Consensus on the terminologies and methodologies for masticatory assessment

Changes in masticatory performance and bite force after treatment with mandibular overdentures retained by four titanium-zirconium mini implants: One-year randomised clinical trial

OBJECTIVE

This prospective study is part of a randomised clinical trial and reports the changes in masticatory performance (MP) and bite force, and explores their influential factors, 1 year after the provision of mandibular overdentures retained by four titanium-zirconium mini implants.

METHODS

Edentulous patients received conventional complete dentures, followed by placement of four mini implants (Straumann® Mini Implant System) in the anterior mandible and converting the conventional prosthesis into a mandibular overdenture. Treatment protocols were randomised using a 2×2 factorial design combining different surgical (flapped vs. flapless) and loading (immediate vs. delayed) protocols. MP was assessed using a two-colour mixing ability test and a colorimetric analysis to measure the level of colour mixing (Variance of Hue-VoH). Maximum voluntary bite force (MBF) was measured by a digital gnathodynamometer in the posterior and anterior regions. Sex, age, surgical and loading protocols and ridge morphology were tested as independent variables. MP and MBF tests were performed at baseline (pre-treatment) and the 3-, 6- and 12-month after implant loading. Descriptive statistics, independent t-test, and linear mixed-effect model (LMM) regression were used for data analysis.

RESULTS

Seventy-four participants were assessed and 73 completed the 1-year follow-up. Statistically significant improvements in functional parameters were observed in all follow-up periods compared to baseline (p < .001). The flapless protocol was associated with higher improvement in MP at the 3-month follow-up (p = .004), while less resorbed ridges were associated with better MP (p = .038) and higher MBF (p < .001).

CONCLUSION

The mandibular overdenture protocol using four titanium-zirconium mini implants was effective in improving MP and MBF of edentulous patients, compared to pre-treatment values. The findings also suggest that improvements in chewing function and bite force are impacted by clinical factors since better outcomes were observed for flapless surgeries and less resorbed edentulous ridges.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.Gov ID NCT04760457.

[Geriatric assessment in dentistry : A review of chewing function tests]

Due to increasing life expectancy and the associated demographic changes, more and more people are dependent on care. To identify a possible need for dental treatment, chewing function tests as assessment instruments have proven their effectiveness. In this article, the reader is given an overview of existing chewing function tests and their implementation. It is important that a patient with pain should be presented to a dentist immediately, regardless of whether a chewing function test is performed. Furthermore, chewing function tests are not a substitute for routine dental examinations, but they could provide information to (dental) laypersons as to whether an appointment should be arranged in a dental practice or whether a dental consultation is necessary.

Four-year assessment of masticatory function in mandibular overdenture wearers: A randomised clinical trial comparing two to four implants to retain the prosthesis

BACKGROUND

Limited data exist on the mid- to long-term masticatory capacity of mandibular overdenture (IOD) wearers, particularly regarding the use of posterior implants to retention.

OBJECTIVES

To periodically evaluate mastication of IOD wearers, comparing the effectiveness of two to four implants to retain the prosthesis.

METHODS

In a randomised controlled clinical trial, 20 complete edentulous patients (14 women), aged 51-84 years (mean age 69.1 ± 9.6), received new bimaxillary complete dentures (CD). After adaptation, baseline measurements of masticatory performance (X50) and swallowing threshold were conducted using the sieving method. Patients were then randomly assigned to groups: control (two intra-foraminal regular implants) and experimental (two intra-foraminal regular implants and two extra-short posterior implants) (n = 10 each). After 4 months, implants were splinted, and a new mandibular IOD was fabricated with bar/clip retention. Mastication was reassessed after 6, 12, and 48 months, and data analysed with repeated measures ANOVA and Sidak's post hoc (α = 0.05).

RESULTS

Despite a loss of two patients per group, masticatory performance significantly improved after mandibular IOD installation (p = .031) in both groups (p = .670). A second improvement was observed after 6 months (p = .027), with no subsequent changes (p > .05). Swallowing threshold improvements were noted with IOD, and no discernible differences between groups were observed (p > .05).

CONCLUSION

Masticatory function significantly improved after mandibular IOD installation, with the number of implants demonstrating minimal influence.

CLINICAL TRIAL REGISTRATION

The present study was not registered in a public database, as mandated. It is important to note that the recommendation for registration was initiated in 2017 by the Committee of Medical Journal Editors, while patient inclusion in the research took place in 2016. Given that the data presented in this manuscript cover a follow-up period of up to 4 years post-surgical intervention, delayed registration was not feasible.

Evaluation of the Association of Chewing Function and Oral Health-Related Quality of Life in a Population of Individuals Aged ≥ 45 Years and Residing in Communities in Switzerland: A Cross-Sectional Study

PURPOSE

To analyse the association of masticatory performance and oral health-related quality of life in a representative population of individuals residing in communities in Switzerland aged ≥ 45 years.

MATERIALS AND METHODS

In total, 100 subjects completed two dedicated and validated questionnaires on their demographic data and the Geriatric Oral Health Assessment Index. A mixing ability test was performed for assessing masticatory performance. The qualitative analysis of the test was performed by categorizing the images into five categories, while the quantitative analysis was performed via a validated custom-made software.

RESULTS

Sixty-six samples could be analysed. Participants younger than 65 years of age showed significantly less frequent chewing deficiencies (17%) compared to those 65 years and older (50%, p < 0.01). However, retired participants had chewing deficiencies significantly more frequently (8%) compared to workers (51%, p < 0.01). A statistically significant positive association of having chewing deficiency was found between employment status (p < 0.01) and the presence of restorations (p = 0.04), while GOHAI did not show any statistically significant association. Overall, the enrolled subjects displayed moderate chewing function. Masticatory performance was positively associated with the number of present restorations.

CONCLUSIONS

The enrolled subjects residing in communities in Switzerland aged ≥ 45 years displayed moderate chewing function. Their masticatory performance was positively associated with the number of present restorations but not associated with oral health related quality of life (GOHAI).

Influence of masticatory side switch frequency on masticatory mixing ability and sensory perception in adults with healthy dentitions: A randomized crossover trial

STATEMENT OF PROBLEM

The advantages and disadvantages of frequently changing sides while masticating remain unclear.

PURPOSE

The purpose of this clinical study was to determine the effect of varying the frequency of masticatory side switches on masticatory mixing ability and sensory perception in dentate adults.

MATERIAL AND METHODS

This nonblinded, randomized 12-period crossover study, conducted at Barcelona Dental School from January to March 2022, included 36 healthy adults with natural dentitions (median age, 23.5 years; 26 women). Participants were randomly allocated to 12 sequences and performed 12 masticatory assays masticating a 2-colored gum for 40 cycles each using the following masticatory styles as interventions: freestyle, unilateral right, unilateral left, and switching sides 5%, 15%, and 25%. The primary outcome was the mixing ability index (MAI), defined as the standard deviation of the red channel intensity of the masticated gum in the color-histogram plugin of the ImageJ software program. Participants also rated the perceived flavor intensity and salivary flow on a visual analog scale. Data were analyzed by repeated measures analysis of variance (α=.05).

RESULTS

The MAI was similar for all masticatory styles (P=.63). Participants perceived greater flavor intensity (mean difference: 8%, 95% CI: 1% to 15%) and salivary flow (mean difference: 11%, 95% CI: 0% to 21%) with 25% side switching compared with freestyle or unilateral mastication.

CONCLUSIONS

Frequently switching the masticatory side while masticating gum does not alter the mixing ability, but it appears to enhance salivary flow and flavor intensity.

Reliability between the two-colour chewing gum and the gummy-jelly tests used for the assessment of masticatory performance

OBJECTIVE

This study aimed to evaluate the reliability of two methods used to assess masticatory performance and attempt to correlate them to achieve interchangeability between the methods.

METHODS

Twelve healthy dentate volunteers (men = 6, women = 6; mean age = 28.3 ± 4.1) with no known dental or medical pathologies were requested to participate in this study. Each participant completed three masticatory performance assessments, including two two-colour mixing-ability tests using chewing-gums (CG: gum#1 and gum#2) and the gummy-jelly (GJ) test. For each method, participants created five samples each (total = 15 measurements per participant, gum#1 = 5, gum#2 = 5, GJ = 5). For the gum#1 and gum#2 methods, the predetermined chewing cycles were fixed at 10, 15, 20, 25 and 30 cycles, and for the GJ method, the time duration was fixed at 10, 15, 20, 25 and 30 s. The parameter measures were submitted to Z-score transformation, and Bland-Altman plots were generated to graphically compare the differences between two techniques against their means. Additionally, mountain plot was used to assess the cumulative distribution of measurement error between the methods.

RESULTS

A total of 180 measurements were recorded. There were significant correlations between the number of chewing cycles/chewing time and masticatory performance using the gum#1 (r = -.753; p < .001), gum#2 (r = -.838; p < .001) and GJ (r = .730). When all tests were considered together for each method, significant correlations were found (p < .001). A descriptive range of mean values aiming to produce reference value ranges for predictive purposes was achieved considering the interchangeably among the methods [CG = GJ (VoH-mg = dL): 10 cycle = 10 s: 0.329 = 110; 15 cycles = 15 s: 0.177 = 164; 20 cycles = 20 s: 0.130 = 205; 25 cycles = 25 s: 0.086 = 200; 30 cycles = 30 s: 0.077 = 267].

