Abstract
Prolonged smartphone use can lead to cervical posture deformities, with cervical extension type being a common condition characterized by increased cervical lordosis, forward head posture, and thoracic kyphosis. These changes may contribute to neck pain, restricted cervical range of motion (ROM), and increased muscle tone. Additionally, cervical extension type is linked to temporomandibular joint (TMJ) dysfunction, affecting mandibular movement and muscle activity. Given the biomechanical connection between the cervical spine and TMJ, addressing cervical dysfunction may benefit TMJ related conditions. This study compared the effects of jaw exercises combined with cervicoscapular exercises versus cervicoscapular exercises alone on mouth opening ROM, mastication muscle properties, and pressure pain threshold (PPT) in individuals with cervical extension type. Thirty-four subjects were randomly assigned to two groups: the experimental group (seventeen subjects) performed jaw exercises combined with cervicoscapular exercises, while the control group (seventeen subjects) performed only cervicoscapular exercises. After 4 weeks, significant improvements were observed in both groups in the mouth opening ROM, muscle properties, and PPT (p < 0.05). The experimental group showed significantly greater improvements in protrusive excursion, the masseter muscle tone, and the stiffness of the masseter and temporalis anterior muscles compared to the control group (p < 0.025). Both groups demonstrated significant increases in the PPT (p < 0.05). These findings suggest that incorporating jaw exercises into cervicoscapular training may provide additional benefits for individuals with cervical extension type, particularly those experiencing temporomandibular joint (TMJ) dysfunction. Further studies are needed to validate these results in a larger and more diverse population.