Dental casting alloys are widely used in applications that place them into contact with oral tissues for many years. With the development of new dental alloys over the past years, many questions remain about their biologic safety.
A material’s response to changes in pH, application of force, or the effect of biological fluids can alter its biocompatibility. Surface features of a material may promote or discourage attachment of bacteria, host cells, or biological molecules . The biological responses to these materials depend on whether they release their components and whether those components are toxic, immunogenic, or mutagenic at the released concentrations .So systemic and local toxicity, allergy, and carcinogenicity all result from elements in the alloy being released into the mouth during corrosion .Biological testing of the material is important in order to observe the behavioral of the material and the possible tissue responds , thus the clinician can choose the correct material with the least adverse effects on the patient .