Improved Prefrontal Activity and Chewing Performance as Function of Wearing Denture in Partially Edentulous Elderly Individuals: Functional Near-Infrared Spectroscopy Study

Rehabilitation with dental prostheses and its influence on brain activity: A systematic review

STATEMENT OF PROBLEM

The consequences of edentulism depend on its complexity and are far-reaching, but limited evidence regarding its association with neurologic health is available.

PURPOSE

The purpose of this systematic review was to establish the relationship between oral prosthetic rehabilitation and the regional increase in brain activity.

MATERIAL AND METHODS

This systematic review was registered in the International Prospective Register of Systematic Reviews (CRD42021262247), and the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guideline was followed. Randomized clinical trials, prospective studies comparing the brain activity of patients rehabilitated with and without the use of dental prostheses, and studies that analyzed the human brain by using noninvasive techniques were used as inclusion criteria. The risk of bias in each study was assessed by using the Risk Of Bias In Non-randomized Studies-of Interventions (ROBINS-I).

RESULTS

The search was carried out in the PubMed/MEDLINE, Embase, Cochrane Library, and https://clinicaltrials.gov databases up to June 2021. After a search conducted by 2 reviewers, 8 articles were included in the review. A regional increase in blood flow and regional cerebral activity during dental prosthesis use was identified in the studies.

CONCLUSIONS

A positive association was found between the different types of prosthetic rehabilitation and brain function. Prostheses may preserve and restore neurological health.

White matter abnormalities mediate the association between masticatory dysfunction and cognition among older adults

BACKGROUND

Masticatory parameters, such as reduced number of teeth and posterior contacts, have been shown to be associated with reduced cognitive status. The underlying mechanisms that affect these associations, are however, not well understood.

OBJECTIVES

The study aims to investigate the association between masticatory dysfunction and cognition and explore the mediating effect of brain structure.

METHODS

In this cross-sectional study, 45 older adults with subjective masticatory dysfunction (mean age 72.3 ± 4.0 years) were included. Mini-Mental State Examination score <25, brain trauma, neurological disease, neurodegenerative disorders, depression or poor Swedish language skills were criteria for exclusion. Cognitive functions (executive function and episodic memory) and masticatory dysfunction defined by functional occluding status (FOS; the number of occluding units and number of remaining teeth) were analysed with partial correlation models. Structural magnetic resonance imaging was performed on 28 feasible participants. Multiple regression analyses were performed to evaluate the predictive value of brain structure and white matter hypointensities (WM-hypo) on cognitive functions. A mediation analysis was applied to assess significant predictor/s of the association between FOS and cognition.

RESULTS

Both episodic memory and executive functions were positively correlated with FOS. WM-hypo predicted cognitive status (executive function, p ≤ .01). WM-hypo mediated 66.6% (p = 0.06) of the association between FOS and executive functions.

CONCLUSION

Associations between FOS and cognitive functions are reported, where FOS, a potential modifiable risk factor, was related to both episodic memory and executive functions. The mediating effect of WM-hypo on the association between FOS and executive functions highlights the impact of the vascularisation of the brain on the link between mastication and cognition. The present study provides increased knowledge that bridges the gap between masticatory dysfunction and cognition.

Muscle activity between dentate and edentulous patients rehabilitated with dental prostheses: A systematic review

BACKGROUND

Adequate muscle activity is important for the success of oral rehabilitation: it maintains the integrity of the stomatognathic system and is responsible for chewing movements needed to break, crush and grind food.

OBJECTIVE

To compare muscle activity using electromyography (EMG) while clenching or chewing soft and/or hard foods among individuals with natural dentition (ND) and edentulous patients rehabilitated with dental prostheses.

METHODS

This review was conducted until March, 2023, and the research question was "Is the muscle activity of edentulous patients rehabilitated with dental prostheses similar to that of dentate individuals?" A search strategy was conducted in PubMed/MEDLINE, The Cochrane Library, Web of Science, Lilacs, Embase and manual journal searches.

