Metal release profiles of orthodontic bands, brackets, and wires: an in vitro study.
AIM
The present study evaluated the temporal release of Co Cr, Mn, and Ni from the components of a typical orthodontic appliance during simulated orthodontic treatment.


MATERIALS AND METHODS
Several commercially available types of bands, brackets, and wires were exposed to an artificial saliva solution for at least 44 days and the metals released were quantified in regular intervals using inductively coupled plasma quadrupole mass spectrometry (ICP-MS, Elan DRC+, Perkin Elmer, USA). Corrosion products encountered on some products were investigated by a scanning electron microscope equipped with an energy dispersive X-ray microanalyzer (EDX).


RESULTS
Bands released the largest quantities of Co, Cr, Mn, and Ni, followed by brackets and wires. Three different temporal metal release profiles were observed: (1) constant, though not necessarily linear release, (2) saturation (metal release stopped after a certain time), and (3) an intermediate release profile that showed signs of saturation without reaching saturation. These temporal metal liberation profiles were found to be strongly dependent on the individual test pieces. The corrosion products which developed on some of the bands after a 6-month immersion in artificial saliva and the different metal release profiles of the investigated bands were traced back to different attachments welded onto the bands.


CONCLUSION
The use of constant release rates will clearly underestimate metal intake by the patient during the first couple of days and overestimate exposure during the remainder of the treatment which is usually several months long. While our data are consistent with heavy metal release by orthodontic materials at levels well below typical dietary intake, we nevertheless recommend the use of titanium brackets and replacement of the band with a tube in cases of severe Ni or Cr allergy.
['Wendl|B|B|', 'Wiltsche|H|H|', 'Lankmayr|E|E|', 'Winsauer|H|H|', 'Walter|A|A|', 'Muchitsch|A|A|', 'Jakse|N|N|', 'Wendl|M|M|', 'Wendl|T|T|']
D003343:Corrosion D006801:Humans D066298:In Vitro Techniques D008670:Metals D009968:Orthodontic Appliances, Removable D016910:Orthodontic Brackets D009969:Orthodontic Wires D012463:Saliva D012464:Saliva, Artificial
Metal release Corrosion Orthodontic materials Allergy Biocompatibility Mass spectrometer