Factors which influence the accuracy of corrosion rate determination of implant materials.

This study has revealed several factors which influence the accuracy and interpretation of electrochemical test results with surgical implant materials. These include variation between corrosion rate determination methods, IR drop, diffusional effects, and inherent statistical variations. The AC impedance method (ACI) is particularly useful for studying electrochemical mechanisms, measuring IR drop, and separating stress-enhanced ion release effects into components related to current density and surface area changes. This method can also measure true surface area even of irregular objects and can detect changes in area caused by cracking or surface plastic deformation. The corrosion rate method which is most accurate, in an absolute sense, must be determined by chemical analysis of the electrolyte.