CONCLUSION

The strong correlations and high consistency between the two masticatory performance methods found in this study conclude that the two assessment methods are reliable and interchangeable. Further evaluations are warranted to arrive at a conversion formula for translation of the results between the two methods.

Relationships between oral function, dietary intake and nutritional status in older adults aged 75 years and above: a cross-sectional study

BACKGROUND

Malnutrition is related to impaired oral health and function that causes poor dietary intake, declining the general health of older adults. The role of dietary intake in the association between oral function and nutritional status of Chinese older adults (aged 75 and above) was examined in this cross-sectional study.

METHODS

Through the randomized cluster sampling method, 267 older adults living in rural areas of Qingdao, Shandong (aged 81.4 ± 4.3, 75-94 years) were chosen as the primary research participants. A Mini Nutritional Assessment - Short Form was used to determine nutritional status, and Food Frequency Questionnaire and 24-hour Food Intake Recall were used to assess dietary intake. The oral function was evaluated by analyzing the teeth, oral problems, bite force, tongue pressure, lip sealing pressure, chewing function questionnaire, whole saliva flow rate, 10-Item Eating Assessment Tool, and water swallow test.

RESULTS

Based on the MNA-SF score, it was divided into a well-nourished group and a malnutrition group, with the malnutrition group comprising 40.6% of participants. The participants in the malnutrition group showed a higher rate of xerostomia, lower bite force, tongue pressure, and lip sealing pressure, and higher Chewing Function Questionnaire and 10-Item Eating Assessment Tool scores. Furthermore, their plant fat, iron, cereals and potatoes, vegetables, fruits, and seafood intake were relatively low. The regression model indicated that exercise frequency, stroke, chewing and swallowing function, intake of vegetables and fruits were risk factors for nutritional status of older adults.

CONCLUSION

Malnutrition was relatively common among the Chinese older adults aged 75 and above, and it was significantly correlated with exercise frequency, stroke, chewing and swallowing function, and intake of vegetables and fruits. Therefore, nutrition management should be carried out under the understanding and guidance of the oral function and dietary intake of the older adults.

Chewing ability and its associated factors among community-dwelling older adults in Chengdu, China: A cross-sectional study

AIM

To investigate the current status of chewing ability and analyze the risk factors among Chinese community-dwelling older adults.

METHODS

In this cross-sectional study, color-changeable gum and a color difference meter were used to assess chewing ability in the population. The statistical analysis employed multivariate logistic regression models to identify and quantify the factors influencing chewing ability.

RESULTS

A total of 373 community-dwelling adults aged 65 and older in Chengdu, in the west of China, were included in this study; 64 individuals (17.2%) exhibited signs of poor chewing ability. Female (odds ratio [OR]: 0.124, 95% CI: 0.057-0.268, p < .001), education level with college degree and above (OR: 0.114, 95% CI: 0.030-0.434, p = .001), number of teeth less than 20 (OR: 5.401, 95% CI: 2.509-11.626, p < .001), and decreased oral diadochokinesis (OR: 4.445, 95% CI: 1.775-11.132, p = .001) were significant factors in chewing ability in this study, after adjustment for potential variables.

CONCLUSIONS

The prevalence of decreased chewing ability among Chinese community-dwelling older adults was 17.2% and decreased chewing ability was associated with men, lower education level, less than 20 teeth and decreased oral diadochokinesis.

The effectiveness of a self-reported questionnaire on masticatory function in health examinations

Periodontal diseases have been reported to be lifestyle-related and associated with metabolic syndrome (MetS). The introduction of dental checkups in a health checkup program may create a synergistic effect and aid the prevention of MetS. In Japan, a chewing function questionnaire has now been introduced into the national health checkup program. The purpose of this study was to investigate whether the questionnaire reflects dental and oral conditions and whether it helps improve general and oral health. A total of 6599 subjects who underwent health checkups or guidance specified by the National Health Insurance of Japan for two consecutive years were included. A single comprehensive question to evaluate masticatory function was asked. Medical and dental examinations and insurance data were collected and used for analysis. In terms of masticatory function during chewing, 82.3% of subjects experienced no problems, 17.3% experienced some difficulty, and 0.4% experienced severe problems. There was a significant relationship between the questionnaire response and dental examinations results for several items of examination. The overall dental consultation rate after health screening was 42.3%. Improvement in periodontal disease was achieved in those who reported some problems with chewing function. Improvement in blood pressure was also observed in those who reported some problem with chewing function and subsequently had a dental consultation. The results of this study indicate that questionnaires on masticatory function reflect the status of dental and oral health. In addition, the results suggested that questionnaire results are potentially linked to improvement in dental and oral health status, and improvement in MetS.

Age related impairments in ingestion from a large population based-sample

OBJECTIVES

Epidemiological data regarding the evolution of problems related to mastication and swallowing with age are lacking. This study aims to (i) describe changes in oral function with age, using data from a large French population, (ii) validate online, self-report uses of an ICF questionnaire in older persons, and (iii) assess whether impairment is related to avoidance of certain foods, xerostomia, body mass index (BMI) and oral health related quality of life (OHRQoL).

METHODS

Volunteers aged ≥18 years with internet access completed a series of questionnaires on sociodemographic, anthropometric and oral health characteristics (oral function, Xerostomia Index (XI), OHRQoL, reasons for avoidance of certain food). Oral function was assessed using items derived from the International Classification of Functioning (ICF). Five ICF items related to ingestion function and six items related to activities and participation were used. A validation study was undertaken to identify those with poor chewing ability and low salivary flow amongst older participants reporting impairment.

FINDINGS

39 597 individuals were included. The prevalence of individuals with impairment for ICF items related to ingestion function and oral activity (eating, drinking and speaking), and the percentage of participants with poor OHRQoL increased significantly with age (p < 0.001). Each ICF item was significantly associated with OHRQoL (p < 0.001), XI (p < 0.001), BMI (p < 0.001) and avoidance of certain food due to chewing or swallowing difficulties.

CONCLUSION

Overall, 21.5% and 13.5% of the study population had chewing and/or biting impairments respectively, which might affect food selection and consumption. These findings raise individual and population-based issues. Further studies are needed to assess whether impairment in oral function might increase frailty in older individuals, and also to compare data with those from other countries.

The predictive value of masticatory function for adverse health outcomes in older adults: a systematic review

Masticatory function is associated with a variety of health outcomes. The aim of this systematic review is to clarify the predictive value of masticatory function for adverse health outcomes, such as frailty, sarcopenia and malnutrition, in older adults. An online literature search covered articles published in English or Dutch in three databases (PubMed, Embase and CINAHL, last searched November 4th 2022). Inclusion criteria were: an observational study design, focus on adults aged ≥65 years and evaluation of the association between masticatory function and health outcomes. Reviews and articles published before the year 2000 were excluded. Methodological quality and risk of bias were assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies of the U.S. National Institutes of Health. Study population demographics, methods for assessing masticatory function, and the association between masticatory function and adverse health outcomes were extracted. From the 34 included studies, 5 studies had a prospective design, 2 had a retrospective design, and the other 27 studies had cross-sectional design. The majority of the studies were conducted in Japan (74%, n = 26). Twenty studies (59%) used one indicator for masticatory function, the other 41% used two (n = 9) or more (n = 5) indicators. Masticatory function was most frequently assessed with the maximum occlusal force (MOF) (79%, n = 27). The identified health outcomes were clustered into 6 categories: physical parameters and sarcopenia, history of falling, nutritional status, frailty, cognitive function and mortality. Despite the complex and multidimensional character of both masticatory function and most identified adverse health outcomes, some significant associations were reported. Prospective studies showed that reduced masticatory function in older adults is associated with incidence of frailty and frailty progression, cognitive decline and all-cause mortality. Regarding the other identified adverse health outcomes, i.e., physical measures and sarcopenia, history of falling and nutritional status, only cross-sectional studies were available and results were less concordant. As all prospective studies showed that reduced masticatory function in older adults is associated with adverse health outcomes, prevention of decline of masticatory function by adequate oral care may contribute to healthy ageing.

Age-related difference in oral adaptation to masticatory perturbation

OBJECTIVES

Mastication can be influenced by intraoral perturbation (e.g., hard food). We developed the masticatory perturbation task (MPT) to assess the perturbation effect during mastication and quantify the degree of adaptation to masticatory perturbation in younger and older adults.

DESIGN

Thirty-eight younger and 38 older participants completed the MPT, which consisted of three trials assessing masticatory performance (MP) without perturbation (i.e., the baseline condition) and three trials assessing MP with perturbation (i.e., the perturbation condition). Perturbation was implemented by concurrently chewing test food on the preferred side and a drinking straw on the nonpreferred side. We estimated the perturbation effect as the ΔMP between the baseline and perturbation conditions and the adaptation effect as the ΔMP between the third and the first trials for both age groups.

RESULTS

We found a significant perturbation effect, i.e., a lower MP in the perturbation condition than in the baseline condition, and an adaptation effect, i.e., a higher MP in the third trial than the first trial, in both groups. Moreover, the older group showed a lower degree of adaptation than the younger group.

CONCLUSION

The masticatory perturbation task revealed the perturbation effect during mastication and the adaptation to masticatory perturbation. The results revealed an association between age and masticatory adaptation.

