Effect of Sudden Deprivation of Sensory Inputs From Periodontium on Mastication.

Anastasios Grigoriadis,Magnus K Åberg,Abhishek Kumar,Mats Trulsson

doi:10.3389/fnins.2019.01316

Anastasios Grigoriadis, Magnus K Åberg + Show 2 more

Open Access

https://doi.org/10.3389/fnins.2019.01316

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Abstract

ObjectiveTo investigate the effect of sudden deprivation of sensory inputs from the periodontium on jaw kinematics and time-varying activation profile of the masseter muscle.MethodsFourteen (age range: 22–26 years; four men) healthy and natural dentate volunteers participated in a single experimental session. During the experiment, the participants were asked to eat six hard visco-elastic test food models, three each before and after an anesthetic intervention. The movements of the jaw in three dimensions and electromyographic (EMG) activity of the masseter muscle on the chewing side were recorded.ResultsThe results of the study showed no significant differences in the number of chewing cycles (P = 0.233) and the duration of chewing sequence (P = 0.198) due to sudden deprivation of sensory inputs from the periodontium. However, there was a significant increase in the jaw opening velocity (P = 0.030) and a significant increase in the duration of occlusal phase (P = 0.004) during the anesthetized condition. The EMG activity of the jaw closing phase was significantly higher during the control condition [116.5 arbitrary units (AU)] than anesthetized condition (93.9 AU). The temporal profile of the masseter muscle showed a biphasic increase in the excitatory muscle drive in the control condition but this increase was virtually absent during the anesthetized condition.ConclusionSudden deprivation of sensory inputs from the periodontium affects the jaw kinematics and jaw muscle activity, with a clear difference in the time-varying activation profile of the masseter muscle. The activation profile of the masseter muscle shows that periodontal mechanoreceptors contribute to approximately 20% of the EMG activity during the jaw closing phase.

Highlights

The rhythmic masticatory movements of the jaws help in the physical breakdown of food morsels into smaller particles and form a soft bolus suitable for swallowing
All the participants confirmed the subjective symptoms related to local anesthesia after the anesthetic intervention
We have previously reported the quantitative parameters of jawmovements, integrated EMG activity during the chewing cycles, and the adaptation of jaw muscle activity to food hardness in these healthy adults (Grigoriadis et al, 2014)

Summary

Introduction

The rhythmic masticatory movements of the jaws help in the physical breakdown of food morsels into smaller particles and form a soft bolus suitable for swallowing. One important class of somatosensory receptors is located in the collagen fibers within the periodontal ligament space of the tooth root. These primary afferent receptors are called periodontal mechanoreceptors (PMRs). The PMRs are efficient in encoding specific information for modulating the jaw motor neuron activity responsible for regulation of forces and jaw movements during chewing (Lund, 1991; Trulsson, 2006). It is suggested that the sensory information from the PMRs are used by the central nervous system to optimize food positioning between the teeth and regulate the force levels and force vectors involved in biting. Mastication is a semiautomatic, subconscious activity that can be brought to conscious control according to the specifics of task demand (Westberg and Kolta, 2011)

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