Influence of surface modification on the in vitro corrosion rate of magnesium alloy AZ31

In recent years, magnesium alloys have been proposed as a new class of metallic bioabsorbable implant material. Unfortunately, the production of hydrogen gas and an increase in alkalinity are both by-products of the degradation process of these materials. This necessitates the development of magnesium alloys with controlled degradation rates. Furthermore, biocompatible coatings that can delay the onset of corrosion would ensure that the mechanical integrity of the implant remains intact in the early stages of healing. This article explores the influence of surface modification by biomimetic calcium phosphate coating, biodegradable polymer coatings, and acid etching on the corrosion rate of the AZ31 magnesium alloy in simulated body fluid. Our results indicate that all of these surface treatments have a positive impact on the corrosion rate of the material and that in the early stages of implantation it is possible to tailor the corrosion rate through an appropriate choice of surface treatment. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 91A: 221-230, 2009