Efficacy of Hamstring Stretching, Ultrasound Therapy, and Pressure Pain Threshold for Masseter Muscle in TMJ Dysfunction Patients: A Randomized Controlled Trial

Abstract

Aim: This study aims to evaluate the impact of adding bilateral hamstring muscle stretching to pressure pain threshold and ultrasound therapy, compared to using pressure pain threshold and ultrasound therapy alone, on pain reduction and maximum vertical mouth opening (MVMO) in individuals with temporomandibular disorders (TMD).

Materials and methods: A total of 56 participants diagnosed with TMD were randomly allocated into 2 groups: The Experimental Group, which received bilateral hamstring stretching, pressure pain threshold application, and ultrasound therapy, and the control group, which received only pressure pain threshold and ultrasound therapy. The study included participants of both genders, aged between 18 and 35 years, with a previous history of TMD pain lasting no longer than 6 months. Assessments were conducted at baseline and after 5 treatment sessions per week over 1 week. Pain levels were measured using the visual analog scale (VAS), and MVMO was assessed using a vernier caliper. Data were recorded and statistically analyzed.

Results: The results showed a significant reduction in pain and an increase in MVMO in both groups. In the Experimental Group, the mean pain score on the VAS decreased from 6.8 ± 1.2 to 2.9 ± 1.1, whereas in the control group, it decreased from 6.7 ± 1.3 to 4.1 ± 1.2 (p < 0.001). Similarly, MVMO improved significantly, with an increase from 31.4 ± 2.6 mm to 39.8 ± 2.1 mm in the Experimental Group, compared to an increase from 31.2 ± 2.8 mm to 36.1 ± 2.4 mm in the control group (p < 0.001). The between-group comparison showed a significant difference in pain reduction and MVMO improvement in the Experimental Group compared to the control group (p < 0.001).

Conclusion: Hamstring stretching combined with ultrasound therapy and pressure pain threshold application was significantly more effective in reducing TMD-related pain and improving MVMO than pressure pain threshold and ultrasound therapy alone. These findings indicate that integrating hamstring stretching into TMD treatment protocols could improve rehabilitation outcomes.

Clinical significance: The findings of this study highlight the potential benefits of integrating hamstring stretching into standard physiotherapy interventions for TMD. Given the significant improvements observed in pain reduction and MVMO, clinicians may consider including hamstring flexibility exercises in rehabilitation programs for TMD patients to achieve better functional outcomes. How to cite this article: Irusappan S, Kurusumuthu FSM, Ramachandran S. Efficacy of Hamstring Stretching, Ultrasound Therapy, and Pressure Pain Threshold for Masseter Muscle in TMJ Dysfunction Patients: A Randomized Controlled Trial. J Contemp Dent Pract 2025;26(1):34-39.

Keywords: Hamstring stretching; Maximum vertical mouth opening; Pain; Pressure pain threshold; Temporomandibular joint dysfunction Ultrasound therapy..