ABSTRACT
ABSTRACT Introduction: After debonding, white spot may appear on the area below the bracket, which is the early clinical sign of carious lesion. There is increased caries risk underneath and adjacent to orthodontic bands and brackets, which call for maximum use of caries preventive procedures using various fluoride application methods. Objective: The aim of the study was to evaluate alterations in the mechanical properties (modulus of elasticity and yield strength) in loading and unloading phases for different orthodontic archwires (nickel-titanium [NiTi] and copper-nickel-titanium [CuNiTi]) when exposed routinely to fluoride prophylactic agents for a predetermined period of time. Methods: Preformed rectangular NiTi and CuNiTi wires were immersed in fluoride solution and artificial saliva (control) for 90 minutes at 37ºC. After immersion, specimens were tested using a 3-point bend test on a universal testing machine. Results: There is a significant reduction in the unloading yield strength when the NiTi and CuNiTi wires were exposed to APF gel. Conclusion: The result suggests that use of topical fluoride agents affect the mechanical properties of the wires, leading to increase in treatment duration. Fluoride prophylactic agents must be used with caution in patients undergoing orthodontic treatment. Injudicious use of these agents may cause corrosive effects on the orthodontic wire surfaces, with alteration in their mechanical properties.
RESUMO Introdução: Após a remoção dos braquetes, manchas brancas podem aparecer na área embaixo deles, as quais são o sinal clínico inicial da lesão cariosa. Existe um maior risco de cáries embaixo e ao redor das bandas e braquetes ortodônticos, o que exige a máxima utilização de procedimentos preventivos de cárie, usando diferentes métodos com aplicação de flúor. Objetivo: O objetivo do presente estudo foi avaliar alterações nas propriedades mecânicas (módulo de elasticidade e resistência ao escoamento), nas fases de carregamento e descarregamento de diferentes fios ortodônticos (níquel-titânio [NiTi] e níquel-titânio com adição de cobre [CuNiTi]), quando expostos rotineiramente a agentes profiláticos fluoretados, utilizados durante um período de tempo predeterminado. Métodos: Os fios pré-contornados retangulares de NiTi e CuNiTi foram imersos em solução fluoretada e saliva artificial (controle) durante 90 minutos a 37°C. Após a imersão, as amostras foram testadas utilizando-se um teste de flexão em três pontos, em uma máquina universal de testes. Resultados: Houve uma redução significativa na resistência ao escoamento na fase de descarregamento quando os fios de NiTi e CuNiTi foram expostos ao gel fluoretado. Conclusão: O resultado sugere que o uso tópico de agentes fluoretados afeta as propriedades mecânicas dos fios, levando a um aumento na duração do tratamento. Os agentes profiláticos fluoretados devem ser utilizados com cautela em pacientes submetidos a tratamento ortodôntico. O uso indiscriminado desses agentes pode causar efeitos corrosivos na superfície dos fios ortodônticos e consequente alteração das suas propriedades mecânicas.
Subject(s)
Humans , Orthodontic Wires , Copper , Dental Alloys , Fluorides , Nickel , Surface Properties , Titanium , Materials Testing , Nickel/adverse effectsABSTRACT
We wanted to compare & evaluate, regularly used orthodontic materials including adhesives & myofunctional appliances for release of Bisphenol A. MethodsBisphenol - A release was assessed from two materials - orthodontic adhesive resin and heat cure acrylic resin [twin block]. Based on materials used, a total of 40 samples was assigned into two groups; Group A and Group B, each containing 20 samples. For Group A [orthodontic adhesive resin], metal brackets were bonded to 20 bicuspid teeth using adhesive resin and cured with LED light. For group B, 20 twin block appliances made from heat cured acrylic resin were used. Then, samples from both the groups were immersed in artificial saliva and then subjecting to thermal treatment from hot (60 ˚C) to cold (4 ˚C) temperatures, followed by shaking for 5 minutes. The samples were again shaken at (37 ˚C) and 1.0-mL aliquots were removed at 24 hours and 7 days after insertion. Gas chromatography / mass spectroscopy was used for the evaluation of leaching of bisphenol A from artificial saliva. ResultsSignificant results were found after 24 hours of analysis in both groups where 70 % samples from group A had bisphenol A release, whereas 80 % samples from group B had bisphenol A release. However, a non-significant result was obtained after 7 days where 20 % samples from group A had bisphenol A release whereas 60% samples from group B had bisphenol A release. The Heat cure acrylic group showed higher Bisphenol - A than that of orthodontic adhesive resin group. It was seen that the levels were lower than the reference dose which were calculated for daily consumption but were statistically significant. CoclusionsBisphenol A is considered as an endocrine disruptor. Degradation of orthodontic materials results in leaching of Bisphenol-A into oral cavity which is a clinical concern.