RESULTS

Ten studies were included in the analysis. Most of them reported that individuals with ND had significant higher muscle activity (clenching or chewing) than complete dentures (CD) users. However, no difference was observed between patients with full mouth implant-supported fixed dental prosthesis (ISFDP) and ND. Additionally, two studies compared patients with mandibular ISFDP with maxillary CD and individuals with ND and found no differences; however, one study concluded that patients with ISFDP with CD (maxillary or mandibular) had lower muscle activity than individuals with ND. Only one study reported a higher muscle activity in patients with full-mouth ISFDP than in individuals with ND.

CONCLUSIONS

Bimaxillary CD users had lower muscle activity than individuals with ND. During rehabilitation, the muscle activity of patients with full-mouth ISFDP and mandibular ISFDP with maxillary CD is similar to individuals with ND.

Impact of Denture Prostheses on Cognitive Functioning in Completely Edentulous Patients: A Pilot Study

AIM

The aim is to evaluate the impact of denture prostheses on cognitive functioning in completely edentulous patients using a novel cognitive assessment tool.

METHODS

Thirty (n=30) completely edentulous patients of age groups above 60 years were taken in the present study group. Pre- and post-cognitive assessments were done on the patients using a novel cognitive assessment tool, Dental Cognitive Functioning Assessment Tool (DCFAT). These assessments were done in the pre-treatment stage and after two weeks and three months of prostheses function.

RESULTS

The mean DCFAT score of 30 patients shows 10.13 recorded prior to denture fabrication and 11.5 and 14 after two weeks and three months of prosthesis function, respectively. A mean difference in the DCFAT score of 1.37 was seen between the pre-denture fabrication stage and two weeks of prosthesis function. The mean difference in DCFAT score of 3.87 was seen between the pre-denture fabrication stage and three months of prosthesis function and the mean difference score of DCFAT score 2.5 was observed after two weeks and three months of prosthesis function. One-way ANOVA was used to investigate the statistical difference between bivariate samples followed by the post hoc Tukey test. The results were statistically significant p < 0.00001.

CONCLUSION

 The inference obtained suggest that the replacement of missing teeth by denture prostheses enhances the cognitive functioning in the elderly population which can eventually reduce the occurrence of dementia.

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 of Tooth Loss with Alzheimer's Disease Tau Pathologies Assessed by Positron Emission Tomography

BACKGROUND

Deterioration of the oral environment is one of the risk factors for dementia. A previous study of an Alzheimer's disease (AD) model mouse suggests that tooth loss induces denervation of the mesencephalic trigeminal nucleus and neuroinflammation, possibly leading to accelerated tau dissemination from the nearby locus coeruleus (LC).

OBJECTIVE

To elucidate the relevance of oral conditions and amyloid-β (Aβ) and tau pathologies in human participants.

METHODS

We examined the number of remaining teeth and the biofilm-gingival interface index in 24 AD-spectrum patients and 19 age-matched healthy controls (HCs). They also underwent positron emission tomography (PET) imaging of Aβ and tau with specific radiotracers, 11C-PiB and 18F-PM-PBB3, respectively. All AD-spectrum patients were Aβ-positive, and all HCs were Aβ-negative. We analyzed the correlation between the oral parameters and radiotracer retention.

RESULTS

No differences were found in oral conditions between the AD and HC groups. 11C-PiB retentions did not correlate with the oral indices in either group. In AD-spectrum patients, brain-wide, voxel-based image analysis highlighted several regions, including the LC and associated brainstem substructures, as areas where 18F-PM-PBB3 retentions negatively correlated with the remaining teeth and revealed the correlation of tau deposits in the LC (r = -0.479, p = 0.018) primarily with the hippocampal and neighboring areas. The tau deposition in none of the brain regions was associated with the periodontal status.

CONCLUSIONS

Our findings with previous preclinical evidence imply that tooth loss may enhance AD tau pathogenesis, promoting tau spreading from LC to the hippocampal formation.

