Assessment of the electrochemical behaviour of Nickel-Titanium-based orthodontic wires: Effect of some natural corrosion inhibitors in comparison with fluoride.

BACKGROUND: The aim of this study is to assess the corrosion resistance behaviour of Nickel-Titanium-based orthodontic wires (NiTi) in different concentrations of Sodium Fluoride (NaF) and the corrosion's inhibitory effect of the extracts of some medicinal plants (essential oils, hydrosols and extract). MATERIAL AND METHODS: In this study we used NiTi (3M) and CuNiTi (ORMCO, 35°C, California) orthodontic wires. The following electrolytes were prepared: Lactate Ringer solution with additions of 0.1%, 0.5% or 1% of Sodium Fluoride and the extracts of different plants: Artemisia, Syzygium aromaticum (Clove) and Celtis australis. Corrosion resistance was studied using anodic potentiodynamic polarisation and electrochemical impedance spectroscopy measurements. At the end of the experiment, microscopic images of wires were performed. ANOVA test with the comparison of Bonferroni and Tukey tests were performed to elucidate comparisons among all groups. RESULTS: The higher sodium fluoride concentration is related to negative corrosion potential for both NiTi and CuNiTi orthodontic wire. Hydrosols are associated to positive values of corrosion potential. CuNiTi has a lower corrosion resistance than NiTi. CONCLUSIONS: The prescription of toothpastes containing sodium fluoride should be reduced especially for patients wearing fixed orthodontic appliances. Eugenol may be considered as alternative of sodium fluoride for orthodontic patients for its anti-microbial and anti-corrosive effects. Key words:Corrosion behaviour, Sodium Fluoride, Nickel-Tatanium, orthodontic wires, corrosion inhibitors, aromatical plants.

Bibliometric study of articles on skeletal Class II malocclusions published in four high impact factor journals.

OBJECTIVE: Perform a bibliometric analysis of the orthodontic literature on skeletal Class II malocclusions during the first decade of the 21st century. MATERIALS AND METHODS: A retrospective, observational, and comprehensive study ranging from January the first 2001 to December 31 2010, based on the articles published in four high impact factor orthodontic journals: Angle Orthod, OCR, EJO, and AJODO (Quotation Report Newspaper of the Scientific Information Institute). RESULTS: In the 4565 reviewed articles, only 338 were published on Class II malocclusions. Brazil, the United States, Turkey, and Germany are the nationalities, which have published the most. The cross-sectional descriptive studies represent 33%, randomized clinical trials (RCTs) 10.5%, meta-analyses 0.3%. DISCUSSION AND CONCLUSION: Kanavakis et al. (2006) reported 72.34% of original articles, 2.83% of synthetic reviews, 8.89% of case reports, and 15.75% of unclassifiable articles. In conclusion, searchers in Orthodontics are invited to publish more clinical trials on skeletal Class II malocclusions.