An Investigation Of Resorption And Tissue Reaction After Subcutaneous Implantation Of Biodegradable Nano-hydroxyapatite/collagen Membrane Materials In Rats

Guided bone regeneration(GBR) is a technique which is used for the treatment of bone defects associated with periodontal disease or endosteal dental implants to facilitate the natural biological potential by creating a favorable environment for periodontal and peri-implant regeneration. Membranes are barriers to protect bone and blood clot, prevent epithelial migration and allow cells with regenerative capacity to repopulate the defect area. In most experimental studies on GBR non-degradable membranes are used. A drawback inherent to such devices is that at the end or in the course of the wound healing they have to be removed. Therefore, the aim of the present study is to investigate a new biodegradable membrane material for use in GBR, which also has excellent mechanical properties and biocompatibility.The studied material is a composite consisting of nano-crystal hydroxyapatite and collage through the self-organization mechanism in Tsinghua University. Subcutaneous study in the rats was performed to assess the histological response and biodegradability of several materials, which are poly(dl-lactide-co-glycolic acid)s, collagen and nano-hydroxyapatite/collagen. This rudimentary study on biocompatibility is basically to improve the property of the membrane and to beused in human.In the study 24 rats were used , 96 implant materials were placed under the dorsal skin of the rats under general anesthesia. Animals were respectively sacrificed on 10, 20, 30 and 45 days after implantation. The specimens were assessed histologically for the composition of the tissue surrounding the membranes, the types of infiltrating cells and the resorption of materials.It was concluded that these membrane materials were well tolerated and were gradually resorbed. Light microscopic examination showed that the poly(dl-lactide-co-glycolic acid)s were resorbed faster than nano-hydroxyapatite/collagen and collagen membranes on 45 days. There were few macrophages and foreign body giant cells in nano-hydroxyapatite/collagen membrane. Scanning electron microscopic examination showed that the surface of nano-hydroxyapatite/collagen had some crystal calcium phosphates, which increased during the time. In addition the resorption process was continuing and these materials were biocompatibility at 45 days.Based on these findings, nano-hydroxyapatite/collagen membrane have good biocompatibility and biodegradability in vivo , which meets the criterion GBR.