Juvenile idiopathic arthritis and the temporomandibular joint: a case-control study of magnetic resonance imaging findings in relation to clinical and psychosocial factors.

AIM: In juvenile idiopathic arthritis (JIA), the temporomandibular joint (TMJ) is a particularly challenging joint to assess both clinically and with imaging. The aim of this article is to investigate TMJ magnetic resonance imaging (MRI) findings in relation to clinical and psychosocial factors in patients with JIA and healthy individuals related to TMJ arthritis in JIA. MATERIALS: In total, 45 patients (6-16 years) with JIA and 16 healthy age- and sex-matched controls were examined according to the diagnostic criteria for temporomandibular disorders (DC/TMD). The subjects answered questionnaires about psychosocial factors (pain intensity, pain-related disability, depression, stress, catastrophising, pain locations, and jaw function) and underwent bilateral MRI of the TMJ. CONCLUSION: This study indicates a substantial overlap of TMJ MRI findings in both the inflammatory domain and the damage domain between JIA patients and healthy individuals. In JIA patients, the inflammatory MRI sign of bone marrow oedema seems to influence orofacial pain intensity.

Trabecular bone histomorphometric measurements and contrast-to-noise ratio in CBCT.

OBJECTIVES: The aim of this study was to evaluate how imaging parameters at clinical dental CBCT affect the accuracy in quantifying trabecular bone structures, contrast-to-noise ratio (CNR) and radiation dose. METHODS: 15 radius samples were examined using CBCT (Accuitomo FPD; J. Morita Mfg., Kyoto, Japan). Nine imaging protocols were used, differing in current, voltage, rotation degree, voxel size, imaging area and rotation time. Radiation doses were measured using a kerma area product-meter. After segmentation, six bone structure parameters and CNRs were quantified. Micro-CT (µCT) images with an isotropic resolution of 20 µm were used as a gold standard. RESULTS: Structure parameters obtained by CBCT were strongly correlated to those by µCT, with correlation coefficients >0.90 for all studied parameters. Bone volume and trabecular thickness were not affected by changes in imaging parameters. Increased tube current from 5 to 8 mA, decreased isotropic voxel size from 125 to 80 µm and decreased rotation angle from 360° to 180° affected correlations for trabecular termini negatively. Decreasing rotation degree also weakened correlations for trabecular separation and trabecular number at 80 µm voxel size. Changes in the rotation degree and tube current affected CNR significantly. The radiation dose varied between 269 and 1153 mGy cm(2). CONCLUSIONS: Trabecular bone structure can be accurately quantified by clinical dental CBCT in vitro, and the obtained structure parameters are strongly related to those obtained by µCT. A fair CNR and strong correlations can be obtained with a low radiation dose, indicating the possibility for monitoring trabecular bone structure also in vivo.