Background <p>Bruxism is a predominant behavior in children and is involved in the development of temporomandibular joint (TMJ) disease and myofacial pain. Bruxism can be classified into; sleep and awake bruxism or primary and secondary bruxism. This habit is characterized by a decrease in mouth opening, pain and increased activity of muscles of mastication and loud sounds during sleep. Management includes sleep hygiene, low-level lasers and physical therapy. The aim of this study was to evaluate changes in pain, mouth opening and muscle activity in children with bruxism after using laser acupuncture versus relaxation physical therapy.</p> Methods <p>Twenty-four children (6–12 years) with a history of bruxism were randomly allocated to 3 groups of 8 individuals each: Group 1: laser acupuncture; Group 2: physical therapy and Group 3: control. At baseline and after 2 months, the visual analog scale (VAS) score for pain (TMJ) score, maximum degree of mouth opening, and maximum voluntary contraction (MVC) score were recorded.</p> Results <p>Compared with the control group, the laser and physical therapy groups presented significant differences in pain, maximum number of mouth openings and MVC (p value are 0, 0.005 and 0 respectively).</p> Conclusions <p>Laser acupuncture and physical therapy are promising options for treating SB in children in terms of pain, mouth opening and muscle activity in comparison to sleep hygiene.</p> Trial registration <p>The study was registered on ClinicalTrials.gov on November 12, 2023, with ID: NCT06131879.</p>