Comparison of particle-size distributions determined by optical scanning and by sieving in the assessment of masticatory performance

Accuracy of newly developed color determination application for masticatory performance: Evaluating color-changeable chewing gum

PURPOSE

Color-changeable chewing gums are used to evaluate masticatory performance, as measured by a colorimeter or visually based on a color scale. Although anyone can use a color scale, the evaluation accuracy depends on the evaluator. We develop an application that can determine the degree of color change in chewing gum using smartphone images, making color evaluation accurate and easy to measure.

METHODS

For the application, 60 chewed gum samples were prepared. Two shots were captured using two smartphone models. To create the application algorithm, a formula was developed to approximately map the color value from the smartphone images to the true value using a colorimeter. A basic validation was performed on 60 new samples covering a range of colors, followed by a field validation on 100 healthy dentate participants aged 20-39 years.

RESULTS

The intraclass correlation coefficient for two repeated shots had a high value ≥ 0.97 in the basic and field validations, confirming reliability. No significant differences were observed in the paired t-test and Wilcoxon signed-rank test, and a significant and strong correlation (correlation coefficient ≥ 0.92) was observed between the evaluation values using the colorimeter and the basic and field validations. Bland-Altman plots further confirmed the validity of the application.

CONCLUSIONS

A software application was developed to enable easy, quick, and accurate determination of the masticatory performance of a chewing gum from images taken using a smartphone with highly reliable and validated results.

Evaluating the Impact of Various Treatment Modalities on the Chewing Efficiency of Anterior Disc Displacements of Temporomandibular Joint Disorder Cases: A Comparative Study

Aim

Internal disc displacement of the temporomandibular joint (TMJ) is identified by an anomaly between the condylar-disc assembly, which, in many cases, may lead to discomfort and malfunction of the chewing function. The study's objective was to assess the effects of four distinct treatment approaches on temporomandibular disorder cases with anterior disc displacements focusing on their chewing efficiency.

Materials and Methods

One hundred participants suffering from reducible TMJ disc displacement were selected for enrollment in the study. Subjects were divided equally into four groups: group I patients were treated with behavioral therapy; group II patients were treated with low-level laser therapy (LLLT); group III patients were treated with anterior repositioning splints; and group IV patients were treated with flat plane splints. Chewing efficiency was assessed utilizing the fractional sieving method and a synthetic food substitute was created using silicon impression material. The statistical analysis encompassed comparisons of chewing efficiency between groups and between baseline and posttreatment within each group, employing analysis of variance (ANOVA) and paired t tests, respectively.

Results

Using the paired t test, a significant difference in chewing efficiency values as expressed by the median particle size was observed between the baseline and 6-month values in all groups (P < 0.05), except for group I where no significant change was noted over the 6 months (P > 0.05). The one-way ANOVA test revealed a statistically significant difference among groups following therapies (P ˂ 0.05). The post hoc Tukey test was employed for pairwise comparisons and revealed statistically significant variances in the main values of chewing efficiency among all groups at a 95% confidence level (P ˂ 0.05).

Conclusion

The study's results suggest that occlusal splints and LLLT are more effective in improving chewing efficiency than behavioral interventions.

Association of masticatory efficiency with deep carious lesions in children

PURPOSE

Masticatory efficiency is defined as an individual ability to grind and pulverize food material, and can be influenced by many factors. This research aimed to investigate the association between masticatory efficiency and deep carious lesion.

METHODS

The research included 48 children (24 male, 24 female) aged from 3 to 14 years. Participants were allocated to two groups; children with no or with only incipient carious lesions were included in the first group (ICDAS levels 0, 1, or 2), and children with bilateral deep carious lesions that are ICDAS levels 4, 5, and 6 were included in the second group. Information on dental parameters (dental status, ICDAS level of each carious lesion), and level of pain (Wong-Baker scale) were collected from each participant. Participants chewed Optosil® test food for 20 masticatory cycles, and chewed particles were analyzed by the optical scanning method.

RESULTS

There is a significant difference in masticatory efficiency variables (number of chewed particles, minimal and maximal Feret diameter, Sauter mean diameter, a mean and total surface of particles) between groups. A positive significant correlation is observed between WBS level and time needed for masticatory performance in a group of children with deep carious lesions.

CONCLUSION

Deep carious lesions in children are associated with a decrease in masticatory efficiency. Moreover, children with carious lesions that provoke a higher level of pain take more time for masticatory cycles.

