Extended Platelet- Rich Fibrin Membrane Combined With Vestibular Incision Subperiosteal Tunnel Access Technique to Treat Localized Gingival Recession

Whole blood (10 mL) will be centrifuged at 700 g for 8 minutes. The upper layer (yellow layer) shows the liquid plasma layer. The most upper layer of platelet- poor plasma (PPP) will be collected in a syringe. then PPP will be heated in a heat block device at 75°C for 10 minutes and thereafter cooled to room temperature for approximately 2 minutes. An injectable albumin gel will then be prepared. Then the liquid platelet-rich layer (liquid-PRF) including the buffy coat layer with accumulated platelets and leukocytes, will be collected in a separate syringe. The albumin gel and native liquid PRF will then be thoroughly mixed by utilizing a female-female luer lock connector. Now injectable e-PRF in final form is ready to be used .

The region distal from the canines, commencing at least 2 mm from the gingival margin with a width of 5-8 mm and a desirable length to cover the entire recipient site is an ideal site for harvesting a FGG from the hard palate for root coverage. Harvesting of FGG is performed as follows: The graft is prepared by outlining with two parallel longitudinal incisions that are interconnected with vertical incisions. Graft deliberation is initiated along the paramarginal incision in a split-thickness fashion with a goal of removing an FGG of 1.5-2-mm thickness without touching the periosteum. The harvested free gingival graft will be de-epithelialized to obtain an DFGG. The donor site wound will be covered by gel foam which will be sutured in place and then healing will occur by secondary intention .

Following Zadeh's (2011) protocol, under local anesthesia, a vestibular access incision is made depending on the treatment site (midline frenum for maxillary anterior, frenal area between canine and lateral incisor for maxillary posterior, and similar for mandibular regions). The incision passes through the periosteum to create a subperiosteal tunnel exposing the facial bone and root dehiscence. In the test group, the extended platelet-rich fibrin (e-PRF) membrane is inserted into the tunnel and secured to the flap with horizontal sutures; in the control group, a de-epithelialized free gingival graft (DFGG) is used similarly. Each tooth's facial enamel is briefly acid-etched, washed, and dried to attach vicryl sutures fixed with flowable composite resin to prevent apical relapse during healing. Finally, the access incision is closed and sutured with vicryl sutures