p = 0.003) and a longer chewing duration (p0.001) to consume each portion of the food, compared to overweight/obese participants. However, there was no significant difference in their chewing rate (p = 0.597). A statistically significant negative correlation between body mass index and the number of chewing cycles (r = -0.296, p = 0.020) and chewing duration (r = -0.354, p = 0.005) was observed. In conclusion, these results suggest that chewing behavior is associated with body weight status in fully dentate healthy adults.

Temporo Mandibular Joint Disorder (TMD) could be caused by forward head posture. Articular sound/TMJ clicking is the most often sign and symptom for TMD that could happen in human being. The presence of TMD such as TMJ clicking would cause an imbalance masticatory system. The purpose of this research is to investigate TMJ clicking effects to masticatory performance. This research was cross-sectional study with a type of epidemiology survey. Subject were children aged 12-15 years old Deutero-Malay sub-races Live in Bandung and was taken using multi-stage random sampling technique. Subject; consisted of 24 children as control group and 28 children as TMJ clicking group. Both group were then checked for masticatory performance using multiple sieve method and 20x chewing of artificial test food. Mastication performance value represented by median particle size (MPS) particle distribution (b) for each group. MPS from TMJ clicking group (3.0571,SD=0.9990) showed higher value than control group (2.28958,SD=0.66838). Statistic analysis with t-test showed that there’s a significant result in both of group (pvalue=0,0024, α = 0,05). Conclussion, temporo mandibular joint clicking subject has lower masticatory performance.

The purpose of this study was to examine, on the basis of masticatory performance (MP), total muscle work (TMW), and range of movement (RoM), whether reduction of the profile of the cusps results in loss of the biomechanical effectiveness of chewing by healthy dentate patients.Twenty healthy patients (10 female, mean age: 24.1 ± 1.2 years) chewed standardized silicone particles, performing 15 masticatory cycles. Three experimental conditions were investigated: chewing on (1) the natural dentition (ND), (2) splints with structured occlusal profiles simulating the patient's natural dentition (SS), and (3) splints with a plane surface (PS). The expectorated particles were analyzed by a validated scanning procedure. The size distribution of the particles was calculated with the Rosin-Rammler function and the mean particle sizes (X50) were determined for each experimental condition. The target variables of the experimental conditions were compared by repeated measures analysis of variance.X50 values calculated for MP differed significantly (P.002) between PS and SS, and between ND and SS. Conversely, no significant differences (P.05) were observed between SS and ND. Regarding muscle work the EMG activity of the masseter differed significantly (P.001) between the left and right sides, with higher values for the right (chewing) side. No significant differences (P.05) were observed for TMW and RoM under the three test conditions.The results confirm the biomechanical significance of structured occlusal surfaces during chewing of brittle test food by young dentate subjects.

The aim of this study was to evaluate the reproducibility of the condensation silicone Optosil Comfort® as an artificial test food for masticatory performance evaluation. Twenty dentate subjects with mean age of 23.3 ± 0.7 years were selected. Masticatory performance was evaluated using the simple (MPI), the double (IME) and the multiple sieve methods. Trials were carried out five times by three examiners: three times by the first, and once by the second and third examiners. Friedman’s test was used to find the differences among time trials. Reproducibility was determined by the intra-class correlation (ICC) test (α = 0.05). No differences among time trials were found, except for MPI-4 mm (p = 0.022) from the first examiner results. The intra-examiner reproducibility (ICC) of almost all data was high (ICC ≥ 0.92, p < 0.001), being moderate only for MPI-0.50 mm (ICC = 0.89, p < 0.001). The inter-examiner reproducibility was high (ICC > 0.93, p < 0.001) for all results. For the multiple sieve method, the average mean of absolute difference from repeated measurements were lower than 1 mm. This trend was observed only from MPI-0.50 to MPI-1.4 for the single sieve method, and from IME-0.71/0.50 to IME-1.40/1.00 for the double sieve method. The results suggest that regardless of the method used, the reproducibility of Optosil Comfort® is high.

Comminution of food is the composite result of selection and breakage. Selection is characterised by the chance that a food particle will at least be damaged by the teeth during chewing. For any size, this chance equals the ratio between the weight of damaged or broken particles and that of all initial particles. The breakage process refers to fracturing of selected particles. The aim was to examine whether a reduced chewing performance of pre-orthognathic surgery patients is due to an impairment of selection, breakage or both. Eight cubes of 8.0 mm of the silicone-rubber Optosil " were used as a test food to determine chewing efficiency for 12 patients (skeletal Angle Class II and dental Angle Class II, subdivision 1) and 12 controls (class I molar relation). Selection and breakage were determined in one-chew experiments using various particle sizes. Chewing efficiency was significantly lower for the patients than for the controls. The selection chance was significantly smaller for the patients, in particular for smaller (< or = 4.8 mm) particles. The degree of breakage was lower for the patients, in particular for medium-sized particles of 4.8 mm. These findings suggest that the reduced chewing performance of pre-orthognathic surgery patients is due to an impairment of both selection and breakage.

