Trans-lymphatic contrast-enhanced ultrasound with sentinel lymph node biopsy for detecting cervical skip metastasis to lymph nodes in early-stage oral tongue squamous cell carcinoma.

OBJECTIVES: The purpose of this study was to assess whether trans-lymphatic contrast-enhanced ultrasound (CEUS) combined with sentinel lymph node biopsy can be used to assess the status of cervical lymph nodes and skip metastasis in patients with early squamous cell carcinoma (SCC) of the oral tongue. METHODS: This study included 21 subjects with early oral tongue SCC who received multiple intramucosal peritumoral injections of Sonazoid. CEUS examinations were performed immediately after Sonazoid injection to identify sentinel lymph nodes (SLNs). The SLNs were excised for histological examination to determine if the lymph nodes has metastases. RESULTS: Thirty-five SLNs were detected by CEUS after Sonazoid injection in the subjects. SLNs were identified in 20 of the total 21 subjects. Four participants had metastasis to lymph nodes, and one had skip metastasis in level Ⅲ. In one subject, SLNs were successfully detected in level Ⅳ without skip metastasis. CONCLUSIONS: Trans-lymphatic CEUS combined with sentinel lymph node biopsy showed high accuracy for evaluating cervical lymph node status. This could be a reliable approach for detecting cervical skip metastases of lymph nodes in early-stage oral cancer patients.

[Three-dimensional finite element analysis on the effect of posterior cross-bite of individual teeth on temporomandibular joint].

OBJECTIVE: To analyze the stress distribution of temporomandibular joint (TMJ) in posterior cross-bite of individual teeth and in normal occlusion during the intercuspal occlusion (ICO). METHODS: On the basis of the geometric TMJ model of normal occlusion, the TMJ finite element model of posterior cross-bite of individual teeth was reconstructed. The occlusal force and boundary conditions were applied on the model. Using three-dimensional finite element method (FEM), the stress distribution of TMJ in posterior cross-bite of individual teeth was analyzed by simulating the ICO load. RESULTS: No significant differences were found in stress distribution in various TMJ structures between posterior cross-bite of individual teeth and normal occlusion. However, the stress level was higher and the stress distribution was more inhomogeneous in posterior cross-bite of individual teeth than in normal occlusion. In the cross-bite malocclusion of individual posterior teeth, the maximum of von Mises stress was 0.792 MPa, the maximum principal stress was 0.598 MPa and the minimum principal stress was -0.744 MPa. But in normal occlusion, the maximum of von Mises stress was 0.592 MPa, the maximum principal stress was 0.395 MPa and the minimum principal stress was -0.554 MPa. CONCLUSIONS: When the ICO load was applied, the stress distribution of TMJ was more inhomogeneous and the stress level was higher in posterior cross-bite of individual teeth than in normal occlusion.