Horizontal Platelet-Rich Fibrin Membrane Block for Peri-Implant Soft Tissue Augmentation: An Experimental Animal Study with Clinical Illustration

<b>Background/Objectives:</b> Adequate peri-implant soft tissue thickness is essential for long-term peri-implant health and esthetics. Horizontal platelet-rich fibrin (H-PRF) has been proposed to support soft tissue regeneration; however, experimental and translational evidence for its application in peri-implant soft tissue augmentation remains limited. This study aimed to evaluate a H-PRF membrane block approach primarily through an experimental animal model, with clinical cases presented to illustrate translational feasibility. <b>Methods:</b> A customized compression device was used to fabricate the H-PRF membrane block. The biological performance of the H-PRF membrane block was first evaluated in a rabbit model, with histologic assessment of peri-implant soft tissue thickness and integration at 8 weeks. Representative clinical cases requiring peri-implant mucosal thickening were subsequently treated with H-PRF membrane block on the buccal aspect of the alveolar bone beneath a supra-periosteal flap to demonstrate clinical applicability. <b>Results:</b> In the animal model, the H-PRF membrane block resulted in a significant increase in peri-implant soft tissue thickness by increasing the lamina propria compared with control sites demonstrated by histologic analysis. The clinical illustrations showed stable buccal soft tissue volume and contour with minimal patient morbidity. <b>Conclusions:</b> Within the limitations of this experimental study, the horizontal H-PRF membrane block technique demonstrated promising biological performance for peri-implant soft tissue augmentation in an animal model. The accompanying clinical illustrations support the translational feasibility of this approach. Clinical relevance: This experimental study provides biological and translational insight into a minimally invasive strategy for peri-implant soft tissue thickening and may inform future controlled clinical investigations.