Explain in brief about Polymers
In comparison to metals and ceramics, polymers are weak and flexible. These are not popular as dental implant materials. Examples of polymeric materials include PMMA, silicone rubber, polyethylene, Poly-Lactic Acid, polysulfone and poly tetrafluoroethylene. The polymer most commonly used is polymethyl methacrylate (PMMA). Initially, solid polymers were used but they appear to have only moderate attachment and are eventually exfoliated. A porous PMMA structure is formed by sandblasting the outer surface. Polyhydroxyethylmethacrylate (HEMA) is manufactured as a porous sponge which, on implantation, becomes invaded with fibrous tissue.
Polymers are chosen mainly as additive for beneficial secondary purposes such as structural isolation or introduction of shock absorbing qualities in load bearing metallic implants. Their most frequent use is still for non-load bearing applications in maxillofacial reconstruction. Certain "bioresorbable" polymers (Poly Lactic Acid) show potential as temporary implant materials that induce healing and bony in growth.