Article ID Journal Published Year Pages File Type
3119499 American Journal of Orthodontics and Dentofacial Orthopedics 2006 5 Pages PDF
Abstract
Introduction: Rare earth magnets have been used in orthodontics, but their corrosion tendency in the oral cavity limits long-term clinical application. The aim of this project was to evaluate several; magnet coatings and their effects on magnetic flux density. Methods: A total of 60 neodymium-iron-boron magnets divided into 6 equal groups-polytetrafluoroethylene-coated (PTFE), parylene-coated, and noncoated-were subjected to 4 weeks of aging in saline solution, ball milling, and corrosion testing. Results: A significant decrease in magnet flux density was recorded after applying a protective layer of parylene, whereas a slight decrease was found after applying a protective layer of PTFE. After 4 weeks of aging, the coated magnets were superior to the noncoated magnets in retaining magnetism. The corrosion-behavior test showed no significant difference between the 2 types of coated magnets, and considerable amounts of iron-leached ions were seen in all groups. Conclusions: Throughout the processes of coating, soaking, ball milling, and corrosion testing, PTFE was a better coating material than parylene for preserving magnet flux density. However, corrosion testing showed significant metal leaching in all groups.
Related Topics
Health Sciences Medicine and Dentistry Dentistry, Oral Surgery and Medicine
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