Purpose and aims This as a pilot study that aims to investigate which inflammatory biomarkers can be found in saliva in children with Juvenile Idiopathic Arthritis (JIA).

The hypothesis is that children with JIA will show a different pattern of inflammatory biomarkers in saliva than healthy Children.

The null hypothesis is that there are no differences.

This is a comparison between 100 children with JIA and 100 healthy children. Saliva will be collected and analyzed with respect to biomarkers.

One-hundred consecutive patients with active JIA, as diagnosed by the Department of Pediatric Rheumatology, Astrid Lindgrens Barnsjukhus, Karolinska University Hospital will be included.

Inclusion criteria are:

• age between 7 and 14 years
• a diagnosis of JIA according to the International League of Associations for rheumatology

Exclusion criteria are:

• current malignancies
• TMJ surgery or trauma within two years
• recent intra-articular glucocorticoid injection in TMJ (within 1 month)
• other conditions or diseases than JIA that may cause orofacial pain. The parents of the patients and/or the patients will give their verbal and written informed consent to participate in the study according to the permission from the regional ethical committee 2011/2:1.

The control group of 100 age and sex matched healthy children will be included at Folktandvården Stockholms Län AB.

Inclusion criteria are:

• age between 7 and 14 years

Exclusion criteria are:

• current malignancies
• TMJ surgery or trauma within two years
• recent intra-articular glucocorticoid injection in TMJ (within 1 month)
• A diagnosis of JIA
• other conditions or diseases than JIA that may cause orofacial pain. The parents of the patients and/or the patients will give their verbal and written informed consent to participate in the study according to the permission from the regional ethical committee 2011/2:1.

Inclusion Criteria:

1. A diagnosis of JIA according to the International League of Associations for rheumatology (ILAR) The parents of the patients and/or the patients will give their verbal and written informed consent to participate in the study according to the permission from the regional ethical committee 2011/2:1

Exclusion Criteria:

1. current malignancies
2. TMJ surgery or trauma within two years
3. Recent intra-articular glucocorticoid injection in TMJ (within 1 month)
4. Other conditions or diseases than JIA that may cause orofacial pain. Fore the controllgroup JIA are excluded

Group 1: 40 consecutive patients with active JIA, as diagnosed by the Department of Pediatric Rheumatology, Astrid Lindgrens Barnsjukhus, Karolinska University Hospital will be included.

Group 2: 40 healthy children, age-and sex-matched.