Autogenous bone graft and ePTFE membrane in the treatment of peri-implantitis. II. Stereologic and histologic observations in cynomolgus monkeys.

The purpose of the present study was to evaluate the effect of autogenous bone graft particles and expanded polytetrafluoroethylene (ePTFE) membrane in the treatment of peri-implantitis with stereologic and histologic methods. Clinical and radiographic findings are reported elsewhere. Experimental peri-implantitis with a bone loss of 4-6 mm was established during 14-22 months around 64 implants with a titanium plasma-sprayed (TPS) surface in eight cynomolgus monkeys (Macaca fascicularis). The defects were treated with autogenous bone+membrane (B+M), autogenous bone (B), membrane (M), or a conventional flap procedure (control) (C). The animals were killed 6 months after surgery. Healthy peri-implant tissue was established irrespective of the applied treatment procedure. However, the amount of bone (autogenous bone graft particles and regenerated bone) and re-osseointegration were significantly higher in defects treated with B+M as compared with the three other treatment modalities. A mean bone-to-implant contact of 45% was estimated within defects treated with B+M. The corresponding values for the B, M, and C groups were 22, 21, and 14%. The present study therefore demonstrates that autogenous bone graft particles covered by an ePTFE membrane is a useful surgical treatment procedure of experimental peri-implantitis around implants with a TPS surface in cynomolgus monkeys. Obviously, there is a background for long-term evaluation in humans.