Observational Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Jul 16, 2022; 10(20): 6876-6889
Published online Jul 16, 2022. doi: 10.12998/wjcc.v10.i20.6876
Comparative study of surface electromyography of masticatory muscles in patients with different types of bruxism
Kai-Wen Lan, Liu-Lin Jiang, Ying Yan
Kai-Wen Lan, Liu-Lin Jiang, Ying Yan, Hospital of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Guangzhou 510080, Guangdong Province, China
Author contributions: Lan KW, Jiang LL, and Yan Y made contributions to conception and design of the project; Lan KW collected the data; Jiang LL participated in the data analysis; Lan KW drafted the initial manuscript; Lan KW, Jiang LL, and Yan Y revised the manuscript and approved the final version.
Institutional review board statement: The study was approved by the medical ethics committee of Hospital of Stomatology, Sun Yat-sen University (No. KQEC-2020-77-01).
Clinical trial registration statement: The study was registered in the Chinese Clinical Trials Registry (No. ChiCTR2100041699).
Informed consent statement: All study participants provided informed written consent prior to study enrollment.
Conflict-of-interest statement: All authors own a patent (No. ZL 202120549626.3, CN) describing the design of the muscle balance occlusal splint, as well as its treatment application for temporomandibular joint disorder and centric bruxism. The patent is licensed to Hospital of Stomatology, Sun Yat-sen University. Dr. Jiang and Dr. Yan own a patent (No. ZL 201620908577.7, CN) describing the design of the maxillary buccal-pterygoid splint, as well as its treatment application for eccentric bruxism. The patent is licensed to Hospital of Stomatology, Sun Yat-sen University.
Data sharing statement: The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
STROBE statement: The authors have read the STROBE Statement—checklist of items, and the manuscript was prepared and revised according to the STROBE Statement—checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Ying Yan, MSc, Chief Doctor, Hospital of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, No. 56 Lingyuan West Road, Yuexiu District, Guangzhou 510080, Guangdong Province, China. yanying2@mail.sysu.edu.cn
Received: March 10, 2022
Peer-review started: March 10, 2022
First decision: April 13, 2022
Revised: April 22, 2022
Accepted: May 21, 2022
Article in press: May 21, 2022
Published online: July 16, 2022
ARTICLE HIGHLIGHTS
Research background

Bruxism is a rhythmic masticatory muscle activity that occurs involuntarily in a non-physiologically functional state. Previous studies have classified bruxism mainly according to its phase of occurrence. However, this classification does not provide targeted guidance for the treatment of bruxism. Bruxism can also be classified according to the type of mandibular movement: Centric bruxism (CB), which is dominated by centric clenching movements, and eccentric bruxism (ECB), which is dominated by eccentric grinding movements. There is a dearth of research classifying the functional status of masticatory muscles in patients with different mandibular movement types of bruxism.

Research motivation

This study analyzed the differences in the functional status of the masticatory muscles affected by different types of bruxism (CB and ECB), thus illustrating the need for diagnostic classification and corresponding treatment for patients with different types of bruxism.

Research objectives

To reflect the mainly involved types of masticatory muscle and the functional status of the masticatory muscle in patients with different types of bruxism.

Research methods

A total of 21 CB subjects and 21 ECB subjects were screened from college students according to a questionnaire and their tooth wear features. Sixteen non-bruxism subjects were also recruited. The surface electromyography signals of the temporalis anterior (TA) and superficial masseter muscle (MM) were measured in different mandibular positions and during the chewing task. The electromyography amplitude and chewing cycle duration parameters were then analyzed.

Research results

The CB group showed a reduced number of muscle maximal motor units, with the MM being more pronounced, a higher proportion of muscle contractions to be recruited for the same load of chewing activity, and the longer chewing cycle duration. The ECB group showed an increased number of TA maximal motor units, and higher MM activity on the non-working side the in unilateral chewing. This study provides a myoelectrophysiological basis for the diagnostic classification of bruxism based on the type of mandibular movement. Since the subjects selected for this study were college students, the effect of bruxism on populations containing people at other age levels is not clear.

Research conclusions

CB mainly affects the MM, and the patients show reduced masticatory muscle contraction efficiency and chewing cycle efficiency. ECB mainly affects the TA, and the patients show enhanced contraction of non-functional lateral muscle bundles.

Research perspectives

The effects of different types of bruxism on people of other ages should be explored in further study to provide a comprehensive picture of the effects of bruxism on masticatory muscle function.