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.

Oral and Pharyngeal Dysphagia in Adults

Patients with oral and pharyngeal dysphagia have difficulty forming a cohesive bolus and/or transferring food from the mouth into the pharynx and esophagus to initiate the involuntary swallowing process. This may be accompanied by nasopharyngeal regurgitation, aspiration, and a sensation of residual food remaining in the pharynx. Abnormalities affecting the upper esophageal sphincter, pharynx, larynx, or tongue, in isolation or combination, result in oropharyngeal dysphagia affecting either or both transit and airway protection. These issues can be addressed with a combination of management of the underlying systemic disease, with surgical intervention or with swallow therapy.

Transitional chelal digit patterns in saprophagous astigmatan mites

Changes in the functional shape of astigmatan mite moveable digit profiles are examined to test if Tyrophagus putrescentiae (Acaridae) is a trophic intermediate between a typical micro-saprophagous carpoglyphid (Carpoglyphus lactis) and a common macro-saprophagous glycyphagid (Glycyphagus domesticus). Digit tip elongation in these mites is decoupled from the basic physics of optimising moveable digit inertia. Investment in the basal ramus/coronoid process compared to that for the moveable digit mastication length varies with feeding style. A differentiated ascending ramus is indicated in C. lactis and in T. putrescentiae for different trophic reasons. Culturing affects relative investments in C. lactis. A markedly different style of feeding is inferred for the carpoglyphid. The micro-saprophagous acarid does not have an intermediate pattern of trophic functional form between the other two species. Mastication surface shape complexity confirms the acarid to be heterodontous. T. putrescentiae is a particularly variably formed species trophically. A plausible evolutionary path for the gradation of forms is illustrated. Digit form and strengthening to resist bending under occlusive loads is explored in detail. Extensions to the analytical approach are suggested to confirm the decoupling of moveable digit pattern from cheliceral and chelal adaptations. Caution is expressed when interpreting ordinations of multidimensional data in mites.

Aberrant occlusal sensitivity in adults with increased somatosensory amplification: a case-control study

OBJECTIVES

Occlusal sensitivity (OS)-the ability to detect fine objects between opposing teeth-mainly relies on the activity of mechanoreceptors located in the periodontal ligament. We tested whether somatosensory amplification (SSA)-the tendency to perceive normal somatic sensations as being intense, noxious, and disturbing, which plays a critical role in hypervigilance-affects OS.

MATERIALS AND METHODS

We measured OS in 66 adults divided into three groups based on their SSA scores (LowSSA, Intermediate - IntSSA, HighSSA) by asking them to bite on aluminum foils (8 to 72 μm thick) and a sham foil, and report whether they felt each foil. We performed 20 trials for each thickness and sham condition (each participant was tested 120 times), and compared the frequency of correct answers (%correct) among groups after adjusting for participants' trait anxiety, depression, self-reported oral behaviors, and masseter cross-sectional area.

RESULTS

%correct was affected by the interaction Foil Thickness-by-SSA (p = 0.007). When tested with the 8 μm foil, the HighSSA group had a lower %correct than the IntSSA (contrast estimate [95% CI]: -14.2 [-25.8 - -2.6]; p = 0.012) and the LowSSA groups (-19.1 [-31.5 - -6.6]; p = 0.001). Similarly, with the 24 μm foil, the HighSSA group had a lower %correct compared to the IntSSA (-12.4 [-24.8-0.1]; p = 0.048) and the LowSSA groups (-10.8 [-22.5-0.8]; p = 0.073).

CONCLUSION

Individuals with high SSA present with an aberrant occlusal sensitivity.

CLINICAL RELEVANCE

Our findings provide novel insights into the relationship between occlusal perception and psychological factors, which may influence an individual's ability to adapt to dental work.

Association Between Subjective Masticatory Function and Mild Cognitive Impairment in Older Adults

AIM

This study aimed to examine the effect of subjective masticatory function on the occurrence of mild cognitive impairment (MCI) by analysing the Korean Longitudinal Study of Ageing (KLoSA) data.

METHODS

The study participants were 2954 KLoSA participants aged 60 years or older in the first wave (2006) who had normal cognitive function. The subjective masticatory function was determined using a survey item, and the responses were grouped into 3 categories, ie, good, moderate, and poor. The occurrence of MCI in the 3 groups was followed up until 2020. Cognitive function was assessed based on the Korean Mini-Mental State Examination score. Age, sex, education level, residence, health insurance type, smoking status, drinking status, and the number of chronic diseases were considered as potential confounders. To examine the occurrence of MCI according to subjective masticatory function, Cox proportional hazard regression analysis was performed.

RESULTS

Cox proportional hazard regression models adjusted for confounders yielded the following results: in men, the risk of MCI was higher in those whose subjective masticatory function was moderate and poor, as compared to those with good subjective masticatory function (adjusted hazard ratio [aHR], 1.33; 95% confidence interval [CI], 1.12-1.58; aHR, 1.23; 95% CI, 1.04-1.46). In contrast, in women, subjective masticatory function did not significantly influence the occurrence of MCI (aHR, 1.05; 95% CI, 0.89-1.24; aHR, 1.08; 95% CI, 0.92-1.28).

CONCLUSIONS

This study suggests that poor masticatory function may be a risk factor for MCI in older men.

The association between objective and subjective oral health conditions and the presence of anorexia of aging among Japanese older Adults1

Anorexia of aging is a risk factor for malnutrition among older adults. This study aimed to evaluate the association between objective and subjective oral health and anorexia among independent older adults. This cross-sectional study targeted independent older adults aged ≥65 years who participated in the Japan Gerontological Evaluation Study conducted in 2022. The outcome variable was the presence of anorexia, as assessed by the Simplified Nutritional Appetite Questionnaire. Exposure variables were dental status (≥20 teeth, 10-19 teeth with/without dentures, and 0-9 teeth with/without dentures) as objective oral health and oral health-related quality of life measured by five items of the short version of the Oral Impacts on Daily Performances (OIDP) (eating, speaking, smiling, emotional stability, and enjoying with others) as subjective oral health. We fitted the Poisson regression model, including possible confounders, and estimated prevalence ratios (PRs) and 95% confidence intervals. Among 19,787 participants (mean age: 74.6 years [1SD = 6.2], male: 48.5%), 9.0% were classified as having anorexia. After adjusting possible confounders, those with ≤19 teeth had a higher proportion of experiencing anorexia compared to those with ≥20 teeth; however, the association was less pronounced among those with dentures (0-9 teeth with dentures: PR = 1.48 [1.31-1.68], and 0-9 teeth without dentures: PR = 2.08 [1.65-2.63]). Even after adjusting for dental status, each item of OIDP was significantly associated with the presence of anorexia (all p < 0.05). The results showed that both objective and subjective poor oral health were significantly associated with a higher probability of developing anorexia of aging. Therefore, improving both objective and subjective oral health through appropriate dental care could contribute to maintaining appetite in later life.

Is Chewing Performance Related to Dietary Intake in Children with Cerebral Palsy?

To examine the relationship between chewing performance and dietary intakes in children with Cerebral Palsy (CP). Forty children with CP aged between 2 and 6 years were included. The Karaduman Chewing Performance Scale (KCPS) and the Mastication Observation and Evaluation (T-MOE) instruments were used to evaluate chewing performance. Daily dietary intakes were measured from a 24-h food record with digital photographs including the amount and textures of all foods consumed during the meal. Chewing function was impaired in 70% of children. There was a negative low-to-moderate correlation between KCPS scores and daily protein intake (r = -0.32, p = 0.04), but not with energy and other macronutrients. The percentage of daily dietary intakes from 'liquid-blenderized' foods were positively correlated with KCPS, and negatively correlated with T-MOE scores (p < 0.001). There was a significant negative association between the percentage of daily dietary intakes from 'easy to chew & regular solid' foods and KCPS scores, and a significant positive association was found with T-MOE scores. In conclusion, the amount of daily protein intake decreased, and daily intake ratios of energy and macronutrients from liquid-blenderized foods increased as chewing performance decreased in children with CP. Timely diagnosis and treatment of chewing dysfunction can serve as a useful treatment option to ensure adequate dietary intake in children with CP, and also to decrease the burden of their parents and improve their quality of life.