Cooked rice is the staple food for Japanese. It has been considered whether cooked rice can be used in the examination of mastication. The purpose of the present study was to ascertain its appropriateness as a test food.The results were as follows:1. The questionnaire was given to 130 people and asked their preference and intake frequency of cooked rice. The survey showed a high preference and intake frequency.2. A model of various textures was prepared using nine combinations in accordance with L9 (34) orthogonal array. The use of 15 or 20g of cooked rice was found to be appropriate. It was concluded that cooked rice was not affected by soaking time (within 12hours) or by the time it was kept (within 6hours).It was also concluded that it was appropriate to use for the evaluation of the masticatory function as a test food.

Summary Because food texture is regarded as an important factor for smooth deglutition, identification of objective parameters that could provide a basis for food texture selection for elderly or dysphagic patients is of great importance. We aimed to develop an objective evaluation method of mastication using a mixed test food comprising foodstuffs, simulating daily dietary life. The particle size distribution (>2 mm in diameter) in a bolus was analysed using a digital image under dark-field illumination. Ten female participants (mean age ± s.d., 27·6 ± 2·6 years) masticated a mixed test food comprising prescribed amounts of rice, sausage, hard omelette, raw cabbage and raw cucumber with 100%, 75%, 50% and 25% of the number of their masticatory strokes. A single set of coefficient thresholds of 0·10 for the homogeneity index and 1·62 for the particle size index showed excellent discrimination of deficient masticatory conditions with high sensitivity (0·90) and specificity (0·77). Based on the results of this study, normal mastication was discriminated from deficient masticatory conditions using a large particle analysis of mixed foodstuffs, thus showing the possibility of future application of this method for objective decision-making regarding the properties of meals served to dysphagic patients.

Made available in DSpace on 2021-07-14T10:36:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-12. Added 1 bitstream(s) on 2021-07-14T11:34:01Z : No. of bitstreams: 1 S2176-94512013000600018.pdf: 118495 bytes, checksum: d707284efb4a15a7ca50978ed6bee384 (MD5) OBJETIVO: o objetivo desse estudo foi avaliar a dor, a performance mastigatória e o limiar de deglutição em pacientes submetidos ao tratamento ortodôntico. MÉTODOS: foram avaliados dez pacientes de ambos os sexos (idade média 17,25 ± 5,21 anos), com dentição permanente completa, submetidos ao tratamento ortodôntico com aparelhos fixos. A performance mastigatória e o limiar de deglutição foram avaliados pela capacidade individual de fragmentação de um alimento teste artificial (Optocal), o qual foi mastigado e as partículas resultantes processadas por um método padronizado com peneiras, apresentando o tamanho mediano das partículas (TMP) das unidades trituradas. A intensidade da dor/desconforto foi avaliada com o uso de uma escala analógica visual. Todos os testes foram realizados nos seguintes momentos: T0: antes da ativação do aparelho ortodôntico; T1: 24 após a ativação, e T2: 30 dias após a ativação. RESULTADOS: os resultados demonstraram um aumento significativo na dor em T1 (T0: 0,60 ± 0,70mm; T1: 66,2 ± 34,5mm), retornando aos valores basais em T2 (3,20 ± 3,82mm). A performance mastigatória também foi reduzida em T1 (TMP: 10,15 ± 1,1mm²) comparada a T0 (TMP: 7,01 ± 2,9mm²) e T2 (TMP = 6,76 ± 1,3 mm²). Entretanto, o tamanho das partículas não foi afetado no teste do limiar de deglutição (T0: 5,47 ± 2,37mm²; T1: 6,19 ± 2,05mm²; T2: 5,94 ± 2,36mm²). CONCLUSÃO: os aparelhos ortodônticos não interferiram no tamanho das partículas que seriam deglutidas, mesmo na presença da dor. OBJECTIVE: The aim of this study was to assess pain, masticatory performance and swallowing threshold of patients undergoing orthodontic treatment. METHODS: Ten patients of both genders (mean age of 17.25 ± 5.21 years), with complete permanent dentition, who underwent orthodontic treatment with fixed appliances were evaluated. The masticatory performance and the swallowing threshold were assessed by patient's individual capacity of fragmenting an artificial test food (Optocal) which was chewed and had the resulting particles processed by a standardized sieving method, presenting the median particle size (MPS) of crushed units. The intensity of pain / discomfort during chewing was evaluated by means of a visual analog scale. All tests were performed at the following times: T0 - before activating the orthodontic appliance; T1 - 24 hours after activation, and T2 - 30 days after activation. RESULTS: The results showed a significant increase in pain at T1 (T0 - 0.60 ± 0.70 mm; T1 - 66.2 ± 34.5 mm), returning to baseline values at T2 (3.20 ± 3.82 mm). Masticatory performance was also reduced in T1 (MPS 10.15 ± 1.1 mm²) in comparison to T0 (MPS 7.01 ± 2.9 mm²) and T2 (MPS 6.76 ± 1.3 mm²). However, particle size was not affected in the swallowing threshold test (T0 - 5.47 ± 2.37 mm²; T1 - 6.19 ± 2.05 mm²; T2 - 5.94 ± 2.36 mm²). CONCLUSION: The orthodontic appliances did not interfere in the size of the particles that would be swallowed, even in the presence of pain. Universidade Federal do Rio Grande do Sul Universidade Estadual Paulista Universidade Estadual de Campinas Universidade Estadual Paulista

