Cortical representation of experimental periodontal pain: a functional magnetic resonance imaging study

Angelika Maurer,Henning Boecker,Ulrike Attenberger,Damian Verma,Lukas Scheef,Annika Reddehase,Alexander Radbruch,Andreas Jäger

doi:10.1038/s41598-021-94775-4

Angelika Maurer, Henning Boecker + Show 6 more

Open Access

https://doi.org/10.1038/s41598-021-94775-4

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Journal: Scientific Reports	Publication Date: Aug 3, 2021
Citations: 2	License type: open-access

Affiliation: University Hospital Bonn

Abstract

The aim of this study was to investigate central pain representations during loading of the periodontium induced by orthodontic and occlusal stress. Nineteen healthy male volunteers (25.7 ± 2.8 years) were tested on two consecutive days: after phenotyping (questionnaires) and determination of warmth (WPT) and heat (HPT) pain thresholds, functional magnetic resonance imaging was performed as event-related paradigm including 36 tooth clenchings of 3 s duration, alternating with rest periods varying between 20–30 s. The task was performed in absence (T1) and 24 h after placement of an elastic separator between the second bicuspid and the first molar on the right side of the lower jaw (T2). No significant changes in WPT and HPT were observed but pain ratings were significantly elevated at T2. Significantly elevated activation at T2, as compared to T1, was found in bilateral sensorimotor cortex, bilateral secondary sensory cortex, supplementary motor area, right rolandic operculum, and bilateral insula. Our data show for the first time in humans that periodontal stimulation, as tested by tooth clenching in the presence of an elastic separator, goes along with specific expressions of pain at behavioral and neuronal network levels. Findings supplement the existing neuroimaging literature on odontogenic pain.

Highlights

The aim of this study was to investigate central pain representations during loading of the periodontium induced by orthodontic and occlusal stress
The molecular consequences of mechanical forces exerted on the periodontium show that longer lasting excessive orthodontic forces result in release of "danger associated molecules"
We were interested to study how brain activation relates to clinical variables of pain perception and, thereby, to understand whether a pain stimulus originating from the periodontium goes along with similar activations as those previously described for a pain stimulus originating from the dental pulp[15, 22]

Summary

Introduction

The aim of this study was to investigate central pain representations during loading of the periodontium induced by orthodontic and occlusal stress. The molecular consequences of mechanical forces exerted on the periodontium show that longer lasting excessive orthodontic forces result in release of "danger associated molecules" These initiate inflammatory responses and pain symptoms via Toll-like receptors[8,9,10] and inflammatory reactions[11] affect nociceptors and sensory nerve fibers located in the periodontal tissue[12]. We investigate for the first-time brain activity stemming from mechanically induced periodontal pain elicited during experimental tooth clenching combined with orthodontic separators. This task-fMRI approach allows directly measuring brain activation as it typically occurs in patients receiving orthodontic treatment and to infer whether this type of pain goes along with typical activation signatures in the human pain matrix. We were interested to study how brain activation relates to clinical variables of pain perception and, thereby, to understand whether a pain stimulus originating from the periodontium goes along with similar activations as those previously described for a pain stimulus originating from the dental pulp[15, 22]

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