Vertical mouth opening in subjects with and without limited neck retraction

Poor head and neck posture has long been recognized as a contributing factor in headaches, cervical pain, facial pain patterns and temporomandibular joint dysfunction syndrome. The purpose of this study was to compare maximum interincisal opening at different degrees of head flexion between non-symptomatic subjects with and without limited neck retraction. Thirty subjects were divided into two groups. Subjects in group 1 (n=17), were able to move into normal estimated ranges of cervical retraction while subjects in group 2 (n=13), were able to reach normal estimated ranges for cervical retraction. Maximum interincisal opening was measured at 0, 15, and 30 degrees of head and neck flexion. No significant difference in maximum mouth opening was observed between the two groups and no interaction effect was identified between mean maximum mouth opening and degree of cervical flexibility. The findings of this study indicate further studies are needed on head and neck posture and its role in the perpetuation of symptoms of temporomandibular joint dysfunction