Hypotheses: The regular professional and individual plaque control in patients with rheumatoid arthritis (standard of care) - i.e. decreasing oral bacterial load, including P. gingivalis - reduces the activity of rheumatoid arthritis Principal objective: To assess the impact of professional periodontal scaling every 6 months combined with the individual plaque control, i.e. toothbrushing plus the use of mouthrinses on rheumatoid arthritis activity.