The effect of water storage on the bending properties of esthetic, fiber-Reinforced composite orthodontic archwires

Objective: To study the effect of water storage on the bending properties of fiber-reinforced composite archwires and compare it to nickel-titanium (NiTi), stainless steel (SS), and betatitanium archwires. Materials and Methods: Align A, B, and C and TorQ A and B composite wires from BioMers Products, 0.014-, 0.016, and 0.018-inch, and 0.019 × 0.025-inch NiTi, 0.016-inch SS, and 0.019 ×0.025-inch beta-titanium archwires were tested (n 5 10/type/size/condition). A 20-mm segment was cut from each end of the archwire; one end was then stored in water at 37°C for 30 days, whilethe other was stored dry. The segments were tested using three-point bending to a maximum deflection of 3.1 mm with force monitored during loading (activation) and unloading (deactivation). Statistical analysis was completed via two-way analysis of variance with wire and condition (dry and water-stored) as factors. Results: In terms of stiffness and force delivery during activation, in general: beta-titanium was > TorQ B > TorQ A > 0.019 × 0.025-inch NiTi and 0.016-inch SS > Align C > 0.018-inch NiTi > Align B > 0.016-inch NiTi > Align A > 0.014-inch NiTi. Water exposure was detrimental to the larger translucent wires (Align B and C, TorQ A and B) because they were more likely to craze during bending, resulting in decreased forces applied at a given deflection. Align A and the alloy wires were not significantly (P >.05) affected by water storage. Overall, the alloy wires possessed more consistent force values compared to the composite wires. Conclusion: Environmental conditions are more likely to affect fiber-reinforced composite archwires compared to alloy wires.