Masticatory performance, self-perception of oral health, oral health-related quality of life and nutritional status of completely edentulous elderly patients submitted to different rehabilitation treatments: A cross-sectional study

BACKGROUND

The impact of treatments on completely edentulous individuals on masticatory performance (MP), oral health-related quality of life (OHRQoL), nutritional status (NS) and socio-economic profile (SP) is unclear in the literature.

OBJECTIVE

To compare the MP, OHRQoL, NS and SP of totally edentulous elderly users of bimaxillary complete dentures (CD) and users of lower implant-supported fixed complete dentures (IFCD).

METHODS

Forty participants were allocated into groups according to rehabilitation treatment (n = 20): bimaxillary CD (G1) and lower IFCD, and upper CD (G2). The evaluation of MP used almonds by the method of sieves. Four questionnaires (Geriatric Oral Health Assessment Index-GOHAI and Oral Health Impact Profile Edent-OHIP-Edent, Brazilian Economic Classification Criteria-ABEP and Mini Nutritional Assessment-MNA) were applied to assess the OHRQoL, SP and NS of the elderly, respectively. After evaluating the statistical assumptions, the Mann-Whitney (α = .05) test was applied to compare the groups regarding MP, OHRQoL, NS and SP. Spearman's correlation (α = .05) was performed to verify the correlation between the MP, the OHRQoL and the NS of the participants.

RESULTS

G2 showed better MP (p < .05) in all masticatory cycles, OHRQoL (p < .05) and NS than the G1. However, the participants' self-perception of oral health did not differ between groups (p < .05). A moderate negative correlation was found between MP and OHRQoL for 40 masticatory cycles (r2  = -0.513; p = .001).

CONCLUSION

Individuals rehabilitated with IFCD had a higher average monthly family income and achieved superior behaviour in MP and OHRQoL, in addition to lower risks of malnutrition when compared to individuals using bimaxillary CD.

Influence of the radius of Monson's sphere and excursive occlusal contacts on masticatory function of dentate subjects

OBJECTIVE

To determine the influence of the radius of Monson's sphere, the number of posterior laterotrusive, mediotrusive, and protrusive contacts, and the chewing rate on food comminution.

DESIGN

Sixty healthy dentate subjects, aged 21.22 ± 2.30 years, were selected. The three-dimensional coordinates of the cusp tips of the lower canine, premolar, and molar teeth were identified from the subjects' digital models. Monson's sphere was designed using the simplex method for function minimisation by adjusting the coordinates on its surface. The contacts were verified using 12 µm metal strips in jaw excursions at 0.5, 1.0, 2.0, and 3.0 mm. The masticatory performance and efficiency, swallowing threshold, and chewing rate were assessed through particle size fractionation. Data were analysed with multiple linear regression (α = 0.05).

RESULTS

The sphere's radius, laterotrusive and protrusive contacts at 0.5 mm, and chewing rate were found to be negative predictor variables for masticatory performance until 20 chewing cycles (R2 = 0.429). For 40 cycles, the radius and total contacts (0.5 mm) were also explanatory factors (R2 = 0.223). Only the radius (R2 = 0.176) and the chewing rate (R2 = 0.082) were found to be significant for 60 cycles and swallowing threshold, respectively. Masticatory efficiency was influenced by masticatory performance until 40 and 60 cycles, as well as the radius and total contacts at 2.0 and 3.0 mm (R2 = 0.958).

CONCLUSION

A larger radius of Monson's sphere and a greater number of posterior excursive contacts were found to be related to better masticatory function.

Structural brain feature is associated with changes of masticatory performance in healthy elderly people: Evidence from longitudinal neuroimaging research over two years

BACKGROUND

Human neuroimaging studies have revealed the association between brain structure and masticatory function. However, the majority of the studies adopted a cross-sectional design, which hardly reveals the change in masticatory function and brain structure between different timepoints, and the dynamical association between changes in masticatory function and changes in brain structure has not been elucidated.

OBJECTIVE

With a longitudinal design, we assessed the association between changes in masticatory performance (MP) and regional brain volume.

METHODS

Twenty-two elderly participants received assessments of the number of missing teeth and MP (via colour-changeable chewing gum) when they entered the study (i.e. the initial stage, T0 ), approximately 6 months later (T0.5 ), and approximately 1-2 years later (T1 ). Difficulty of food intake was assessed using a questionnaire. The participants received magnetic resonance imaging (MRI) at T0 and T1 . The brain volume of the motor-related area was estimated using FreeSurfer for MRI data. The associations between different stages were analysed using Spearman's rho correlation coefficients.

RESULTS

(1) Individually, a smaller volume of right primary motor cortex at T0 was associated with increased MP from T0 to T1 , suggesting the brain's role in changing oral functions; (2) higher MP at T0 was associated with an increased volume of the left superior frontal cortex from T0 to T1 p, suggesting a potential effect on brain plasticity, and (3) increased difficulty to eat was associated with decrease MP but not brain volume of motor-related area.

CONCLUSIONS

The preliminary findings revealed a complicated pattern of structural brain features and masticatory function in elderly people, and either the hypothesis that the brain predisposes masticatory function or the hypothesis that mastication reshapes the brain is oversimplified.

Does occlusal morphology of artificial teeth improve chewing of removable dentures wearers? A systematic review and meta-analysis

PURPOSE

This systematic review aimed to verify whether anatomic, semi-anatomic, or nonanatomic occlusal morphology of artificial teeth improves the masticatory function of complete or removable partial denture wearers.

MATERIALS AND METHODS

According to the PICO strategy, six databases and the grey literature were searched to identify randomized (RCT) and non-randomized clinical trials (N-RCT) comparing masticatory function, in terms of masticatory performance and efficiency, and muscle activity as primary outcomes; and patient-reported results (O) in individuals using removable dentures (P) with different occlusal morphologies of artificial teeth (I/C). Masticatory ability, satisfaction with the prosthetic treatment, and oral health-related quality of life (OHRQoL) were evaluated as secondary outcomes. Risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials (RoB 2.0) for RCT and Risk of Bias for non-randomized studies with intervention (ROBINS-I) for N-RCT studies. Meta-analyses were performed to compare primary outcomes and masticatory ability between the occlusal morphologies of artificial teeth of complete or removable partial dentures (α = 0.05). Certainty of the evidence was verified using the GRADE approach.

RESULTS

Eleven studies (seven RCTs and four N-RCTs) were included. The risk of bias was considered low for two studies, some concerns for five, and high for the last four studies. Meta-analyses showed that removable partial dentures with anatomic artificial teeth improved masticatory efficiency for carrot chewing (MD 6.31; 95% CI [3.39, 9.22], I2 = 0%). However, masseter and temporal muscle activities increased when removable partial dentures with nonanatomic teeth were used (MD -756.97; 95% CI [-892.25, -621.68], I2 = 100%). Masticatory ability was not influenced by occlusal morphology during chewing of all foods in complete denture users: Carrot (MD -0.88, 95% CI [-8.98, 7.23], I2 = 57%); sausage (MD -8.86, 95% CI [-23.05, 5.33], I2 = 71%); apple (MD -5.78, 95% CI [-28.82, 17.26], I2 = 87%); and cheese (MD -4.16, 95% CI [-15.14, 6.82], I2 = 62%). The certainty of evidence for all evaluated outcomes was very low, mainly due to very serious problems found in the parameters of inconsistency, indirectness, and imprecision.

CONCLUSIONS

Despite the very low certainty of evidence, the occlusal morphology of artificial teeth influences masticatory function. Anatomic teeth improved the masticatory efficiency and muscle activity of removable partial denture wearers. Nonanatomic teeth increased temporal and masseter muscle activity, which negatively affected chewing in removable partial denture users. However, patients using complete dentures with anatomic and semi-anatomic teeth presented similar masticatory ability.

Effect of digital complete dentures manufactured using the custom disk method on masticatory function

Statement of problem

The effect of using the custom disk method (CDM) for fabricating digital dentures on patients' masticatory function should be studied to support its use in clinical practice.

Purpose

To investigate the effect of digital dentures fabricated using CDM on patients' masticatory function.

Material and methods

This single-center prospective clinical study included 20 patients with edentulous maxillary and mandibular arches who used a complete denture. The digital impression and complete denture manufacturing procedures using CDM have already been reported by Kanazawa et al. (2018) [32] and Soeda et al. (2022) [18] Thedigital dentures fabricated with CDM were delivered to the participants, and periodic adjustments were made until the patient could use the denture without pain. A color-changeable chewing gum, two types of gummy jellies that can evaluate the masticatory function, and pressure-sensitive sheets were used to evaluate the participants' masticatory function at baseline, 1 month, and 6 months following adjustment of the new digital complete dentures fabricated with CDM. These masticatory function values had already been measured in the previous conventional dentures and were recorded as baseline values.

Results

The study participants included 8 women and 12 men (mean age, 77.6 years). The color-changeable chewing gum analysis indicated that there was no significant improvement of masticatory function from baseline to 1 M (P = .083) and 6 M (P = .157).The gummy jelly analysis indicated no significant differences between the masticatory function baseline and 1 month (P = .387); however, a significant improvement was observed from baseline to 6 months (P = .020). Tests with Glucolum indicated a significant improvement from baseline to 1 month (P = .012) and 6 months (P = .003). The maximum bite force and occlusal contact area showed no significant difference at any time point.

