Analysis of Human Tissue Response To Bone Graft Substitutes

Objectives: Bone graft substitutes are used in place of autogenous bone to repair bone defects in the oral cavity. The most common types of these materials are processed human or bovine bone, and synthetic materials (hydroxyapatites, calcium sulfate or beta-tricalcium phosphate).There is considerable uncertainty regarding their efficacy in humans at different time periods. The aim of this study was to investigate several different methods for analyzing the human healing response to various extraction socket regenerative therapies.

Methods: Prior to implant placement a bone graft substitute was placed in an extraction socket in order to develop maximal bone at the site. During placement, a 2mm diameter trephine bone core was removed. Cores were evaluated using Faxitron x-ray micrographs, light microscopy imaging, and scanning electron microscopy in backscattered electron imaging (BEI) mode. Materials evaluated included BioOss™, Puros™, and calcium sulfate (BoneGen™,Capset™). Time periods varied with most samples taken 4-8 months after grafting. Concentration was on refining the methodology to extract maximum information from the three analytical techniques used.

Results: The biologic response to these graft materials varied. In some cases the cores exhibited extensive vital human bone and little graft material, while in other cases a composite of new bone and significant amounts of graft was present. Variability was based on type of graft material and time period implanted, but the number of cases of each material is too small at this time to make statistically significant conclusions.

Conclusion: This project allowed us to develop a multi-level, standard protocol for obtaining maximal information on human tissue response to bone graft substitutes from bone-cores taken at the time of implant placement. This will allow us to make comparisons and recommendations regarding the use of bone graft materials and time periods for different grafting applications.