In-vitro Study: Biodegradation of Orthodontic Brackets in Artificial Saliva I

Objective: The objectives of this study are to evaluate the effects of artificial saliva on chemical and structural changes of orthodontic metallic brackets and compare the changes between different metallic brackets in the biodegradation process. Method: A total of 240 metallic orthodontic brackets of two different manufacturers were used; 120 nickel-titanium brackets from Dentarum and 120 stainless steel brackets from American Orthodontic.  The control group was 120 brackets of both manufacturers were immersed in distilled water for a period of 28 days at 37^oC under mechanical agitation. Meanwhile, the experimental groups were immersed in artificial saliva under the same conditions for 28 days. All solutions were tested for the release of ions using inductively coupled plasma mass (ICP) spectrometry at 1, 7 and 28 days. Surface roughness was tested using scanning electron microscope (SEM) and profilometer. Energy-dispersive X-ray (EDX) spectroscopy was performed to detect changes in chemical compositions. Statistical analysis was performed using SPPS Version 20. Result: The results showed that there was statistically significant difference in the amount of ions released from the orthodontic brackets immersed in the different solutions. The results of surface roughness measurements using the profilometer showed significant increase after biodegradation especially for American orthodontic metallic brackets and with artificial saliva. Conclusion: In general, our study showed that there is a significant difference in biodegradation between different metallic orthodontic brackets.  Stainless steel brackets show more aggressive chemical and structural changes compared to nickel- titanium brackets.