METAL PARTICLES AND TISSUE CHANGES ADJACENT TO MINIPLATES - A RETRIEVAL STUDY

Peri-implant soft tissue and bone from 12 patients undergoing removal of stainless steel miniplates and screws after healing of jaw fracture s were studied with regard to histomorphology and metal content. Three patients with titanium plates were also included. Light microscopy an d Scanning electron microscopy with energy-dispersive X-ray microanaly sis were used. Non-osseous tissue adjacent to devices of both material s showed fibrosis, including areas of mild chronic inflammation. The c ellular picture was dominated by fibroblasts with small aggregates of lymphocytes and scattered macrophages. A connective tissue collar was found between the bone tissue and the screws of both stainless steel a nd titanium. Bone formation was also evident adjacent to screws of bot h materials. Stainless steel or titarium particles 5-50 mu m in diamet er were found in both soft tissue and bone next to implants of their c orresponding bulk material. The amount of metal impregnation varied be tween individual sections, and fewer particles were found in the bone specimens than in soft tissue. The mild inflammatory changes were not restricted to areas of metal impregnation.