The use of color-changeable chewing gum in evaluating food masticability

PURPOSE

We assess masticatory performance using color-changeable chewing gum, which shifts from yellow-green to red upon chewing. Previous studies used a colorimeter to reveal the cut-off a* values of the gum's color (a* represents the degree of color between red and green) to determine which foods are masticable (masticable meat, masticable soft side dish, and inadequate masticatory performance). Since a more convenient method is required, we examined the validity and reliability of visual measurement using a color scale to indicate masticable foods by observing the chewing gum's color.

METHODS

Fifty patients (male, 48%), aged ≥ 65 (mean, 82.6) years were enrolled. Using color-changeable chewing gum, three groups were formed according to the cut-off a* values: masticable meat, masticable soft side dish, and inadequate masticatory performance. For the color scale classification, one physiatrist and one dietitian simultaneously, individually, and visually determined the chewing gum color and classified it into one of the three groups. Criterion-related validity was evaluated using the kappa coefficient of agreement between the results from the two methods. Inter-rater reliability was examined using the kappa coefficient of agreement between the three groups judged by the two raters on a color scale.

RESULTS

The kappa coefficients of the agreement for the classifications were 0.908 and 0.909 for the physiatrist and dietitian, respectively. The inter-rater agreement between two raters on the color scale was 0.938 for the kappa coefficient.

CONCLUSION

The color scale indicated masticable foods without a colorimeter. This method can be useful in older adult facilities and homes.

Effects of tooth loss on behavioral and psychological symptoms of dementia in app knock-in mice

OBJECTIVES

Many patients with Alzheimer's disease experience behavioral and psychological symptoms of dementia (BPSD), which significantly affect their quality of life. It is known that 5-Hydroxytryptamine (5-HT) plays a crucial role in the development of BPSD. However, the relationship between tooth loss and Alzheimer's disease symptoms, particularly aggression, has remained unexplored. Although nutritional status is known to influence the progression of dementia, the specific effect of tooth loss on peripheral symptoms, notably aggression, is not well understood.

METHODS

In our study, we conducted maxillary molar extractions in aged C57BL6J and AppNL-G-F mice and observed their condition over a 3-month period. During this time, we documented significant behavioral and genetic differences between mice in the control groups and mice that underwent tooth extraction. Notably, mice that underwent tooth extraction exhibited a considerable decline in cognitive function and an increase in aggression at 3 months after tooth extraction compared with the control groups (C57BL6J or AppNL-G-Fmice).

RESULTS

Our findings suggest that molar loss may lead to reduced 5-HT levels in the hippocampus, possibly mediated by the trigeminal nerve, contributing to the development of aggression and BPSD in Alzheimer's disease.

CONCLUSION

This study sheds light on the intricate relationships between oral health, 5-HT, and Alzheimer's disease symptoms, offering valuable insights into potential therapeutic avenues for managing BPSD in patients with dementia.

Chewing Well Modulates Pharyngeal Bolus Transit During Swallowing in Healthy Participants

Mastication is controlled by central pattern generator in the brainstem and can be modulated by volition. The aim of this study was to investigate the effect of chewing well on swallowing. Twenty-six healthy participants were instructed to eat 8, 12, and/or 16 g of steamed rice with barium sulphate under the following two conditions: chewing freely task (CF; chewing naturally in their usual manner) and chewing well task (CW; chewing the food with a request to "chew well"). We evaluated bolus transport and swallowing movement using videofluoroscopy and electromyography of the masseter, suprahyoid and thyrohyoid muscles. The chewing time and pharyngeal transit time (PTT) at the first swallow showed high reproducibility in both CF and CW. PTT for CW was significantly shorter and longer than CF in 12 and 16 g, respectively. In 12 g, CW increased the pharyngeal bolus velocity and decreased thyrohyoid EMG activity during swallowing compared with CF. In 16 g, the difference between CW and CF in the estimated swallowed bolus volume was positively correlated with that in upper esophageal sphincter transit duration. We speculate that CW modulates PTT during swallowing depending on the mouthful volume.

Comparison of volumetric loss and surface roughness of composite dental restorations obtained by additive and subtractive manufacturing methods

Statement of problem

Permanent crown materials produced with new generation additive manufacturing and traditional subtractive manufacturing materials have not been compared in terms of wear resistance.

Purpose

This study aims to compare the volumetric loss related to wear and resulting surface roughness after aging in a chewing simulator between resin nano ceramics produced with milling technique and permanent crown materials produced with three dimensional (3D) printing.

Materials and methods

Three different hybrid composite-ceramic (HCC) (The three materials are GC: Cerasmart, VE: Vita Enamic, and GV: Grandio Voco.) and one 3D printed definitive crown resin (FormLabs Permanent Crown Resin) were investigated before aging (n:8), the surface roughness of all samples was measured with a profilometer, and 1 randomly selected sample from each subgroup was imaged with scanning electron microscope (SEM). 3D scans of each sample were obtained with a desktop scanner. Thermomechanical aging was performed using a chewing simulator. Four hundred thousand cycles were completed under a vertical occlusal force of 49 ± 0.7 N with a thermal cycle of 1.7 Hz 5-55° and with a dwell time of 120 s, mimicking 2 years of aging. The imaging procedures were repeated, and the change in surface roughness was evaluated. 3D images were also overlapped, and the volumetric loss was calculated with the relevant inspector software. The data obtained were analyzed by two-way ANOVA (p < 0.05).

Result

The results showed significant statistical differences for both parameters (p > 0.05). The highest volumetric loss was found in the GV group while the lowest volumetric loss was in the VE group. The highest surface roughness values were observed in the GV group, while the lowest values belonged to the VE one.

Conclusion

Of the restorative materials evaluated, the VE group is suitable for long-term restorations, whereas the GV one is suitable for medium-term restorations. It is promising in terms of 3D printing technologies that the 3D material gives comparable results with the GV group.

Clinical i̇mplication

Additive manufacturing techniques are a successful method that accelerates the manufacturing process. Permanent crown resins are promising alternatives to conventional production.

Impact of Compensating Curves on Mastication of Complete Denture Wearers: A Randomised Triple-Blind Clinical Trial

INTRODUCTION

The application of occlusal concepts in prosthodontics is still under debate.This study assessed the impact of compensating curves on the comminution of complete denture wearers.

METHODS

Seven edentulous subjects, aged 64.6 ± 2.0 years, were rehabilitated with new muco-supported complete dentures and tested in two occlusal plane settings: with and without compensating curves. A randomised triple-blind clinical trial was conducted, considering one-week and one-month as adaptation periods for dentures. After each trial, the subjects were crossed over to their respective groups. One-week was also chosen as the washout period, and after that, the subjects were re-examined. The masticatory performance and swallowing threshold were determined while chewing Optocal test food. The multiple sieve method was used for fractionation and granulometry.

RESULTS

During the masticatory performance and swallowing threshold estimates, no differences were found between the median particle sizes obtained with the both occlusal plane conditions (P ⟩ 0.05). However, the swallowing threshold improved after one month, resulting in smaller particle sizes. Moreover, the chewing rates for the both test foods were also increased (P ⟨ 0.05).

CONCLUSIONS

These findings suggest that the compensating curves did not have an impact on the masticatory function of subjects wearing complete dentures.

Deep learning and predictive modelling for generating normalised muscle function parameters from signal images of mandibular electromyography

Challenges arise in accessing archived signal outputs due to proprietary software limitations. There is a notable lack of exploration in open-source mandibular EMG signal conversion for continuous access and analysis, hindering tasks such as pattern recognition and predictive modelling for temporomandibular joint complex function. To Develop a workflow to extract normalised signal parameters from images of mandibular muscle EMG and identify optimal clustering methods for quantifying signal intensity and activity durations. A workflow utilising OpenCV, variational encoders and Neurokit2 generated and augmented 866 unique EMG signals from jaw movement exercises. k-means, GMM and DBSCAN were employed for normalisation and cluster-centric signal processing. The workflow was validated with data collected from 66 participants, measuring temporalis, masseter and digastric muscles. DBSCAN (0.35 to 0.54) and GMM (0.09 to 0.24) exhibited lower silhouette scores for mouth opening, anterior protrusion and lateral excursions, while K-means performed best (0.10 to 0.11) for temporalis and masseter muscles during chewing activities. The current study successfully developed a deep learning workflow capable of extracting normalised signal data from EMG images and generating quantifiable parameters for muscle activity duration and general functional intensity.

