TYPE-I AND TYPE-III COLLAGEN IN THE TISSUE CAPSULES OF TITANIUM AND STAINLESS-STEEL IMPLANTS

Collagen plays an important role in wound healing and as such is prese nt in connective tissue capsules around implanted materials. The propo rtion of type I collagen to type III collagen is lower during wound he aling than that found in normal dermis, but the amount of type I colla gen gradually increases and type III decreases as healing continues. T he intent of this research was to investigate a possible correlation b etween implant metals and type I and type III collagen formation in th e ensuing soft-tissue capsules. Smooth implants of grade 4 commerciall y pure titanium and 316L stainless steel were placed via injection nee dle into the subcutaneous tissue of 12 rats for 6 weeks. The soft-tiss ue capsule that formed around each implant was evaluated histologicall y and by immunofluorescence. Although the two metal implant types diff er in many respects, they were chosen for their differences in surface conductivity. Titanium oxide is semiconducting, whereas the oxide of stainless steel is conducting. Impedance spectroscopy was used for con ductivity analysis of the surface. No qualitative differences were fou nd in amount of type I or type III collagen in the capsules of the two metals. However, the capsules around titanium stained for type I coll agen were thicker than capsules around stainless steel. In addition, t ype I collagen showed evidence of a greater association with densely p acked, highly orientated collagen fibers. (C) 1997 John Wiley & Sons, Inc.