Histological evaluation of palatal donor site healing with leukocyte–platelet–rich fibrin versus collagen sponge

Background: The palate is the primary donor site for autogenous connective tissue grafts in periodontal and peri-implant plastic surgery, yet healing by secondary intention often results in morbidity. Collagen sponge (CS) and leukocyte–platelet-rich fibrin (L-PRF) have been proposed to enhance donor site repair, but comparative histological evidence in humans remains scarce. Objective: To compare the histological characteristics of palatal donor site healing following coverage with CS or L-PRF. Material and Methods: A retrospective cross-sectional histological study was performed on palatal biopsies collected four months after connective tissue graft harvesting covered with CS (n = 9) or L-PRF (n = 9). Epithelial type and thickness, lamina propria thickness, submucosal composition, inflammatory infiltrate, vascular congestion, and edema were evaluated using hematoxylin–eosin staining. Results: Both biomaterials supported uneventful healing without necrosis or severe inflammation. Compared with CS, L-PRF was associated with thicker epithelium, a higher frequency of hyperparakeratinization, and the presence of orthokeratinization. Lamina propria thickness was slightly greater in L-PRF, while fibrous submucosa predominated in both groups. Mild leukocyte infiltration and transient edema were more common with L-PRF, suggesting a more active regenerative response. Conclusions: CS and L-PRF both promoted favorable palatal donor site healing. L-PRF demonstrated histological features consistent with enhanced tissue regeneration, likely due to its growth factor content. These preliminary findings warrant validation in randomized controlled trials with larger sample sizes.