Purpose: The purpose of this study was to determine whether the clinical outcome of TMJ prolotherapy is dependent on dextrose concentration.Patients and Methods: This study included eighteen patients with symptomatic subluxation or dislocation of the TMJ who randomly assigned into one of two equal-sized groups. Patients in group A received 4 injections of dextrose solution consisted of 2 ml of 5% dextrose and 1 ml of 2% mepivacaine, whereas patients in group B received injections of another dextrose solution consisted of 2 ml of 10% dextrose and 1 ml of 2% mepivacaine. Each patient received four injections each six weeks apart for each TMJ. A verbal scale expressing TMJ pain at rest, TMJ pain at function, maximal mouth opening (MMO), clicking sound, and frequency of luxations per day were assessed at each injection appointment and 3 months after the last injection. The collected data were then statistically analyzed.Results : By the end of the study, each group was pain free at rest and showed significant improvement in TMJ pain at function, MMO and clicking sound as well. Contrary, the frequency of luxation was insignificant in each group. The differences throughout the study intervals between the both groups in pain on rest and clicking were not statistically significant. But in MMO and frequency of luxation were insignificant except in 4th visit. On the other hand, differences in pain on function in both groups were significant except after 3 months follow up period. Conclusion: Based on these observations of this study, both isotonic and hypertonic dextrose is promising and effective in rehabilitation of the symptomatic hypermobile tempromandibular joint, that may support the believe that the precise concentration of dextrose is not critical as it is strongly hypertonic solution. However, prospective studies with large sample sizes and long-term follow-up are needed.