Association between occlusal features and masticatory function in Hong Kong preschool children: a survey with one-year longitudinal follow-up

BACKGROUND

Mastication is important for breaking down food, aiding swallowing and nutrients absorption, and is therefore fundamental to a child's development. Studies have shown poor masticatory function to be associated with younger age and presence of caries. However, studies of the association between masticatory function and malocclusion yielded contradictory results. The aim of this study is therefore to investigate the association between three-dimensional occlusal features with masticatory function, among preschool children in Hong Kong.

METHODS

Self-administered questionnaires on masticatory function in three domains, namely general chewing difficulty, requiring help when eating different food types and increased preference for soft food were completed by parents. Information on non-nutritive sucking habits and basic demographics were also collected in the questionnaire. Clinical examinations were conducted to record three-dimensional occlusal features and presence of caries. Baseline investigations and one-year follow-ups were undertaken for 1,566 and 996 preschool children. Association of poor masticatory function with occlusal features, sucking habits and caries was investigated using chi-squared tests. Binomial logistic regressions were then carried out incorporating any significant factors identified. Longitudinal analysis of the one-year follow-up data was carried out to investigate whether improved occlusal features, sucking habits and caries resulted in better masticatory function.

RESULTS

In the cross-sectional study, the first domain of general chewing difficulty was associated with caries and thumb/digit sucking. The second domain of requiring help when eating different food types was associated with the male sex, younger age, caries and pacifier use. The last domain of increased preference for soft foods was associated with caries and thumb/digit sucking. Occlusal features, including abnormal overjet and unilateral permanent molars not in contact, were significantly associated with poor masticatory function in the bivariate analyses, but were not significant in the logistic regressions. In the longitudinal analysis, general chewing difficulty was found to improve in those of older age and those with resolved anterior crossbite. Less help was required to eat meat in those with fewer caries. Similarly, less help was required to eat food containing bones in those with reduced pacifier use. Preferences for eating soft foods was reduced in those who developed a normal overjet.

CONCLUSIONS

The study identified significant relationships between masticatory difficulties and factors associated with age, gender, active caries, and non-nutritive oral habits such as thumb/digit sucking and pacifier use. Younger children and males required more assistance with certain food types. Active caries and thumb/digit sucking habits contributed to general masticatory difficulties and preference for soft foods. The one-year follow-up indicated that improvement in masticatory function varies across age cohorts and were associated with improved occlusal features, such as resolution of anterior crossbite and normalized overjet, reduced pacifier use, and a decrease in the number of decayed teeth.

Gross and microanatomic description of the dental pads of the Florida manatee, Trichechus manatus latirostris, and their importance to mastication

OBJECTIVE

Florida manatee feeding ecology is critical to species survival, but the role of dental pads in feeding has received limited attention. This study characterized the gross and microscopic anatomy of the manatee's dorsal and ventral dental pad in relation to these structures' importance in mastication, which furthers our understanding of manatee feeding and health.

DESIGN

Whole heads from 6 animals (4 male and 2 female) of varying sizes were examined grossly. Sections (5 µm) from throughout the dorsal and ventral dental pads were stained with Hematoxylin and Eosin to document microanatomy. The thickness of the epithelium and stratum corneum were measured.

RESULTS

The ventral dental pad epidermal (1129-3391 µm) and stratum corneum (331-1848 µm) thickness increased with increased body size. The dorsal dental pad epidermal (690-1988 µm) and stratum corneum (121-974 µm) thickness varied relative to size. The dental pad anatomy, including the thickened stratum corneum, indicates an importance similar to molars in grinding and physically breaking up plant material. Extensive appendages including filiform-like papillae and well-developed rete were observed and likely provide physical support for mastication.

CONCLUSION

While the sample size limits specific conclusions based on sex or age, it provides a good overview of the anatomy of the dental pads. The manatee is the only mammal known to have a ventral dental pad and the well-developed grinding surfaces demonstrates a crucial role in mastication for these structures. These dental pads should be evaluated during health checks and necropsies and considered in future research on manatee's feeding mechanisms.

The ultrastructure of macaque mesencephalic trigeminal nucleus neurons

Primary afferents originating from the mesencephalic trigeminal nucleus provide the main source of proprioceptive information guiding mastication, and thus represent an important component of this critical function. Unlike those of other primary afferents, their cell bodies lie within the central nervous system. It is believed that this unusual central location allows them to be regulated by synaptic input. In this study, we explored the ultrastructure of macaque mesencephalic trigeminal nucleus neurons to determine the presence and nature of this synaptic input in a primate. We first confirmed the location of macaque mesencephalic trigeminal neurons by retrograde labeling from the masticatory muscles. Since the labeled neurons were by far the largest cells located at the edge of the periaqueductal gray, we could undertake sampling for electron microscopy based on soma size. Ultrastructurally, mesencephalic trigeminal neurons had very large somata with euchromatic nuclei that sometimes displayed deeply indented nuclear membranes. Terminal profiles with varied vesicle characteristics and synaptic density thicknesses were found in contact with either their somatic plasma membranes or somatic spines. However, in contradistinction to other, much smaller, somata in the region, the plasma membranes of the mesencephalic trigeminal somata had only a few synaptic contacts. They did extend numerous somatic spines of various lengths into the neuropil, but most of these also lacked synaptic contact. The observed ultrastructural organization indicates that macaque trigeminal mesencephalic neurons do receive synaptic contacts, but despite their central location, they only avail themselves of very limited input.

Biomechanical and Cortical Control of Tongue Movements During Chewing and Swallowing

Tongue function is vital for chewing and swallowing and lingual dysfunction is often associated with dysphagia. Better treatment of dysphagia depends on a better understanding of hyolingual morphology, biomechanics, and neural control in humans and animal models. Recent research has revealed significant variation among animal models in morphology of the hyoid chain and suprahyoid muscles which may be associated with variation in swallowing mechanisms. The recent deployment of XROMM (X-ray Reconstruction of Moving Morphology) to quantify 3D hyolingual kinematics has revealed new details on flexion and roll of the tongue during chewing in animal models, movements similar to those used by humans. XROMM-based studies of swallowing in macaques have falsified traditional hypotheses of mechanisms of tongue base retraction during swallowing, and literature review suggests that other animal models may employ a diversity of mechanisms of tongue base retraction. There is variation among animal models in distribution of hyolingual proprioceptors but how that might be related to lingual mechanics is unknown. In macaque monkeys, tongue kinematics-shape and movement-are strongly encoded in neural activity in orofacial primary motor cortex, giving optimism for development of brain-machine interfaces for assisting recovery of lingual function after stroke. However, more research on hyolingual biomechanics and control is needed for technologies interfacing the nervous system with the hyolingual apparatus to become a reality.

Oral health and healthy ageing: a scoping review

BACKGROUND

Good oral health is an important part of healthy ageing, yet there is limited understanding regarding the status of oral health care for older people globally. This study reviewed evidence (policies, programs, and interventions) regarding oral health care for older people.

METHODS

A systematic search of six databases for published and grey literature in the English language by the end of April 2022 was undertaken utilising Arksey and O'Malley's scoping review framework.

RESULTS

The findings from oral health policy documents (n = 17) indicated a lack of priorities in national health policies regarding oral health care for older people. The most common oral health interventions reported in the published studies (n = 62) included educational sessions and practical demonstrations on oral care for older adults, nurses, and care providers. Other interventions included exercises of facial muscles and the tongue, massage of salivary glands, and application of chemical agents, such as topical fluoride.

CONCLUSION

There is currently a gap in information and research around effective oral health care treatments and programs in geriatric dental care. Efforts must be invested in developing guidelines to assist both dental and medical healthcare professionals in integrating good oral health as part of healthy ageing. Further research is warranted in assessing the effectiveness of interventions in improving the oral health status of the elderly and informing approaches to assist the integration of oral health into geriatric care.

