The aim of this study is to investigate the clinical efficacy of entire papilla preservation technique with and without the adjunct of amelogenins (EMD) and bone substitutes.

The present study is designed as a single-centre, parallel group, randomized, controlled clinical trial comparing the efficacy of EPP with or without biomaterials. Each patient will contribute with a single intrabony defect. Three months after completion of initial periodontal therapy, all the experimental sites will be accessed with the "EPP" technique (Aslan et al., 2017a) and carefully debrided. EDTA gel will be applied on the instrumented root surfaces. A combination of EMD and deproteinized bovine-derived bone substitute will be applied in the test group (EPP EMD + BS), while the control group (EPP) will not receive any regenerative biomaterial. Patients will be enrolled in a stringent maintenance programme with recalls on a weekly basis for the first month and then monthly controls for professional tooth cleaning up to 1 year. Clinical parameters will be recorded immediately before regenerative surgery (baseline) and 12 months after the regenerative periodontal surgery.

Inclusion Criteria:

• Systemically healthy
• Clinical diagnosis of advanced periodontitis
• Having one isolated intrabony defect with probing depth (PD) ≥7 mm, clinical attachment level (CAL) ≥8 mm and at least 4 mm intrabony component involving predominantly the interproximal area of the affected tooth.
• Full-mouth plaque score (FMPS) ≤20%.
• Full-mouth bleeding score (FMBS) ≤20%.

Exclusion Criteria:

• Smokers
• Patients with known systemic diseases such as diabetes and cardiovascular diseases or using medications that affect periodontal tissues, pregnant or lactating women
• One-wall intrabony defects
• Defects that involve buccal and lingual sites
• Presence of inadequate endodontic treatment and/or restoration in the relevant teeth.