PubMed Central, : RMMJ Rambam Maimonides Medical Journal Rambam Health Care Campus 2025; 16(1): e0002. ISSN: 2076-9172Published online 2025 January 30. doi: 10.5041/RMMJ.10538

Author (Year)^ref	Objective	Results and Conclusions
Ko et al. (2022)¹⁷	To investigate the association between changes in masticatory function and cognitive impairment by analyzing longitudinal data of older Korean patients	Dementia group: T-FTU significantly decreased from T1 to T2 (9.81±2.78 to 9.11±3.16, respectively, P=0.008). Control Group: no significant change observed. Mean observation period of 9 years: significantly more teeth extracted and neglected, needing prosthetic restoration in the dementia group vs controls. Regression analysis: number of missing/neglected teeth (OR=1.195, 95% CI=1.025–1.393, P=0.023); previous alcohol consumption (OR=4.445, 95% CI=1.831–1.795, P=0.001) significant risk factors of dementia. Possible causative relationship between missing or neglected dentition and dementia onset.

Costa et al. (2022)¹⁸	To establish the relationship between oral prosthetic rehabilitation and the regional increase in brain activity	Two reviewers searched PubMed/MEDLINE, Embase, Cochrane Library, and https://clinicaltrials.gov databases up to June 2021. A total of 8 articles were included in the review, all of which identified a regional increase in blood flow and regional cerebral activity during dental prosthesis use. A positive association was found between different types of prosthetic rehabilitation and brain function. Prostheses may preserve and restore neurological health.

Ahmed et al. (2021)¹⁹	To assess the influence of dental prostheses on cognitive functioning in elderly population	19 studies met the inclusion criteria; 15 were selected, with 4 excluded from review with reason. The authors concluded that dental prostheses play a significant role in preventing cognitive impairment and act as a protective factor in enhancing cognitive function in patients with dementia-related and neurodegenerative diseases.

Moussa (2020)²⁰	To evaluate the influence of restoring lost posterior occlusal contacts with removable partial dentures on brain activity and cognitive function in controlled type 2 diabetic patients	EEG assessment demonstrated an increase in mean value after 1 month of wearing removable partial dentures. Cognitive scores for MMSE displayed an increase in total mean value after 1 month; outcomes were statistically significant (P<0.05). Restoration of lost posterior occlusal contact in controlled type 2 diabetic patients with removable partial dentures improved brain function and cognitive status.

Tan et al. (2020)²¹	To investigate (a) changes in masticatory performance with POR, (b) the association between POR and neurocognitive function using fMRI, and (c) outcomes of OHRQoL.	Four edentulous patients (mean age: 73±1.4 years) received new complete RDPs which were later changed to mandibular RDPs with two retained implants (IR-RDPs). Improvements in masticatory performance and OHRQoL were observed from complete RDPs to IR-RDPs. Prosthetic adaptation was associated with neurocognitive changes, with activity levels approaching or exceeding those seen before insertion, over a 6-week period. These pilot data suggest both behavioral and neural associations between POR and cognition.
Chuhuaicura et al. (2019)²²	The relationship between mastication as a protective factor of cognitive decline and the effect on brain blood flow in adults	Analysis and qualitative analysis of 9 clinical descriptive studies suggested that the most activated brain areas during mastication are the frontotemporal cortex, the caudate nucleus, and the thalamus. These findings revealed a positive correlation between chewing intensity and perfusion of the principal trigeminal nucleus. The study concluded that masticatory function may act as a protective factor in patients with cognitive impairment and neurodegenerative diseases. Several mechanisms, including the increase of cerebral blood flow, are suggested to be involved in this beneficial effect.

Fukutake et al. (2018)²³	To determine the impact of cognitive function on perception in older adults living independently	This study comprised 987 participants (466 men, 521 women), aged 69–71 years. The number of teeth, use of removable dentures, and cognitive function, respectively, were significantly related to the stereognostic score. Cognitive impairment, even in the preclinical stage, was associated with reduced oral perception after controlling for gender, number of teeth, and use of dentures in older adults living independently.

Banu et al. (2016)²⁴	To assess brain activity and cognitive function in edentulous patients under two conditions: edentulous, with conventional dentures, and edentulous mandibular IODs, considering mastication effects before and after treatment	The study included 10 patients aged between 55 and 65 years. The amplitude, power of alpha waves, and cognitive scores gradually increased, with the highest mid-range values observed for the IOD group. Findings highlighted the significance of two mandibular IODs in improving an individual’s mental state, primarily due to functional improvement with prostheses when loaded with implants rather than solely the presence of an implant without any function.

Matsuda et al. (2014)²⁵	To identify how changes in the VDO affect sensory perception and brain activity in complete denture users, using EEG	The study included 21 patients (average age, 77 years). No significant differences were found in neuronal activity values before and after chewing gum with either of the dentures (P>0.05). However, a significant decrease in occlusal force was observed between the original denture and the denture with a −3 mm VDO (P<0.05). Both psychological state and occlusal force were influenced by immediate changes in the VDO of the complete denture.

Luraschi et al. (2013)²⁶	To investigate cortical brain changes using fMRI following complete denture renewal, and to examine how these changes relate to prosthodontic treatment adaptability, as measured by chewing efficiency and maximum bite force	Cohort: 10 complete denture patients (mean age ± standard deviation: 70.3±9.1 years). Changes in brain activity occurred during adaptation to dental prostheses replacement and appeared to recover activity levels seen before insertion during motor tasks involving dental occlusion 3 months following insertion.
Ohkubo et al. (2013)²⁷	To analyze the effect of occlusion on overall body health with a specific focus on brain function	The sensorimotor cortex was found to be affected by the placement of occlusal interference devices, splints, and implant prostheses. Brain activity can change depending on the force of movements in the oral and maxillofacial area. Therefore, chewing and other movements stimulate activity in the cerebral cortex, which may be helpful in preventing the degradation of brain function.
Kimoto et al. (2011)²⁸	To investigate changes in regional brain activity during gum chewing when edentulous subjects transitioned from complete mandibular dentures to removable IODs	Results revealed that IOD treatment significantly suppressed brain activity induced by chewing in the prefrontal cortex. Induced brain activities in the primary sensorimotor cortex and cerebellum tended to decrease with IOD, although not statistically significant. No significant changes observed in brain activity in the supplementary motor area, thalamus, and insula between gum chewing with CD vs IOD. Statistical parametric mapping analysis demonstrated a significant decrease in neuronal activity in the frontal pole during gum chewing with IOD compared to CD (P<0.05), specifically within the prefrontal cortex. Gum chewing in elderly edentulous patients may result in differential neuronal activity in the frontal pole within the prefrontal cortex between the two prosthodontic treatments: mandibular CDs and IODs.

Hosoi (2011)²⁹	The relationship between brain function activity, measured by EEG, and dental prosthesis treatment in elderly patients with complete and partially edentulous conditions	Treatment with complete dentures improved function and enhanced brain function activation. Patients evaluated according to Eichner classification: Use of partial dentures increased brain function activation after chewing. These results indicate that the occlusal contact area and occlusal force influence brain function activation.