Influence of particle size of autogenous bone grafts on the early stages of bone regeneration: A histologic and stereologic study in rabbit calvarium

Purpose: The aim of this study was to investigate the influence of particle size of autogenous bone grafts on the early stages of bone regeneration. Materials and Methods: Bicortical skull bone defects were prepared in 15 rabbits (4 in each rabbit). Two defects were filled at random with either small (0.5 to 2 mm(3)) or large (10 mm(3)) autogenous bone particles. In addition, 1 defect was left unfilled (control defect). All defects were covered bicortically by expanded polytetrafluoroethylene membranes. The animals were divided randomly into 3 groups and sacrificed after 1, 2, and 4 weeks, respectively. Histologic and stereologic evaluations were performed after the sections were blinded. Results: No significant differences in total vessel surface area could be identified among the 3 groups. The total volume of newly formed bone in defects with small particles was larger and more mature compared to defects with large particles after 2 and 4 weeks. Furthermore, the resorption of small particles was more pronounced after 4 weeks, documenting a higher level of bone substitution compared to large particles. Discussion: The early stages of bone regeneration were influenced by the particle site of autogenous bone grafts. Conclusion: The present study indicated that particles of 0.5 to 2 mm(3) in size should be preferred to particles of 10 mm(3) in size for bone grafting.