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Despite numerous studies on ion release from orthodontic appliances, no clear conclusions can be drawn due to complex interrelations of multiple factors. Therefore, as the first part of a comprehensive investigation of cytotoxicity of eluted ions, the objective of this study was to analyze four parts of a fixed orthodontic appliance. Specifically, NiTi archwires and stainless steel (SS) brackets, bands, and ligatures were immersed in artificial saliva and studied for morphological and chemical changes after 3-, 7-, and 14-day immersion, using the SEM/EDX technique. Ion release profiles were analyzed for all eluted ions using inductively coupled plasma mass spectrometry (ICP-MS). The results demonstrated dissimilar surface morphologies among parts of the fixed appliance, due to variations in manufacturing processes. The onset of pitting corrosion was observed for the SS brackets and bands in the as-received state. Protective oxide layers were not observed on any of the parts, but adherent layers developed on SS brackets and ligatures during immersion. Salt precipitation, mainly KCl, was also observed. ICP-MS proved to be more sensitive than SEM/EDX and exhibited results undetected by SEM/EDX. Ion release was an order-of-magnitude higher for SS bands compared to other parts, which was attributed to manufacturing procedure (welding). Ion release did not correlate with surface roughness. [ABSTRACT FROM AUTHOR]

There is limited information on whether metals such as aluminum (Al) can migrate from orthodontic braces to saliva and subsequently contribute to its exposure in humans. This study aimed to assess this experimentally by incubating elastomeric orthodontic ligatures in artificial saliva for 30 days and other components of orthodontic braces (brackets, arch wires, and retainers) up to 180 days. As demonstrated, significantly higher levels of Al were leached from elastomeric ligatures (mean ± SD 28.2 ± 6.8 μg compared with their stainless steel counterparts (3.6 ± 0.1 μg) during 30 days. The higher the incubation time, the greater levels of Al leaching to artificial saliva were observed with the highest levels found for CNA β arch wire (252 ± 12 μg), Ni-Ti-Al arch wire (224 ± 11 μg), ceramic brackets (199 ± 10 μg), stainless steel arch wire (108 ± 5 μg), and metallic brackets (81.0 ± 4.2 μg) after 180 days of incubation. However, considering the tolerable weekly intake (TWI) established by the European Food Safety Authority, the intraoral use of orthodontic braces considered in this study would in the worst case constitute 0.04% and 0.09% of TWI in 70-kg adults and 30-kg children, respectively. In conclusion, the orthodontic braces considered in this study have no contribution to Al exposure in humans and can be considered safe in this regard. [ABSTRACT FROM AUTHOR]

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Aim: The objective of the present study was to evaluate in vitro, the influence of different ligatures, archwire material and archwire sizes on static frictional resistance. Methods: The frictional resistance was evaluated by using different ligatures Gray, Purple, Alastic, Teflon coated stainless steel ligature and 0.009"Stainless steel ligatures on 0.017"×0.025" and 0.019"×0.025" TMAand SS archwires using standard edgewise brackets with zero degree tip and torque mounted on Perspex blocks using an universal testing machine with a cross head speed of 5mm/min with unstimulated saliva as a lubricant. Results: Mean and SD values were calculated. Data was statistically analyzed using three way analysis of variance (ANOVA), pair wise comparison by Tukeys multiple post hoc test and multiple regression analysis to calculate coefficient of static friction. The results showed that irrespective of wire size and wire material combination Teflon coated SS ligatures produced the least frictional resistance while Gray elastomeric modules produced the highest with Alastic, SS ligature and purple falling in between. Multiple linear regression analysis of static friction revealed that only arch wire size has significant influence on static friction with groups and archwire composition showing negligible influence. Interpretation and conclusion: (a)Teflon coated stainless steel ligatures produced lowest frictional forces with all wire, material contributions followed by Alastic, Stainless steel, Purple and gray elastomeric modules. (b)Increase in arch wire dimension has increased the frictional resistance, whereas archwire composition has minimal effect on frictional resistance. [ABSTRACT FROM AUTHOR]