Effects of Steam and Dry-Heat Sterilization on Bending Properties of Niti Wires Publisher



Alavi S¹ ; Raji SH¹ Show Affiliations
Source: Orthodontic Waves Published:2009

Abstract

Purpose: Nickel-titanium arch wires have a prominent role in orthodontic appliances due to their desirable mechanical properties. The purpose of the present study is to determine the effects of autoclave and dry-heat sterilization on the bending properties of three types of NiTi superelastic wires. Methods: In this experimental study, three commercial types (Force I, Rematitan LITE, and G & H) of superelastic NiTi wires, 0.016 in. in diameter, were selected. From each type of wire, 20 specimens were prepared. The specimens were initially subjected to the three-point bending test at a rate of 1 mm/min on the Dartec testing machine in order to determine their load-deflection properties before sterilization. Then, 10 specimens of each type of wire were subjected to dry-heat sterilization (160 °C, 120 min) and 10 to autoclave sterilization (121 °C, 15 psi, 24 min). After sterilization, the specimens were subjected to the three-point bending test again and their load-deflection curves were plotted. The values for bending properties obtained before and after sterilization were subjected to the Duncan and ANOVA tests at the 0.05 significance level. Results: Our findings revealed considerable changes in the load-deflection properties of the test wires as a result of dry-heat sterilization. These changes included decreasing in applied force in both loading and unloading phases and reducing of wire superelasticity. Conclusion: Steam and dry-heat sterilization cause changes in the mechanical properties of superelastic NiTi arch wires. © 2009 Elsevier Ltd and the Japanese Orthodontic Society.