Drug Therapy in Cognitive Disorders and Its Effects on Oral Health

Dementia and Alzheimer’s disease are the two most characteristic cognitive disorders presenting numerous cognitive dysfunctions such as memory loss, functional impairment, speech impairment, and orientation problems. In India, there is an increased risk in the elderly population leading to the prevalence of Alzheimer's and dementia-related diseases. Therefore, it is not only general health care practitioners but also oral health care providers also play a major role in rehabilitating and treating this type of patient. So, it is necessary for oral health care providers to understand the pharmacologic agents used for the management of Alzheimer’s and dementia-related diseases. This article gives an insight into the management of dementia and Alzheimer’s disease and also an update on the drug therapies for AD and outlines their implications on oral health.

Comparison of the effect of conventional and implant-retained overdentures on brain activity and cognition in a geriatric population - A Functional MRI study

PURPOSE

This study aims to evaluate the effect of rehabilitation with complete dentures versus implant-retained overdenture on activity in various parts of the brain cognition in a geriatric edentulous population via Functional MRI (fMRI) studies and the Mini-Mental State Examination (MMSE).

METHODS

Ten completely edentulous patients were rehabilitated with both complete dentures and two-implant retained overdentures for three months each. fMRI studies were performed for each modality during chewing and recall tasks at three time periods: T0: Completely Edentulous(CE) T1: after three months of wearing Conventional Complete Dentures(CD) and T2: after three months of wearing Implant-retained Overdentures (IOD). The Z scores obtained from the fMRI at these phases of examination were tabulated and correlated with MMSE scores obtained at the corresponding time periods.

RESULTS

Z scores obtained during the memory recall tasks at T2 were the greatest (Prefrontal Cortex (p=0.059) and Hippocampus (p=0.036). The MMSE scores obtained were significantly higher for the IODs when compared to the CDs and Baseline values (p < 0.05)Conclusion: IODs may potentially result in superior sensory feedback in edentulous patients and lead to improved cognitive performance when compared to conventional complete dentures.

Influence of Dental Prostheses on Cognitive Functioning in Elderly Population: A Systematic Review

Aim

The aim of the systematic review was to assess the influence of dental prostheses on cognitive functioning in elderly population.

Materials and Methods

This systematic review was conducted according to the PRISMA guidelines. The initial electronic search was conducted using the following search databases: MEDLINE (PubMed), Cochrane Library, Google Scholar, and EMBASE. The search was limited to English language using the search items/keywords: "dental prostheses and cognitive functioning," "dental prostheses and brain function," "Tooth loss and cognitive loss," "mastication and prefrontal activity," and "prostheses on mental state." The search strategy was followed using the PICOS framework.

Results

A total of 19 studies were selected according to the selection criteria. Out of 19 studies, 15 studies were included and 4 studies were excluded from the review.

Conclusion

With the available evidence in the literature, it can be concluded that dental prostheses have a very significant role in preventing the cognitive impairment and act as a protective factor in enhancing the cognitive function in patients with dementia-related diseases and neurodegenerative diseases.

Number of teeth, denture wearing and cognitive function in relation to nutritional status in residents of nursing homes

BACKGROUND

Although statistical associations between tooth loss and cognitive decline have been reported, there are few previous studies on denture wearing. Additionally, it remains unclear whether nutritional status mediates this association.

OBJECTIVE

Our purpose was to test for the hypothesis that the association between the number of teeth and denture wearing with cognitive function is mediated by nutritional status in residents of nursing homes.

MATERIALS AND METHODS

We enrolled 162 participants who required long-term care (mean age: 87.7 ± 7.5 years, 26 men and 136 women) and were admitted to eight nursing homes in Fukuoka city, from September 2013 to March 2014. A trained dentist conducted dental and swallowing examinations, and the care-staff assessed nutritional status, comorbid conditions and cognitive function using the Clinical Dementia Rating (CDR).