Masticatory performance in patients with jaw muscle pain: A case control study

Introduction

Masticatory function is often impaired in patients with painful temporomandibular disorders (TMD) therefore more detailed studies on comminution and mixing ability are warranted in well-defined TMD patients with chronic myalgia. Moreover, there is a need to explore the correlation between any changes in perceived pain or fatigue in such patients and the masticatory function.

Materials and methods

Self-assessments using questionnaires regarding pain, oral health, jaw function, masticatory ability, fear of movement and psychosocial signs were answered by all the participants. A series of chewing tasks involving viscoelastic food and two-colored gum was performed. Optical imaging and analyzing was conducted. Bite force as well as characteristics of pain and fatigue were assessed.

Results

In patients, the fragmented soft candy particles were less in number and had larger median of area and minimum Feret's diameter after standardized chewing compared to healthy individuals (P = 0.02). Surprisingly, the two-colored Hue-Check gum was less mixed by the healthy controls since they displayed a greater variance of the hue (P = 0.04). There were significant differences between the patients and the healthy controls in the self-assessed masticatory ability mainly regarding pain-related variables.

Conclusions

Objectively, TMD patients with chronic myalgia exhibited an impaired masticatory performance with less efficiency in comminuting soft viscoelastic food compared to the pain-free healthy control group. There was an agreement between the patients' self-assessed masticatory ability and the efficiency of their masticatory function.

Use of handgrip strength measurement as an alternative for assessing chewing function in people with dementia

Background

Chewing ability and handgrip strength can be independent explanatory factors of physical fitness. The usability of measurement procedures for assessing chewing function in people with dementia seems to be limited. This study aimed to show an association between handgrip strength and chewing function to enable the use of handgrip strength measurement as an alternative for determining chewing parameters in people with dementia. 

Methods

The data analysed here are part of the OrBiD (Oral Health, Bite Force and Dementia) pilot study. A total of 120 participants were assigned to five evaluation groups based on their cognitive abilities using the Mini-Mental State Examination (MMSE). The MMSE groups in this data analysis were “no dementia” (noDem, MMSE 28–30), “mild cognitive impairment” (mCI, MMSE 25–27), and “mild dementia” (mDem, MMSE 18–24). Handgrip strength, maximum occlusal force, and chewing efficiency were measured. 

Results

The Mini-Mental State Examination scores among all participants (n = 71) resulted in a median of 27 and a range of 18–30. An association between maximum handgrip strength and the cognitive impairment of the participants was shown. Nevertheless, the use of handgrip strength measurement as an alternative for determining chewing function was not verified in this study.

Conclusions

The feasibility and reliability of chewing function measurements in people with dementia should be investigated. Existing measurement procedures may need to be adapted or new assessments may need to be developed to be usable in people with dementia.

Trial registration

ClinicalTrials.gov NCT03775772.

Biomechanical properties of masticatory balance in cases with RPDs-The influence of preferred and nonpreferred chewing side: A pilot study

Objectives

Removable partial dentures (RPDs) are inserted with the aim to restore masticatory function. There is however inconsistent evidence supporting the alleged improvements, posterior occlusal contacts being one of the decisive factors. We hypothesized that the distribution of abutment teeth in RPDs influences masticatory performance and functional parameters. To evaluate the masticatory performance and functional parameters in patients with a RPD using a single mathematical parameter (tilting index [TI]) for both jaws that predicts biomechanical behavior on the basis of the distribution of abutment teeth.

Materials and Methods

Masticatory performance was measured in patients wearing long‐time adapted RPDs using the standardized test food optocal, yielding the mean particle size (X₅₀). Mastication on the preferred and nonpreferred chewing sides was analyzed. Total muscle work (TMW) was calculated using bipolar electromyographic recordings of the masseter and anterior temporalis muscle. Functional parameters were subjected to multiple linear regression analysis including X₅₀ as a dependent variable and functional units (FU), the number of teeth, bite forces, and sagittal and frontal components of TI (TI α and TI β) as independent variables.

Results

When the preferred chewing side was tested, none of the investigated parameters correlated significantly with X₅₀. In contrast, chewing on the nonpreferred side was correlated significantly with performance for most variables (p < .05). This means that increased dental support improved chewing performance with RPDs under these conditions.

Conclusions

In well‐adapted RPDs, the distribution of abutment teeth as expressed by the tilting index seems to be of subordinate importance for masticatory performance.

