Effects of two Fluoride Mouthwashes on Surface Topography and Frictional Resistance of Orthodontic Wires

Abstract

Objectives: We compared the effects of fluoride mouthwashes on surface topography of orthodontic wires, and static and kinetic frictional forces between stainless-steel (SS) orthodontic brackets and SS and nickel-titanium (NiTi) archwires.
 Materials and Methods: This in vitro, experimental study evaluated 240 standard SS maxillary central incisor brackets and 0.018-, and 0.025×0.019-inch NiTi and SS archwires. Different combinations of wire diameters and wire types were exposed to artificial saliva (control), 0.05% sodium-fluoride (NaF) for 1 minute daily, or 0.2% NaF for 1 minute weekly (37°C) for 3 months. The wires were pulled in the bracket slots by 5mm in a universal testing machine (10mm/minute). The static and kinetic forces were measured. The surface topography of the wires was inspected under a scanning electron microscope (SEM). Three-way ANOVA followed by Bonferroni post-hoc tests were used for statistical analysis (P<0.05).
 Results: The mean static and kinetic frictional forces of 0.025×0.019- inch NiTi wired in the 0.05%NaF group were significantly greater than the SS wire. The mean kinetic frictional force in the 0.05%NaF group was significantly greater than the 0.2%NaF and artificial saliva groups for all wires. The mean static and kinetic forces in 0.2%NaF were significantly greater than in artificial saliva. In all groups, larger wires showed higher mean frictional forces. SEM results revealed higher wire surface roughness in the 0.05%NaF group followed by the 0.2%NaF group.
 Conclusion: Weekly use of 0.2%NaF mouthwash is recommended during sliding mechanics to minimize frictional forces between SS and NiTi wires and SS brackets.

Does the initial surface roughness of different CuNiTi wires affect the frictional resistance?

“…The literature reinforces the need for a deeper assessment with CuNiti wires 1 , controlling the in vitro testing environment, as a dry environment may promote higher sliding and frictional resistance when assessing different orthodontic wires 16 . The importance of controlling variables such as environment and temperature during in vitro tests becomes evident for assessing the correlation of surface roughness and frictional resistance of the different bracket-wire systems.…”

“…Surface roughness was also assessed in rectangular rhodium-coated NiTi wires, which showed rougher surfaces than non-coated wires 14 , 15 . There are reports of higher frictional resistance of CuNiTi wires than rectangular TMA, NiTi, and stainless steel wires 1 .…”

“…The frictional resistance force between brackets and orthodontic wires during the sliding mechanics may complicate the effectiveness of dental movement due to the reduction of the force applied 1 . In this context, bracket systems have been subjected to several changes, including the finishing of surfaces, bracket material, and different ligation methods 2 , in an attempt to control the increase of frictional resistance.…”

Clinical effect of chlorhexidine and sodium fluoride on corrosion behavior and surface topography of nitinol orthodontic archwires

“…However, it may affect the characteristics of the oxide layer [ 24 ]. Consequently, the corrosion resistance of titanium alloys decreases in solutions having fluoride [ 25 – 31 ].…”

“…In addition, a non-statistically significant difference was found between the NaF and CHX groups, as both induced a higher corrosion rate than the control group. The overall p -value of both parts of the comparison between groups (control, NaF, and CHX) was statistically significant, particularly between the control group and NaF [ 20 , 31 ]. But others reported not statistically significant, particularly between the control group and NaF [ 8 ].…”