In this study over a period of 6 months, it could be demonstrated that mucosal tissue thickening above implants with PRF led to reduced tissue thickness when performed in a split-flap technique.

The initial post-operative dehiscence and the associated complete loss of mucosal and augmented tissue above the implant were observed in all test patients.

PRF is supposed to be a good healing aid in various aspects of dentistry [18]. Choukron and his associates introduced this technique to implant dentistry to improve bone healing [15]. According to his studies, the natural fibrin framework protects growth factors from proteolysis, so they can stay active for a longer period (up to 28 days [17]). This leads to an effective neovascularization and an accelerated wound closing with less post-operative infections [16, 19]. Though PRF has been tested successfully in surgical procedures with reference to hard tissue augmentation (sinus lift, socket preservation) [20, 21] and in the field of periodontal regeneration [22], publications of PRF usage in combination with soft tissue augmentation are rare and allow no real conclusion so far.

The first assumption that comes up is whether the higher tension on the flaps caused by the additional volume of the PRF membranes was adequately compensated. This can be clearly affirmed. Split flaps were expanded widely until the middle of the adjacent teeth. In addition to that, a very sensitive suture material was used to secure an adaption completely free of tension (illustration 8). The essential point that needs to be critically reviewed in this study is the insertion of PRF in combination with a split-flap technique. The bilayered insertion of PRF allows a better nutrition of the augmentation material itself and avoids higher peri-implant bone loss due to trauma and infection of the periosteum [22]. However, this highly technique-sensitive procedure requires much experience. Moreover, the initial thin mucosa is split into two extremely thin layers. A sufficient nutrition of the flap requires a minimum flap thickness of 0.8–1.2 mm [23, 24]. Since the blood supply of these flaps with reduced thickness cannot be provided only from the lateral, additional nutrition from the periosteum and the bone is necessary to maintain a livid flap. This may explain the punctual dehiscence above the implant itself, which occurred in all 10 test patients. According to the authors’ observations during this study, the nutrition problem coming up with the split-flap technique seems to be the crucial factor for the poor results with reference to soft tissue thickening.