Monitoring of Changes in Masticatory Muscle Stiffness after Gum Chewing Using Shear Wave Elastography

Abstract

This study aimed to investigate if intensive exercise affects the stiffness of the masticatory muscles measured with shear-wave elastography. The study included a cohort of healthy adults (n = 40) aged 40 ± 11 years. In each individual, the stiffness of both the masseter and temporalis muscle was examined three times: at baseline, after 10 min of intensive exercise (chewing gum), and after 10 min of relaxation. Stiffness values (median (IQR)) of both the masseter and temporalis muscle were the lowest at the baseline (11.35 (9.7–12.65) and 10.1 (9.1–10.95)), increased significantly after the exercise (12.5 (11.1–13.25) and 10.3 (10.2–10.52)) and then dropped significantly after 10 min of relaxing (11.75 (9.95–12.6) and 10.2 (9.65–11.9)). The stiffness of the temporalis muscle was significantly lower than that of the masseter muscle. The values of the stiffness of the masseters correlated significantly with the values of the stiffness of the temporalis muscles. Shear wave elastography proved to be a sensitive method for showing changes in the stiffness of the muscles involved in the mastication occurring as a response to the effort, which increased the muscle stiffness. Further research is needed to broaden knowledge on the impact of eating habits and the occurrence of parafunctions on the development of temporomandibular disorders and the condition of masticatory muscles.

Determination of Reference Values of the Masseter Muscle Stiffness in Healthy Adults Using Shear Wave Elastography

“…The effect of age on stiffness has been reported in the literature for other muscles but not for the masseter muscle. Ekby et al [18] examined the stiffness of biceps brachii in a group of 133 healthy subjects and reported similar findings to our study. They found that shear modulus values increased with age in full extension of the muscle, especially in people over 60 years of age.…”

“…We analyzed data obtained from 140 healthy volunteers (74 men and 66 women) with a median age of 50 years (95% confidence interval (CI): 45.9-55). For women, the median The stiffness of the masseter muscle was measured with the Aixplorer Ultimate device (SuperSonic Imagine, Aix-en-Provence, France) using a high-frequency linear probe SL 18-5 (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). The obtained measurements were validated using the elasticity QA Phantom model 049A (Computerized Imaging Reference Systems, Inc, Norfolk, VA, USA).…”

“…Another limitation is that we examined only healthy adult subjects. The literature data show that the stiffness of the masseter muscle can increase in some disorders such as TMD [15] and after exercise [18], or decrease after applying therapeutic methods such as massage [11]. Therefore, this study shall be regarded as a reference for analyzing the disorders and conditions of the masseter muscle.…”

Stiffness of the Masseter Muscle in Children—Establishing the Reference Values in the Pediatric Population Using Shear-Wave Elastography

“…For this reason, there is a need to characterize each of the muscles separately and provide values for the healthy muscle and each pathological condition individually. There is also a need to investigate factors influencing muscle stiffness such as age, treatments or exercise because such factors were proved to change masseter muscle stiffness in adults [34,35].…”

Assessment of the masseter stiffness in patients during conservative therapy for masticatory muscle disorders with shear wave elastography

“…The results of shear wave elastography were proved reliable and reproducible [ 17 , 18 ]. Furthermore, the literature reports suggest that this tool is reliable in measuring the changes in stiffness of the masseter muscle in response to physical therapy (namely massage) [ 19 , 20 ] and exercise [ 21 ], both of which may be used in TMD management. However, there is little evidence on the use of shear wave elastography to evaluate treatment effects in patients undergoing conservative treatment for masticatory muscle disorders.…”