Study of occlusal acoustic parameters in assessing masticatory performance

Background

Previous masticatory studies have focused on a variety of measurements of foods and boluses or kinematic parameters and sound during mastication. To date, the masticatory sound research of has been limited due to the difficulties of sound collection and accurate analysis. Therefore, significant progress in masticatory sound has not been made. Meanwhile, the correlation between acoustic parameters and mastication performance remains unclear. For the purpose of exploring the acoustic parameters in measuring mastication performance, the bone-conduction techniques and sound analysis were used, and a statistical analysis of acoustic and occlusal parameters were conducted.

Methods

The gnathosonic and chewing sounds of fifty-six volunteers with healthy dentate were recorded by a bone-conduction microphone and further analyzed by Praat 5.4.04 when intercuspally occluding natural foods (peanuts) were consumed. The granulometry of the expectorated boluses from the peanuts was characterized by the median particle size of the whole chewing sequence (D50^a) and the median particle size during the fixed chewing strokes (D50^b). The chewing time of the whole chewing sequence (CT^a), the chewing time of the fixed chewing strokes (CT^b), the chewing cycles (CC), and the chewing frequency (CF) were recorded and analyzed by the acoustic software. The acoustic parameters, including gnathosonic pitch, gnathosonic intensity, mastication sound pitch of the whole chewing sequence (MP^a), mastication sound pitch of the fixed chewing strokes (MP^b), mastication sound intensity of the whole chewing sequence (MI^a) and mastication sound intensity of the fixed chewing strokes (MI^b), were analyzed. Independent sample t-test, Spearman and Pearson correlation analyses were used where applicable.

Results

Significant difference in parameters CC, MI^a, CF and D50^a were found by sex (t-test, p < 0.01). The masticatory degree of the test foods was higher in women (CC, 24.25 ± 5.23; CF, 1.70 ± 0.21 s⁻¹; D50^a, 1655.07 ± 346.21 μm) than in men (CC, 18.14 ± 6.38; CF, 1.48 ± 0.18 s⁻¹; D50^a, 2159.21 ± 441.26 μm). In the whole chewing sequence study, a highly negative correlation was found between MI^a and D50^a, and a highly positive correlation was found between MI^a and CF (r =  − 0.94, r = 0.82, respectively, p < 0.01). No significant correlation was found between the remaining acoustic parameters and mastication parameters. In the fixed chewing strokes study, a highly negative correlation was found between MI^b and D50^b (r =  − 0.85, p < 0.01). There was no significant correlation between the rest of the acoustic parameters and the mastication parameters.

Conclusions

Mastication sound intensity may be a valuable indicator for assessing mastication. Acoustic analysis can provide a more convenient and quick method of assessing mastication performance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-02018-9.

Impact of food texture modifications on oral processing behaviour, bolus properties and postprandial glucose responses

Several studies have demonstrated food texture manipulation on oral processing behaviour (OPB). We explored the effect of texture-differences of equivalent carbohydrate load on OPB, bolus properties and postprandial glycaemic responses (PPG). In a randomised cross-over, within-subjects, non-blinded design, healthy male participants (N = 39) consumed fixed portions of white rice (WR) and rice cake (RC) while being video recorded to measure microstructural eating behaviours. PPG was compared between test foods over a period of 120-min, and the bolus properties and saliva uptake at swallow were measured for both test foods. RC displayed higher instrumental hardness, chewiness and Young's modulus than WR (p = 0.01), and participants perceived RC as more springy and sticky than WR (p < 0.001). The RC meal was chewed more per bite (p < 0.001) and consumed at a faster eating rate (p = 0.033) than WR. WR bolus particles were smaller at swallow (p < 0.001) with a larger total surface area (p < 0.001), compared to RC. The glucose response for RC was significantly higher during the first 30-min postprandial period (p = 0.010), and lower in the later (30-120 min) postprandial period (p = 0.031) compared to WR. Total blood glucose iAUC did not differ significantly between WR and RC meals despite their large differences in texture, OPB and bolus properties. Oro-sensory exposure time was a significant predictor of glucose iAUC30min for both test meals (RC, p = 0.003; WR, p = 0.029). Saliva uptake in the bolus was significantly positively associated with blood glucose during the first 30-min postprandial period for the RC meal (p = 0.008), but not for WR. We conclude that food texture modifications can influence OPB and bolus properties which are key contributors to the dynamic evolution of the glycaemic response. Total blood glucose responses were the same for both test foods, though differences in oral processing and bolus properties influenced temporal changes in PPG.

