Effect of dry heat and steam sterilization on load-defl ection characteristics of β-titanium wires: An in vitro study

Abstract

Background: Sterilization techniques could affect the characteristics of orthodontic wires. The aim of the present study was to evaluate the effect of steam and dry heat sterilization techniques on load-defl ection behavior of fi ve types of β-titanium alloy wires.

Materials and Methods: The samples consisted of 30 straight lengths of fi ve types of β-titanium alloy wires: Titanium Molybdenum Alloy (TMA) Low Friction (TMAL), TMA Low Friction Colored (HONE), Resolve (RES), BetaForce (BETA), and BETA CNA (CNA). Thirty wire segments were divided into three groups of 10. Group 1 was the control group and the group 2 samples were sterilized by dry heat in an oven (60 minutes at 160°C) and group 3 by steam in an autoclave (15 minutes at 121°C). Then all the wire samples underwent a three-point bending test in a testing machine to evaluate loaddefl ection properties. Data was analyzed by repeated measures ANOVA and Scheffé’s test (α= 0.05).

Results: The results showed that dry heat sterilization signifi cantly increased force levels during both loading and unloading of CNA, BETA and RES and during loading of HONE (P < 0.05). Steam sterilization signifi cantly increased force levels during both loading and unloading of BETA and during unloading of HONE (P < 0.05), with no effects on the load-defl ection characteristics of TMAL, CNA and RES (P > 0.05).

Conclusion: It appears dry heat sterilization increases stiffness of RES, BETA, CNA and HONE but autoclave sterilization did not have any effect on load-defl ection characteristics of most of the β-titanium wires tested, indicating that clinicians who want to provide maximum safety for their patients can autoclave TMAL, RES and CNA before applying them.

Key Words: Beta titanium, orthodontic wire, sterilization