Ultrasound assessment of temporomandibular joint capsule-condyle distances across Angle's occlusal classifications

To investigate the morphological characteristics of the temporomandibular joint (TMJ) capsule-condyle distance using ultrasound imaging in individuals with different Angle's occlusal classifications.

Ultrasound imaging was performed in both transverse and longitudinal planes, capturing measurements with the mouth closed and open. Six specific joint space distances were recorded: LLC, LLO, LTC, LTO, ATC, and ATO.

All six joint space measurements showed significant deviation from a normal distribution. Median values ranged from 0.9 mm to 1.1 mm, with interquartile ranges between 0.5 mm and 0.8 mm (P < .05). Venn diagram analysis demonstrated strong co-occurrence of altered joint spaces in both mouth positions. Pearson correlations revealed significant positive relationships between measurements, notably between ATC and LTC (r = 0.62) and between LLO and LTO (r = 0.52). Moderate correlations were also seen between open- and closed-mouth measurements. Occlusal classification and laterality had no significant effects on joint space (η² ≈ 2.92-2.95, P > .05).

Ultrasound assessments showed that TMJ capsule-condyle distances were not significantly affected by Angle's classification. This may reflect the limitation of ultrasound in detecting subtle morphological variations, suggesting a need for higher-resolution imaging in future studies.