Guided tissue regeneration for using a chitosan membrane: an experimental study in rats.

Barrier membranes are employed clinically to deflect the growth of gingival tissues away from root surface. They provide an isolated space over the regions with the defective tissues that allow the relatively slow growing periodontal ligament fibroblasts to be repopulated onto the root surface. Several makes of bioabsorbable membranes are now commercially available. In this study, we have employed chitosan as barrier membrane material and evaluated it for a guided tissue regeneration application. Three types of chitosan membranes: Chi-NaOH, Chi-Na(5)P(3)O(10), and Chi-Na(2)SO(3)(each was gelated by NaOH, crosslinked by Na(5)P(3)O(10) and Na(2)SO(3), respectively), were prepared to be evaluated by the following categories: the mechanical strength to create an effective space, the rapid rate to reach hydrolytic equilibrium in phosphate-buffered solution, and the ease of clinical manipulative operations. Consequently, standardized, transosseous and critical sized skull defects were made in adult rats and the defective regions were covered with the specifically prepared chitosan membranes. After 4 weeks of recovering, varying degrees of bone healing were observed beneath the chitosan membranes in comparison to the control group. The chitosan covered regions showed a clear boundary space between connective tissues and bony tissues. Apparently, this process resulted in a good cell occlusion and beneficial osteogenesis effect to the bone. As for the control group, the bone defect was filled with connective tissue, and a destruction of the integrity of newly formed bone was observed. Among the chitosan membranes tested in this study, Chi-NaOH membrane provided a higher percentage of new bone formation than those from the Chi-Na(5)P(3)O(10) and Chi-Na(2)SO(3) families.