RESUMO
The effects of sterilization on the mechanical properties and the surface topography were determined on 0.017 x 0.025-inch Nitinol and Titanal arch wires. Three approved heat sterilization methods were used: dry heat, formaldehyde-alcohol vapor, and steam autoclave. Elastic moduli were obtained on 1-inch segments in 3-point bending. Laser scans of flatwise wire surfaces were conducted to detect surface alterations--whether they were caused by tarnish, corrosion, or pitting. Tensile properties were determined on 7-inch lengths: the 0.1% yield strength, the ultimate tensile strength, and the percent elongation at break. Within the confines of the present sterilization experiments, no detrimental changes were observed for either the selected mechanical properties or the surface topography. When the mean values of the two products were compared, Nitinol was less compliant but stronger than Titanal. Laser spectroscopy showed that Titanal possessed at least three times more specular reflectivity than Nitinol.
Assuntos
Ligas Dentárias , Níquel , Aparelhos Ortodônticos , Fios Ortodônticos , Esterilização , Titânio , Ligas , Fenômenos Químicos , Físico-Química , Elasticidade , Etanol , Formaldeído , Temperatura Alta , Vapor , Propriedades de Superfície , Resistência à TraçãoRESUMO
Using specular reflectance, the surface roughness of six representative orthodontic archwire products was determined. Among the four alloy groups which are commonly used in orthodontics, stainless steel appears the smoothest, followed by cobalt-chrome, beta titanium, and nickel-titanium. A clearer understanding of the parameters which contribute to sliding mechanics will be possible when these results are combined with future experiments on the coefficient of friction.