RESULTS

Poisson regression analysis showed that 0-19 teeth without dentures were associated with severe cognitive impairment (CDR 3) (prevalence ratio = 2.00; 95% confidence interval: 1.13-3.55) after adjustment for sex, age, suspected swallowing dysfunction and comorbid conditions. Mediation analysis confirmed that the nutritional status as a mediator of this association (the percentage mediated effect through nutritional status was 23.1%).

CONCLUSION

There is an association between dental status and cognitive impairment in elder individuals, and dentures and poor nutrition are involved in this association. However, due to the cross-sectional design of this study, there is a possibility that this association is bidirectional.

Activation of Prefrontal Cortex in Process of Oral and Finger Shape Discrimination: fNIRS Study

Background

The differences in the brain activities of the insular and the visual association cortices have been reported between oral and manual stereognosis. However, these results were not conclusive because of the inherent differences in the task performance-related motor sequence conditions. We hypothesized that the involvement of the prefrontal cortex may be different between finger and oral shape discrimination. This study was conducted to clarify temporal changes in prefrontal activities occurring in the processes of oral and finger tactual shape discrimination using prefrontal functional near-infrared spectroscopy (fNIRS).

Methods

Six healthy right-handed males [aged 30.8 ± 8.2 years (mean ± SD)] were enrolled. Measurements of prefrontal activities were performed using a 22-channel fNIRS device (ETG-100, Hitachi Medical Co., Chiba, Japan) during experimental blocks that included resting state (REST), nonsense shape discrimination (SHAM), and shape discrimination (SHAPE).

Results

No significant difference was presented with regard to the number of correct answers during trials between oral and finger SHAPE discrimination. Additionally, a statistical difference for the prefrontal fNIRS activity between oral and finger shape discrimination was noted in CH 1. Finger SHAPE, as compared with SHAM, presented a temporally shifting onset and burst in the prefrontal activities from the frontopolar area (FPA) to the orbitofrontal cortex (OFC). In contrast, oral SHAPE as compared with SHAM was shown to be temporally overlapped in the onset and burst of the prefrontal activities in the dorsolateral prefrontal cortex (DLPFC)/FPA/OFC.

Conclusion

The prefrontal activities temporally shifting from the FPA to the OFC during SHAPE as compared with SHAM may suggest the segregated serial prefrontal processing from the manipulation of a target image to the decision making during the process of finger shape discrimination. In contrast, the temporally overlapped prefrontal activities of the DLPFC/FPA/OFC in the oral SHAPE block may suggest the parallel procession of the repetitive involvement of generation, manipulation, and decision making in order to form a reliable representation of target objects.

Application of Deep Learning in the Identification of Cerebral Hemodynamics Data Obtained from Functional Near-Infrared Spectroscopy: A Preliminary Study of Pre- and Post-Tooth Clenching Assessment

In fields using functional near-infrared spectroscopy (fNIRS), there is a need for an easy-to-understand method that allows visual presentation and rapid analysis of data and test results. This preliminary study examined whether deep learning (DL) could be applied to the analysis of fNIRS-derived brain activity data. To create a visual presentation of the data, an imaging program was developed for the analysis of hemoglobin (Hb) data from the prefrontal cortex in healthy volunteers, obtained by fNIRS before and after tooth clenching. Three types of imaging data were prepared: oxygenated hemoglobin (oxy-Hb) data, deoxygenated hemoglobin (deoxy-Hb) data, and mixed data (using both oxy-Hb and deoxy-Hb data). To differentiate between rest and tooth clenching, a cross-validation test using the image data for DL and a convolutional neural network was performed. The network identification rate using Hb imaging data was relatively high (80‒90%). These results demonstrated that a method using DL for the assessment of fNIRS imaging data may provide a useful analysis system.

Effects of denture wearing on coordinated features of jaw and neck muscle activities during chewing in partially edentulous elderly patients

PURPOSE

This study was performed to examine how denture wearing improves jaw and neck muscle coordination during chewing in partially edentulous elderly patients.