Conclusions

Significant improvement in masticatory function was observed upon evaluation with gummy jelly and Glucolum 6 months after delivering the new digital complete dentures. Under limited conditions, the digital denture fabricated using CDM resulted in good recovery of the masticatory function in elderly edentulous patients. The present results combined with the cost-effectiveness and patient satisfaction associated with CDM indicate its clinical utility.

Oral frailty among dentate and edentate older adults in long-term care

BACKGROUND

The objectives of this study were to compare oral frailty (OFr) among edentate and dentate older adults living in long-term care facilities (LTCF) and to clarify how edentulism and oral disease burden (ODB) of dentate older adults are associated with OFr.

METHODS

The population of this study comprised 94 edentate and 209 dentate residents in LTCF in Helsinki, Finland, who had previously participated in a nutritional study. The participants underwent a clinical oral examination. The dentate residents were further divided into three ODB groups based on asymptotic dental score. The edentate and different ODB groups were compared with each other regarding demographics and oral and medical findings. OFr was defined as ≥ 2 of following: having a diet of soft/pureed food, residue of food in the oral cavity, inability to keep the mouth open during examination, unclearness of speech, dry mouth. The association between OFr and edentulousness and various levels of ODB was analyzed by a multivariate logistic model.

RESULTS

Participants with low ODB had significantly less OFr than their edentate peers (p = 0.009). Furthermore, the edentate and dentate with high ODB had similar odds for OFr.

CONCLUSIONS

Edentulousness and high ODB are equally harmful conditions and may predispose to OFr. This study suggests that maintaining healthy natural teeth and good oral health (low ODB) may protect against OFr.

TRIAL REGISTRATION

The Ethics Committee of the Hospital District of Helsinki and Uusimaa approved the protocols for the nutritional status and oral healthcare studies and the merging of the data, including patient medical records (Register number HUS/968/2017).

Chewing performance of patients with worn dentition before and after restorations: A scoping review

BACKGROUND

Tooth wear is a multifactorial complex process related to the loss of dental tissue, due to chemical or mechanical processes, by abrasion, attrition, erosion. Restorative treatment represents an attempt to rebuild and recreate the lost structure.

OBJECTIVE

This scoping review aims to investigate whether restorative treatment of worn dentition (either with direct or indirect adhesive composite adhesive procedures or with prosthetic techniques) can have an impact on the masticatory performance parameters.

METHODS

A scoping review was conducted on multiple databases (Pubmed, Medline CENTRAL, ICTRP), following the PRISMA guidelines. Abstracts of research papers were screened for suitability, and full-text articles were obtained for those who satisfied the inclusion and exclusion criteria.

RESULTS

Only one article meet the inclusion criteria of the review. Restorative treatment of worn dentition although have a positive impact on the self-report ability to chew, has no effect on the masticatory performance test.

CONCLUSION

At the moment, not enough evidence to comment on the actual therapeutic role of restorative treatment on tooth wear is available. Clinicians, before taking any clinical decision, should carefully discuss with patients the needs and expectations of the treatment plan.

Chewing ability and associated factors in older adults in Germany. Results from GEDA 2019/2020-EHIS

BACKGROUND

Oral well-being is an important component of general well-being and quality of life, as it is greatly influenced by the ability to chew and speak, and thus by central factors of social interaction. Because quality of life and participation are important factors for health in older age, the aim of this article was to examine the chewing ability, including associated factors, for the older population in Germany on the basis of a nationally representative sample.

METHODS

Database is the German Health Update (GEDA 2019/2020-EHIS), a population based cross-sectional survey of the Robert Koch Institute. In the telephone interview, participants aged 55 years and older were asked: "Do you have difficulty biting and chewing on hard foods such as a firm apple? Would you say 'no difficulty', 'some difficulty', 'a lot of difficulty' or 'cannot do at all/ unable to do'?" Prevalences and multivariate prevalence ratios (PR) were calculated with 95% confidence intervals (95% CI) from log-Poisson regressions. Sociodemographic, health-, behavioral- and care-related characteristics were investigated as associated factors.

RESULTS

The analyses were based on data from 12,944 participants (7,079 women, 5,865 men). The proportion of people with reduced chewing ability was 20.0%; 14.5% had minor difficulty, 5.5% had major difficulty. There were no differences between women and men. The most important associated factors for reduced chewing ability were old age (PR 1.8, 95% CI 1.5-2.1), low socioeconomic status (PR 2.0, 95% CI 1.7-2.5), limitations to usual activities due to health problems (PR 1.9, 1.6-2.2), depressive symptoms (PR 1.7, 1.5-2.1), daily smoking (PR 1.6, 95% CI 1.3-1.8), low dental utilization (PR 1.6, 95% CI 1.4-1.9), and perceived unmet needs for dental care (PR 1.7, 95% CI 1.5-2.1).

CONCLUSIONS

One fifth of adults from 55 years of age reported reduced chewing ability. Thus, this is a very common functional limitation in older age. Reduced chewing ability was associated with almost all investigated characteristics. Therefore, its prevention requires a holistic view in the living environment and health care context of older people. Given that chewing ability influences quality of life and social participation, maintaining or improving chewing ability is important for healthy aging.

The relationships between mastication and cognitive function: A systematic review and meta-analysis

Masticatory function such as chewing is expected to modify human cognitive function, and/or the possibility of improving cognitive function is also predicted. This systematic review investigated whether masticatory function affects cognitive function for older/young adults. Full articles written in English from January 2000 to April 2022 were collected using PubMed and Cochrane Library. Target outcomes were cognitive function test scores, cognitive processing speed (reaction time), and masticatory function. For each research question, two independent reviewers conducted the search and screening, data extraction, quality assessment, and risk of bias assessment. The reviewers resolved any disagreements by discussion. From 226 articles retrieved, 20 were included in this review. Older adults with lower scores on the cognitive function test had lower masticatory performance, lower chewing ability, chewing difficulty, and decreased number of teeth. An increased risk of cognitive impairment was found in older adults with masticatory dysfunction. For young adults, gum chewing significantly reduced the processing speed of cognitive tasks compared to no gum chewing. Although most of the evidence included had a low level of evidence and a high risk of bias because of the research designs, the results still suggest that mastication may be a factor in improving cognitive function.

Chewing Analysis by Means of Electromagnetic Articulography: Current Developments and New Possibilities

Chewing is a complex procedure that involves sensory feedback and motor impulses controlled by the trigeminal system in the brainstem. The analysis of mandibular movement is a first approximation to understanding these mechanisms. Several recording methods have been tested to achieve this. Video, ultrasound, the use of external markers and kinesiographs are examples of recording systems used in research. Electromagnetic articulography is an alternative method to those previously mentioned. It consists of the use of electromagnetic fields and receiver coils. The receiver coils are placed on the points of interest and the 3D coordinates of movement are saved in binary files. In the Oral Physiology Laboratory of the Dental Sciences Research Center (Centro de Investigación en Ciencias Odontológicas-CICO), in the Faculty of Dentistry at the Universidad de La Frontera (Temuco, Chile) several research studies have been carried out using the AG501 3D EMA articulograph (Carstens Medizinelektronik, Lenglern, Germany). With this device, they developed a series of protocols to record mandibular movement and obtain new information, such as the 3D Posselt polygon, the area of each polygon, individualized masticatory cycles and speed and acceleration profiles. Other investigations have analyzed these parameters, but separately. The AG501 allows for holistic analysis of all these data without altering natural movement. A limitation of this technology is the interference generated by its metallic elements. The aim of the present work is to show the developed methods used to record mandibular movement in the CICO, using the AG501 and compare them with others used in several research studies.

Associations of oral health status and swallowing function with cognitive impairment in the aging population: a cross-sectional study

BACKGROUND

The purpose of this study was to investigate the relationships of oral health status and swallowing function with cognitive impairment in community-dwelling older adults from Changsha, Hunan Province, China.

METHODS

In this cross-sectional study, we analyzed the data of 215 participants aged ≥ 50 years which were retrieved from the Xiangya and Panasonic mild cognitive impairment (MCI) Study, a community-based study conducted among the residents of the urban areas of Hunan province in China. Demographic information of all participants was collected. We determined oral function by evaluating oral hygiene, oral dryness, occlusal force, tongue pressure, chewing function, swallowing function, remaining teeth number, and other indicators. The mini-mental state examination (MMSE) was used to screen for cognitive function. The relationship between each oral function evaluation item and cognitive function was investigated using correlation analysis. The associations between oral health status and swallowing function with cognitive impairment were inferred using multiple regression analysis.

RESULTS

The general characteristics of participants showed statistically significant correlation coefficients in number of teeth remaining (p = 0.003) and number of teeth lost (p < 0.0001). Almost half of the 25 participants (48%) were aged from 70-80 years. Only 25 older adults (11.6% of the participants) were determined to have cognitive impairment by MMSE sores less than 24. Tongue pressure in male participants was the only significant independent variable that was associated with cognitive impairment (p = 0.01971). The results indicate that male participants with lower MMSE scores had a relative deficiency in tongue pressure.

CONCLUSIONS

In this cross-sectional study, the oral health status and swallowing function of participants were in relatively good condition and showed low correlations with cognitive impairment. However, lower tongue pressures were associated with lower MMSE scores in males, indicating it could serve as a novel oral function index for evaluating cognitive impairment.

