Treatment of Periodontal Intra-bony Defects With a Volume Stable Collagen Matrix or Deproteinized Bovine Bone Mineral With 10% Collagen

Inclusion Criteria * Patients with localized or generalized periodontitis Stage III and Stage IV, Grade A-B-C * Males and females * Age at least 18 years and older * Presence of interdental intra-bony defects (I, II and III walls) in either the maxilla or the mandible with a PD ≥ 6 mm * Defects with an intra-bony component \> 3 mm for both groups * Intra-bony defect located only at one aspect (mesial or distal) * Presence of at least 2 mm of keratinized soft tissue. Exclusion Criteria * Patients with systemic disease that could interfere with periodontal wound healing * Prolonged antibiotic treatment or anti-inflammatory treatment within 4 weeks prior to surgery * Pregnant or lactating * Smokers with \> 10 cig./day * Patients with FMPS and FMBS \> 25 % after completion of non-surgical periodontal therapy * Multi-rooted teeth with furcation involvement * Third molars * Teeth with circumferential defects * Interdental craters * Written Informed Consent