Juvenile chronic arthritis. Dentofacial morphology, growth, mandibular function and orthodontic treatment.

In children with Juvenile Chronic arthritis (JCA), temporomandibular joint involvement may lead to disturbances in dentofacial growth and mandibular function. The aim of this thesis was to study the dentofacial morphology, temporomandibular joint destruction and mandibular function in JCA children, and the relation between these factors. The intention was also to make a longitudinal study of the changes in facial morphology during growth and during treatment with functional appliances. Thirty-five JCA children, 12 boys and 23 girls, aged 7-16 years (mean 11.2 years), and the control groups, with either normal or distal occlusion, were studied by means of panoramic radiographs, lateral cephalograms, study casts, recordings of signs and symptoms of temporomandibular disorders (TMD), bite force and chewing characteristics. A method to evaluate the condylar height on panoramic radiographs was developed. Panoramic radiographs are found to be reliable for evaluation of the condylar height, provided the same panoramic machine is used. The dentofacial morphology in JCA children is characterized by a smaller, more retrognathic and steeper inclined mandible compared to that of healthy children with ideal occlusion. Compared to healthy children with distal occlusion, no difference in mandibular retrognathia could be demonstrated but the JCA children showed a smaller, more steeply inclined mandible. The presence and extent of condylar lesions play a significant role in the development of the facial morphology and also contribute to the facial heterogeneity among JCA children. During growth the JCA children without radiographically visible condylar lesions showed a growth pattern resembling that of healthy children with normal occlusion, while children with condylar lesions showed aggravation of the mandibular retrognathia and a tendency towards a backward-rotating growth pattern. The chewing movements in JCA children are restricted by the disease and by the presence of condylar lesions. In JCA children with distal occlusion, interaction between both factors (JCA and malocclusion) resulted in further alterations of the chewing movements and chewing velocity. Subjective signs and clinical symptoms of TMD are more frequently found in JCA children, some of which are significantly correlated to radiographic changes in the condyle. The bite force and the endurance time are about half of that of healthy children. A low molar bite force is significantly correlated to a low mouth-opening capacity. The orthodontic treatment with functional appliances resulted in improvement in the dental malocclusion, while the skeletal effects were of minor magnitude in both the JCA children and in healthy children with distal occlusion.(ABSTRACT TRUNCATED AT 400 WORDS)