Assessment of the Efficacy of Dentin Graft and Xenograft in Bone Regeneration and the Enhancing Effect of Mesenchymal Stem Cells

Background/Objectives: The use of dentin grafts in bone regeneration has gained increasing attention as an alternative to conventional grafting materials. Mesenchymal stem cells (MSCs), known for their osteogenic potential, have been combined with various biomaterials to enhance regenerative outcomes. This study aimed to evaluate the regenerative potential of dentin grafts and bovine-derived xenografts, with or without MSCs, in experimentally created bone defects in a rat model. Methods: A total of 25 male rats were randomly assigned to five groups: control, dentin graft, dentin graft and MSC, xenograft, and xenograft and MSC. Standardized 2-mm cortical defects were created bilaterally in the femoral shafts. Histological and immunohistochemical analyses were performed after a 90-day healing period. Statistical evaluation was carried out using the Kruskal–Wallis H test and Bonferroni-adjusted pairwise comparisons. Results: Complete healing was achieved in all groups without evidence of complications or inflammatory reactions. Immunohistochemical staining demonstrated no positive vascular endothelial growth factor (VEGF), collagen type I (COL1), or osteopontin (OPN) reactions in defect areas, consistent with complete maturation, although collagen type 3 (COL3) positivity was observed in residual xenograft material. Quantitative analysis showed that the dentin graft and MSC group achieved the highest degree of new bone formation (M = 92.88%, SD = 6.09), significantly greater than the control (p = 0.002) and xenograft groups (p = 0.013). Conclusions: Both dentin grafts and xenografts demonstrated enhanced bone defect healing when combined with MSCs. Nevertheless, dentin grafts in conjunction with MSCs yielded the most favorable regenerative outcomes, suggesting their clinical superiority over conventional xenografts.