Marital dissatisfaction and functional performance in older adults: Heterogeneity in the association by educational level

RATIONALE

The marital relationship is an important source of the well-being of older adults. Despite existing literature on marital dissatisfaction and adverse health outcomes, little is known about whether marital dissatisfaction is associated with functional performance in older adults.

OBJECTIVE

Drawing on stress process model and health behavior model, this study examined the longitudinal association between marital dissatisfaction and older adults' functional performance. Furthermore, we sought to investigate whether this association varies based on educational level.

METHODS

Using seven waves (12 years) of the Korean Longitudinal Study of Ageing (KLoSA) from 2006 to 2019, this study estimated fixed effects models to account for unobserved individual-level confounders. Objectively measured hand grip strength and subjective assessments of vision, hearing, masticatory functions, as well as limitations in activities of daily living (ADLs) and instrumental activities of daily living (IADLs) were used to evaluate functional performance. An interaction model was used to determine whether educational level moderates the association.

RESULTS

Fixed effects estimates revealed that marital dissatisfaction is negatively associated with grip strength, as well as masticatory, vision, and hearing functions, while also showing a positive association with limitations in ADLs and IADLs. The results of this study provided evidence on heterogeneity in the association by educational level. The associations between marital dissatisfaction and functional performance, including grip strength, mastication, and hearing, were driven primarily by those with older adults with a higher level of education.

CONCLUSION

The findings of this study suggest that marital dissatisfaction is a robust predictor of functional performance in older adults. Efforts to address marital dissatisfaction has the potential to improve functional performance, particularly for older adults with higher levels of education.

Effect of salivary fluid characteristics on the physical features of in vitro bread bolus: From the absence of saliva to artificially simulated hypersalivation

Saliva facilitates food oral processing, bolus formation, swallowing, and sensory perception, in addition to contributing to oral health and phonation. Ageing, health affections, and polymedication are among many causes altering salivary production, modifying the mastication process, the food impregnation ratio, and in turn altering the characteristics of the bolus, swallowing, and digestion. In this in vitro work, using the AM2 masticator apparatus, which replicates the mechanical actions taking place while chewing solid foods and produces realistic food bolus in various oral conditions, we investigated the effect of salivary fluid characteristics, i.e., composition, quantity (from absence to hypersalivation), temperature, and enzymatic action, on the physical characteristics (i.e., particle size distribution (PSD), bolus mass, salivary fluid content) of in vitro boluses of Traditional French baguette. A ready-to-swallow bolus of baguette displayed on average a d50 value (median particle size by mass) of 4.1 ± 0.4 mm, with saliva fluid constituting ∼ 35 % of the final bolus mass. The absence of saliva in mouth led to a deficient oral processing, forming bread boluses constituted by extremely big particles (ca. 80 % of particles had a size > 7.1 mm) that likely cannot be swallowed safely. On the contrary, an excess of saliva favoured an excessive breaking down of bread, leading to bread boluses constituted by smaller particles than those formed under healthy salivary conditions (d50 decreased from 4.1 mm to 3.1 mm), having a higher salivary fluid content (+10 %). On the other hand, the salivary fluid temperature did not affect PSD, d50, bolus mass, or salivary fluid content of in vitro bread boluses, however, the addition of human salivary α-amylase did, favouring particle size reduction (d50 decreased to 2.6 mm). Therefore, beyond the correlation between bolus hydration by saliva and food properties such as hardness and moisture content, our findings indicate that the quantity of salivary fluid present in the oral cavity and the enzymatic activity of salivary α-amylase during bread mastication significantly influence both the particle size distribution and the fluid content of bread boluses, ultimately determining the physical properties of the bolus and, therefore, potentially impacting the subsequent swallowing process.

Assessing Prevalence and Characteristics of Oro-bulbar Involvement in Children and Adults with SMA Type 2 and 3 Using a Multimodal Approach

Bulbar and jaw muscles are impaired in patients with Spinal Muscular Atrophy (SMA) but the assessment of their severity and progression are limited by the lack of age-appropriate and disease-specific measures. We investigated mastication and swallowing in children and adults with SMA, sitters and walkers. In a 2-year multicentre cross-sectional prospective study, lip and tongue strength (Iowa Oral Performance Instrument), chewing and swallowing (Test of Masticating and Swallowing Solids), active mouth opening (aMMO) were compared to age-appropriate normative data. The perceived burden of oro-bulbar involvement (SMA-Health Index) was recorded. 78 patients were included, 45 children (median age 7.4 years),22 adults (median age 26.8 years) on nusinersen and 11 untreated (median age 32.7 years). Forty-three percent children had reduced mouth opening, 50% had prolonged total time to eat. These issues were more prominent in sitters than in walkers (p = 0.019, p = 0.014). Sixty-six percent needed increased swallows for bolus clearance. Nusinersen treated adults had median aMMO, tongue strength and total time at TOMASS values within normal range (z score: -1.40, -1.22, -1.32, respectively) whereas untreated adults had reduced aMMO (z score: -2.68) and tongue strength (z score: -2.20). Only a minority of children (2/17) and treated adults (5/21) reported burden in swallowing or mastication compared to all untreated adults (5/5). After 16 months, mastication and swallowing were stable in treated children and adults, whether sitters or walkers. The reported multimodal approach to assess oro-bulbar functions demonstrate that swallowing and mastication are impaired in SMA despite patients' perception. These results suggest a trend towards stabilization of oro-bulbar function in patients on long-term treatment with nusinersen.

Reduced mastication during growth inhibits cognitive function by affecting trigeminal ganglia and modulating Wnt signaling pathway and ARHGAP33 molecular transmission

Binding of brain-derived neurotrophic factor (BDNF) to its receptor tyrosine kinase B (TrkB) is essential for the development of the hippocampus, which regulates memory and learning. Decreased masticatory stimulation during growth reportedly increases BDNF expression while decreasing TrkB expression in the hippocampus. Increased BDNF expression is associated with Wnt family member 3A (Wnt3a) expression and decreased expression of Rho GTPase Activating Protein 33 (ARHGAP33), which regulates intracellular transport of TrkB. TrkB expression may be decreased at the cell surface and affects the hippocampus via BDNF/TrkB signaling. Mastication affects cerebral blood flow and the neural cascade that occurs through the trigeminal nerve and hippocampus. In the current study, we hypothesized that decreased masticatory stimulation reduces memory/learning in mice due to altered Wnt3a and ARHGAP33 expression, which are related to memory/learning functions in the hippocampus. To test this hypothesis, we fed mice a powdered diet until 14 weeks of age and analyzed the BDNF and TrkB mRNA expression in the right hippocampus using real-time polymerase chain reaction and Wnt3a and ARHGAP33 levels in the left hippocampus using western blotting. Furthermore, we used staining to assess BDNF and TrkB expression in the hippocampus and the number of nerve cells, the average size of each single cell and the area of intercellular spaces of the trigeminal ganglion (TG). We found that decreased masticatory stimulation affected the expression of BDNF, Wnt3a, ARHGAP33, and TrkB proteins in the hippocampus, as well as memory/learning. The experimental group showed significantly decreased numbers of neurons and increased the area of intercellular spaces in the TG. Our findings suggest that reduced masticatory stimulation during growth induces a decline in memory/learning by modulating molecular transmission mechanisms in the hippocampus and TG.

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.

The effects of endoscope placement in the hypopharynx on swallowing-related measures in healthy adults

PURPOSE

The purpose of this study was to determine whether transnasal passage of a flexible endoscope results in changes in salivary flow rate (SFR), spontaneous swallow frequency (SSF), and masticatory efficiency (ME) in healthy adults.

METHODS

Data were collected from 15 healthy adults, 20-63 years of age. SFR and SSF were measured at baseline, after endoscope insertion, and after endoscope removal. The Test of Masticating and Swallowing Solids was administered at baseline and while the endoscope was in the hypopharynx. A repeated measures ANOVA was used to determine the effect of endoscope insertion on SFR and SSF. A paired samples t-test was used to determine the effect of endoscope insertion on total mastication time and number of masticatory cycles required with a cracker bolus. Statistical significance was set at α = 0.05.

