Metals and Metalloids Release from Orthodontic Elastomeric and Stainless Steel Ligatures: In Vitro Risk Assessment of Human Exposure

In Vitro Comparison to Evaluate Metal Ion Release: Nickel-Titanium vs. Titanium-Molybdenum Orthodontic Archwires

Background When metals used in orthodontic materials are exposed to the oral environment, teeth, and gingivae over an extended period of time, they may gradually deteriorate. As a result, the patient is exposed to higher concentrations of metals and metal ions than what they would be exposed to through food and other sources. The goal of the current in vitro experiment was to evaluate and contrast the metal ion release from orthodontic archwires made of titanium-molybdenum alloy (TMA) and nickel-titanium (NiTi). Methods For 90 days, 20 orthodontic archwires in each group were immersed in 50 milliliters of simulated saliva using different containers. Atomic Absorption Spectrometry (AAS) (Shimadzu Corporation, Kyoto, Japan) was used to assess and compare metal ion emission. The unit of measurement is parts per million (PPM). Results The findings indicated that the discharge of nickel metal from the NiTi archwire (Group A) was much higher than that from the TMA archwire (Group B), with a statistical significance level of p < 0.001. It was discovered that Group B's release of titanium was statistically significantly (p < 0.05) higher than Group A's titanium release, which did not include the release of any other metals. Conclusion The study findings indicated that the amounts of metal ions released from the orthodontic archwires made of titanium molybdenum and nickel-titanium alloy were within safety limits.

Toxicological Profile of Biological Environment of Two Elastodontic Devices

Malocclusion and teething problems are common health problems globally, affecting people of all ages, especially children and adolescents. In addition to the pathophysiological complications associated with orthodontic problems, they also affect the well-being of the individual. Orthodontic appliances are frequently used, even from an early age, and their activity in different biological environments is very varied and incompletely described. Due to these considerations, the purpose of the study was to evaluate the toxicological profile of the biological environment (saliva at three pH values: 3, 7, and 10) of two elastodontic orthodontic appliances: Myobrace (MB) and LM TrainerTM 2 (LMD). In vitro techniques applied were conducted on human keratinocytes to evaluate cell viability (Alamar blue assay) and gene expression real-time reverse transcription–polymerase chain reaction (RT-PCR technique). In addition, it was assessed the irritating effect on the vascular plexus using as a biological model the chorioallantoic membrane of the hen’s egg by applying the hen’s egg-chorioallantoic membrane (HET-CAM) method. The obtained results showed a decrease in cell viability up to 82% in the case of LMD at pH = 3, a slight increase in mRNA expression for the anti-apoptotic marker (Bcl-2 and Bcl-xL), and a decrease in mRNA expression for the pro-apoptotic marker (Bad), and any type of toxic change at the capillary level (irritation score being below 0.9). Based on the data obtained, it can be stated that MB and LMD biological environments, at different pH values, present a safe toxicological profile.

The contribution of orthodontic braces to aluminum exposure in humans: an experimental in vitro study

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.