Ultrasonography: A step forward in temporomandibular joint imaging. A preliminary descriptive study

Ultrasonography (USG) is a cost-effective and noninvasive imaging modality commonly employed for imaging the abdominal region and extremities. Currently, with the availability of higher frequency probes and higher resolution devices, USG imaging of the temporomandibular joint (TMJ) looks promising. The aim is to evaluate and demonstrate the role of USG as an imaging modality of TMJ by visualizing the static and dynamic relationship of the joint, assessment of joint space and eliciting reproducibility at both open and closed mouth positions. 30 volunteers were selected based on the inclusion criteria in line with the research diagnostic criteria/temporomandibular disorders guidelines. High-resolution USG (≥12 MHz) of the right TMJ (chosen for uniformity) was done in the left decubitus position on (n=30) volunteers. The joint disc movement was directly visualized during opening and closing motions. The vertical joint space was assessed using the firmware and accurate reproducibility was checked. At the closed mouth position, the measured values ranged from 0.2 mm to 0.7 mm with a median of 0.05 cm and a mean of 0.4 0.15 mm. At the position of maximal mouth opening, the measured values ranged from 0.9 mm to 1.5 mm with a median of 1.1 mm and a mean of 1.1 0.17 mm. USG enables visualization of the dynamic relationship between joint structures, with particular importance to the condyle and disc position. The articular disc appears on the USG as a thin layer of hyperechogenicity surrounded by a hypoechoic halo, located between 2 hyperechoic lines viz, the condyle and the articular eminence We recommend ultrasonographic imaging as a noninvasive diagnostic technique with relatively high specificity for patients with temporomandibular disorders.