RESULTS

SFR was found to be significantly increased during endoscope placement in the hypopharynx (M = 0.471 g/min, SD = 0.175, p = 0.002) as well as following endoscope removal (M = 0.481 g/min, SD = 0.231, p = 0.004), as compared to baseline (M = 0.310 g/min, SD = 0.130). Total mastication time and number of masticatory cycles required with a cracker bolus were significantly decreased when the endoscope was present in the hypopharynx, as compared to baseline t(14) = 3.054, p = 0.009; t(14) = 3.250, p = 0.006, respectively.

CONCLUSIONS

Visualization of swallowing during FEES is an important method for objectively evaluating several anatomical and functional parameters of the pharynx and larynx. Insertion of the endoscope into the hypopharynx during FEES may stimulate salivary secretion and improve ME, which could influence interpretation of FEES and resulting clinical recommendations.

Kinematics of lateral tongue-pushing movement in coordination with masticatory jaw movement: An anteroposterior projection videofluorographic study

OBJECTIVE

During the mastication of solid food, the tongue pushes the bolus laterally to place it onto occlusal surfaces as the jaw is opened. This movement is referred to as tongue-pushing (TP). TP has an important role in efficient chewing, but its kinematic mechanisms remain unclear. The present study quantified the kinematics of TP and its coordination with masticatory jaw movements.

METHODS

Videofluorography (VFG) in anteroposterior projection was recorded while 14 healthy young adults ate 6 g each of cookies and meat. Small lead markers were glued to the tongue surface (left, right, and anterior) and buccal tooth surfaces (upper molars and lower canines). The position of the tongue and lower canine markers relative to the upper occlusal plane was quantified with Cartesian coordinates, using the right upper molar as the origin. Jaw motion during chewing was divided into TP and Non-TP cycles, based on the lateral movement of the food and tongue markers. The side of the jaw that compressed food particles was defined as the working side, while the other side was termed the balancing side. Horizontal and vertical displacements of tongue and jaw markers were compared between TP and Non-TP cycles, as well as between food types.

RESULTS

The mediolateral displacement of all tongue markers was significantly larger in TP than in Non-TP cycles. Vertical displacement was also significantly greater in TP than in Non-TP cycles for the anterior and working side tongue markers. TP cycles occurred more frequently with meat-chewing than with cookie-chewing.

CONCLUSION

TP is accomplished by rotation and lateral movements of the tongue surface on the working side and the anterior tongue blade, along with medial movement on the balancing side. These movements produce lateral shift and rotation of the tongue surface toward the working side in concert with jaw opening. Designing exercises to improve the strength of the lateral motion and rotation of the tongue body may be useful for individuals with impaired tongue function for eating and swallowing.

Effect of mandibular bilateral distal extension denture design on masticatory performance

PURPOSE

Removable partial dentures have a wide range of applications as missing tooth prostheses, and the denture design can be quite diverse. However, the factors affecting masticatory function remain unclear. We investigated the effect of denture design, especially the use of indirect retainers and major connectors, on masticatory function in patients with mandibular bilateral distal extension dentures.

METHODS

Fifty-three patients with mandibular Kennedy Class I and Eichner classification B occlusal support were included in this study. Masticatory performance (MP) was assessed using gummy jelly. For the dentures, the type of major connector (bar or apron), presence or absence of indirect retainers, number of rests, and number of artificial teeth were evaluated. The number of functional teeth and occlusal support, Eichner classification, maxillary denture usage, mandibular residual ridge height, and duration of denture use were also evaluated. The factors influencing on the MP were evaluated using the Mann-Whitney U test, Spearman's correlation coefficient, and logistic regression analysis.

RESULTS

MP was significantly higher when the major connector was bar-type or when there was an indirect retainer than with an apron-type or no indirect retainer. MP was positively correlated with the number of functional teeth, occlusal support, and number of rests. Logistic regression analysis revealed that the number of functional teeth and the presence or absence of an indirect retainer were factors that significantly influenced the MP.

CONCLUSIONS

An indirect retainer setting is useful for achieving good masticatory performance in mandibular bilateral distal extension dentures.

Relationship between oral frailty and locomotive syndrome in working-age individuals: a cross-sectional survey of workers in Japan

BACKGROUND

Although the relationship between oral and physical frailty in older adults has been investigated, few studies have focused on the working-age population. This study examined the relationships of the number of remaining teeth and masticatory ability, i.e., signs of oral frailty, with locomotive syndrome (LS) in the working-age population.

METHODS

The number of remaining teeth, masticatory ability, and presence of LS in 501 participants from four companies were examined. The relationships between the number of remaining teeth groups (≥ 20 teeth or ≤ 19 teeth) and LS and between the masticatory ability groups (high or low) and LS were examined. A binomial logistic regression analysis was conducted using LS from the stand-up test as the objective variable and the two subgroups based on the number of remaining teeth and potential crossover factors as covariates.

RESULTS

The analysis included 495 participants (354 males and 141 females; median age, 43 years). The median number of remaining teeth among the participants was 28, and 10 participants (2.0%) had ≤ 19 teeth. The mean masticatory ability values were 39.9 for males and 37.7 for females, and 31 participants (6.3%) had low masticatory ability. In the stand-up test, those with ≤ 19 teeth had a higher LS rate than those with ≥ 20 teeth. The odds ratio for LS in the group with ≤ 19 remaining teeth was 5.99, and the confidence interval was 1.44-24.95.

CONCLUSIONS

The results confirmed signs of oral frailty in the working-age population. Further, the number of remaining teeth possibly affects standing movement. Thus, oral frailty is associated with LS in the working-age population.

Association of masticatory efficiency with deep carious lesions in children

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Difference in the Electromyographic Behavior of the Masticatory and Swallowing Muscles During Cued Versus Spontaneous Swallowing

The risk of dysphagia and/or aspiration is determined using screening tests, such as the repeated saliva swallowing test and modified water swallowing test, which evaluate cued swallowing. However, humans masticate and swallow foods with various consistencies, forms, and amounts, without conscious awareness. Therefore, this study aimed to examine the difference in the behavior of masticatory and swallowing muscles during spontaneous versus cued swallowing through a series of mastication and swallowing processes by evaluating surface electromyogram (sEMG) signals. The effect of the consistency and amount of food on the behavior of these muscles was also investigated. The sEMG recordings of the masseter muscles and anterior belly of the digastric muscle for 12 subjects, and genioglossus muscle for 5 subjects were obtained. The genioglossus activity was recorded using custom-made ball electrodes. The test foods were cookies and tofu, in amounts of 2 g and 4 g. The normalized muscle activity (integrated EMG), duration of the muscle activity, initial activation timepoint of each muscle, and total duration of swallowing were compared among four conditions. The activity of each muscle was significantly higher during the swallowing of cookies than tofu, for 4 g vs 2 g, and for cued versus spontaneous swallowing. The duration of each muscle activity, initial activation timepoint, and total duration of swallowing were significantly longer for cookies versus tofu, for 4 g vs 2 g, and for spontaneous versus cued swallowing. These results suggest that the behavior of the masticatory and swallowing muscles is affected by cued swallowing and by the consistency and amount of food.

ACTIVATION OF FIXED LABIAL APPLIANCES, BRIEFLY AT INITIATION, MAY REDUCE MASTICATORY PERFORMANCE AND BITE FORCE

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Duarte L, Bezerra AP, Flores-Mir C, De Luca Canto G, Pereira LJ, Vega Gonçalves TMS. Activation and installation of orthodontic appliances temporarily impairs mastication. Angle Orthod. 2022 Mar 1;92(2):275-286. doi: 10.2319/061,221-469.1. PMID: 34,878,525; PMCID: PMC8887415.

SOURCE OF FUNDING

Not reported.

TYPE OF STUDY/DESIGN

Systematic review with meta-analysis of data.

Association between oral hypofunction and general health: a systematic review

BACKGROUND

Oral hypofunction comprises 7 oral function conditions, including mastication, swallowing, pronouncing, oral hygiene, and oral dryness. However, it remains unresolved whether having oral hypofunction and each individual condition adversely affect general health. This study aimed to investigate the association between oral hypofunction and general health, encompassing physical, psychological, and social dimensions.

