Comparative study to assess the efficacy of topical application of 0.2% hyaluronic acid vs platelet rich fibrin in decreasing a postoperative pain following free gingival graft procedure .

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- Patients of both groups will be subjected to:

1. Case history including personal data, medical, surgical history and family history.
2. Clinical Examination.

After local infiltration of anesthesia, an adequate size of supraperiosteal recipient bed was prepared to receive the palatal graft of 15 mm mesio-distal width with 8 mm apico-coronal extension.. The free gingival graft extended from the mesial line angle upper 5 and distal line angle of upper 6 .

The coronal horizontal incision, will be 15 mm long, at least 2 mm apical from the gingival margin. A second horizontal incision will be drawn 8 mm apico coronal . Care will be taken to obtain a graft thickness of 1.5 mm. Thickness will be measured at the central point of the graft during the surgery by using an endodontic file then the grafts will be positioned, and firmly adapted to the bed, and stabilized with simple periosteal sutures.

Preparation of platelet rich fibrin:( intervention group) The classic PRF protocol was introduced by Choukroun & coworkers. PRF requires around 10 ml of blood to be collected from the forearm of patient without anticoagulant in a glass coated plastic tubes. After collection, the blood will be quickly subjected to centrifugation at 2700-3000 rpm for 12 minutes. After the completion of cycle, the blood become separated into three distinct layers; platelet poor plasma at the top, PRF in the middle and a red blood corpuscular base in the bottom. Pliers will be inserted into the tube to gently grab the fibrin clot with attached RBC's. The clot thus obtained will be compressed to form plugs to be placed in the palatal donor site and stabilized by criss cross resorbable suture then covered by periodontal pack

control group Control group: As the intervention group but the palatal wound will receive a .2% hyaluronic acid gel then covered by periodontal dressing

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Inclusion Criteria for participants:

• Patients with mucogingival defects scheduled for free gingival graft
• Age at least 18 years.
• Not having any systemic disease that could compromise wound healing
• No previous periodontal surgery on the experimental sites.

Exclusion Criteria for participants:

• Systemic diseases that may be a contraindication for any surgeries.
• Loss of maxillary premolars and molars.
• Pregnancy or lactation
• Smoking

both the participants and the investigator can't be blinded only outcome assessor will be blinded .