Effects of food particle loss on the evaluation of masticatory ability using image analysis

PURPOSE

To examine how particle loss affects the evaluation of masticatory ability using the image analysis method.

METHODS

The subjects were divided into two groups:Y-group (healthy young adults: 10 male, 10 female; mean age 27.6 ± 1.9 years), and D-group (denture wearing older adults: 13 male, 9 female; mean age, 75.1 ± 5.3 years). Raw carrots, peanuts, and a combined test food from 5 daily food materials (mixed foods) were selected as test foods. Images of the boluses were captured and processed after the subjects freely masticated the test foods until the point of swallowing or completed half strokes of total chewing cycles. The median particle size (X₅₀) was calculated from the data for each particle. We compared X₅₀ calculated from all particles obtained from the masticatory bolus (as X_50N) with the X₅₀ of only selectively larger particles (as X_50R).

RESULTS

Significant correlations were observed between X_50N and X_50R (p < 0.01) determined in almost all masticatory conditions. In particular, for particle sizes of 2 mm or more, the correlation coefficient between X_50N and X_50R was notably strong (r > 0.75).

CONCLUSION

The method of analyzing only larger particles makes it possible to evaluate masticatory ability without losing the characteristics of the original particle size distribution of the entire bolus. This finding can be applied for the evaluation of masticatory ability, especially among older adults who have difficulty retrieving the total amount of test food due to decreased activities of daily living.

Masticatory function before and after masticatory muscle-related temporomandibular disorder treatment: An observational study

BACKGROUND

Muscle-related temporomandibular disorders (TMD) may affect the masticatory function. Chewing function can be assessed objectively using bolus-kneading tests, such as two-colour chewing-gum mixing ability test.

OBJECTIVE

The aim was to compare the masticatory function with a two-colour chewing-gum test before and after treatment of the masticatory muscle-related temporomandibular disorder.

METHODS

Twenty-one patients with masticatory muscle disorder according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were recruited as an experimental group, and further twenty-one participants without any TMD were included as controls. Pain intensity (scored on a visual-analogue scale) and maximum mouth opening (MMO) were recorded. Jaw Functional Limitation Scale-8 (JFLS-8) was conducted on all patients. Before and after treatment, masticatory function was evaluated with a validated bolus-kneading test, using two-colour chewing gum.

RESULTS

There was no statistically significant difference in chewing function before and after treatment in the experimental group (p = .715). When these values were compared with the control group, there were no statistically significant differences (p = .489, p = .890). There was no correlation between masticatory function and VAS, MMO, JFLS-8 before and after treatment in the experimental group.

CONCLUSION

The two-colour chewing-gum test is not sensitive when the masticatory performance is not severely impaired.

What does 'toughness' look like? An examination of the breakdown of young and mature leaves under cyclical loading

The material property of leaf toughness is considered the crucial mechanical challenge facing folivorous primates. Mature leaves have higher recorded toughness values than young leaves on average, leading to many assumptions about the patterning of food breakdown that follow a tough/not-tough dichotomy. We tested three hypotheses about how leaves break down under repetitive loading cycles, predicting that mature leaves (i) experience more force during simulated occlusal loads, (ii) more effectively resist fragmentation into small pieces, and (iii) show a more gradual decline in resistance over consecutive cycles than young leaves. Under displacement control using a mechanical testing system, we subjected young and mature leaves to 20 cycles of axial loading using interlocking steel wedges, then collected and quantified the size of the leaf fragments. While we found that mature leaves experienced more overall force than young leaves (p < 0.001), they also shattered into smaller pieces (p = 0.004) and showed a steeper decline in their resistance to the cycles over the course of a test (p < 0.01). These results suggest that putatively 'tougher' foods (i.e. mature versus young leaves) do not necessarily resist fragmentation as commonly assumed. The current tough/not-tough paradigm of primate foods may not accurately reflect how leaves break down during masticatory behaviour.

Increased oral processing and a slower eating rate increase glycaemic, insulin and satiety responses to a mixed meal tolerance test

PURPOSE

Variations in specific oral processing behaviours may contribute to differences in glucose, insulin and satiety responses to a standardised test meal. This study tested how natural variations in oral processing between slower and faster eaters contribute to differences in post-prandial glucose (PP glucose), insulin response (PP insulin) and post-meal satiety for a standardised test meal.

METHODS

Thirty-three participants with higher risk for type 2 diabetes consumed a standardised test-meal while being video recorded to derive specific oral processing behaviours. Plasma glucose, insulin and satiety measures were collected at baseline, during and post meal. Participants were split into slower and faster eaters using median split based on their eating rates and individual bolus properties were analysed at the point of swallow.

