Incidence of temporomandibular involvement in juvenile idiopathic arthritis

Temporomandibular joint (TMJ) involvement is a frequent feature in cross-sectional prevalence studies among juvenile idiopathic arthritis (JIA) patients. The cross-sectional design makes it almost impossible to study the incidence. Follow-up data on TMJ involvement are sparse. In this study patients were reviewed with an interval of a minimum of 1 year and a maximum of 2 years to study the yearly incidence of TMJ involvement and to obtain follow-up data on TMJ involvement and orthopantomogram (OPT) alterations.

Children with JIA from a previous study on TMJ involvement were included. OPTs were scored according to Rohlin's grading system (grade 0-5). A paediatric rheumatologist measured the level of disease activity during the interval.

Eighty-nine of the 97 patients were included in this study with a mean follow-up of 14 months. The yearly incidence of TMJ involvement was 7.1% in patients with JIA. Improvement on the OPT was seen in 27 patients (66%), and 19 of these patients no longer showed any signs of TMJ involvement. Worsening on the OPT was seen in four patients (10%). Disease activity was significantly lower in the improved patients than in the patients with worsening.

Condylar lesions due to arthritis can improve over time, indicating a regenerative capacity of the mandibular condyle. As condylar improvement seems to be associated with low disease activity, it is important to consider the TMJ when deciding on a therapeutic regimen.