METHODS

Oral hypofunction was diagnosed following the criteria proposed by the 2016 Japan Society of Gerodontology, comprising 7 oral function conditions. Oral hypofunction was diagnosed when at least 3 conditions presented. The selected studies eligible for reviewing were based on the PI(E)CO criteria: P (population), adult and older adults; I/E (intervention/exposure), having oral hypofunction by considering overall and individual 7 oral function conditions; C (comparator), not having oral hypofunction; O (outcome), the general health status, encompassing physical, psychological, and social dimensions. Electronic search limited to English articles was performed through PubMed, Scopus, and Cochrane Database of Systematic Reviews databases from January 2016 to June 2023. The included studies were assessed for quaility and risk of bias using the modified Newcastle-Ottawa scale. Qualitative analyses were performed on the general outcome, and having oral hypofunction considering overall and individual oral function conditions.

RESULTS

Ten studies were included in the final syntheses. One was a prospective cohort, one was a case-control, and the others were cross-sectional studies. All included studies were high quality. General health outcomes were mostly frailty, sarcopenia, and malnutrition, whereas mild cognitive impairment,social withdrawal, and gastric cancer prognosis were identified in one of the included studies. The association between general health and having oral hypofunction was stronger than when considering an individual condition. The health outcomes were predominantly associated with mastication and swallowing, whereas their relationships with oral hygiene and dryness were less likely to be reported.

CONCLUSIONS

The present review found an association between the presence of oral hypofunction and impaired general health. However, the specific impact on individual physical, psychological, and social dimensions cannot be distinctly delineated. Further prospective studies are required to clarify the causal-effect relationship between oral and general health.

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.

Prolonged cyclical loading induces Haversian remodeling in mandibles of growing rabbits

Bone adaptation to mechanical loading happens predominantly via modeling and remodeling, but the latter is poorly understood. Haversian remodeling (cortical bone replacement resulting in secondary osteons) is thought to occur in regions of low strain as part of bone maintenance or high strain in response to microdamage. However, analyses of remodeling in primates have revealed an unappreciated association with the number of daily load cycles. We tested this relationship by raising 30 male domestic rabbits (Oryctolagus cuniculus) on disparate diets from weaning to adulthood (48 weeks), facilitating a naturalistic perspective on mandibular bone adaptation. A control group consumed only rabbit pellets and an 'overuse' group ate hay in addition to pellets. To process hay, which is tougher and stiffer, rabbits increase chewing investment and duration without increasing bite force (i.e., corpus mean peak strain is similar for both foods). Corpus remodeling in overuse rabbits is ∼1.5 times that of controls, measured as osteon population density and percent Haversian bone. In the same subjects, there was a significant increase in overuse corpus bone formation (ratio of cortical area to cranial length), consistent with previous reports on the same dietary manipulation and bone formation in rabbits. This is the first evidence that both modeling and remodeling are simultaneously driven by the number of load cycles, independent of strain magnitude. This novel finding provides unique data on the feeding apparatus, challenges traditional thought on Haversian remodeling, and highlights the need for experimental studies of skeletal adaptation that examine mechanical factors beyond strain magnitude.

[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.

Effect of mastication evaluation and intervention on body composition and biochemical indices in female patients with obesity: a randomized controlled trial

BACKGROUND

A limited number of studies have evaluated the masticatory indices of individuals with obesity who only chew their food a few times and for shorter duration or who were provided with an instructional intervention. This study aimed to examine the effects of a 6-month instructional mastication intervention on the body composition and biochemical indices in female patients with obesity.

METHODS

Female patients with obesity were randomly classified into a conventional treatment group (CTG; 12 individuals), which only received normal nutritional and exercise guidance, and a mastication intervention group (MIG; 16 individuals), which received an additional mastication guidance. The MIG received guidance on foods requiring increased number of chews and chewing duration, eating techniques, and the proper method of cutting foods.

RESULTS

Changes in the masticatory, body composition, and biochemical indices were compared before and after the 6-month intervention. The values of body composition indices decreased significantly in both groups; however, the rate of change in body mass index significantly decreased in the MIG. In addition, the values of biochemical indices were significantly decreased in the MIG compared with that in the CTG, which is attributed to the addition of mastication instruction to female patients with obesity.

CONCLUSION

Increasing the number of chews and duration of chewing times for carbohydrates, which are staple foods, possibly contributed to weight loss and improvement of glucose metabolism.

TRIAL REGISTRATION

UMIN, UMIN000025875. Registered on 27 Jan 2017.

The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised subjects: a systematic review and meta-analysis

BACKGROUND

Xerostomia negatively affects quality of life. Symptoms include oral dryness; thirst; difficulty speaking, chewing, and swallowing food; oral discomfort; mouth soft tissue soreness and infections; and rampant tooth decay. The objective of this systematic review and meta-analysis was to investigate if gum chewing is an intervention that results in objective improvements in salivary flow rates and subjective relief from xerostomia.

METHOD

We searched electronic databases including Medline, Scopus, Web of Science, Embase, Cochrane Library (CDSR and Central), Google Scholar and the citations of review papers (last searched 31/03/23). The study populations included: 1) elderly people with xerostomia (> 60 years old, any gender, and severity of xerostomia), and 2) medically compromised people with xerostomia. The intervention of interest was gum chewing. Comparisons included gum chewing vs. no gum chewing. The outcomes included salivary flow rate, self-reported xerostomia, and thirst. All settings and study designs were included. We conducted a meta-analysis on studies where measurements of unstimulated whole salivary flow rate for both a gum chewing, and no gum chewing intervention (daily chewing of gum for two weeks or longer) were reported. We assessed risk of bias using Cochrane's RoB 2 and ROBINS-I tools.

RESULTS

Nine thousand six hundred and two studies were screened and 0.26% (n = 25) met the inclusion criteria for the systematic review. Two of the 25 papers had a high overall risk of bias. Of the 25 papers selected for the systematic review, six met the criteria to be included in the meta-analysis which confirmed a significant overall effect of gum on saliva flow outcomes compared to control (SMD = 0.44, 95% CI: 0.22-0.66; p = 0.00008; I² = 46.53%).

CONCLUSIONS

Chewing gum can increase unstimulated salivary flow rate in elderly and medically compromised people with xerostomia. Increasing the number of days over which gum is chewed increases the improvement in the rate of salivation. Gum chewing is linked with improvements in self-reported levels of xerostomia (although it is noted that no significant effects were detected in five of the studies reviewed). Future studies should eliminate sources of bias, standardise methods to measure salivary flow rate, and use a common instrument to measure subjective relief from xerostomia.

STUDY REGISTRATION

PROSPERO CRD42021254485.

Orofacial function and temporomandibular disorders in Parkinson's Disease: a case-controlled study

BACKGROUND

The difficulties and challenges faced by people with Parkinson's disease (PD) in performing daily orofacial function are not systematically investigated. In this study, specific orofacial non-motor and motor symptoms and functions were systematically examined in PD patients in comparison to a matched control group.

METHODS

The clinical case-controlled study was conducted from May 2021 to October 2022 and included persons with PD and age- and gender-matched persons without PD. The participants with PD were outpatients diagnosed with PD at the Department of Neurology at Bispebjerg University Hospital in Copenhagen, Denmark. The participants underwent a systematic clinical and relevant self-assessment of the orofacial function and temporomandibular disorders (TMD). The primary outcomes were objective and subjective assessments of the general orofacial function, mastication, swallowing, xerostomia and drooling. The secondary outcomes were the prevalence of TMD and orofacial pain. The difference in outcome measures between the two groups was analysed using chi-square and Mann-Whitney U test.

RESULTS

The study included 20 persons with PD and 20 age- and gender-matched persons without PD. Both objectively and subjectively, persons with PD had poorer orofacial function than the control group. Persons with PD had also a significantly more severe limitation of jaw mobility and jaw function. The objective masticatory function was also significantly reduced for persons with PD compared to the control group, and 60% of persons with PD found it difficult to eat foods with certain consistencies while 0% of the control group reported that problem. Persons with PD could swallow less water per second and the average swallowing event was significantly longer for PD persons. Even though PD persons reported more xerostomia (58% for persons with PD and 20% for control persons), they also reported significantly more drooling than the control group. Additionally, orofacial pain was more prevalent in PD persons.