RESULTS

There were large variations in eating rate (p < 0.001). While there was no significant difference in PP glucose response (p > 0.05), slower eaters showed significantly higher PP insulin between 45 and 60 min (p < 0.001). Slower eaters had longer oro-sensory exposure and increased bolus saliva uptake which was associated with higher PP glucose iAUC. Faster eating rate and larger bolus particle size at swallow correlated with lower PP glucose iAUC. A slower eating rate with greater chews per bite significantly increased insulin iAUC. Faster eaters also consistently rated their hunger and desire to eat higher than slower eaters (p < 0.05).

CONCLUSIONS

Natural variations in eating rate and the associated oral processing contributed to differences in PP glucose, PP insulin and satiety responses. Encouraging increased chewing and longer oral-exposure time during consumption, may promote early glucose absorption and greater insulin and satiety responses, and help support euglycaemia.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04522063.

Consensus on the terminologies and methodologies for masticatory assessment

A large number of methodological procedures and experimental conditions are reported to describe the masticatory process. However, similar terms are sometimes employed to describe different methodologies. Standardisation of terms is essential to allow comparisons among different studies. This article was aimed to provide a consensus concerning the terms, definitions and technical methods generally reported when evaluating masticatory function objectively and subjectively. The consensus is based on the results from discussions and consultations among world‐leading researchers in the related research areas. Advantages, limitations and relevance of each method are also discussed. The present consensus provides a revised framework of standardised terms to improve the consistent use of masticatory terminology and facilitate further investigations on masticatory function analysis. In addition, this article also outlines various methods used to evaluate the masticatory process and their advantages and disadvantages in order to help researchers to design their experiments.

Comparison of smartphone-camera and conventional flatbed scanner images for analytical evaluation of chewing function

BACKGROUND

The two-colour mixing test is a quick method to assess chewing function (CF). The use of smartphone cameras for acquiring images may help in further simplifying the process.

OBJECTIVE

This study evaluated the reliability of smartphone-camera images of chewing gums to assess CF.

METHODS

Five test samples of a bicoloured chewing gum were produced by a single fully dentate adult volunteer. The specimens were flattened to 1-mm thick wafers. The two sides of the wafers were digitised with a conventional flatbed scanner (control) and were photographed 20 times using 8 different smartphones. The images were assessed optoelectronically to obtain the variance of hue (VoH) and subjectively by visual assessment (SA) using a categorical scale (SA1-SA5). Spearman's correlation and regression models were used for statistical analyses.

RESULTS

The intra-group variability for SA1-SA3 was <1% for all smartphones, but significantly higher than controls for SA4 and SA5 (smartphone: SA4 = 5.57%; SA5 = 8.76%; control: SA4 = 2.5%; SA5 = 0.79%). VoH was progressively lower from SA1 to SA5 for all imaging devices (r > -.97; P < .001). VoH comparisons between control and smartphone images revealed significant differences for the individual SA categories, and however, the magnitude of differences was small and non-significant when the full range of SA levels were considered. The linear mixed model regression showed significant effects for all the smartphones (P < .001) and SA levels (P < .001) in relation to the flatbed scanner values.

CONCLUSIONS

Smartphone cameras may be used to evaluate colour mixture for a bolus-kneading test, however, the precision is lower with higher degrees of colour mixing.

Differences in comminution progress during mastication in healthy dentate and denture-wearing elderly people

PURPOSE

This study aimed to investigate the effect of removable denture prostheses on the comminution progress in elderly people.

METHODS

Twenty-two denture wearers of Eichner's classification B and C (75.1±5.3 years old) and 20 young fully dentate subjects (27.6±1.9 years old) participated in the masticatory examination, which used a combined test food from 5 daily food materials. Full masticatory cycles lasting until subjects needed to swallow and the half number of the cycles were adopted as masticatory conditions. Digital images of food particles under wet conditions were obtained for each bolus, and particles were analyzed by calculating the homogeneity and particle size indices.

RESULTS

The characteristic properties of the food particles were observed using a homogeneity index in the elderly denture group for half masticatory strokes. Their homogeneity index was significantly higher than that of the young dentate group. By contrast, no significant difference was observed in the indices for particles immediately before swallowing between two groups.

CONCLUSIONS

The comminuted particle size before swallowing in healthy denture wearers was not significantly different from that in the natural dentate group. The comminution of the first-half process in denture wearers was typical and could be one possible focus for meal property specifications in future studies.

