Evaluation of the Effect of Two Mouthwashes on the Mechanical Properties of Orthodontic Wires

(In Vitro Study)

Abstract

Objective: This study was to evaluate the effect of both sodium fluoride (NaF) and sodium fluoride with chlorhexidine (NaF + CHX) mouthwashes on the mechanical properties of orthodontic wires.

Materials and Methods: The sample consisted of 30 stainless steel (S.S) and nickel titanium (NiTi) wires (0.017 x 0.025 inches). 15 wires of each type were divided into three subgroups. The second group of each type was immersed in a 0.05% NaF rinse, the third group in a 0.05% NaF+0.012% CHX rinse, and the first group of each type (as supplied by the manufacturer) was immersed in a 37°C temperature for 90 minutes. The yield strength, maximum tensile stress, and Young's modulus were calculated.

Results: The yield strength, maximum stress, and Young's modulus values of NiTi wires decreased significantly when immersed in NaF rinse, and to a lesser extent when immersed in NaF+CHX rinse. The decrease was also slight for S.S wires.

 Conclusions: The decrease in mechanical properties of NiTi wires when immersed in NaF rinse was statistically significant, while the decrease in the remaining immersed groups was statistically insignificant.