Chewing and its influence on swallowing, gastrointestinal and nutrition-related factors: a systematic review

The study aimed to evaluate the hypothesis that chewing is a mechanical and physiological contributor to swallowing, physiologic/pathologic processes of the gastrointestinal tract (GIT), and nutrition-related factors. A search strategy was applied to three different databases to investigate if chewing function in adults affects the swallowing, physiologic/pathologic processes of the GIT, and nutrition-related factors compared to controls with no exposure. The included studies were evaluated for methodological quality and risk of bias and certainty of evidence. The results showed 71 eligible studies. Overall, the results showed that 46 studies supported the hypothesis while 25 refuted it. However, the GRADE analysis showed low to very low certainty of the evidence to support the hypothesis that chewing is an important contributor in the swallowing process, and physiologic/pathologic processes in the GIT. The GRADE analysis also showed a moderate to very low certainty of the evidence to suggest that chewing function contributes to nutrition-related parameters. The overall results of the current study showed that a majority (64.7%) of the studies (46 out of 71) supported the hypothesis. However, robust studies with proper design, adequate sample size, and well-defined outcome parameters are needed to establish conclusive evidence.

Side switch frequency while masticating different chewing materials, and its relationship with other masticatory behaviors and sensory perceptions

OBJECTIVE

This cross-sectional study aimed to establish normative values for masticatory side switch (MSS) frequency in young Mexican adults and to assess the relationship between various indices and MSS frequency when masticating different chewing materials.

DESIGN

We enrolled 101 dentate adults and performed four masticatory assays that involved masticating different chewing materials (i.e., two-colored chewing gum, sweet cracker, salty cracker, and bread). Participants were asked to eat and swallow these foods and to chew the gum for 40 cycles and the following indices were determined: MSS index (MSSI), unilateral chewing index, chewing cycle duration, and number of cycles before terminal swallowing. The participants then rated perceived flavor intensity, salivary flow, and muscle fatigue during each trial.

RESULTS

The MSSI ranged from 0.03-0.06 (10th percentile) to 0.48-0.54 (90th percentile). A repeated-measures general linear model revealed a mean MSSI value of 0.28 (95 %CI, 0.25-0.30) adjusted by several factors. Male sex, soft food, and the last chewing period were associated with lower MSS frequency. Spearman's test showed a high correlation for the MSSI among the different foods. MSSI correlated negatively with the unilateral chewing index for each chewing material and with number of cycles for the sweet cracker. However, no significant correlation was detected between MSSI and sensory perception.

CONCLUSIONS

In healthy dentate individuals, the mean MSS relative frequency is 25-30 % with an 80-central percentile of 5-50 % of the maximum possible side changes. Lower MSS frequencies were detected in men, when chewing soft food, and during the final chewing period.

Lip and tongue pressure and the functionality of oro-facial structures in healthy individuals

BACKGROUND

With the ageing process changes in the musculature of oro-facial structures take place, consequently there is a reduction in the strength and mobility of the lips, tongue and cheeks.

OBJECTIVE

The aim of this study was to correlate oro-facial structures and chewing and swallowing functions among a group of senior citizens and young adults and check the influence of lip and tongue pressure of these functions.

METHODS

This is an observational, cross-sectional and analytical study. Thirty seniors with an average age of 67.13 years and 30 young adults with an average age of 22.03 years participated in the study. The Oro-facial Myofunctional Assessment Protocol with Scores for the Elderly and the Oro-facial Myofunctional Assessment Protocol with Expanded Scores were also used. The evaluation of the force of pressure of the lips and tip and dorsum of the tongue was carried out using the Biofeedback device Pró-Fono: Lip and Tongue Pressure.

RESULTS

Young adults had a higher evaluation score for the aspect/posture of the face, cheeks, lips, mentalis muscle, tongue, mobility of lips, tongue, jaw and cheeks, chewing and swallowing functions, total time and chewing strokes, and tip pressure and dorsum of tongue. According to the Structural Equation Modelling, a direct relationship was found between the tongue dorsum pressure force and the swallowing function.

CONCLUSION

With healthy ageing changes occurring in the appearance, posture and mobility of the lips, tongue, jaw and cheeks, with the seniors and reduced performance of chewing and swallowing functions.

Orofacial dysfunction after stroke-A multidisciplinary approach

OBJECTIVE

This paper describes the study protocol in an ongoing clinical trial evaluating oral screen training as part of a post-stroke rehabilitation programme. Baseline data were related to four domains: dysphagia, lip function, masticatory performance and patient-related outcome measures (PROM).

BACKGROUND

Stroke is one of the most common causes of disability-adjusted life years, and dysphagia is a common remaining problem after stroke. Rehabilitation using oral screen training has been suggested to improve swallowing, but evidence is still insufficient.

MATERIALS AND METHODS

Patients diagnosed with stroke with persisting objective and/or subjective swallowing dysfunction after primary rehabilitation were assessed for eligibility. In total, 25 patients were included. Objective function was assessed by swallowing capacity test (SCT), lip force and masticatory performance, subjective function by EAT-10 and NOT-S and PROM by LiSat-11 and ESAS.

RESULTS

Baseline data presented a heterogeneous pattern with no significant association between objective and subjective dysfunction. Most of the participants (20/25) showed impaired swallowing capacity in SCT, and 23/24 revealed orofacial dysfunction according to NOT-S. The most common subjective item reported was chewing and swallowing problems (19/24).

CONCLUSION

The heterogenous findings in the included tests and the lack of correlations emphasise the importance of multidisciplinary approaches to identify objective and subjective orofacial post-stroke dysfunction in clinical practice to be able to offer evidence-based individualised care. The included participants were representative of stroke patients with dysphagia, which supports proceeding with the planned intervention.

Influence of different presentations of denture adhesives on masticatory function of complete denture wearers: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Denture adhesives improve the mastication of complete denture wearers. However, the impact of denture adhesives with different presentations on mastication remains unclear.

PURPOSE

The purpose of this systematic review was to answer the focused question, "Do different presentations of denture adhesives affect the masticatory function of complete denture wearers?".

MATERIAL AND METHODS

This review was guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six databases and the non-peer-reviewed literature were searched up to July 2021. Only clinical studies (randomized clinical trials and nonrandomized clinical trials) comparing the use of different denture adhesive presentations (cream, powder, or strips) were included, without language or follow-up restrictions. The risk of bias was assessed by using the Cochrane tools (RoB 2.0 and ROBINS-I). Masticatory performance, by using single and multiple sieves, masticatory performance with color-changing chewing gum (mixing ability), swallowing threshold (particle size and number of cycles), jaw kinematics, and occlusal force were considered. Meta-analyses were conducted to evaluate masticatory performance (single sieve) and occlusal force outcomes (α=.05), and the certainty of the evidence was determined with the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) evaluations.

RESULTS

Nine studies (6 randomized and 3 nonrandomized clinical trials) were included. The risk of bias was considered moderate. Meta-analyses showed no differences between cream and powder denture adhesives for masticatory performance (standard mean difference=0.02; 95% CI=-0.46 to 0.50, P=.93) or between cream and strip denture adhesives for occlusal force (mean difference=14.35; 95% CI=-11.14 to 39.84, P=.27). Similarly, in qualitative analysis, cream and powder denture adhesives' performances were similar regarding masticatory performance with color-changing chewing gum (mixing ability), occlusal force, swallowing threshold (particle size and number of cycles), and jaw kinematics (P>.05). However, for resorbed ridges, cream denture adhesive resulted in a higher masticatory performance than strip (P<.05). When comparing powder to strip denture adhesives, the occlusal force was higher in the powder group (P<.05). The certainty of evidence was very low for all evaluated outcomes.

CONCLUSIONS

Different presentations of denture adhesives seem to improve the masticatory function of complete denture wearers in a similar way. However, the qualitative analysis showed that, in patients with a resorbed ridge, a cream denture adhesive may be better than strips to improve mastication, although the certainty of evidence was very low.

Factors related to masticatory performance in junior and senior high school students and young adults: A cross-sectional study

PURPOSE

Maintaining good masticatory function from a young age promotes lifelong health, yet limited studies have explored masticatory performance in young individuals. We investigated the relationship of sex, age, and individual oral functions with masticatory performance among junior and senior high school students and young adults.

METHODS

This cross-sectional study included students aged 12-13, 14-15, and 16-17 years (groups S1, S2, and S3, respectively) and young adults aged 20-40 years (group YA). We assessed oral functions, the number of functional teeth, and anthropometric measurements. Masticatory performance was evaluated using color-changeable chewing gum. We analyzed sex-related differences in each group and age-related differences in each sex. Multiple linear regression analysis was performed using masticatory performance as the dependent variable to investigate related factors.

RESULTS

Among the 522 children and 100 young adults, males exhibited significantly higher masticatory performance than females in groups S1, S3, and YA. Among males, groups S2, S3, and YA exhibited significantly higher masticatory performance than group S1. Among females, group S2 exhibited higher masticatory performance than groups S1 and S3. Male sex, the maximum occlusal force and tongue pressure, and the number of functional teeth were significantly correlated with masticatory performance.

