A Critical Appraisal of the Use and Properties of Nickel–Titanium Dental Alloys

Abstract

Nickel–titanium (NiTi) archwires are used in dentistry for orthodontic treatment. NiTi alloys have favourable mechanical characteristics, such as superelasticity and shape memory, and are also known as a corrosion-resistant alloy. In specific cases, an archwire could be attacked by certain types of corrosion or wear degradation, which can cause the leaching of metal ions and a hypersensitive response due to increased concentrations of Ni in the human body. A systematic search of the literature retrieved 102 relevant studies. The review paper focuses on three main fields: (i) electrochemical properties of NiTi wires and the effect of different environments on the properties of NiTi wires (fluoride and low pH); (ii) tribocorrosion, a combination of chemical and mechanical wear of the material, and (iii) the biocompatibility of NiTi alloy and its subsequent effect on the human body. The review showed that corrosion properties are affected by microstructure, pH of saliva and the presence of fluorides. A high variation in published results should be, therefore, interpreted with care. The release of nickel ions was assessed using the same unit, showing that the vast majority of metal ions were released in the first few days of exposure, then a stable, steady state was reached. In tribocorrosion studies, the increased concentrations of Ni ions were reported.

RETRACTED: Titanium and titanium alloys in dentistry: Current trends, recent developments, and future prospects

“…Restorations on individual teeth are often filled with filler materials to cure decay. More wide-ranging refurbishments, such as dental bridges, crowns, and implant-aided restorations, are also done with patient-specific restoration techniques (( Baumgarten, 2018 ; Močnik and Kosec, 2021 ).

Figure 14 Titanium in restorative dentistry a) Filling of Dental decay, b) Ti crown covered with porcelain c) Spatula ( Philip et al., 2017 ).

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Influence of casein phosphopeptide-amorphous calcium phosphate on the surface topography and composition of nickel-titanium archwires during orthodontic treatment with fixed appliances

“…The corrosion of NiTi alloy in a biological environment leads to the precipitation of dissolved Ni ions, thus increasing their content on the surface [27], and this corresponds to the findings in the group exposed to ROH. In addition, the deposition of corrosion products prevented significant release of Ni ions from the archwires by blocking the sites of corrosion, which further amplified the Ni content on the surface [28].…”

Experimental Investigation of the Impact of Niobium Additions on the Structural Characteristics and Properties of Ti–5Cr–xNb Alloys for Biomedical Applications

“…Concerns have been raised regarding the leaching of aluminum, vanadium, and nickel ions from biometals, such as Ti-6Al-4V and Ti-Ni (nitinol) alloys, due to potential longterm health issues [3,4]. These ions have been associated with neurological disorders, enzymatic disturbances, and toxicity, and even carcinogenicity in the case of nickel.…”