Long-term follow-up of tissue reactions caused by Teflon paste and cross-linked collagen in rats.

A 6-month follow-up study was carried out to compare local tissue reactions of polytetrafluoroethylene (Teflon paste) and cross-linked collagen (Zyplast), two injectable antireflux agents. Injections were made intradermally, intramuscularly, and into the bladder wall. Cross-linked collagen showed no foreign-body reaction. It maintained its original location and became well integrated with the surrounding tissue, forming an extra pad that was seen throughout the whole observation period. In contrast, Teflon caused a strong foreign-body reaction: single pearls of the agent became encapsulated within granulomatous tissue. However, a few pearls were seen still free with minimal surroundings several weeks after the injection. We conclude that both injectable agents cause a long-lasting reaction in rats that is strong enough to act as an extra support at the site of injection. [ABSTRACT FROM AUTHOR]