CONCLUSIONS

Masticatory function development differed by sex, with males exhibiting higher masticatory performance than females. We identified that male sex, the maximum occlusal force and tongue pressure, and the number of functional teeth were significantly associated with masticatory performance. Our findings provide a basis for masticatory performance assessment in different age groups.

Assessment and Improvement of Masticatory Performance in Frail Older People: A Narrative Review

According to the World Health Organization (WHO), the estimated number of older adults is around 962 million and is projected to increase to 2.1 billion by 2050. The oral frailty concept is associated with gradual oral function loss in relation to aging. There is a need to emphasize the improvement of oral function based on an evaluation of masticatory performance in patients with various oral conditions or systemic diseases and especially in the frail elderly. The present narrative review presents an overview of the current state of the assessment and improvement of masticatory performance in frail older people. To fully encompass oral frailty, oro-facial hypofunction, or oro-facial fitness, dental Patient Reported Outcomes (dPROs) should be included; nevertheless, there are limited evidence-based rehabilitation approaches. The concept of oral frailty, oro-facial hypofunction, or oro-facial fitness should involve dental Patient Reported Outcomes (dPROs), and in this sense, there are only a few evidence-based rehabilitation procedures to improve oro-facial hypofunction besides prosthodontics. It must be considered that reduced neuroplastic capacity in old individuals might preclude a positive outcome of these strategies that might need to be accompanied by functional training and nutritional counseling.

Association between masseter muscle volume, nutritional status, and cognitive status in older people

OBJECTIVES

Clinical evidence has suggested that oral function is associated with cognitive, physical, and nutritional status of older people. A smaller volume of masseter, a crucial muscle for mastication, was associated with frailty. It has remained unknown if smaller masseter is associated with cognitive impairment. The current study investigated the association between masseter muscle volume, nutritional status, and cognitive status in older people.

MATERIALS AND METHODS

We recruited 19 patients with mild cognitive impairment (MCI), 15 patients with Alzheimer's disease (AD), and 28 sex and age-matched non-cognitive impairment (non-CI) older subjects. The number of missing teeth (NMT), masticatory performance (MP), maximal hand-grip force (MGF), and calf circumference (CC) were assessed. The masseter volume index (MVI) was calculated based on the masseter volume measured using magnetic resonance imaging.

RESULTS

The MVI was significantly lower in the AD group, compared to the MCI as well as the non-CI group. Multiple regression analyses revealed that the MVI was significantly associated with nutritional status (as indexed by CC) in the analysis of combination of NMT, MP, and the MVI. Moreover, the MVI was a significant predictor of CC only in patients with cognitive impairment (i.e., MCI+AD) but not in the non-CI group.

CONCLUSIONS

Our findings suggested that in addition to the NMT and MP, masseter volume is a critical oral factor associated with cognitive impairment.

CLINICAL RELEVANCE

Reduction of MVI should be carefully monitored for patients with dementia and frailty, to whom a lower MVI may indicate worse nutrient intake.

Changes in masticatory performance and the new onset of diabetes mellitus in older adults: a 5-year longitudinal study

Objective

Although masticatory performance is affected by age-related reduction in number of teeth (or treatment), the relationship between longitudinal changes in masticatory performance and diabetes mellitus is unknown. This longitudinal study investigated the association between changes in masticatory performance and new-onset diabetes mellitus among community-dwelling Japanese older adults.

Methods

The data of 214 older adults living in Ohnan Town, Shimane, Japan, who participated in two surveys conducted between 2012 and 2017 were analyzed. Diabetes mellitus was defined as a hemoglobin A1c level ≥ 6.5% or self-reported diabetes mellitus. The masticatory performance (measured by number of gummy jelly pieces collected after chewing) was evaluated by dental hygienists. Masticatory performance was categorized into two groups (high or low) based on the median in each survey; further, four groups (Group A: remained consistently high, Group B: changed from low to high, Group C: remained consistently low, Group D: changed from high to low) were used to determine longitudinal changes in masticatory performance. Logistic regression was used to analyze the association between changes in masticatory performance and new-onset diabetes mellitus.

Results

Overall, 10.3% of participants had diabetes mellitus at the follow-up survey. Multivariate analysis showed that Group D (odds ratio 8.69, 95% confidence interval 1.98-38.22) was positively associated with the development of diabetes mellitus compared with Group A after adjusting for sex, age, body mass index, alcohol consumption, physical activity, and eating speed.

Conclusions

Deteriorating masticatory performance for 5 years may cause diabetes mellitus among older adults.

Chewing Efficiency Test in Subjects with Clear Aligners

The aim of this study was to evaluate the masticatory function of subjects with clear aligners and to propose a simple and repeatable method for the clinical and experimental evaluation of masticatory function. For the testing we used almonds, a natural substance that can be easily found and stored, has intermediate consistency and hardness, is insoluble in saliva, and has the ability easily lose the moisture absorbed in the mouth. Thirty-four subjects using the Invisalign® (Align Technology, Santa Clara, CA, USA) protocol were randomly selected. This was an “intercontrol test”, i.e., all subjects under the same conditions acted as controls but also as cases whilst wearing the clear aligners. Patients were asked to chew an almond for 20 s, once with aligners and once without aligners. The material was then dried, sieved, and weighted. Statistical analysis was performed to investigate any significative differences. In all our subjects, the efficiency of chewing with clear aligners was found to be comparable to the efficiency of chewing without clear aligners. In detail, the average weight after drying was 0.62 g without aligners and 0.69 g with aligners, while after sieving at 1 mm, the average weight was 0.08 g without aligners and 0.06 g with aligners. The average variation after drying was of 12%, and after sieving at 1 mm, it was 25%. In summary, there was no substantial difference between chewing with or without clear aligners. Despite some discomfort in chewing, the clear aligners were well tolerated by most subjects, who wore them without difficulty even during meals.

Association between masticatory performance and oral conditions in adults: A systematic review and meta-analysis

OBJECTIVES

To give an overview of the evidence on the associations between oral condition factors and masticatory performance of adults, and to evaluate the direction and level of the associations.

DATA/SOURCES

Medline (PubMed), Embase (Ovid) and CINAHL Plus (EBSCOhost) were searched up to May 2022 for cross-sectional studies on oral conditions and masticatory performance in adults. Methodological quality of the included studies was independently evaluated based on the Joanna Briggs Institute critical appraisal checklist for analytical cross-sectional studies. Data on the associations between oral condition factors and masticatory performance were extracted. Meta-analysis was conducted on correlation coefficients.

STUDY SELECTION

Of the 8,035 records identified, 97 articles (88 studies) were included in the qualitative synthesis, and 18 studies were included in the meta-analyses. Among the oral condition factors that had associations with masticatory performance, the number of natural/remaining teeth or functional tooth pairs was reported by the largest number of studies, followed by perioral muscle status, dental prosthetic status, oral moisture status and periodontal status. Results of the meta-analyses showed that the positive association with the number of natural/remaining teeth was the strongest (pooled correlation coefficient: 0.51, 95%CI: 0.48 to 0.54), followed by the number of functional tooth pairs, maximum tongue force/pressure, while the association with the oral moisture status was the weakest.

CONCLUSIONS

Number of natural/remaining teeth and functional tooth pairs, perioral muscle status, oral moisture status, dental prosthetic status and periodontal status are the main oral condition factors influencing masticatory performance. Based on the limited evidence available, among these factors, the number of natural/remaining teeth has the strongest positive association, with a very low quality of evidence.

CLINICAL SIGNIFICANCE

This study provides valuable information on the oral condition factors associated with masticatory performance, which would be important for policymakers and clinical practitioners when deciding on the strategies for improving the masticatory performance of adults. This review highlights the need for standardization of measures and classifications of masticatory performance and oral conditions.

REGISTRATION

PROSPERO (registration number: CRD42021256824).

Association between masticatory dysfunction and gastroesophageal reflux disease: A population-based study in the elderly

BACKGROUND

Caries and periodontal disease may cause tooth losses and chewing difficulty, especially in the elderly. Ingesting poorly chewed food may delay gastric emptying and favour the development of gastroesophageal reflux disease (GERD).

OBJECTIVE

This study investigated the association between masticatory dysfunction and GERD in the elderly from a rural area in southern Brazil.

METHODS

This census invited all 489 elderly from a city to participate. The study used a GERD symptoms questionnaire, followed by an oral examination. Masticatory dysfunction was analysed based on the chewing difficulty for some food groups. Tooth loss and chewing self-perception were also considered as exposure variables. Poisson regression determined the association among variables by calculating the prevalence ratio [PR (95% confidence interval)].

RESULTS

The response rate was 93.1% (n = 455, average age of 70.9 years, 50.5% men). The prevalence of GERD in this population was 36.9%. GERD was associated with chewing difficulty for vegetables (PR = 1.54), meats (PR = 1.34) and cereals (PR = 1.43) but not with poor chewing self-perception (PR = 0.80) and tooth loss (PR = 1.22). GERD was also associated with xerostomia (PR = 1.63) and the female gender (PR = 1.35).

CONCLUSION

Elderly people from a rural area with a reduced number of teeth present chewing difficulty and a high prevalence of GERD, indicating an association between GERD and masticatory dysfunction.

Subjective and Objective Assessment of Chewing Performance in Older Adults with Different Dental Occlusion

OBJECTIVES

Satisfactory masticatory function is a significant indicator of improved oral health-related quality of life in older adults, either with or without artificial teeth. The purpose of this study was to examine masticatory performance of older adults with different prosthodontic reconstructions and occlusion, as well as to compare subjective and objective assessment of chewing performance.

