Objective <p>To evaluate the intra-articular injection of 5% Dextrose efficacy in treating difficulty chewing patients with Temporomandibular Joint (TMJ) Closed Lock (CL).</p> Materials and methods <p>This pilot study included twenty female patients suffering from symptoms of Disc Displacement without Reduction (DDwoR) with limited mouth opening (Closed Lock) mentioned in the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Participants were randomly assigned into two groups; the study group patients were injected with D5W, while the control group patients were injected with 0.9% normal saline. The chewing Pain Index (CPI) was measured based on the criteria recommended by the International Association of Oral and Maxillofacial Surgeons (IAOMS) that assessed mandibular function by relating pain with the type of food eaten and using it as an index of improvement in function. The CPI was measured before and thrice after injection (2 weeks, 2 months, and 6 months). The significance level was set at α = 0.05.</p> Results <p>A decrease in the CPI grades was observed in both groups, with a significant difference in favor of the study group at all follow-up times(&lt; 0.001).</p> Conclusion <p>D5W improved the chewing function in female closed-lock patients.</p>