CONCLUSIONS

Persons with PD have a compromised orofacial function. Furthermore, the study indicates a link between PD and orofacial pain. In order to screen and treat persons with PD accordingly, healthcare professionals should be aware of and address these limitations and symptoms.

TRIAL REGISTRATION

The trial was approved by the Regional Committee on Research Health Ethics of the Capital Region (H-20,047,464), the Danish Data Protection Agency (514 - 0510/20-3000), and registered at ClinicalTrials.gov (NCT05356845).

The effects of the size and strength of food on jaw motion and temporomandibular joints

Mastication displays much importance in people's lives. The masticatory mandibular motion associated with dental kinematics also impacts temporomandibular joint (TMJ) kinematics and even TMJ health status. How food properties impact kinematical parameters of TMJs is a meaningful question for the conservative treatment of temporomandibular disorders (TMD) and evidence for the diet recommendation of TMD patients. The aim of this study was to find the primary mechanical properties influencing the masticatory motion. The potato boluses with different boiling times and sizes were chosen. The optical motion tracking system was adopted to record the masticatory trials of chewing boluses with various mechanical properties. The mechanical experiments revealed that increasing boiling time could reduce compressive strength. Moreover, multiple regression models were built to find the primary property of food influencing the TMJ kinematics, including condylar displacement, velocity, acceleration, and crushing time. The results showed that the bolus size had a significant primary influence on condylar displacements. The chewing times had a significantly minor influence on condylar displacements, while bolus strength had only a small impact on condylar displacements. Furthermore, condylar displacements on the non-working side were more affected by bolus size and chewing times than on the working sides. The crushing time of the bolus was significantly influenced by the compressive strength. Meals with small sizes and soft properties were therefore advised to lessen condylar displacements and relax the crushing process, and further reduce the loadings in the TMJ.

Impact of varying food hardness on mastication/swallowing

The purpose of this study was to analyze mastication and swallowing in the elderly and confirm the association with dysphagia characteristics. A questionnaire was developed to evaluate the masticating and swallowing functions of the elderly. Mastication was analyzed using electromyography, and tongue/lip pressures were measured using Iowa Oral Performance Instrument. The results of the questionnaire showed that statistical difference in the number of teeth between the group without and with, decreased ability to swallow, and there was a correlation with lip pressure. Additionally, the higher number of teeth, the higher muscle activity, and there is a positive correlation between the number of chews and the lip pressure. Consequently, our findings suggested oral health parameters are closely associated with mastication/swallowing ability. Finally, based on the results obtained for different foods tested, we suggested that texture-modified foods are necessary to enhance swallowing ability.

The impact of residual ridge morphology on the masticatory performance of complete denture wearers

Statement of the problem

Morphology of the residual ridge (RR) is expected to influence the masticatory performance (MP) of complete denture (CD) patients, but considerable details of this relationship are unknown.

Purpose

We aimed to investigate the association between the objective MP and RR morphology of CD wearers and other contributory factors affecting their MP.

Materials and methods

Sixty-five patients with well-fitting upper and lower CDs with no complaints of pain were enrolled. The objective MP was measured using test gummy jelly and a fully automated measuring device. The RR form was divided into U-type, V-type, I-intermediate, and F-Flat, then combinations of upper and lower RR forms (combined RR) were classified. The height was measured using CD's denture basal surface replicas, while occlusal contact of CDs was assessed using a tooth contact analysis system. The relationship between surveyed factors and MP was evaluated using Spearman's rank correlation, Kruskal-Wallis test, generalized linear regression, and analysis of covariance.

Results

Participants with F-F and V-F combined RR forms had the lowest MP, while those with U-U and U-I forms had the highest MP, regardless of RR height. Participants with low RR height had the lowest MP, and those with high RR height had the highest MP, regardless of RR form. The analysis of covariance revealed that mandibular RR height, combined RR forms, and total occlusal contact area significantly affected the MP.

Conclusions

Our findings confirmed that the mandibular RR height, RR form combinations, and occlusal contact influence the MP of CD wearers.ClinicalImplications:The MP of CD wearers varied, depending on the height and form of the RR, as well as the occlusal contact area of the CDs. The results of this manuscript show that the morphology of the denture bearing area and the occlusion of the CDs are essential factors in predicting the treatment outcome of CD wearers. This allows the clinician to fabricate a complete denture with the denture basal surfaces adjusted and occlusion provided according to the patient. CD patients can be educated on how to chew to improve MP based on their own RR morphology.

Associations between Temporomandibular Disorders, Pain, Jaw and Masticatory Function in Dentofacial Deformity Patients: a Cross-sectional Study

BACKGROUND

Patients with dentofacial deformity often present with impaired masticatory function, orofacial pain, and temporomandibular disorders (TMD). This study investigates the relationship between TMD, pain, jaw, and masticatory function at different stages of orthognathic surgical (OS) treatment.

METHOD

A total of 120 OS patients were prospectively recruited and grouped as pre-orthodontic (group 1), pre-surgery (group 2), 4-month post-surgery (group 3), 24-month post-surgery (group 4), in addition to 30 controls (group 0). Outcomes were assessed using: Jaw Function Limitation Scale (JFLS), McGill pain questionnaire, DC/TMD instrument, voluntary maximum bite force (MVBF), and masticatory efficiency (ME) using two-colored chewing gum. Data were analyzed using structural equation modeling.

RESULTS

The prevalence of non-painful TMD did not differ between groups (P = 0.827). However, the prevalence of painful TMD differed between groups (P = 0.001). Amongst the painful TMDs, the highest prevalence was observed for masseter myalgia in group 2 (P = 0.031), and importantly group 4 did not differ from group 0 (P = 0.948). The MPQ score was significantly higher in group 1 (P = 0.001) compared to group 0, and the JFLS score was significantly higher in group 1, 2 and 3 compared to group 0. Notably MPQ (P = 0.756) and JFLS (P = 0.572) scores in group 4 were not different from group 0. However, MVBF (P = 0.996) and ME (P = 0.991) did not differ between groups 1 and 4. Association of self-reported pain and jaw function with masticatory function was observed in OS patients.

CONCLUSION

OS was not associated with a negative impact on TMD. Jaw function and pain levels were similar to controls at the 24-month follow-up. Masticatory function was further affected by the surgery and seems to require a longer recovery time. Moreover, it was confirmed that pain and TMD were associated with limitations in jaw function and impacts on masticatory function.

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.

Understanding the pathophysiology of sleep bruxism based on human and animal studies: A narrative review

BACKGROUND

Sleep bruxism (SB) is a common sleep disorder that affects approximately 20% of children and 10% of adults. It may cause orodental problems, such as tooth wear, jaw pain, and temporal headaches. However, the pathophysiological mechanisms underlying SB remain largely unknown, and a definitive treatment has not yet been established.

HIGHLIGHT

Human studies involving polysomnography have shown that rhythmic masticatory muscle activity (RMMA) is more frequent in otherwise healthy individuals with SB than in normal individuals. RMMA occurs during light non-rapid eye movement (non-REM) sleep in association with transient arousals and cyclic sleep processes. To further elucidate the neurophysiological mechanisms of SB, jaw motor activities have been investigated in naturally sleeping animals. These animals exhibit various contractions of masticatory muscles, including episodes of rhythmic and repetitive masticatory muscle bursts that occurred during non-REM sleep in association with cortical and cardiac activation, similar to those found in humans. Electrical microstimulation of corticobulbar tracts may also induce rhythmic masticatory muscle contractions during non-REM sleep, suggesting that the masticatory motor system is activated during non-REM sleep via excitatory inputs to the masticatory central pattern generator.

CONCLUSION

This review article summarizes the pathophysiology of SB and putative origin of RMMA in both human and animal studies. Physiological factors contributing to RMMA in SB have been identified in human studies and may also be present in animal models. Further research is required to integrate the findings between human and animal studies to better understand the mechanisms underlying SB.

