Ulcers caused by mucosal irritation of fixed orthodontic appliances remain an unsolved problem, and more research is needed to improve the pain caused by orthodontic appliances to provide more comfortable treatment for these patients. This study investigated the effect of probiotic Lactogum on pain and ulceration in patients undergoing fixed orthodontic treatment. In this study, 64 patients over 12 years of age and candidates for fixed orthotic treatment were divided into case and control groups (n=32). The control group received orthodontic waxes, and the case group received the same orthodontic waxes and "Lactogum" probiotic lozenges from the beginning of the treatment. The number of ulcers, the amount of pain, and the location of the ulcer were recorded and compared between the two groups. An independent-sample t-test was used to compare the pain level and number of ulcers between the two groups. A significance level of 0.05 was considered for all tests. SPSS 17 was used for data analysis. The mean number of ulcers in the case group was significantly lower than the control group (P<0.001). The mean pain in the case group was significantly lower than in the control group (P<0.001). The most frequent location of ulcers was the buccal mucosa, followed by the labial mucosa. Lactogum probiotic lozenges can reduce traumatic oral ulcers and pain levels in patients undergoing fixed orthodontic treatment. However, larger clinical trials are encouraged to confirm these findings.