For non infected sockets, a 15c blade (Stoma, Storz am Mark GmbH, Emmingen-Liptingen Germany) was used to cut a 1-cm long vestibular access incision , 3-4 mm apical to the mucogingival junction of the involved tooth. The socket orifice and the vestibular access incision were connected by a subperiosteal tunnel that was created using a periotome and a micro-periosteal elevator (Stoma, Storz am Mark GmbH, Emmingen-Liptingen Germany). Implants, (Biohorizons, Birmingham, Al, USA) , were installed using a 3D printed surgical guide (Surgical Guide Resin, Form 2, Formlabs). A flexible cortical membrane shield (OsteoBiol® Lamina, Tecnoss®, Torino, Italy) of heterologous origin, 0.6 mm in thickness was prepared by hydrating and trimming it. It was then tucked through the vestibular access incision, till it extended 1 mm below the socket orifice, and stabilized using a membrane tack (AutoTac System Kit, Biohorizons Implant Systems, Birmingham, Alabama Inc, USA) to the apical bone. The gap between the implant and the shield/the labial plate was then filled with particulate bone graft [75% autogenous bone chips harvested form local surgical sites and 25% inorganic bovine bone mineral matrix (MinerOss X , Biohorizons, Birmingham, Al, USA)]. For the infected sockets, the 6-day protocol was implemented. Atraumatic extraction of the infected tooth by the periotome was followed by curettage, mechanical debridement and chemical irrigation using metronidazole irrigation solution (500mg/100ml, Amrizole, Amria Pharma, Alexandria, Egypt). The root of the involved tooth was cleaned with an ultrasonic cleaner, cut to its apical third, reimplanted into the socket and maintained there for 6 days by bonding its crown to the adjacent teeth using composite resin. Implant and crown placement were done as described above for the non-infected socket group.
