Evaluation of the effect of three mouthwashes on the mechanical properties and surface morphology of several orthodontic wires: An in vitro study

Abstract

Background: The aim of this study was to evaluate and compare the changes in the mechanical
properties and surface morphology of different orthodontic wires after immersion in three
mouthwash solutions.
Materials and Methods: In this in vitro study, five specimens of each of 0.016 inch nickel
titanium (NiTi), coated NiTi, and stainless steel orthodontic wires were selected. The specimens
were immersed in 0.05% sodium fluoride (NaF), 0.2% chlorhexidine, Zataria multiflora extract, and
distilled water (control) for 1.5 h at 37°C. After immersion, loading and unloading forces at 0.5 mm
intervals and the elastic modulus (E) of the wires were measured using a three‑point bending test.
Surface changes were observed with a scanning electron microscope (SEM). Two‑way analysis of
variance and Bonferroni tests were used to compare the properties of the wires. The level of
significance was set at 0.05.
Results: Statistically significant changes in loading and unloading forces and E of the orthodontic wires were observed after immersion in different mouthwash solutions (P < 0.05). A pairwise comparison showed a nonsignificant difference between the effect of different mouthwashes on the E of different types of wires (P > 0.05). SEM images showed surface changes in some types
ofthe orthodontic wires.
Conclusion: The mouthwashes used in this study seemed to change the mechanical properties
and surface quality of the orthodontic wires.
Key Words: Elastic modulus, mechanical processes, mouthwashes, orthodontic wire