METHODS

Sixteen patients classified as Eichner's index B2 or B3 and 16 young dentate subjects were enrolled. Jaw and neck muscle activities during chewing were recorded using electromyography with and without denture wearing, then analyzed using intermuscular Electromyography (EMG)-EMG transfer and EMG-EMG coherence function analyses to clarify quantitative, temporal, and functional coordination of jaw and neck muscle activities while chewing. Occlusal force and masticatory scores were also determined.

RESULTS

Denture wearing increased the power values for jaw closing muscle activities, and improved occlusal area and force, and masticatory score. Gain values for jaw closing and opening muscle activities were decreased in those wearing dentures compared to those not wearing dentures. Denture wearing resulted in equivalent gain values for jaw closing and opening muscle activities as compared to the young subjects. Coherence values for chewing and non-chewing side neck muscle activities were increased as compared to not denture wearing.

CONCLUSIONS

The suitability of denture wearing can be evaluated from the viewpoint of gain as a quantitative parameter showing coordination between jaw closing and opening muscle activities. Such evaluation can be performed from the viewpoint of coherence as a parameter of functional coordination between jaw and neck muscle activities during chewing in partially edentulous elderly patients. The gain parameter in regard to jaw muscle activities may be compensated to a state equivalent to that seen in young subjects by wearing an appropriate denture.

A Systematic Review of the Application of Functional Near-Infrared Spectroscopy to the Study of Cerebral Hemodynamics in Healthy Aging

Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies have shown that healthy aging is associated with functional brain deterioration that preferentially affects the prefrontal cortex. This article reviews the application of an alternative method, functional near-infrared spectroscopy (fNIRS), to the study of age-related changes in cerebral hemodynamics and factors that influence cerebral hemodynamics in the elderly population. We conducted literature searches in PudMed and PsycINFO, and selected only English original research articles that used fNIRS to study healthy individuals with a mean age of ≥ 55 years. All articles were published in peer-reviewed journals between 1977 and May 2019. We synthesized 114 fNIRS studies examining hemodynamic changes that occurred in the resting state and during the tasks of sensation and perception, motor control, semantic processing, word retrieval, attentional shifting, inhibitory control, memory, and emotion and motivation in healthy older adults. This review, which was not registered in a registry, reveals an age-related reduction in resting-state cerebral oxygenation and connectivity in the prefrontal cortex. It also shows that aging is associated with a reduction in functional hemispheric asymmetry and increased compensatory activity in the frontal lobe across multiple task domains. In addition, this article describes the beneficial effects of healthy lifestyles and the detrimental effects of cardiovascular disease risk factors on brain functioning among nondemented older adults. Limitations of this review include exclusion of gray and non-English literature and lack of meta-analysis. Altogether, the fNIRS literature provides some support for various neurocognitive aging theories derived from task-based PET and fMRI studies. Because fNIRS is relatively motion-tolerant and environmentally unconstrained, it is a promising tool for fostering the development of aging biomarkers and antiaging interventions.

Effect of fixed dental prosthesis on the brain functions of partially edentulous patients - pilot study with power spectrum density analysis

Purpose:

This study was done to analyse the influence of fixed dental prosthesis (FDP) on brain function by analysing power spectral density of partially edentulous patients.

Materials and methods:

The study included unilateral missing mandibular molar replacement patients. The patients were restored with three-unit metal ceramic FDP restorations. The cognitive function was analysed with a mental state questionnaire. Power spectral density (PSD) analysis of EEG alpha waves was made pre- treatment, post treatment and 3 months after FDP treatment to analyse the brain function. The data in various phases were obtained before and after chewing. The results were statistically analysed.

Results:

The mean pre and post treatment PSD was 0.0175 (SD ±0.0132) and 0.0178 (SD ±0.0135). The mean post treatment PSD after three months was 0.024 (SD± 0.019). The results were analysed with repeated ANOVA and were statistically significant. (p<0.01).

