Mechanical properties and surface characterization of translucent composite wire following topical fluoride treatment

Objective: To determine the effects of a fluoride prophylactic agent on the mechanical properties and surface quality of a preformed round translucent composite archwire while comparing it with nickel-titanium (Ni-Ti) and multistranded stainless steel wires. Materials and Methods: The wires were immersed in an acidulated phosphate fluoride solution (APF) or in distilled water (control) for 1.5 hours at 37 degrees C. Flexural modulus of elasticity (E) and yield strength (YS) of the wires were measured using a three-point bending test in a universal testing machine. The springback ratio (YS/E) was calculated for each wire. The influence of fluoride treatment on properties of the wires was statistically analyzed using Student's t-test at alpha =.05. Surface changes were observed with a scanning electron microscope. Results: Fluoride treatment produced a statistically significant reduction in E, YS, and YS/E of the composite wire (P <.05). In addition, a significant decrease in E of Ni-Ti wire was found after exposure to fluoride, upon comparison with distilled water control treatment. On the other hand, no significant effect of fluoride treatment was found on YS and YS/E of Ni-Ti wire and on studied properties of the multistranded stainless steel wire (P >.05). Corrosive changes in surface topography were observed after exposure to the fluoride agent and were more pronounced with the composite wire. Conclusions: These results suggest that using a topical fluoride agent with translucent composite wire could decrease the mechanical properties and might damage the surface of the wire, potentially contributing to prolonged orthodontic treatment. (Angle Orthod. 2012;82:8-13.)