This study used 1.5 Tesla magnetic resonance imaging (MRI) to evaluate the positional and morphological changes of the disc and condyle in patients with closed lock treated nonsurgically. A total of 20 joints (19 patients) which were successfully unlocked by nonsurgical treatment were studied. Nonsurgical treatment was gradually applied a fbllows: 1. mandibular manipulation, 2. anterior splint assisted manipulation, 3. pumping manipulation, 4. stabilization splint therapy. The joints were evaluated by MRI in the closed-and open-mouth positions before and after treatment. Posttreatment MRI was also performed with the splint in place. Each imaging procedure was made in the same sagittal plane.
After treatment, 19 patients experienced significant improvement in pain, range of motion, and mandibular dysfunction. Post-treatment MRI revealed that only one joint was normal. Six joints had anterior disc displacement with reduction (DWR), and 13 joints had anterior disc displacement without reduction (DNR). Evidence of disc repositioning with the splint in place was seen in 4 joints in the DWR group. Disc mobility increased with improved condylar translation in 19 joints. Disc deformity progressed in 10 joints of the DNR group.
These results suggest that successful treatment for internal derangement with closed lock may require an increase in the mobility of the disc, regardless of disc position.