Ultrasonographic findings in normal temporomandibular joints.

The purpose of this study was to determine some ultrasonographic standards of temporomandibular joints with normally positioned discs. Nineteen patients from 18 to 45 years old (average age: 27.4 years; 16 females and 3 males), with history of orofacial pain, but without clinical or radiological signs of disc displacement, underwent ultrasonography (US) and magnetic resonance imaging (MRI) for the examination of their joints. In 30 joints, the distance between the most lateral point of the articular capsule and the most lateral point of the mandibular condyle (lateral capsule-condyle distance) was measured, as well as the distance between the most anterior point of the articular capsule and the most anterior point of the mandibular condyle (anterior capsule-condyle distance). In the closed-mouth position, the average values found for the lateral capsule-condyle distance were 1.4 mm and 1.6 mm, respectively in the longitudinal (coronal) and transverse (axial) scans. In the open-mouth position, the average distance was 1.2 mm, in both longitudinal (coronal) and transverse (axial) scans. The average values found for the anterior capsule-condyle distance were 2.3 mm in the closed-mouth position and 1.1 mm in the open-mouth position, both in transverse (axial) scans. Intra-examiner agreement, measured in terms of the intraclass correlation coefficient, varied from 0.83 to 0.93. We believe that this study can contribute to the validation of US as a diagnostic method for temporomandibular joint disorders, provided that the obtained measurements be used in future studies as normal reference values.