Shear wave elastography as a diagnostic method for bruxism

Abstract

Background: Bruxism is a common parafunctional activity that may alter the structural and mechanical properties of the masseter muscle. Shear wave elastography (SWE) provides a noninvasive and objective method for evaluating muscle stiffness. Despite increasing interest in SWE, its diagnostic value in bruxism has not been fully established.

Methods: This comparative study included 2 groups: a bruxism group and a healthy control group. Bruxism was diagnosed in accordance with the diagnostic criteria for temporomandibular disorders (DC/TMD) by a dentist with 20 years of clinical experience. The control group comprised volunteers without bruxism, confirmed using the same diagnostic criteria. All participants underwent B-mode ultrasonography (US) in the supine position with their heads tilted to the opposite side at rest. US was used to assess the length and thickness of the masseter muscles, while SWE was used to measure muscle stiffness, reported in kilopascals (kPa).

Results: Masseter muscle length was significantly shorter and SWE values were significantly higher in patients with bruxism compared to controls (P < .05). A cutoff SWE value of 13.55 kPa was identified, yielding a sensitivity of 86.0% and specificity of 87.5% for the diagnosis of bruxism. The sample size in this study was larger than in previous SWE-based bruxism studies, enhancing the reliability of these findings.

Conclusion: SWE demonstrates high diagnostic performance in identifying bruxism and may serve as a valuable objective tool in clinical practice. A threshold of 13.55 kPa can aid in distinguishing affected individuals with high sensitivity and specificity.

Keywords: bruxism; elasticity imaging techniques; mastication; sleep bruxism; ultrasonography.

Figure 1.

Inclusion and exclusion criteria.

Figure 2.

Masseter muscle (white arrowhead) in transverse plane with thickness measurement taken in thickest portion with mandibular cortex (white arrow) in parallel with probe.

Figure 3.

Masseter muscle SWE measurements with 2 mm ROI with 3 samples from each slice with an IQR/median value < 30%. IQR = interquartile range, ROI = region of interest, SWE = shear wave elastography.

Figure 4.

ROC curve analysis for masseter length (mm), thickness (mm) and elastography value (kPA). ROI = region of interest.