To evaluate the impact of photobiomodulation therapy (PBMT) on injection pain perception and compare it with a topical oral anesthetic gel. A total of 30 patients of six to nine years old seeking pulpotomy treatment of maxillary secondary primary molars of both sides were considered for this split-mouth triple-blind randomized clinical trial. On one side of the maxilla, the low-level-laser (diode laser, 808 nm, 250 mW; 16.25 J; 32.5 J/cm ) was irradiated upon the buccal gingiva of the tooth, while a Benzocaine 20% topical anesthetic gel was applied on the other side. A gel with the same taste (strawberry) was applied for the placebo. The Wong-Baker Faces Pain Rating Scale was used to evaluate the injection pain and post-operation pain at two timestamps, one hour and 24 hours after treatment. Patients' heart rate was also evaluated. Paired-T, Wilcoxon-signed-rank test, McNemar and Friedman tests were used for statistical analyses. Results demonstrated that PBMT could significantly decrease the injection pain perception and heart rate alternations compared to the topical anesthetic gels (P=0.000). However, no significant differences were documented between the two methods concerning the 1hour (P=0.26) and 24-hours (P=1.00) post-operation pain. PBMT can be an effective non-pharmacological technique for controlling injection pain.