Heterologous Fibrin Biopolymer for Post-Extraction Alveolar Bone Healing in Streptozotocin-Induced Diabetic Rats

Type 1 diabetes mellitus (DM1) is characterized by autoimmune destruction of pancreatic β-cells, resulting in insulin deficiency and persistent hyperglycemia, which impair bone metabolism and compromise post-extraction alveolar bone healing. Heterologous fibrin biopolymer (HFB) has previously demonstrated biocompatibility, biodegradability, bioactivity, and osteoconductive properties under normoglycemic conditions. Therefore, the study investigated the association of HFB with post-extraction alveolar bone healing in streptozotocin-induced diabetic rats, using the diabetic blood clot as a biological control. Forty-eight adult male Wistar rats were induced to DM1 by a single intraperitoneal injection of streptozotocin (52 mg/kg). Animals were included after confirmation of hyperglycemia (fasting blood glucose ≥ 250 mg/dL) measured seven days after STZ administration: blood clot (BCG; n = 24) or HFB (HFBG; n = 24). Seven days after DM1 induction, the right maxillary incisor was extracted, and the sockets were filled according to group allocation. Animals were euthanized at 7, 14, and 42 days post-extraction. Fasting blood glucose levels were monitored, and pancreatic insulin immunohistochemistry was performed to characterize the diabetic condition. Alveolar bone healing was assessed by micro-CT, histological (HE), histomorphometric, and picrosirius red analyses. The diabetic phenotype was confirmed by persistent fasting hyperglycemia (260-589 mg/dL) and reduced pancreatic insulin immunostaining in β-cells. At 42 days, bone volume (BV) was 31.86% higher in the HFBG than in the BCG (p < 0.05). BCG exhibited higher trabecular number (Tb.N), while HFBG exhibited higher trabecular thickness (Tb.Th) (p < 0.05). Histologically, the HFBG shows a more mature, compact, and organized bone structure, whereas the BCG presents bone tissue with a more trabecular and immature architecture. HFBG showed the lowest percentage of thin fibers at the late stage, whereas BCG maintained similar values from 14 to 42 days (p < 0.05). These findings suggest that HFB was associated with favorable changes in selected late-stage parameters of post-extraction alveolar bone healing in an STZ-induced diabetic model.