clinical outcomes of modified coronally advanced tunnel technique using sub-epithelial connective tissue graft , xenogenic collagen matrix (XCM) and XCM with injectable platelet rich fibrin in the treatment of RT1 gingival recession : A three arm randomized controlled clinical trial

There are various surgical techniques and their modifications for the treatment of gingival recession. These include pedicle grafts (lateral sliding or double papillae) with or without connective tissue grafts, epithelised autogenous grafts (free gingival), sub-epithelial connective tissue grafts (SCTG), coronally advanced flaps (CAF) alone, CAF preceded by a free gingival graft, and CAF with a simultaneous SCTG.

SCTG helps in improved long-term stability of complete root coverage (CRC) and it is accepted as the gold standard in the treatment of gingival recessions. However, the requirement of a second surgical site, limited amount of graft, rather low patient tolerance and high complication rates in donor area are the major disadvantages of SCTG.

To reduce these disadvantages, barrier membrane, platelet-rich plasma, platelet-rich fibrin, enamel matrix derivatives and graft substitute materials have been used as an alternative to SCTG. But studies have shown that only SCTG in conjunction with CAF was able to enhance the ability to achieve complete root coverage and to improve recession reduction.

Human acellular dermal matrix (ADM) was introduced as SCTG substitute with various surgical techniques aiming root coverage but no additional benefit over CAF+SCTG was found. Additionally, there is a possible risk for disease transmission as it is derived from cadavers which limited the use of this material.

Recently, a new bi-layer xenogeneic collagen matrix (XCM) has been used in periodontal regenerative procedures. XCM is composed of a cell occlusive layer with compact collagen fibre and a spongious layer with porous collagen structure. This porous layer provides stabilization of blood clot and necessary space that helps in cell migration and might increase the formation of keratinized tissue. Hence, XCM seems to be a promising soft tissue graft substitute when used with CAF. It is not only less invasive and time consuming but also provides unlimited off-the-shelf supply of graft material and has been cleared by U S Food and Drug Administration (FDA).

Injectable platelet-rich fibrin (i-PRF) has been produced by changing the type of the tube, centrifugation time and speed; specifically, the blood is centrifuged in plastic tubes at 700 rpm for 3 min (Miron & Choukroun, 2017). I-PRF prepared according to low-speed centrifugation concept can provide a significant advantage for the regeneration process, as it is rich in platelets, leucocytes and growth factors (Choukroun & Ghanaati,2018).