The main purpose of the trial is to investigate the effect of locally delivered ciclosporin as an adjunct to non-surgical mechanical debridement in the treatment of chronic periodontitis and to compare it to mechanical debridement alone.

Inclusion Criteria:

• Patients in good general health
• 2 pairs of contralateral interproximal periodontal sites with probing depths of ≥7mm in single-rooted teeth not associated with furcations or root furrows.The test sites should have a distance of at least two teeth to the control sites.
• Teeth selected should have a vital pulp as determined by thermal or electric stimulation

Exclusion Criteria:

• Patients already included in other clinical trials involving therapeutic intervention (either medical or dental)
• Periodontal treatment during the last 6 months
• Antibiotic treatment 6 months prior to the start of the trial
• Antibiotic prophylaxis required for dental treatment
• Patients with acute infectious lesions in the areas of intended treatment
• Regular anti-inflammatory medication
• Known history of ciclosporin allergy
• Ongoing medication that may affect the clinical features of periodontitis
• Patients who are smokers
• Patients that are immuno-compromized or on immunosuppressive medication
• Patients who are pregnant or lactating