Standard procedure for the measurement of masticatory performance is the fractionated sieving of fragmented test food, which is substantially time consuming. The aim of this study was to introduce a less laborious, comparable, and valid technique based on scanning. Fifty-six Optocal chewing samples were minced by wearers of complete dentures with 15 and 40 chewing strokes and analyzed by both a sieving and a scanning method. The sieving procedure was carried out using ten sieves (5.6, 4.0, 2.8, 2.0, 1.4, 1.0, 0.71, 0.5, 0.355, and 0.25 mm) and measuring the weight of the specific fractions. Scanning was performed with a flatbed scanner (Epson Expression1600Pro, Seiko Epson Corporation, Japan, 1,200 dpi). Scanned images underwent image analysis (ImageJ 1.42q, NIH, USA), which yielded descriptive parameters for each particle. Out of the 2D image, a volume was estimated for each particle. In order to receive a discrete particle size distribution, area–volume-conversion factors were determined. The cumulated weights yielded by either method were curve fitted with the Rosin–Rammler distribution (MATLAB, The MathWorks, Inc., Natick, USA) to determine the median particle size X 50. The Rosin–Rammler distributions for sieving and scanning resembled each other and showed an excellent correlation in 15/40 chewing strokes (r = 0.995/r = 0.971, P

Particle sizes obtained with progressive chewing cycles were quantified by use of an optical scanning device and compared with the sieving method. The aim of this study was to validate the optical method by comparison with sieving using a natural test food, almond. Masticatory efficiency was assessed in six dentate subjects. The almonds were chewed for 1, 4, 8, 16 and 32 chewing strokes. Each experiment was replicated. The chewed material was sieved through a 1 mm aperture sieve on a Büchner funnel and dried after washing with water and 100% alcohol. The dried particles were weighed and scanned by an optical scanning device for number and size. The same samples were sieved and weighed with a conventional sieve method. The results of both methods were described by particle size distributions based on the volume of particles. The results derived from the optical scanning and sieving showed similarity. It can be concluded that the optical method is simple to use, faster than sieving and needs little skill in the use of equipment. The comparison of the results validates both methods.

A study was conducted for the purpose of grasping the influence of food characteristics on electromyographic (EMG) patterns during mastication. Cheese, kamaboko, takuan, senbei, surume and gumi were used as test food. Vertical jaw movement and EMG activities were recorded simultaneously from 10 healthy adults. EMG signal was divided according to the period of the maximum opening position of vertical jaw movement.EMG profile for chewing stroke was accomplished by normalizing each period to 100% from the beginning of mastication to swallowing. The relationship between the texture of test materials and the EMG profiles was evaluated.The obtained results were as follows:1. The EMG profile of each test material showed various patterns. The degree of variability in the masseter was larger than that in the temporal and digastric muscles.2. Owing to the delay of the onset of EMG activity, the duration of activity in the temporal and masseter muscle was shortened as mastication progressed.3. Cheese showed the largest difference between the beginning of mastication and just before swallowing in the EMG profile of the temporal and masseter muscles. Surume showed least change in the EMG profile.

