ROTTERDAM, The Netherlands, and PHILADELPHIA, Pennsylvania—Nearly half of children with newly diagnosed juvenile idiopathic arthritis (JIA) have involvement of the temporomandibular joint (TMJ). Two research groups studying the problem report that, once the underlying inflammatory arthritis is under control, the actual healing of the damaged condyles jaw problems might resolve. But magnetic resonance imaging (MRI) may be required for accurate diagnosis.^1,2

Marinka Twilt, MD, PhD, from Sophia Children’s Hospital in Rotterdam, The Netherlands, reported 5-year follow-up data from the Temporomandibular Joint Rheumatologic Involvement Project (TRIP).¹ The study of 84 children found that TMJ involvement had decreased to 40% at year 5 from 49% at baseline.

First report of regenerative of condyles

Patients with TMJ were younger at onset than those without jaw involvement. Those who had condylar alterations at year 5 also had significantly longer disease duration than those without condylar alterations.

Compared with baseline, involved condyles became normal by year 5 in 60% of patients with unilateral involvement and in 14% of those with bilateral involvement. In 9 of the 23 patients with bilateral TMJ involvement at baseline, severity had decreased to only unilateral involvement by year 5.

“Normalization of the alterations was seen in 27 (63%) of the 43 improved condyles [at 5 years]; therefore, the condyles were regenerated,” Dr. Twilt reported. Condylar involvement was evaluated by means of orthopantomogram (OPG) imaging. The investigators attribute the observed improvements to advances in treating JIA, including switching to second-line treatments earlier in the disease course. “Treatment has shifted gradually from chasing failure (gradual add-on approach) to early aggressive therapy. This early aggressive therapy will probably lead to low disease activity earlier in the course of the disease and might explain why condylar improvement has not been observed in past studies,” Dr Twilt said.

Dr. Twilt also pointed out that clinical signs of TJM arthritis such as limited chewing ability, limited maximal mouth opening, pain, pain during jaw excursion, clicking or crepitation, or mouth breathing, were scarce during the baseline examinations but that chances of TMJ involvement were high even in patients without such symptoms. This highlights the importance of using imaging early to bring “silent” TMJ arthritis in children with JIA under control. “[I]t does not only lead to growth disturbances of the mandible with consequent aesthetic problems, such as the well-known ‘bird face’ appearance, but it can also lead to oral health problems such as difficulty chewing, and can cause problems with intubations,” Dr. Twilt said. TMJ is thought to result from inflammatory disturbance of the growth center of the mandible, which is on the articular surface of the mandibular condyle.

Translating research into practice

Like Dr. Twilt’s group, Pamela F. Weiss, MD, at the Children’s Hospital of Philadelphia, recommends baseline screening for TMJ involvement in all children with new onset JIA.² Dr. Twilt said that MRI is the gold standard but is costly, requires sedation in small children, and is not avialable in all orthodontic and dental practices; OPG is more widely available in those settings. Ultrasound (US) has attracted interest as a potential screening method, but Dr. Weiss and colleagues found that US missed all of the cases of acute TMJ detected by MRI in 32 children with JIA and missed more than half of the cases of chronic TMJ arthritis.

“Findings on MRI along with responses to treatment among asymptomatic patients with normal jaw examination findings suggest that a history review and physical examination are not sufficient to screen for TMJ disease. Our results also suggest that MRI and US findings are not well correlated, and that MRI is preferable for the detection of TMJ disease in new-onset JIA,” Dr. Weiss said.

She found that 56% of JIA subjects who had TMJ arthritis identified on MRI had improved maximal incisal opening after corticosteroid injection. Of those, 71% had no clinical TMJ symptoms at baseline, and 63% had normal findings on baseline jaw examination. “Given the high prevalence of TMJ disease at the time of JIA diagnosis, and given that TMJ disease is often undetectable by jaw examination and history review, universal screening with MRI for TMJ arthritis at the time that JIA is diagnosed should be considered,” Dr. Weiss concluded.

References

1. Twilt M, Schulten AJM, Verschure F, et al. Long-term follow-up of temporomanibular joint involvement in juvenile idiopathic arthritis. Arthritis Care Res. 2008;59:546-552.
2. Weiss PF, Arabshahi B, Johnson A, et al. High prevalence of temporomandibular joint arthritis at disease onset in children with juvenile idiopathic arthritis, as detected by magnetic resonance imaging but not by ultrasound. Arthritis Rheum. 2008;58:1189-1196.