MATERIAL AND METHODS

This study included 100 participants aged 65 and more. The chewing function questionnaire (CFQ) with answers on the Likert scale 0-4 (0 = no difficulties; 4 = maximum difficulties) was used as an indicator of subjective masticatory assessment. The two-color chewing gum test was used as objective assessment of masticatory function (mixing ability), based on the Z-score values. Dental occlusion was assessed using functional teeth units (FTU).

RESULTS

The results obtained using the CFQ and the clinical mixing ability test are in compliance with each other (r = 0.742). A decrease in the number of natural teeth, especially posterior teeth, progressively reduced chewing ability and increased difficulties in mastication. Participants with less FTUs, or with FTUs that are a part of removable denture, had greater reduction in masticatory function compared to those with FTUs composed of natural teeth or fixed partial dentures.

CONCLUSION

This study revealed a strong positive correlation between the subjective masticatory assessment in older adults using the validated questionnaire and the objective clinical test of the mixing ability of two chewing gums. Our data on influence of the number and the type of FTU on masticatory performance will be valuable when planning prosthodontic therapy.

Maria MT, Marito P, Takano H, Khaing AMM, Nokubi T, Ono T. Masticatory Performance Test Using a Gummy Jelly for Older People with Low Masticatory Ability

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

The Test of Mastication and Swallowing Solids and the Timed Water Swallow Test: Reliability, associations, age and gender effects, and normative data

BACKGROUND

Quantitative measures can increase precision in describing swallowing function, improve interrater and test-retest reliability, and advance clinical decision-making. The Test of Mastication and Swallowing Solids (TOMASS) and the Timed Water Swallow Test (TWST) are functional tests for swallowing that provide quantitative results.

AIMS

To explore the relationship between TOMASS and TWST; evaluate test-retest and interrater reliability; explore age and gender effects; and gather normative data.

METHODS & PROCEDURES

Healthy community dwelling participants (n = 298, ≥ 20 years old) were recruited. Of those, 126 were included in the reliability study. Participants completed the TWST and TOMASS.

OUTCOMES & RESULTS

Associations between TWST and TOMASS measures were found using Pearson's correlation coefficient. Age was positively associated with an increase in the number of bites (n = 292, r = 0.15, p = 0.009), masticatory cycles (n = 291, r = 0.33, p < 0.0001) and duration (n = 292, r = 0.32, p < 0.0001) for the TOMASS. For the TWST, age was positively associated with an increase in duration (n = 296, r = 0.23, p < 0.0001), and negatively associated with volume (n = 296, r = -0.205, p < 0.0001), and swallowing capacity (n = 296, r = -0.24, p < 0.0001). Females required more bites, masticatory cycles, swallows and longer time than males in TOMASS. In TWST, females required more swallows, longer time, and had lower volume per swallow and reduced swallowing capacity than males. Intraclass correlation coefficient (ICC) revealed good test-retest reliability and moderate to excellent interrater reliability.

CONCLUSIONS & IMPLICATIONS

This study provides support for the validity of the TOMASS and TWST. Reduced efficiency in one of the tests might indicate a need to evaluate performance in the other. Extended chewing time and increased number of masticatory cycles might be compensatory behaviours for reduced oral processing abilities that are motor, sensory and/or mechanical.

WHAT THIS PAPER ADDS

The TOMASS and TWST are functional tests of swallowing that provide quantitative results. They are easy to incorporate as part of the clinical evaluation of swallowing due to low cost and quick administration. Age and gender effects were found for the TWST and TOMASS, but they were only tested on relative measures rather than absolute measures. Different types of crackers used for TOMASS led to differences in performance and in normative values. What is already known on the subject Associations between performance during TWST and TOMASS were found: time, number of swallows and time per swallow were correlated, meaning that need for more time and more swallows is reflected in both drinking and chewing. The study provides further support for age and gender effects in TWST and TOMASS, on both relative and also on absolute measures, which were not investigated previously. Longer durations in TOMASS and TWST with an increase in age, are likely to be the result of compensatory behaviours to allow safe swallowing. Normative data for a country-specific cracker are presented (Israel). What are the potential or actual clinical implications of this work? Reduced efficiency in one of the tests might indicate a need to evaluate performance in the other. Establishing country specific norms for commonly available crackers is necessary, since crackers size and ingredients, such as fat content and moisture, influence chewing and swallowing. There is a balancing act between safety and efficiency in older adults' swallowing behaviour. Reducing pace in eating and drinking probably supports safer swallowing.

Mandibular implant-assisted removable partial denture - Kennedy Class I to Class III modification - Case series with masticatory performance and satisfaction evaluation

In this work, we present 5 cases of Kennedy Class I patients with atrophic posterior mandible treated with the placement of 01 short WS Neodent® implant and a healing screw to support the removable prosthesis, transforming them into Kennedy Class III patients. To quickly evaluate and verify the benefit of this treatment, masticatory performance was evaluated with maximum bite force and chewing ability. A VAS questionnaire was also applied for a practical preoperative and postoperative evaluation of overall quality of life-changing for the patient after this treatment. This treatment plan was planned in order to reduce drastically the treatment costs and morbidity, and to enhance oral function and the quality of life for these patients. Also, this treatment lead to residual bone preservation, enhanced masticatory function and patient satisfaction. Especially in countries with a large number of patients with missing teeth and socio-economic difficulties to be fully rehabilitated with dental implants and fixed prosthesis treatment options with reduced costs are important to be in our armamentary os possibilities. Key words:Dental implants, masticatory performance, chewing, oral function, mixing ability.

Reduced mastication is a risk factor for Rome IV postprandial distress syndrome in patients investigated with upper endoscopy

BACKGROUND AND AIMS

Reduced mastication could force the stomach to do extra work on crushing food and contribute to dyspeptic symptoms. This study aimed to assess the relationship between mastication and dyspepsia.

METHODS

This cross-sectional study involved 209 consecutive patients referred for elective upper endoscopy. Before endoscopy, an expert dentist performed an oral examination and scored chewing function in three levels (normal, regular, and reduced), and applied questionnaires for assessment of dyspepsia (Rome IV), xerostomia, and mastication (normal, regular, and reduced). A reduced masticatory function was defined when an oral examination or mastication questionnaire rated the chewing as poor. Associations between mastication, confounders, and dyspepsia were estimated by prevalence ratio [PR (95% Confidence Interval)] using Poisson regression.

RESULTS

Thirty-four patients showed relevant organic conditions in the upper gastrointestinal tract (moderate to severe reflux oesophagitis, peptic ulcer, neoplasia, and surgical modification) and were excluded. Among 175 patients with non-organic diseases (aging 51.3 ± 15.7 years; 61.7% women), 50 (28.6%) had reduced mastication, and 125 (71.4%) had normal/regular mastication. After adjusting for age and xerostomia, reduced mastication was associated with postprandial distress syndrome [PR = 1.93 (95%CI 1.27 - 2.91)] but not with epigastric pain syndrome [PR = 1.09 (95%CI 0.75 - 1.60)].

CONCLUSIONS

In patients referred for upper digestive endoscopy, reduced mastication was associated with postprandial distress syndrome but not with epigastric pain syndrome. An interdisciplinary approach with dentists and physicians might benefit dyspeptic patients with postprandial distress syndrome.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2021 dental literature in restorative dentistry to inform busy dentists regarding noteworthy scientific and clinical progress over the past year. Each member of the committee brings discipline-specific expertise to coverage of this broad topical area. Specific subject areas addressed, in order of the appearance in this report, include COVID-19 and the dental profession (new); prosthodontics; periodontics, alveolar bone, and peri-implant tissues; implant dentistry; dental materials and therapeutics; occlusion and temporomandibular disorders; sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence daily dental treatment decisions with an emphasis on future trends in dentistry. With the tremendous volume of dentistry and related literature being published daily, this review cannot possibly be comprehensive. Rather, its purpose is to update interested readers and provide important resource material for those interested in pursuing greater details on their own. It remains our intent to assist colleagues in negotiating the extensive volume of important information being published annually. It is our hope that readers find this work useful in successfully managing the patients and dental problems they encounter.

Food Bolus Properties in Relation to Dentate and Prosthetic Status

The objective of this study is to evaluate food bolus properties (mass, moisture content and food comminution) in patients wearing fixed or removable dental prostheses. Methods: A cross-sectional study was conducted on a convenience sample of patients aged at least 55 years old. Patients chewed a 10 g sample of fresh raw carrot until they felt ready to swallow. The mass of the food bolus was determined as collected and after drying. Food comminution was assessed by the multiple sieve method. Results: Patients with fixed prostheses compared to those with removable prostheses registered a similar mass of food bolus as collected (4.40 g vs. 4.60 g; p = 0.856); a higher mass of dried food bolus (3.46 g vs. 0.86 g; p < 0.001); lower moister of food bolus (24.65% vs. 82.35%; p < 0.001); and better food comminution (mass of smaller particles, of size below 2 mm, represented 65.93% vs. 20% of dried food bolus). In removable denture wearers, food comminution was slightly better in partially than in completely edentulous patients, and rather similar in completely edentulous patients with either implant overdenture or complete denture in the mandible, and complete denture in the maxilla. Conclusions: The current results suggest that food bolus properties are dependent on the dentate and prosthetic status.

