Abstract
Background & aim: Management of Temporomandibular joint disorders are challenging that necessitates continuous research of efficient treatment options. This study aimed at evaluating the clinical efficacy of magnesium sulfate injection in the treatment of myofascial pain in patients with parafunctional habits versus local anesthetic injection.

Methodology: Forty patients with myofascial pain disorder as a result of parafunctional habits are randomly assigned equally into two groups; the study group (group I) undergone injection with magnesium sulfate (MgSO4), 0.5ml for each trigger point, while the control group (group II) undergone injection with plain local anesthesia (3% Mepivacaine), 0.5ml for each trigger point. Repeated injections were performed within one week interval for one month. Each patient was assessed in terms of pain intensity, maximum mouth opening and lateral jaw motions pre-operatively, immediately pre-operatively and six months post-operatively.

Results: The results indicated a significant time improving effect with no significant difference due to group effect (either injection of our studied materials) and obviously no significant effect due to interaction between time and group (nearly same therapeutic effects). The effect size due to time was high regarding pain scores, MMO and was intermediate regarding both lateral movements; p value < .05
Conclusion: Injections of magnesium sulfate and local anesthesia are both useful in treating myofascial pain brought on by parafunctional habits.