Periodontal wound healing following GTR therapy of dehiscence-type defects in the monkey: short-, medium- and long-term healing.

OBJECTIVE: To describe periodontal wound healing in dehiscence-type defects following guided tissue re-generation (GTR) therapy. METHODS: Ten adult Macaca fascicularis monkeys were used. Buccal dehiscence-type defects were created at the maxillary second pre-molars and second molars. After 3 months, GTR surgery was performed. The animals were euthanized at 6 weeks, 6 months and 2 years after surgery. Block biopsies were harvested, and prepared for histological analysis. RESULTS: A new attachment apparatus was structured already after 6 weeks of healing. A 10-20 microm thin layer of acellular extrinsic fibre cementum (AEFC) had formed along the instrumented root surface. At 6 months, the thickness of the supracrestal cementum was comparable with that at 6 weeks, while the thickness of the subcrestal cementum had increased to 40-60 microm. In this zone, the cementum consisted of an inner layer of AEFC attached to the circum-pulpal dentin and an outer layer of cellular mixed fibre cementum (CMFC). The numerical extrinsic fibre density was twice that at 6 weeks. At 2 years, the periodontal tissues resembled the pristine periodontium. CONCLUSION: Periodontal healing following GTR therapy of recession-type defects will result in a restitutio ad integrum, i.e. healing by re-generation. A continuous maturation process occurs over at least 2 years.