Effects of Mandibular Retrusive Deviation on Prefrontal Cortex Activation: A Functional Near-Infrared Spectroscopy Study

Abstract

The objective of this study was to evaluate occlusal condition by assessing brain activity in the prefrontal cortex, which is associated with emotion. Functional near-infrared spectroscopy (fNIRS) was used to detect changes in cerebral blood flow in the prefrontal cortex of 12 healthy volunteers. The malocclusion model was a custom-made splint that forced the mandible into retrusion. A splint with no modification was used as a control. The cortical activation during clenching was compared between the retrusive position condition and the control condition. A visual analog scale score for discomfort was also obtained during clenching and used to evaluate the interaction between fNIRS data and psychiatric changes. Activation of the prefrontal cortex was significantly greater during clenching in the mandibular retrusive condition than during clenching in the control condition. Furthermore, Spearman rank-correlation coefficient revealed a parallel relation between prefrontal cortex activation and visual analog scale score for discomfort. These results indicate that fNIRS can be used to objectively evaluate the occlusal condition by evaluating activity in the prefrontal cortex.

The relation of poor mastication with cognition and dementia risk: a population-based longitudinal study

“…Reduced masticatory stimulation might lead to cognitive decline through decreases in cerebral blood flow, decreases in activation of the cortical area and blood oxygen levels, particularly to the frontal cortex [12,13].…”

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

“…Hence, we considered that prefrontal chewing cognition in elderly edentulous subjects could be evaluated by this technique during chewing performance with and without use of a denture prosthesis. fNIRS is considered to be suitable for examinations of prefrontal activities during chewing performance with and without wearing a denture in clinical conditions, as several previous studies utilized it to detect prefrontal activities during jaw clenching [ 32 ] and chewing [ 28 , 55 , 56 ]. In the present study, we attempted to determine the qualities of prefrontal activities in partially edentulous elderly individuals during chewing while wearing a denture as compared with young healthy controls.…”

Influence of lack of posterior occlusal support on cognitive decline among 80‐year‐old Japanese people in a 3‐year prospective study

“…A systematic review reported that tooth loss predicts cognitive decline, because tooth loss might reduce mastication‐induced sensory stimulation and lead to poor nutritional intake . Another study reported that the occlusal condition affects the activation of the brain through blood flow . Animal experiments using mice reported that extraction of molar teeth resulted in learning and memory deficits .…”

“…11 Another study reported that the occlusal condition affects the activation of the brain through blood flow. 12 Animal experiments using mice reported that extraction of molar teeth resulted in learning and memory deficits. 13 In humans, one cross-sectional study suggested that the posterior occlusal support is associated with cognitive function, and that a lack of posterior occlusal support influences cognitive decline to a greater extent than the number of teeth alone.…”