Clinical and instrumental tmj evaluation in children and adolescents with juvenile idiopathic arthritis: a case—control study

To investigate temporomandibular joint (TMJ) involvement signs such as muscle pain, the ratio of masseter and temporal muscle activity, mouth opening width and jaw deviation during mouth opening in children and adolescents with juvenile idiopathic arthritis (JIA), a group of 32 subjects with JIA and a control group of 32 healthy subjects were evaluated. Data were collected clinically by muscle palpation (masseters, anterior temporalis and sternocleidomastoids) and instrumental analysis (electromyography and kinesiography). Higher pain was registered in the masseter and sternocleidomastoid muscles on both sides and in the right anterior temporalis in the JIA group compared to the control group (p < 0.05). Electromyography showed no statistically significant difference in the frequency of the pathological ratio of masseter and temporal muscle activity (MM/TA < 1) both in the JIA group and in the control group. Kinesiography showed a statistically significant difference in mouth opening width and jaw deviation during mouth opening between the groups (p < 0.05): JIA subjects showed lower mouth opening values and wider deviation on mouth opening; 29 out of 32 JIA subjects showed jaw deviation towards the right side. JIA affects the TMJ, causing myalgia in the head and neck muscles, a reduction in mouth opening width and an increase in jaw deviation during mouth opening.