text: Many different materials have been used as perianal injectable bulking agents, including: autologous fat (fat tissue transferred from elsewhere in the body), Teflon, bovine glutaraldehyde cross-linked collagen (collagen from cows), carbon-coated zirconium beads, polydimethylsiloxane elastomer, dextranomer/non-animal stabilised hyaluronic acid, hydrogel cross-linked with polyacrylamide, porcine dermal collagen (collagen from pig skin), and synthetic calcium hydroxylapatite ceramic microspheres.