Conclusion:

The study displayed improvement in brain function of partially edentulous patients with FDP rehabilitation.

Functional Connectivity Between the Trigeminal Main Sensory Nucleus and the Trigeminal Motor Nucleus

The present study shows new evidence of functional connectivity between the trigeminal main sensory (NVsnpr) and motor (NVmt) nuclei in rats and mice. NVsnpr neurons projecting to NVmt are most highly concentrated in its dorsal half. Their electrical stimulation induced multiphasic excitatory synaptic responses in trigeminal MNs and evoked calcium responses mainly in the jaw-closing region of NVmt. Induction of rhythmic bursting in NVsnpr neurons by local applications of BAPTA also elicited rhythmic firing or clustering of postsynaptic potentials in trigeminal motoneurons, further emphasizing the functional relationship between these two nuclei in terms of rhythm transmission. Biocytin injections in both nuclei and calcium-imaging in one of the two nuclei during electrical stimulation of the other revealed a specific pattern of connectivity between the two nuclei, which organization seemed to critically depend on the dorsoventral location of the stimulation site within NVsnpr with the most dorsal areas of NVsnpr projecting to the dorsolateral region of NVmt and intermediate areas projecting to ventromedial NVmt. This study confirms and develops earlier experiments by exploring the physiological nature and functional topography of the connectivity between NVsnpr and NVmt that was demonstrated in the past with neuroanatomical techniques.

Prefrontal Consolidation and Compensation as a Function of Wearing Denture in Partially Edentulous Elderly Patients

Background

The cognitive effects of wearing a denture are not well understood. This study was conducted to clarify the effects of denture use on prefrontal and chewing muscle activities, occlusal state, and subjective chewing ability in partially edentulous elderly individuals.

Methods

A total of 16 partially edentulous patients were enrolled. Chewing-related prefrontal cortex and jaw muscle activities were simultaneously examined using a functional near-infrared spectroscopy (fNIRS) device and electromyography, under the conditions of unwearing, and wearing a denture. Occlusal state and masticatory score were also determined under both conditions. Using multiple linear regression analysis, associations between prefrontal and chewing activities with wearing were examined using change rates.

Results

Chewing rhythmicity was maintained under both conditions. As compared with unwearing, the wearing condition was associated with improved prefrontal cortex and chewing muscle activities, occlusal state in regard to force and area, and masticatory score. Also, prefrontal activities were positively associated with burst duration and peak amplitude in masseter (Mm) and temporal muscle activities, as well as masticatory scores. In contrast, prefrontal activities were negatively associated with occlusal force.

Conclusion

Wearing a denture induced a positive association between burst duration and peak amplitude in Mm and temporal muscle activities and prefrontal activity, which may indicate a parallel consolidation of prefrontal cortex and rhythmical chewing activities, as well as masticatory scores. On the other hand, denture use induced a negative association of occlusal force with prefrontal activities, which might suggest that prefrontal compensative associations for the physiocognitive acquisition depended on biomechanical efficacy gained by wearing a denture.

The relation between teeth loss and cognitive decline among Saudi population in the city of Riyadh: A pilot study

Background

Teeth are necessary for sensory input to the brain during the chewing process, but how the decrease in this sensory input, due to loss of teeth, may cause weak memory and lead to cognitive decline is not well understood. This pilot public survey aiming to assess the correlation between the number of missing teeth, periodontal disease, and cognitive skill in the city of Riyadh.

Material& Methods

A multicenter cross-sectional survey, targeting geriatric population aged ≥60 years, was performed in Riyadh City, Saudi Arabia. The Montreal Cognitive Assessment (MoCA) was conducted to all participants to assess their cognitive function. Assessment of oral health status was carried out, including the number of present dentation and their periodontal status. Community periodontal-index (CPI) was used to assess the periodontal condition. The primary variables were number of missing teeth, periodontal disease and MoCA test scores. Chi-square test and Pearson’s correlation coefficients were computed and the significant P- value was set at <0.05.