The purpose of this study is to measure the dynamics of the atmospheric pressure under the maxillary complete dentures in the edentulous patients and to elucidate the relationship between the atmospheric pressure and the stability of the denture.The dynamics of atmospheric pressure, which induced during the prescribed functions of the mouth, were recorded as the waves.The following results were obtained.1. In the process of the seating of the denture, the atmospheric pressure under the denture (APD) became higher than the external one.2. APD increased and decreased alternately during tapping movements.3. APD decreased during the light opening movements and decreased more during the following wide opening movements.4. APD became lower than the external one during the tapping or the opening movements.5. APD decreased gradually as repeating increase and decrease every biting movement, during mastication of the test food (peanuts, carrots, kamaboko).6. APD equaled to the external one when the denture was separated completely from the tissue.7. The dynamics of atmospheric pressure under the maxillary complete denture seems to be influenced by oral conditions, denture designs and foods properties, and to be useful as an index of the denture stability.

The force-deformation characteristics of two artificial test foods (Optosil and Optocal) for measurements of food comminution during mastication were investigated in a bite simulator and compared with those of carrots and peanuts. The influence of cusp geometry was evaluated by use of a flat plate and three cusp forms. The forces at the yield point were lower for Optocal than for Optosil artificial test food. The forces needed for Optocal overlapped those needed for carrots and peanuts. The natural foods showed more variation in the force and percentage of deformation at the yield point than the artificial foods. The artificial foods reflected the differences in cusp form better than did the natural foods. The use of artificial foods fulfills a need for standardization and warrants consideration in studies of mastication.

This study investigated the relationships between the ability of 38 patients with complete dentures to comminute a tough artificial test food and their answers to questions about the chewing experience. Also, clinical assessments were made of denture quality and oral conditions. Significant but weak relationships were found between the ability to comminute the test food and the subjective chewing experience as well as the degree of resorption of the mandibular residual ridge. Masticatory ability is conceivably determined by many other factors as well. Results indicate that dentists cannot rely on asking denture wearers about chewing problems and clinical responses with respect to oral conditions and denture quality for predicting those patients' masticatory abilities. The ability of wearers of complete dentures to comminute tough foods should be determined individually by a series of chewing tests.

Masticatory performance has often been measured by determining an individual's capacity to comminute a test food. Another method to determine masticatory performance, which is now widely used, evaluates the ability to mix and knead a food bolus. Two-coloured chewing gum and paraffin wax have been used as test foods for the quantification of the mixing ability. The aim of our study was to compare the results obtained with the comminution of an artificial test food and the results obtained from mixing of a two-coloured chewing gum. The degree of mixing of the colours of the chewing gum was quantified with an optical method. Twenty young subjects with a natural dentition ( average age 24 years) and twenty elderly subjects, mostly with complete dentures ( average age 72 years), participated in the study. Significant differences in masticatory performance between the two groups were detected with both methods. However, the comminution test was better in discriminating the masticatory performance of the two groups. The mixing ability test with the two-coloured chewing gum proofed to be a good method to determine masticatory function in subjects with a compromised masticatory performance ( elderly subjects). However, the method appeared to be less suitable for subjects with a good masticatory performance ( young subjects).

Summary-In previous in vitro experiments using an Instron instrument, each test food was found to have characteristic textural properties. In uivo experiments were now made (1) to determine the degree to which variations in the vertical jaw movements during the crushing phase of mastication can be explained by the inherent properties of the foodstuff being chewed, and (2) to establish the degree to which the foodstuff being chewed can be identified by certain features of the jaw dynamics. Five adults were used for chewing tasks with standardized pieces of beef, carrot or peanut. Each subject made two trials with each foodstuff. The movement of the lower incisal point was monitored; features of movement associated with jaw closing in the first chewing cycle were considered. Five of these features were not suitable to categorize the various test foods. Each of the remaining 4, however, was able to distinguish either one food from the 2 others (2 cases), or one from another (2 cases). Pattern recognition techniques based upon principal component analysis could differentiate jaw closing patterns associated with chewing bee.f from those involving peanut or carrot. The extent to which peanut could be distinguished from carrot was not as predictable as the categorization of peanut or carrot versus beef. Cross-correlation of in oitro forcetime breakage characteristics and the jaw movement data showed that on average 52% of the variation in the vertical jaw movement during crushing of food could be explained by the inherent properties of the food. Because the masticatory apparatus acts as a low-pass filter, the high-frequency components of food breakage characteristics found in vitro were attenuated in uiuo. It appears that the inherent filter properties of the masticatory apparatus limit the range of sensory and motor function of the jaw.