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Metal release from simulated fixed orthodontic appliances.
1Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Korea. hwang@yumc.yonsei.ac.kr
Summary
Metal ion release from orthodontic appliances, including stainless steel and nickel-titanium (NiTi) archwires, generally decreased over three months in artificial saliva. Chromium, nickel, and iron release stabilized within weeks for most tested materials.
Area of Science:
- Biomaterials Science
- Orthodontics
- Materials Science
Background:
- Orthodontic appliances commonly utilize stainless steel and nickel-titanium (NiTi) alloys.
- These materials can release metal ions into saliva, the oral medium.
Purpose of the Study:
- To quantify metal ion release from fixed orthodontic appliances over time.
- To compare ion release from different types of stainless steel and NiTi archwires.
Main Methods:
- Simulated fixed orthodontic appliances (brackets, tubes, bands) were immersed in artificial saliva (pH 6.75, 37°C) for 3 months.
- Four groups were tested: stainless steel archwires (Ormco, Dentaurum) and NiTi archwires (copper NiTi, Bioforce sentalloy).
- Chromium, nickel, and iron ion concentrations were measured at various time points.
Main Results:
- Chromium release stabilized between 2-8 weeks, nickel between 3 days-3 weeks, and iron between 1 day-2 weeks, depending on the archwire group.
- A general decrease in metal ion release was observed as immersion time increased over the 3-month study period.
- No further increase in metal ion release was detected after initial stabilization periods.
Conclusions:
- Metal ion release from tested orthodontic appliances plateaus within weeks.
- The rate of metal ion release decreases over extended immersion periods.
- The study provides insights into the long-term stability of metal ions from common orthodontic materials.