Dynamic Quantitative Imaging of the Masseter Muscles in Bruxism Patients with Myofascial Pain: Could It Be an Objective Biomarker?

Examination of the masseter muscle in patients with hemifacial microsomia using high-frequency ultrasound and shear wave elastography

BACKGROUND

This study aimed to prospectively investigate the reference values for masseter muscle thickness and hardness using ultrasonography and shear wave elastography, respectively, in patients with hemifacial microsomia (HFM).

METHODS

We enrolled 51 patients, aged 5-20 years, with HFM including 31 males and 20 females. The upper-lower, left-right, and anterior-posterior diameters of 102 masseter muscles and stiffness of 98 masseter muscles were determined by examining the unaffected and affected sides of each participant's face.

RESULTS

The upper-lower, left-right, and anterior-posterior diameters of the masseter muscle were significantly smaller at rest (4.26 ± 0.83, 2.94 ± 0.75, and- 0.80 ± 0.25 cm, respectively) and during contraction (3.95 ± 0.78, 2.71 ± 0.78, and 0.87 ± 0.29 cm, respectively) in the affected side than those in the healthy side (5.45 ± 0.66, 3.87 ± 0.49, and 0.97 ± 0.20 cm, respectively, at rest and 4.99 ± 0.45, 3.49 ± 0.53, and 1.07 ± 0.23 cm, respectively, during contraction, p < 0.05). In the resting state, the hardness of the masseter muscle on the affected side (0.77 ± 0.66 m/s) was significantly greater than that on the healthy side (0.42 ± 0.41 m/s; p < 0.05). The magnitude of changes in the upper-lower, left-right, and anterior-posterior diameters of the biting muscle in the occlusal state were significantly smaller on the affected side (-0.30 ± 0.27, -0.23 ± 0.17, and 0.08 ± 0.08 cm, respectively) than those in the healthy side (-0.47 ± 0.38, -0.37 ± 0.25, and 0.10 ± 0.12 cm, respectively, p < 0.05).

CONCLUSIONS

The knowledge of these values allows for better understanding of the disease characteristics of HFM, which may be used for its diagnosis, treatment, and prognosis. Patients experiencing different severity levels exhibited significant differences in the morphology and function of the masseter muscle on the affected-side (p < 0.05).

EVIDENCE LEVEL

Level III.

Population Analysis of Masseter Muscle Tension Using Shear Wave Ultrasonography across Different Disease States

Objective: This study aimed to evaluate the distribution and trends of masseter muscle tension in patients with temporomandibular joint (TMJ) pain, examining gender-specific differences and the impact of various TMJ disorders. Methods: From January 2020 to June 2024, a total of 734 patients presenting with facial pain radiating to the head and neck, localized around and extending from the TMJ, were referred for ultrasonographic examination. After applying exclusion criteria, 535 patients (72.9%) were included in the study. The patient cohort consisted of 343 females (64.1%) and 192 males (35.9%), with muscle tension measured using the Aixplorer ultrasound system equipped with a shear wave device. Data were collected and analyzed across different age groups and TMJ conditions, including "no changes", "exudate", "arthrosis", and "disc displacement". Results: The study found that males exhibited higher muscle tension across all conditions, particularly in the "no changes" (40.4 kPa vs. 32.1 kPa, 25.9% higher) and "exudate" (38.5 kPa vs. 29.7 kPa, 29.6% higher) categories, indicating increased muscle strain and inflammation during middle age. In females, a trend of decreasing muscle tension with age was observed, with a significant reduction from 36.2 kPa in the 20-30 age group to 24.3 kPa in the 60-70 age group (32.9% reduction), suggesting a reduction in muscle mass or strength due to aging. Both genders showed high muscle tension in the presence of exudate, with females peaking in the 40-50 age group at 37.1 kPa and males peaking earlier in the 20-30 age group at 41.2 kPa (10.9% higher in males), highlighting potential gender differences in inflammatory response. In the arthrosis group, males displayed a consistent increase in muscle tension with age, peaking at 37.5 kPa in the 50-60 age group (50.7% increase from the 20-30 age group), while females showed high tension, particularly in the 40-50 age group at 31.0 kPa (82.4% higher compared to the 20-30 age group), indicating the need for targeted joint health interventions in middle-aged women. Conclusions: This study reveals significant gender-specific differences in masseter muscle tension among patients with TMJ pain. Males were found to be more affected by muscle strain and inflammation during middle age, whereas females showed a significant decrease in muscle tension with age. The presence of exudate significantly impacted muscle tension across all age groups for both genders. These findings underscore the importance of tailored clinical interventions and preventive strategies to manage TMJ disorders effectively.

