[Orthodontic wires in a simulated oral environment:change in mechanical properties]
In this study,some different kinds of orthodontic archwires were tested to evaluate the changes of their mechanical properties.The results showed that in oral environment,all wires suffered degradation of their properties:the force-generating capacity decreased and the permanent deformation increased.The force-generating capacity decreased and the permanent deformation increased.The force decay resulted mainly from the tooth movement.The deformation occurred within 7 days.Chinese-NiTi alloy suffered less stress-relaxation and residual deformation than the stainless steel wires.Arch wires with vertical loops showed similar properties with NiTi,which could deliver more constant force.