The structure of periodontal tissues formed following guided tissue regeneration therapy of intra-bony defects in the monkey

Objective: To describe the periodontal tissues formed following guided tissue regeneration (GTR) therapy of intra-bony defects (IBD). Methods: Eight adult Macaca fascicularis monkeys were used. Proximal IBD were created at the mandibular second pre-molars and second molars. After 3 months, GTR surgery was performed. The animals were euthanized at 6 months and 2 years after surgery. Block biopsies were harvested, and prepared for histological analysis. Results: At 6 months the defect had healed with new cementum (NC), periodontal ligament (PDL) and bone. The NC seemed to be firmly anchored to the dentin. Supra-crestally, the NC consisted of a 10 mu m thick layer of acellular extrinsic fibre cementum (AEFC). Sub-crestally, the NC was considerably thicker and consisted of an inner layer of AEFC and an outer thicker layer of cellular mixed fibre cementum (CMFC). The extrinsic fibre density amounted to about 10 fibres per 100 mu m. The PDL was wider than the pristine PDL and widened in coronal direction. After 2 years of healing, the thickness of the NC in the sub-crestal compartment had increased by about 20 mu m and the fibre density had increased by about 50%. Conclusion: After 2 years of healing the structure of the regenerated tissues resembled that of pristine periodontal tissues.