Orthodontic Rare Earth Magnets—In Vitro Assessment of Cytotoxicity

Abstract

The aim of this study was to assess and compare in vitro the cytotoxic effects of uncoated and parylene-coated rare earth magnets, used in orthodontics. Cytotoxicity of samarium-cobalt magnets (SmCo₅ and Sm₂Co₁₇) and neodymium-iron-boron magnets (Nd₂Fe¹⁴B) was assessed by two in vitro methods, the millipore filter method and an extraction method. Orthodontic stainless steel brackets served as controls.

Uncoated SmCo₅-magnets showed high cytotoxicity while uncoated Sm₂Co₁₇-magnets demonstrated moderate cytotoxicity. Uncoated neodymium-iron-boron magnets, as well as parylene coated Sm₂Co¹⁷-magnets and parylene-coated neodymium-iron-boron magnets, showed negligible cytotoxicity. Short-term exposure to a static magnetic field did not cause any cytotoxic effect on the cells.

Index words:

• Cytotoxicity Tests
• Dental Alloys
• Magnetics
• Millipore Filter Test
• Neutral Red Assay