This study is meant to assess clinically and radiographically the possible predictable results regarding the use of nanocrystalline hydroxyapatite bone graft substitute together with papilla preservation flap versus papilla preservation flap alone in the treatment of periodontal intrabony defects. Patients will be randomly assigned to either test or control group. The two groups will be equally prepared for both surgical procedures. Then the decision of which group will receive (PPF techniques + Nanocrystalline hydroxyapatite bone graft) and which will receive (PPF techniques only) will be taken.

Treatment of intrabony defects has been indicated mainly to decrease the residual probing depths and so improve tooth prognosis. However, the rationale behind periodontal regeneration was to decrease the pocket depth, improve clinical attachment level and achieve bone fill of severely compromised tooth. However, application of all regenerative strategies needed to be protected by stable soft tissues to avoid exposure and bacterial contamination. That's why modified and simplified papilla preservation flap techniques were developed to maintain the primary closure of interdental sites. The modified papilla preservation technique was developed in order to achieve and maintain primary closure of the flap and to increase the ability to create space for regeneration in the interdental area. The modified papilla preservation technique could be successfully applied in sites in which the interdental space width is at least 2 mm at the most coronal portion of the papilla and in conjunction with a variety of regenerative materials as bone grafts. When interdental sites were narrower, a different papilla preservation procedure had been proposed, the simplified papilla preservation flap In the past years, different Alloplastic synthetic bone graft materials had shown clinical acceptance in the treatment of periodontal osseous defects.Recently, it has been claimed that there were promising results from using nano-sized ceramics as a class of bone graft substitutes due to their improved osseointegration properties. That's why a synthetic nanocrystalline hydroxyapeptite bone grafting material has been introduced for the augmentation of intrabony defects. This gave the nanocrystalline hydroxyapatite bone graft many advantages such as providing a close contact with the surrounding tissues, bioresorbability and extremely high number of nano-sized particles and molecules on the surface.

Inclusion Criteria:

• Patient-related criteria:

  • Patient consulting in the outpatient clinic.
  • Able to tolerate surgical periodontal procedures.
  • Patient ready to perform oral hygiene instructions.
  • Compliance with the maintenance program.
  • Provide informed consent.
  • Accepts the 6 months follow-up period.

Teeth related criteria:

• Mature permanent tooth.
• Tooth with two or three-walled intra-bony defect, CAL ≥ 5mm with intra osseous defect ≥ 3mm.

Exclusion Criteria:

• Patient-related criteria:

  • Medically compromised patients.
  • Pregnant or nursing women.
  • Uncooperative patients.
  • Smokers.

Teeth related criteria:

• Teeth with one wall intra-bony defect.
• Teeth with supra-bony defects.
• Teeth with grade II or III mobility.
• Teeth with proximal carious defects or proximal faulty restorations.

the records of the study participants will be assigned code numbers and the results will be assessed by a third party . coding will not be broken until all assessment and statistics will be completed