Comparison of ultrasonography-based masticatory muscle thickness between temporomandibular disorders bruxers and temporomandibular disorders non-bruxers

To compare masticatory muscle thickness in patients with temporomandibular disorders (TMDs) during rest and clenching, and by body position, using ultrasonography. This prospective study included 96 patients with TMD (67 females, 29 males; mean age: 40.41 ± 17.88 years): group 1, comprising 66 patients with TMD without bruxism (TMD_nonbruxer), and group 2, comprising 30 patients with concurrent TMD and bruxism (TMD_bruxer). In patients with TMD, bruxism was correlated with the presence of tinnitus, muscle stiffness, sleep problems, psychological stress, and restricted mouth opening. The masseter muscle significantly thickened during clenching (11.16 ± 3.03 mm vs 14.04 ± 3.47 mm, p < 0.001), whereas the temporalis muscle showed no significant increase in thickness from resting to clenching in an upright position (7.91 ± 1.98 vs 8.39 ± 2.08, p = 0.103). Similarly, during clenching in the supine position, the masseter muscle was significantly thicker compared with rest (11.24 ± 2.42 vs 13.49 ± 3.09, p < 0.001), but no significant difference was observed in temporal muscle thickness (8.21 ± 2.16 vs 8.43 ± 1.94, p = 0.464). In comparison between two groups, the average thickness of the masseter muscle was greater among TMD_bruxers than among TMD_nonbruxers in both the upright and supine positions (all p < 0.05). In the generalized lineal model, female sex (B = - 1.018, 95% confidence interval [CI] - 1.855 to - 0.181, p = 0.017) and bruxism (B = 0.868, 95% CI 0.567 to 1.169, p = 0.048) significantly predicted changes in masseter muscle thickness. Female sex (B = - 0.201, 95% CI - 0.299 to - 0.103, p = 0.011), increased age (B = - 0.003, 95% CI - 0.005 to 0.000, p = 0.038), and muscle stiffness (B = - 1.373, 95% CI - 2.369 to - 0.376, p = 0.007) were linked to decreased temporal muscle thickness. Comparing TMD nonbruxer and bruxer muscle thicknesses in upright and supine positions revealed significant increased thickness in the masseter muscle during clenching but not in the temporalis muscle. Masseter muscle thickness varied significantly by sex, body position, and resting/clenching, notably influenced by bruxism. These findings emphasize the relevance of these factors in clinical examinations of patients with TMD.

Prevalence of Bruxism in alcohol abusers: a systematic review conducted according to PRISMA guidelines and the cochrane handbook for systematic reviews of interventions

BACKGROUND

Bruxism, a common oral parafunctional behavior characterized by the grinding or clenching of teeth, is a multifactorial condition with potentially detrimental effects on oral health and overall well-being. In recent years, there has been growing interest in understanding the relationship between bruxism and alcohol abuse, as both are prevalent issues that may share underlying factors and exacerbate each other. This systematic review, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, aims to evaluate the frequency of bruxism among individuals with alcohol abuse.

METHODS

A comprehensive search of electronic databases, including PubMed, Lilacs, Scopus and Web of Science, will be conducted to identify relevant studies published up to the knowledge cutoff date in January 2023. The search strategy will include keywords related to bruxism, alcohol abuse, and their synonyms. Inclusion criteria will encompass original research studies, such as observational, cross-sectional, cohort, and case-control studies, as well as clinical trials, that examine the relationship between bruxism and alcohol abuse. Two independent reviewers will perform the study selection, data extraction, and quality assessment, with discrepancies resolved by consensus.

RESULTS

The systematic review will present a summary of the identified studies, including the study design, characteristics of the study populations, and key findings related to the association between bruxism and alcohol abuse. The potential mechanisms underlying this relationship will also be explored. Subgroup analyses and the quality of evidence will be assessed. Finally, the implications of this association for clinical practice and further research will be discussed.

CONCLUSIONS

This systematic review will contribute to a better understanding of the interplay between bruxism and alcohol abuse, shedding light on potential risk factors, mechanisms, and clinical implications. The findings may have significant implications for the prevention, management, and treatment of bruxism, particularly in individuals with a history of alcohol abuse.