Dental deafferentation and brain damage: A review and a hypothesis

Abstract

In the last few decades, neurobiological and human brain imaging research have greatly advanced our understanding of brain mechanisms that support perception and memory, as well as their function in daily activities. Knowledge of the neurobiological mechanisms behind the deafferentation of stomatognathic systems has also expanded greatly in recent decades. In particular, current studies reveal that the peripheral deafferentations of stomatognathic systems may be projected globally into the central nervous system (CNS) and become an associated critical factor in triggering and aggravating neurodegenerative diseases. This review explores basic neurobiological mechanisms associated with the deafferentation of stomatognathic systems. Further included is a discussion on tooth loss and other dental deafferentation (DD) mechanisms, with a focus on dental and masticatory apparatuses associated with brain functions and which may underlie the changes observed in the aging brain. A new hypothesis is presented where DD and changes in the functionality of teeth and the masticatory apparatus may cause brain damage as a result of altered cerebral circulation and dysfunctional homeostasis. Furthermore, multiple recurrent reorganizations of the brain may be a triggering or contributing risk factor in the onset and progression of neurodegenerative conditions such as Alzheimer's disease (AD). A growing understanding of the association between DD and brain aging may lead to solutions in treating and preventing cognitive decline and neurodegenerative diseases.

Characteristics of Chewing: An Update of the Literature

“…The activation of different areas of the cerebral cortexresulting from chewing had already been previously proposed in studies where the mastication of chewing gum demonstrated an increase in regional blood flow of the brain in areas such as the primary sensorimotor area, complementary motor areas, insula, cerebellum and corpus striatum (Momose et al, 1997). Given that a deterioration in masticatory function is dependent on the presence of teeth, current studies suggest that the process of peripheral deafferentation in the stomatognathic system could project globally in the central nervous system and become a critical factor that could trigger and/or aggravate neurodegenerative diseases (Jou, 2018). A recent qualitative systematic review indicates that masticatory function can act as a protective factor in subjects with cognitive decline and neurodegenerative diseases by increasing cerebral blood flow.…”

Relationship between oral health status and cognitive functions

“…Длительное время считалось, что стоматологические проблемы возникают из-за трудностей при осуществлении ухода за полостью рта в случаях ухудшения когнитивных функций, памяти и физических способностей у пациентов с деменцией. Однако в недавних исследованиях высказывается предположение, что потеря зубов и окклюзионная дисфункция также могут влиять на когнитивные функции и вызывать развитие деменции [41].…”

“…Нейровизуализационные исследования с использованием функциональной магнитнорезонансной томографии (фМРТ) показали, что во время жевания возникает активация нескольких областей головного мозга (первичной соматосенсорной коры, первичной моторной коры, дополнительной моторной коры, премоторной коры, префронтальной коры, островка, задней теменной коры, таламуса, стриатума и мозжечка). Потеря зубов оказывает влияние на координацию зубного ряда той же дуги, а также зубного ряда на противоположной дуге во время жевания и может вызывать сенсорную и моторную реорганизацию коры головного мозга [41,42].…”

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

“…When one of these 'musicians' change their function or are removed, it results in structural and functional deafferentations of the adjacent and opposing teeth. This causes a mistune in the 'natural melody' and leads to sustained and even permanent reorganizations of sensory and motor cortices [6]. However, this ability for reorganization dwindles as age progresses, thereby leaving edentulous geriatric patients more susceptible to cognitive dysfunction.…”