Results

Of 95 participants, overall, 57 (60%) and 38 (40%) were male and female, respectively, with a mean age of 65.67 ± 6.32 years. Females showed more significant cognitive decline than males (P < 0.001). Cognitive decline was significantly high in participants with low educational level 19 (95%), unemployment 41 (79%), and lower income people 26 (79%), while being cognitive intact was significantly higher in highly educated 13 (87%), retired 21 (62%), and higher income people 28 (74%) at (P < 0.001). An advanced age and greater number of missing teeth are associated with lower MoCA test scores. No statistical significant correlation with regard to periodontal disease and MoCA test scores.

Conclusion

Based on the preliminary data, positive correlation was confirmed when the number of missing teeth and cognitive skill were assessed. Therefore, larger, multi-center regional surveys are needed to investigate further this relationship.

Occlusal force predicts global motion coherence threshold in adolescent boys

Background

Beneficial effects of mastication on cognitive abilities in the elderly have been shown in human studies. However, little is currently known about the effect of masticatory stimulation on cognitive and perceptual ability in younger populations. The purpose of the present study is to investigate the influences of masticatory stimulation on perceptual ability in adolescent boys.

Methods

The present study examined the relationship between occlusal force (i.e., masticatory stimulation) and visual perception ability in adolescent boys. Visual perception ability was quantified by measuring global motion coherence threshold using psychophysical method. As an index of masticatory stimulation, occlusal force was measured by pressure sensitive film. We also measured participants’ athletic ability, e.g. aerobic capacity and grip strength, as potential confounding factor.

Results

The multiple regression analysis revealed a significant negative correlation between global motion coherence threshold and occlusal force, which persisted after controlling for confounding factors such as age and aerobic capacity.

Conclusions

This finding indicates that masticatory stimulation enhances visual perception in adolescent boys, indicating the possibility that beneficial effects of masticatory stimulation are observed not only in the elderly but in developing population consistently with the findings of the previous animal studies.

Environmental Enrichment and Successful Aging

The human brain sustains a slow but progressive decline in function as it ages and these changes are particularly profound in cognitive processing. A potential contributor to this deterioration is the gradual decline in the functioning of multiple sensory systems and the effects they have on areas of the brain that mediate cognitive function. In older adults, diminished capacity is typically observed in the visual, auditory, masticatory, olfactory, and motor systems, and these age-related declines are associated with both a decline in cognitive proficiency, and a loss of neurons in regions of the brain. We will review how the loss of hearing, vision, mastication skills, olfactory impairment, and motoric decline accompany cognitive loss, and how improved functioning of these systems may aid in the restoration of the cognitive abilities in older adults. The human brain appears to require a great deal of stimulation to maintain its cognitive efficacy as people age and environmental enrichment may aid in its maintenance and recovery.

The Effect of Number of Teeth and Chewing Ability on Cognitive Function of Elderly in UAE: A Pilot Study

Cognitive decline is one of the major causes of disability among the aging population. The aim of this study was to explore the relationship between oral health parameters (number of teeth, chewing ability, and presence of a denture) and cognitive function in the elderly across the UAE. Fifty persons (age ≥ 60; 71.26 ± 10.23) were enrolled in the study. Cognitive status was assessed using the standardized mini-mental state examination (SMMSE) and accordingly, cognitively normal subjects scoring ≥24 were considered as the control group and cognitively impaired individuals scoring ≤23 were considered as the low scoring group. Chewing ability was examined, number of teeth was noted, and demographical data was collected. The results of this pilot study showed that individuals with low SMMSE scores were significantly less educated (P < 0.01) and had fewer number of remaining teeth (P < 0.05) and impaired chewing ability (P < 0.05). These results demonstrate a significant link between the number of teeth, chewing ability, and cognitive function. However, this pilot study had its limitations and was the first of its kind in the UAE and Gulf region; therefore, future research addressing the limitations is needed to further explore this association.