- History of severe allergic reactions (Anaphylaxis) to several allergins and specific allergies to or other substances found in the stent or impression material (ie: Plasticized Methacrylate Polymer, methyl methacrylate monomer, alkyl dimethacrylate, benzophenone, Toluidine and Hydroquinone), waxes containing Pine Rosin, and to the list of ingredients for the impression material.