Evaluation of the effects of occlusal splint and masseter muscle injection in patients with myofascial pain: a randomised controlled trial

Myofascial pain is one of the common symptoms in patients with temporomandibular joint disorders (TMD). Occlusal splint (OS) and masticatory muscle trigger point (TP) local injections are primary treatment options. We aimed to investigate the effects of these treatments using clinical and elastography measures. Patients who were diagnosed with myofascial pain according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were included. There were 16 patients in each group. Group 1 was treated with occlusal splint, Group 2 was treated with occlusal splint and masseter muscle lidocaine injection, Group 3 was treated with masseter muscle lidocaine injection and Group 4 consisted of healthy volunteers. Degree of pain and maximum mouth opening (MMO) were recorded. Masseter muscle stiffness was evaluated by Shear wave elastography. Measurements were repeated at 1st and 3rd months of post-treatment. Pain decreased at all times in all the patients (p = 0.001). Pain in Group 2 and Group 3 approached 0 level at 3rd month. MMO increased from baseline to 1st month and from 1st month to 3rd month and masseter stiffness decreased from baseline to 1st month and to 3rd month (p = 0.001) in all groups. Occlusal splint and masseter muscle lidocaine injection were effective in reducing pain and increasing MMO in patients with myofascial pain. All treatments reduced masseter muscle stiffness. All the treatment modalities had clinically similar and successful outcomes.