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.

The influence of habitual consumption of chewing gums in the outcome of masticatory performance tests using two-coloured chewing gums

The aim of this study is to assess the influence of regular consumption of chewing-gums on the Masticatory Performance (MP); and to determine if increasing the consumption improves the MP of non-regular consumers. We recorded the chewing-gums consumption rate (CGC) and measured the MP of 265 participants (µ = 47.09, σ = 22.49 years) using the Variance of the Histogram of the Hue (VhH) image processing method. Then, participants were instructed to increase the consumption, and the MP was measured again (SESSION) two and four days after. Normality of MP was verified with Kolmogorov-Smirnov and Shapiro-Wilk tests. The association between the age and the consumption rate was measured with GEE and the eta-squared statistic. Finally, a 3 × 3 mixed ANOVA with SESSION as the within-subject factor and CGC as the between-subjects factor was run. Session-wise and group-wise comparison were performed with post hoc Bonferroni. No systematic error was detected for VhH (p = 1.00). Kolmogorov-Smirnov and Shapiro-Wilk tests confirmed the normality of the distribution of MP (p > 0.05). There was a significant effect of SESSION on MP, F(1.746, 457.328) = 59.075, p < 0.001; furthermore, there were significant differences in MP between SESSIONs. Additionally, there was a significant effect of CGC on MP, with F (2, 356.53) = 564.73, p < 0.001. In conclusion, the chewing-gum consumption habits influence the two-coloured chewing gum mixing test. The apparent MP of non-regular consumers can be improved by prescribing a controlled increase in the consumption of chewing-gums for a few days.

Measuring the effects of in vitro mastication on bolus granulometry of shredded meat: A proposal for a new methodological procedure

People with poor oral status and/or neuromuscular deficiencies avoid eating meat because of chewing and swallowing difficulties. Consequently, they expose themselves to the risk of malnutrition and sarcopenia or nutrient deficiencies. To develop a new process for meat preparation, it is necessary to understand how meat is broken down during food oral processing to become a swallowable bolus. However, it is unknown whether the initial texture of meat impacts the meat bolus granulometry. As meat particles are fibrous, making the granulometry analysis with sieving methods is difficult. As the approach of meat bolus granulometry is necessary, it is of importance to control the methodological parameters that affect the measures. This study describes a procedure that allows granulometry analysis of shredded meat before and after in vitro mastication. Meat particles were dispersed in glycerol before image analysis. Granulometry curves were then drawn using generalized linear models, particle by particle, or after applying virtual sieves. Artificial meat bolus granulometry was also analyzed by manual sieving and the different methods were compared through several characteristics, including D₅₀. Image analysis in glycerol preserves meat particles and allows particle distribution characterization and shape descriptors analysis. This method is well adapted to shredded meat and could be performed to evaluate the mastication of meat preparations adapted for deficient mastication.

Systematic review of measurement properties of methods for objectively assessing masticatory performance

The objectives of this study is to identify methods for objectively assessing masticatory performance (MP) and to evaluate their measurement properties. A secondary objective was to identify any reported adverse events associated with the methods to assess MP. Bibliographic databases were searched, including MEDLINE, Embase, Web of Science Core Collection, Cochrane, and Cinahl databases. Eligible papers that satisfied predefined inclusion and exclusion criteria were appraised independently by two investigators. Four other investigators independently appraised any measurement properties of the assessment method according to the consensus-based standards for the selection of health measurement instruments checklist. The qualities of the measurement properties were evaluated using predefined criteria. The level of evidence was rated by using data synthesis for each MP assessment method, where the rating was a product of methodological quality and measurement properties quality. All studies were quality assessed separately, initially, and subsequently for each method. Studies that described the use of identical assessment method received an individual score, and the pooled sum score resulted in an overall evidence synthesis. The level of evidence was synthesized across studies with an overall conclusion, that is, unknown, conflicting, limited, moderate, or strong evidence. Forty-six out of 9,908 articles were appraised, and the assessment methods were categorized as comminution (n = 21), mixing ability (n = 23), or other methods (n = 2). Different measurement properties were identified, in decreasing order construct validity (n = 30), reliability (n = 22), measurement error (n = 9), criterion validity (n = 6), and responsiveness (n = 4). No adverse events associated with any assessment methods were reported. In a clinical setting or as a diagnostic method, there are no gold standard methods for assessing MP with a strong level of evidence for all measurement properties. All available assessment methods with variable level of evidence require lab-intensive equipment, such as sieves or digital image software. Clinical trials with sufficient sample size, to infer trueness and precision, are needed for evaluating diagnostic values of available methods for assessing masticatory performance.

