Page 72 - Demo

Chapter 370such, TMJ materials should be able to support proper functioning of locospecific cell types, such as osteoblasts. Foreign body giant cell reactionsImplantation of a biomaterial in the body can lead to a cascade of inflammatory reactions, starting with blood-material interactions and provisional matrix formation, and followed by acute and chronic inflammation. Finally granulation tissue can develop, leading to fibrous capsule development, as well as a foreign body reaction. Foreign body reactions are known to lead to degradation of biomaterials through an oxidative chain cleavage reaction triggered by macrophages and foreign body giant cells, leading to subsequent device failure. Because of this chemical degradation, the surface of the implant becomes brittle and more susceptible to physical damage; as physical damage occurs, cracks open in the material exposing new surfaces to oxidants released by the macrophages and foreign body giant cells. (15)Metal hypersensitivityMetal hypersensitivity can develop at any age and has a much higher incidence in females.(44) It should also be noted that patients can develop metal hypersensitivity even after implantation. Induction of hypersensitivity to metals can be caused by chronic exposure to low concentrations of metals or sudden exposure to high concentrations of metals. Acute stressors, such as viral and bacterial infections, as well as psychological trauma, have also been described as possible induction mechanisms.(18,19,45) Current data suggest that about 10% to 15% of the population has an allergy to one or more of the metallic components currently used in the field of implantology. The incidence is even higher amongst patients with an implant: 23%. Up to 63% of patients with a failing prosthesis have been shown to test positive for metal hypersensitivity.(19,46) While nickel (Ni) is most often the responsible element, Co, Cr, vanadium (V), aluminum (Al), and even Ti can also cause an allergic reaction. Ions and particles can be released from the implant by either dissolution, corrosion, or wear. These particles will act as haptens (initiators of an Nikolas de Meurechy NW.indd 70 05-06-2024 10:14