Potential release of trace metal ions from metallic orthodontic appliances and dental metal implants: A Review of in vitro and in vivo experimental studies

Metallic wear nanoparticles, corrosion products and trace metal ions release from metallic materials, e.g. metallic alloys and pure metals, implanted into the human and animal's body in orthodontic surgery is becoming a major cause for concern. Additionally, metallic wear nanoparticles can themselves undergo a corrosion process contributing to the total level of dissolved metal ions. This review briefly provides an overview of both metallic alloys and pure metals used in implant materials in dental surgery. A short section is dedicated to important biomaterials and their corrosive behavior in both real solutions and various types of media that model human and animal's biological fluids and tissues. The present review gives an overview of analytical methods, techniques and different approaches applied to the measurement of in vivo and in vitro trace metals released into body fluids and tissues from patients and animals carrying metal dental implants and metallic orthodontic appliances. Reference levels of ion concentrations in body fluids and tissues that have been determined by a host of studies are compiled, reviewed and presented in this paper. This review summarizes data, describing the potential toxicity of metal wear debris, free metallic ions and corrosion products release from metallic orthodontic appliances (metal surgical implants) in vivo and in vitro. Finally, a collection of published clinical data on in vivo and in vitro released trace metals from metal dental implants is included.