The aim of the present study was to compare between nanocrystalline hydroxyapatite and tricalcium phosphate carried on PRP membrane in treatment of Miller's class 1 gingival recession in human.

gingival recession (GR) is apical movement of the gingival margin beyond the cement-enamel junction. The use of free gingival grafts, sliding pedicle grafts, subepithelial connective tissue grafts, envelope or tunnelling techniques, the use of acellular dermal, connective tissue allografts, guided tissue regeneration, Platelet rich fibrin (PRF), and coronally advanced flap (CAF) are the surgical methods that have been developed to treat gingival recession. For treatments of intrabony defects, a synthetic nanocrystalline hydroxyapatite (NcHA) bone graft has been introduced. Osteoconductivity, bioresorbability, and close contact are benefits of NcHA material. Critical size defects showed quick healing when the NcHA was utilised as a bone graft alternative. NcHA binds to bone and increases osteoblast activity to promote bone regeneration. A promising bone replacement material, tricalcium phosphate (TCP) is known for its strong bioactivity and resorbable qualities. Tricalcium phosphate (TCP) is one of the most popular and effective artificial bone substitutes. It is osteoinductive as well as osteoconductive. These characteristics enable full bone defects regeneration together with its cell-mediated resorption. In this study, we compared between nanocrystalline hydroxyapatite and tricalcium phosphate carried on PRP membrane in treatment of Miller's class 1 gingival recession in human.

Inclusion Criteria:

• Patients with good systemic health and no contraindication for periodontal surgery.
• Patients who are able to maintain good oral hygiene.
• Gingival thickness for the site selected should be ≥1mm.
• The height of keratinized gingiva (HKG) for the site selected should be ≥1 mm (HKG is the distance between the most apical point of the gingival margin and the mucogingival junction).

Exclusion Criteria:

• Active infectious diseases (hepatitis, tuberculosis, HIV, etc….).
• Medically compromised patients.
• Patients taking medications known to cause gingival enlargement.
• Pregnant patients and smokers.
• Previous mucogingival surgery at the defect.
• Restorations or caries in the area to be treated and non vital tooth.
• Teeth which are tilted or rotated.