The evaluation of lateral pterygoid signal intensity changes related to temporomandibular joint anterior disc displacement

Objectives The aim of this study was to evaluate lateral pterygoid muscle (LPM) signal intensity changes related to different degrees of disc status groups using magnetic resonance imaging (MRI). Methods Four groups were established according to disc displacement of examined temporomandibular joint (TMJ) and opposing TMJ. MRI scans were obtained with a 1.5 T device. The signal intensity was measured from the sagittal slice where midportion of the muscle belly was observed. The regions of interest were placed over the superior and inferior heads of LPM. To normalize differences in signal intensity, signal intensity of the grey matter and white matter of the brain was also measured. Signal intensity ratio (SIR) was calculated. Measurements were performed in both T1- and T2-weighted images. Results In the intergroup comparisons, a statistically significant difference was found for SIR1 sup., SIR1 inf., SIR2 sup. and SIR2 inf. variables ( p 0.05). For SIR1 sup., SIR1 inf., SIR2 sup. and SIR2 inf. variables, significant differences were found between five binary comparison groups (1–2, 1–3, 2–3, 0–2, 0–3) ( p