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.

Keywords: Elastic modulus; mechanical processes; mouthwashes; orthodontic wire.

Figure 1

Three-point bending apparatus.

Figure 2

Close up view of the jig with two brass rods and brackets in place.

Figure 3

Mean elastic modulus of the studied wires after immersion in different solutions (GPa).

Figure 4

Load-deflection curve for three subgroups of control group (G1). (G1a: DW + NiTi wire; G1b: DW + coated wire; G1c: DW + SS wire).

Figure 5

Representative scanning electron microscope images of wire surfaces in different studied groups. (G1a: DW + NiTi wire; G1b: DW + coated wire; G1c: DW + SS wire; G2a: NaF + NiTi wire; G2b: NaF + coated wire; G2c: NaF + SS wire; G3a: CHX + NiTiwire ; G3b: CHX + coated wire; G3c: CHX + SS wire); G4a: ZM + NiTi wire; G4b: ZM + coated wire; G4c: ZM + SS wire).