Assessing masticatory performance with a colour-mixing ability test using smartphone camera images

Background

Colour‐mixing ability tests are frequently used to assess masticatory performance, but the image acquisition process may be cumbersome and technique sensitive.

Objectives

To evaluate the reliability of smartphone camera images in assessing masticatory performance using a colour‐mixing ability test.

Methods

Participants were recruited into three groups of dental state (n = 20 each): fully dentate, removable partial denture wearers and complete denture wearers. After performing a colour‐mixing ability test, images of the gum specimens (Hue‐Check Gum©) were captured with two smartphones and compared with the images obtained from a flatbed scanner by two examiners. The images were analysed with a subjective‐ (SA) and an opto‐electronical assessment (VoH). Inter‐ and intra‐rater reliability were tested. ANOVA models with repeated measures were used for statistical analysis (⍺ = .05).

Results

All three image acquisition techniques were able to distinguish masticatory performance between different dental states. For SA, inter‐rater reliability was fair to substantial and intra‐rater reliability was substantial to almost perfect. For VoH, inter‐rater reliability with the smartphones was at times different between two examiners, but the intra‐rater assessment was reliable. The opto‐electronic analysis with smartphone images underestimated the masticatory performance significantly when compared to the flatbed scanner analysis. Seven‐day ageing of the specimens did not significantly affect the results.

Conclusions

The assessment of masticatory performance with the Hue‐Check Gum© is a reliable method. The use of smartphones may occasionally underestimate masticatory performance; image acquisition with a flatbed scanner remains the gold standard. A centralised analysis of the photographed wafer may foster the reliability of the diagnosis.

Growth curves for mandibular range of motion and maximum voluntary bite force in healthy children

Mandibular range of motion and bite force are indispensable variables for the evaluation of mandibular function. There are a variety of medical and dental conditions that can negatively affect mandibular function. Values for mandibular range of motion (i.e., active and passive maximum interincisal mouth opening, protrusion, and laterotrusion) and anterior maximum voluntary bite force (AMVBF) in healthy children and adolescents can help in recognizing temporomandibular dysfunction. In this longitudinal study, 169 healthy children aged 6-18 years were included. They were examined at four time points over 1 year. Mixed model analysis was performed to produce growth curves of mandibular range of motion and AMVBF. Average active maximum interincisal mouth opening was significantly higher in boys with 50.0 mm compared to 47.8 mm in girls. Boys also had a significantly higher AMVBF than girls with an average of 169.0 N versus 140.0 N, respectively. Growth curves of active and passive maximum interincisal mouth opening showed an increase with age, albeit levelling off through puberty. The growth curves of AMVBF in girls reach a plateau phase at ages 12-14 years, after which the curve descends; in boys, the AMVBF tended to increase up to 18 years of age, although a slow-down after 14 years of age was noted.

Oral hypofunction and association with need for daily assistance among older adults in long-term care

BACKGROUND

Oral hypofunction (OHF) is related to occlusal status and bite force. It has specific symptoms and varying degrees of severity.

OBJECTIVES

OHF was determined with five signs. The relationships between OHF and need for assistance in oral hygiene, moving, eating, and occlusal status in older adults living in long-term care (LTC) were examined.

METHODS

A comprehensive clinical oral examination was conducted on 393 residents who lived in LTC in Helsinki, Finland. The five signs to determine OHF were mouth dryness, visible food residue on oral or denture surfaces, ability to keep the mouth open during examination, clearness of speech, and diet of pureed or soft food. Score points of 0-2 were given for each sign and the sum was categorized as mild, moderate, or severe OHF. Participants were divided into three groups accordingly, and occlusal status was determined based on contact units. In addition, nurses collected background information on number of medications and level of cognition. Need for assistance was based on oral hygiene, moving, and eating.

RESULTS

Of participants (n=319), 21% showed severe and 41% moderate OHF. Occlusal status differences between the OHF groups were significant. OHF severity associated linearly with increased severity of cognitive impairment and increased need for assistance in oral hygiene, eating, and moving.

CONCLUSIONS

OHF score based on the five signs can be used to determine OHF severity. OHF was common and associated with occlusal status, cognitive impairment, and need for assistance in oral hygiene, moving, and eating in older adults living in LTC.

Gastric emptying rate of a solid meal in patients with anterior open bite malocclusion: A preliminary study

Objectives:

The objective of the study was to investigate the relationship between anterior open bite (AOB) malocclusion and digestion by evaluating mastication and gastric emptying (GE) of a solid meal.

Material and Methods:

We recruited 26 female participants and divided them into two groups according to their occlusion status: The control group with normal occlusion (n = 11; age: 25.2 ± 2.8 years; and body mass index [BMI]: 21.1 ± 1.9 kg/m2) and the AOB group with AOB malocclusion (n = 15; age: 23.2 ± 5.5 years; BMI: 21.0 ± 1.6 kg/m2). GE, chewing, and occlusion were assessed simultaneously. A food questionnaire survey was also administered on the same day.

Results:

A significant positive correlation was noted between open bite and the occlusal analysis findings. Negative correlations were found between the food questionnaire score and both the open bite and occlusal analysis findings, which confirmed that AOB affects mastication. However, no significant difference in the GE rate parameters was observed between the two groups.

Conclusion:

Adaptive mechanisms may have a compensatory effect on the GE rate. However, the lack of tooth contact in the anterior occlusal region resulted in reduced masticatory ability. Orthodontic treatment should thus be considered, regardless of the presence of digestive problems, to improve mastication.

Current Perspectives on Food Oral Processing

Food oral processing (FOP) is a fast-emerging research area in the food science discipline. Since its first introduction about a decade ago, a large amount of literature has been published in this area, forming new frontiers and leading to new research opportunities. This review aims to summarize FOP research progress from current perspectives. Food texture, food flavor (aroma and taste), bolus swallowing, and eating behavior are covered in this review. The discussion of each topic is organized into three parts: a short background introduction, reflections on current research findings and achievements, and future directions and implications on food design. Physical, physiological, and psychological principles are the main concerns of discussion for each topic. The last part of the review shares views on the research challenges and outlooks of future FOP research. It is hoped that the review not only helps readers comprehend what has been achieved in the past decade but also, more importantly, identify where the knowledge gaps are and in which direction the FOP research will go.

Effect of frozen storage on preservation of a silicone-based test food material

Aim: This study aimed to evaluate the effect of frozen storage on the physical properties of a silicone-based test food material, highly used to evaluate the masticatory performance in research settings. Methods: A total of 1,666 silicone cubes of Optosil Comfort® with 5.6-mm edges were shaped and stored at -18°C. The cubes were subsequently tested for flexural strength (maximum force, displacement, stress, and strain) before breaking (n = 136), changes in weight and size (n = 170), and masticatory performance (n = 1360) at eight timepoints: immediately after cube preparation (baseline, no freezing), and 1, 2, 3 and 4 weeks, and 2, 4 and 6 months after frozen storage. The cubes were thawed 8 h before each assessment. Results: The maximum force, stress, maximum displacement, and deformation values for the cubes were not affected by freezing (P > 0.05). At all of the time points, the cubes exhibited similar weight (P = 0.366) and size (identical values). The masticatory performance for the cubes also showed no differences from baseline through 6 months (P = 0.061). Conclusion: Freezing Optosil Comfort® silicone cubes did not alter the physical and mechanical properties of the material, being suitable to optimize the assessment of masticatory parameters for research purposes.

Masticatory performance in patients undergoing free fibula flap for mandible reconstruction

Background

To explore the masticatory performance in patients undergoing an osteo(cutaneous) free fibula (OFF) flap for mandible reconstruction by a prospective design.

Methods

A total of 56 patients who had undergone OFF flap reconstructions for mandibular reconstruction secondary to malignant (squamous cell carcinoma) or benign (ameloblastoma) tumor resection were prospectively enrolled. They were asked to complete the masticatory performance test by the weigh method and the chew domain of the University of Washington quality of life questionnaire (version 4) preoperatively and at 3, 6, and 12 months postoperatively. The pair nonparametric test was used to analyze the dynamic change of masticatory performance and subjective chew function.

Results

Fifty-one patients were included for analysis finally. The mean masticatory performance for patients with malignant tumors were 53.4% ± 10.3%, 36.4% ± 10.3%, 42.6% ± 9.6%, 52.8% ± 10.9%, and 53.1% ± 11.8% preoperatively, at 2 weeks, 3 months, 6 months, and 12 months postoperatively, respectively. Compared with the preoperative level, the masticatory performance had a significant reduction immediately after surgery (p < 0.001), followed by a return to the baseline level within three months. A similar trend was noted for those with benign tumors. The mean score of chew domain for patients with malignant tumors were 100 ± 0, 54.3 ± 32.9, 81.4 ± 24.5, and 92.9 ± 17.8 preoperatively, at 3 months, 6 months, and 12 months postoperatively, respectively. Compared with the preoperative level, the subjective chew function was greatly affected within the first three months (p < 0.001), and it gradually recovered to the baseline level in the following nine months. A similar trend was noted in patients with benign tumors.

Conclusions

The masticatory performance and subjective chew function was significantly affected after OFF flap reconstructions in the short term, but both recovered to the preoperative levels within 9–12 months.

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.