Immediate effects of myofascial release and post-isometric relaxation on muscle properties and pain in symptomatic bruxism: A randomized, controlled, double-blind trial

Objective This double-blinded randomized controlled trial investigated the immediate effects of myofascial release (MFR) and post-isometric relaxation (PIR) on muscle stiffness, tone, pain, and maximum mouth opening (MMO) in individuals with bruxism, compared with a control group. Methods Sixty participants were randomized into MFR (n = 20), PIR (n = 20), or control groups (n = 20). Each intervention was a single standardized session. The primary outcomes were muscle stiffness and tone, while secondary outcomes included pain severity (VAS), and MMO. Results Both MFR and PIR significantly reduced masseter and sternocleidomastoid stiffness and tone (p < .05), except left sternocleidomastoid stiffness in MFR, with no changes in controls. MFR was superior to control for pain (p = .010) and masseter stiffness (p = .030), while PIR showed superiority only for left tone (p = .034). Both interventions reduced VAS scores (p < .001) and improved MMO (p < .05). Conclusion A single MFR or PIR session reduced stiffness, tone, and pain and improved MMO in bruxism. MFR showed stronger effects, whereas PIR yielded limited benefits.