Metal Ion Release and Biocompatibility of Orthodontic Appliances
Summary
Orthodontic appliances, typically fabricated from alloys such as stainless steel, nickel-titanium and cobalt-chromium, undergo electrochemical degradation in the dynamic oral environment. This process releases metal ions into saliva, mucosal tissues and systemic circulation, raising concerns over allergic reactions, oxidative stress and cellular toxicity. The extent of ion liberation is influenced by alloy composition, mechanical strain, pH fluctuations and interaction with fluoride-containing agents. Assessments of biocompatibility combine in vitro measurements of cytotoxicity and genotoxicity with clinical observations of mucosal responses and systemic biomarkers. Advances in surface passivation and novel coating technologies aim to attenuate corrosion rates and minimise adverse tissue reactions. A comprehensive understanding of corrosion mechanisms and biological pathways activated by metal exposure is essential for optimising material choice, safeguarding patient health and informing evidence-based clinical protocols worldwide.
Research from Nature Portfolio
In a foundational in vivo investigation, the temporal release of nickel and titanium ions was quantified over a six-month period of fixed-appliance therapy. Salivary and urinary concentrations were measured by inductively coupled plasma optical emission spectroscopy, revealing a significant rise in nickel levels at three and six months, whereas titanium exhibited more modest variability. Scanning electron microscopy of retrieved archwires demonstrated surface roughening and micro-corrosion features. The study emphasised the modulatory role of salivary pH and oral hygiene practices on ion liberation and highlighted the need for longitudinal monitoring to characterise cumulative exposure and guide safer appliance design.
Metal Ion Release and Biocompatibility of Orthodontic Appliances publication trend
The graph below shows the total number of articles in metal ion release and biocompatibility of orthodontic appliances across all publications each year (not limited to Nature Index journals).
Technical terms
Biocompatibility: The ability of a material to perform without eliciting undesirable local or systemic effects in a biological environment.
Corrosion: The electrochemical or chemical degradation of metals through interaction with their environment.
Reactive oxygen species (ROS): Chemically reactive molecules derived from oxygen that can damage cellular components.
Cytotoxicity: The property of a substance to cause damage or death to living cells.
Genotoxicity: The potential of a compound to damage genetic information in cells, leading to mutations.
References
- Oral and Extra-Oral Manifestations of Hypersensitivity Reactions in Orthodontics: A Comprehensive Review. Journal of Functional Biomaterials (2024).
- Toxicity of Metal Ions Released from a Fixed Orthodontic Appliance to Gastrointestinal Tract Cell Lines. International Journal of Molecular Sciences (2023).
- Metal Ion Release from Orthodontic Archwires: A Comparative Study of Biocompatibility and Corrosion Resistance. Molecules (2024).
- Evaluation of the release of nickel and titanium under orthodontic treatment. Scientific Reports (2020).
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