Which variables should be controlled when measuring the granulometry of a chewed bolus? A systematic review

The distribution of food particles in a chewed bolus characterizes the food destruction after food oral processing (FOP). Previous reviews report that it could be affected by a lot of parameters as the number of chewing strokes, the dental status, but the conditions for producing reproducible data allowing inter-studies comparison have not been clearly described yet. This systematic review aims to identify the variables that can affect bolus granulometry determination, and to calculate their relative weights in the median particle size (D₅₀ ) variations. The systematic review focuses on granulometry expressed as D50 of the most used foods (peanuts, carrots, and almonds) and materials (Optosil and Optocal). Based on 58 studies, 5 variables among 60 being extracted could explain the D₅₀ variations. Conceptual differences between the conditions for FOP should be considered. After Chewing-test, the bolus is collected after a predefined number of strokes and its granulometry characterizes the effects of the dental and muscular apparatus on food destruction, while after Mastication-test the bolus is collected at the swallowing threshold, and its granulometry reflects the outcome of the abilities of the subject to adapt his/her mastication behavior to food texture. Experimental conditions related either to physical sieving or image analysis used to analyze the collected boluses impact the D₅₀ values. Finally, when type of test, sieving conditions, type of food or material, number of chewing strokes, and the oral status of the subjects are controlled, mean D₅₀ values are reproducible and could be used for inter-studies comparisons. PRACTICAL APPLICATIONS: This review provides tables that could be useful to control mean D₅₀ variations in further research.

The association between a mixing ability test and patient reported chewing ability in patients treated for oral malignancies

Introduction

Mastication has been assessed in several ways in the past. Both patients reported and objective assessment methods have been developed. The University Medical Center (UMC) Utrecht has developed a mixing ability test (MAT) using a two‐coloured wax tablet. The present study investigates the association between the mixing ability test and a chewing related questionnaire in patients treated for oral malignancies.

Patients and methods

In a cohort study, patients treated for oral malignancies were assessed 4‐6 weeks before and 4‐6 weeks after treatment, as well as 6 months, 1 year and 5 years after treatment. The mixing ability test was assessed using 10 and 20 chewing strokes and was compared to seven questions about several aspects of mastication. Regression analysis was performed and density plots were drawn for statistical analysis.

Results

One hundred and twenty‐three patients were included in this study. The questionnaire was less predictive for the 10‐chewing stroke test and the test was less discriminatory for different food types than the 20‐chewing stroke mixing ability test. Three questions about the ability to chew solid, soft and thickened liquid food types were found to be significantly predictive for the 20‐chewing stroke test. Threshold values on the mixing ability index were around 20 for the ability to chew solid food types and 24 for soft food types.

Conclusion

The 10‐chewing stroke mixing ability test is less suitable than 20‐chewing strokes for patients with and treated for oral cancer. The 20‐chewing stroke mixing ability test has a fair association with self‐reported outcomes.

[Development and validation of the Mini Dental Assessment : A procedure for improved estimation of need for dental treatment in geriatrics]

BACKGROUND

In the future there will be an increasing demand for professional care with simultaneous retention of the dentition in older people. Due to inadequate dental knowledge, it is often not possible for caregivers to adequately assess dental deficits.

OBJECTIVE

The aim of the study was to develop and validate a simple tool (Mini Dental Assessment, MDA) to assess possible dental treatment needs (DTN) of residential geriatric facilities by nursing personnel.

MATERIAL AND METHODS

In the study 169 patients (51 from the University Hospital Giessen, 118 from the Bonifatius Hospital Lingen) underwent a dental examination. The dental status was evaluated based on the California Dental Association (CDA) criteria and the DTN determined. In addition, the time since the patients last visit to a dentist (TLVD) and denture age (DA) were documented and a chewing function test (carrot eating test, CET) was carried out. In a second study 155 patients were examined (115 from the University Hospital Giessen, 40 from the Bonifatius Hospital Lingen) corresponding to the reference sample and including a further chewing function test (after Schimmel und Slavicek) and questionnaires on quality of life (Oral Health Impact Profile (OHIP), Denatl Impact on Daily Living (DiDDL)).