Longitudinal electromyographic analysis of jaw-closing muscle activities during ingestive behaviors from pre-weaning to juvenile periods in rats

This longitudinal study investigated developmental changes in jaw-closing muscle activities during ingestive behaviors in rats. On postnatal day (P) 10, electromyography (EMG) electrodes were inserted into the masseter and temporalis muscles of rat pups. EMG activities were recorded for the following ingestive behaviors between P14 and P49: for suckling, including nipple attachment and rhythmic sucking on P14 and for pasta biting, pellet chewing, and milk licking between P21 and P49. Burst rhythms and muscle coordination (i.e., the correlation and time lag) between masseter and temporalis activities were assessed for each behavior. The burst rhythms of nipple attachment and rhythmic sucking on P14 were significantly slower than those of pasta biting, pellet chewing, and milk licking on P21. Muscle coordination differed between suckling on P14 and mastication and licking on P21. Between P21 and P49, increases were observed in burst rhythms for pasta biting and pellet chewing. The rate of increases in burst rhythms was higher for pasta biting than for pellet chewing. Muscle coordination between the two muscle activities for pasta biting did not significantly change between P21 and P49, whereas that for pellet chewing significantly changed between P21 and P24 and stabilized after P24. Burst rhythms for milk licking did not significantly change over time, while muscle coordination between the two muscle activities changed from agonist to antagonist muscle-like activity on approximately P35. The present results demonstrate that distinct patterns of rhythmic jaw-closing muscle activities emerge before weaning, they continue to change over time, and they exhibit unique developmental dynamics for each behavior after weaning.

Changes in the occlusal function of orthognathic patients with vertical malformations after combined orthodontic surgical therapy: a prospective clinical study

The aim of this study was to assess the changes in occlusal patterns during combined surgical and orthodontic therapy in patients with vertical jaw malformations. Twenty-six orthognathic patients (18 female, eight male; median age 25 years, interquartile range 11.5 years) and 10 control patients (five female, five male; median age 29.8 years, interquartile range 13.5 years) recruited from neutral configured patients attending the Department of Orthodontics, were investigated. Based on cephalometry, the patients were grouped into vertical skeletal configurations of either open, deep, or natural bite cases. Registrations of the occlusal contacts were taken using a digital occlusal sensor immediately before surgery and at 9 months after the surgical intervention. Before the intervention, open and deep bite patients showed significantly less efficient occlusal patterns than the untreated controls regarding total tooth contact (P < 0.001), time of occlusion (P = 0.002), occlusal asymmetry (P = 0.001), anterior tooth contact (P < 0.001), and posterior tooth contact (P < 0.001). After surgery, the parameters in the deep bite patients were similar to those in the controls; however, in open bite patients, total tooth contact (P = 0.003), occlusal asymmetry (P = 0.011), and posterior tooth contact (P = 0.035) differed significantly. In conclusion, combined orthodontic and surgical correction of vertical malocclusions was found to improve occlusal function in patients with deep bite to the level of controls.

Mastication in overweight and obese children: A comparative cross-sectional study

OBJECTIVE

The objective of this study was to analyze masticatory characteristics in children from 7 to 10 years, and to compare these characteristics among normal weight, overweight and obese children.

METHODS

This is a cross-sectional study, conducted in northeast Brazil, with a sample of 160 children, aged 7 to 10 years. The authors evaluated: nutritional and dental status; food intake; masticatory parameters and orofacial myofunctional characteristics. The children were divided according to nutritional status into normal weight (n = 101), overweight (n = 33) and obesity (n = 26) groups.

RESULTS

The results showed that Obese children had a larger bite size (g) (median = 6.0, Q1-Q3 = 4.0-9.0, p = 0.049) and performed fewer masticatory sequences (median = 3.0, Q1-Q3 = 2.0-3.2, p = 0.024) than children with normal weight (median = 5.0, Q1-Q3 = 4.0-7.0; median = 4.0, Q1-Q3 = 3.0-5.0). Furthermore, obese children finished feeding in a shorter time (s) (median = 62.5, Q1-Q3 = 50.5-70.0, p = 0.039) than normal weight children (median = 66.0, Q1-Q3 = 56.5-78.0) and overweight children (median = 66.0, Q1-Q3 = 58.0-81.5).

CONCLUSIONS

The present results suggest that obese children present changes in mastication, evidenced by larger bite-size, performing fewer masticatory sequences and rapid mastication, which may contribute to increased food consumption and the development of excess weight.

"Association between posterior unilateral functional crossbite and asymmetrical spinal flexion: A prospective study"

Background

Unilateral posterior crossbite (UPC) with functional shift is a malocclusion that may have the potential to affect the masticatory function and the flexibility of the spine due to intrinsic occlusal, structural and functional asymmetries sustained by marked asymmetrical muscular activation.

Research question

To investigate whether the presence of UPC with functional shift is associated with reverse chewing pattern and altered spine flexion.

Methods

Patients with UPC and a control group of patients with normal occlusion were recorded when chewing soft and hard boluses using a Kinesiograph (Myotronics-Noromed Inc., USA) and spine alignment was assessed with an electronic inclinometer Spinal Mouse® system (Idiag AG, Switzerland).

Results

There were 87 children with UPC in the patients' group among whom 38, with median (IQR) age 8.0 (7.3-9.3) years, had measurements before and after treatment. The UPC patients showed a higher percentage of anomalous/reverse chewing patterns on the crossbite side compared with a control group (p < 0.001). Moreover, a clear difference was observed between left and right flexion angles of the spine in the patients' group (p < 0.001 and p = 0.001, paired t-test) with the crossbite side being more flexible compared to the non-crossbite side. No such differences were seen in the control group, nor post-treatment for right and left crossbite (p = 0.44 and p = 0.15 respectively, paired t-test).

Significance

This study suggests an association between UPC, asymmetrical chewing patterns and asymmetrical flexion of the spine. These results may help improve understanding of any association between dental malocclusions and spine posture and hence aid diagnosis and treatment strategies.

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).

Masticaticatory muscles characteristics in relation to adiposity and general muscular fitness: a population-based study

There is still considerable controversy surrounding the impact of mastication on obesity. The aim of this study was to identify the interplay between the masticatory muscles, teeth, and general muscular fitness and how they contribute to body adiposity in a general German population. This cross-sectional study included 616 participants (300 male, 316 female, age 31-93 years) from the population-based Study of Health in Pomerania. The cross-sectional areas of the masseter, medial and lateral pterygoid muscles were measured using magnetic resonance imaging (MRI), muscular fitness assessed by hand grip strength (HGS) and body fat distribution was measured by bioelectrical impedance analysis (BIA) and MRI. The overall prevalence of obesity was high in our cohort. The cross-sectional area of the masseter muscles was positively associated with the number of teeth, body mass index (BMI) and HGS, and negatively associated with the BIA-assessed body fat when adjusted for age, sex, teeth, and BMI. Especially the correlation was strong (p < 0.001). Analogous relationships were observed between the masseter, HGS and MRI-assessed subcutaneous fat. These associations were most pronounced with masseter, but also significant with both pterygoid muscles. Though the masticatory muscles were affected by the number of teeth, teeth had no impact on the relations between masseter muscle and adiposity. Physical fitness and masticatory performance are associated with body shape, controlled and directed by the relevant muscles.

Measurement of quality of life in orthognathic surgery using an original questionnaire: About a series of 123 cases

INTRODUCTION

The aim of this study was to measure changes in the quality of life of patients who had orthognathic surgery using an original questionnaire, designed for this purpose.

MATERIAL AND METHOD

This single-center retrospective study included all patients who had orthognathic surgery in our center between 2014 and 2019. An original questionnaire comprising 13 items in 4 domains was sent to patients postoperatively by email after telephone contact and obtaining their consent. Items were scored on a 5-point scale ranging from (-1), worse than before surgery, to (+3), better than before surgery.

RESULTS

All data were collected in a standardized way. In total, 123 patients responded. The mean score for all surgeries combined was +1.14, indicating an improvement in QOL considered to be "low to moderate". A total of 118 patients (95.9%) reported an improvement following surgery, including 18 patients (14.6%) who reported a marked improvement. The greatest improvement was observed for psychosocial aspects and morphology.

CONCLUSION

This study shows a positive effect of orthognathic surgery on patients' QOL, including self-perception, relationships with others, or functional aspects as mastication and breathing. We propose an original tool that is easy to use by patients to measure quality of life following orthognathic surgery.