Orofacial aspects of juvenile idiopathic arthritis in children

Abstract

Aims: This thesis, which investigates orofacial aspects and temporomandibular joint (TMJ) involvement in juvenile idiopathic arthritis (JIA), aims to improve knowledge about the variables to include in a clinical examination, radiographic imaging techniques, and whether saliva can be used as a medium for disease monitoring.

Material and methods: In a prospective longitudinal study comprising 59 children diagnosed with JIA, clinical and radiological data were collected. Demographic data and data on patient history of localized pain and dysfunction were recorded. Clinical examinations were performed according to the Research Diagnostic Criteria for Temporomandibular Disorders at baseline and repeated after one year and after two years. Radiological examinations were performed with panoramic imaging (PAN) and cone beam computed tomography (CBCT) at baseline and at the two-year follow-up. A classification system for how to grade TMJ morphology on PAN and CBCT was proposed and evaluated using radiological data from this longitudinal study. In a case control study, stimulated whole saliva was collected from 30 children with JIA and 30 healthy age-matched controls. Self-reported orofacial pain was recorded, and saliva flow rate calculated. Saliva samples were analyzed for presence and concentration of 21 immunological active proteins using the Luminex system and customized R&B bead-based immunoassay.

Results: The result from the longitudinal study showed a higher proportion of TMJ deformities in children self-reporting TMJ pain and dysfunction. However, self-reported pain was not predictive of change in TMJ status over time. TMJ deformities were associated with a smaller maximum unassisted mouth opening (MUO), palpatory TMJ pain, and TMJ crepitations, but palpatory muscle pain, although common, did not correlate with TMJ deformities. Predictive of finding TMJ deformities was number of years with disease and a smaller MUO. When using the proposed classification system for TMJ morphology, PAN and CBCT recognized presence of TMJ abnormality equally well. The reliability of PAN to distinguish between normal and abnormal TMJ morphology was good, and CBCT was found to be superior for assessing the severity of TMJ abnormality. Regarding presence of immunological biomarkers in saliva, 14 of 21 examined proteins were found in the saliva samples. However, no significant differences in concentrations were found between children with JIA and healthy children. No difference in saliva flow rate was observed between children with JIA and controls, but there was an association between lower salivary flow rate and children reporting orofacial pain regardless of group.

Conclusion: In children with JIA, self-reported TMJ pain and dysfunction were common. A high degree of TMJ deformities were found, but clinical variables only showed subtle variations from what is considered normal. No single clinical variable was found to predict or indicate TMJ involvement in JIA. Regarding radiological methods evaluated, the technique that provides diagnostically acceptable information at the lowest radiation dose should be used. The result showed that PANs can be used to determine whether TMJ deformities are present in children with JIA; however, this finding needs to be confirmed in future studies. Furthermore, with the current level of knowledge and based on the results presented, saliva cannot be recommended as a medium for monitoring disease activity in JIA.