RESULTS

A total of 108 patients required dental treatment. The mean value (±SD) for the TLVD was 2.5 ± 3.8 years and 10.8 ± 8.9 years for the DA. There was a positive correlation (Spearman, P < 0.005) between the DTN and degree of comminution in the CET (3.4 ± 1.8 grade). Based on the results an assessment tool was developed using the variables CET, TLVD and DA weighted by the respective regression coefficients (10:3:1). The resulting mean total MDA score was 51.32 ± 28.14. A sensitivity/specificity analysis was conducted and a receiver operating characteristic (ROC) curve calculated (area under curve, AUC: 0.805; 95% CI: 0.738-0.873). The ROC curve from the follow-up study showed a good agreement with the ROC curve from the reference study (AUC 0.829, 95% CI: 0.751-0.907).

CONCLUSION

Based on the results of the study it could be shown that the MDA is a suitable instrument for making a valid statement on the assessment of DTN of patients in long-term care facilities. The validation study revealed the validity of the MDA in its originally developed form and the addition of two further chewing function tests did not significantly improve the validity of the MDA. Overall, the MDA appears to be an appropriate tool to help nursing home personnel to assess the necessity for nursing home residents to visit a dentist.

Determining chewing efficiency using a solid test food and considering all phases of mastication

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, X_50,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 X_50,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 X_50,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.

Individuality of masticatory performance and of masticatory muscle temporal parameters

OBJECTIVE

Mammalian mastication serves to improve intra-oral food reduction. Insufficient food reduction creates potential swallowing problems, whereas over-reduction may accelerate tooth wear and increase feeding time. Either extreme has consequences. The study's objectives were: (1) to study the relationship between food reduction, number of chews in a sequence, and chewing rate, (2) to study how controlling the number of chews and chewing rate variability affects food reduction, and (3) to assess how dentoskeletal morphological and electromyographical (EMG) characteristics impact food reduction.

DESIGN

Twenty-three healthy, fully-dentate adults chewed a standardized test food under three conditions: (1) no control, (2) number of chews controlled, and (3) number of chews and chewing rate controlled. EMG activity was sampled from masseter and temporalis muscles bilaterally. Demographic, occlusal contact area in maximum intercuspation, and cephalometric data were obtained.

RESULTS

In uncontrolled conditions, food reduction and bout duration varied more than expected across subjects. Subjects with poor reduction under controlled conditions were those with poor reduction under uncontrolled conditions. Only occlusal contact area correlated with chewing performance under uncontrolled conditions. Chewing cycle duration, EMG burst duration, and EMG peak onset latency increased when the number of chews was restricted. EMG amplitude, a surrogate for bite force, increased in tasks controlling the number of chews and chewing rate. Chewing rate variability was difficult to diminish below individual-specific levels.

CONCLUSIONS

Results: provided evidence that bite force, chewing rate, chewing performance and chewing bout duration reflected individual preferences. Future work will determine whether similar findings occur among other mammals.

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

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

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

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

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

PURPOSE

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

STUDY SELECTION

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

RESULTS

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

CONCLUSION

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

Functional adaptation of the masticatory system to implant-supported mandibular overdentures

OBJECTIVES

The purpose of this study was to investigate the adaptation behavior of the stomatognathic system after immediate loading (24 to 72 h after surgery) of two implants supporting mandibular overdentures, assessed on insertion and three months later. The study hypothesis was that insertion of the overdentures would significantly change masticatory performance and muscle activity at both times.

MATERIAL AND METHODS

Thirty subjects (nine female, mean age 69.64 ± 11.81 years; 21 male, mean age 68.67 ± 7.41 years) who participated in a randomized clinical trial were included in the study. Each patient was examined three times: (i) at baseline, after already having worn new dentures for three months (T1); (ii) immediately after insertion of the overdentures on the implants (T2); and (iii) after an adaptation period of three months (T3). Examination comprised assessment of masticatory performance with artificial test food (Optocal), and simultaneous bilateral surface EMG recording of the masseter and anterior temporalis muscles. Particle-size distribution (representative value X₅₀ ), maximum muscle contraction (MVC), and total muscle work (TMW; area under the curve) were compared by use of repeated-measures analysis of variance (ANOVA).

RESULTS

At T3, all measured variables (i.e., masticatory performance and muscle activity) were significantly different from those at T1. At T2, no significant changes were observed. The study hypothesis had to be rejected for T2 but accepted for T3.

CONCLUSION

Functional rehabilitation (in terms of masticatory performance and masticatory muscle activity) does not occur immediately after immediate loading of two implants with mandibular overdentures, but requires a significant time for functional improvement.