Effect of fluoride on mechanical properties of NiTi and CuNiTi orthodontic archwires: an in vitro study

Abstract

Introduction: After debonding, white spot may appear on the area below the bracket, which is the early clinical sign of carious lesion. There is increased caries risk underneath and adjacent to orthodontic bands and brackets, which call for maximum use of caries preventive procedures using various fluoride application methods. Objective: The aim of the study was to evaluate alterations in the mechanical properties (modulus of elasticity and yield strength) in loading and unloading phases for different orthodontic archwires (nickel-titanium [NiTi] and copper-nickel-titanium [CuNiTi]) when exposed routinely to fluoride prophylactic agents for a predetermined period of time. Methods: Preformed rectangular NiTi and CuNiTi wires were immersed in fluoride solution and artificial saliva (control) for 90 minutes at 37ºC. After immersion, specimens were tested using a 3-point bend test on a universal testing machine. Results: There is a significant reduction in the unloading yield strength when the NiTi and CuNiTi wires were exposed to APF gel. Conclusion: The result suggests that use of topical fluoride agents affect the mechanical properties of the wires, leading to increase in treatment duration. Fluoride prophylactic agents must be used with caution in patients undergoing orthodontic treatment. Injudicious use of these agents may cause corrosive effects on the orthodontic wire surfaces, with alteration in their mechanical properties.

The effect of salbutamol sulphate inhalation (an anti‐asthmatic medication) on the surfaces of orthodontic Archwires

“…Previous studies showed that fluoride affected titanium‐containing archwires more, leading to a higher surface roughness due to a decreased corrosion resistance of the archwire, 15,24,35–37 which agrees with our findings. Also, one study found that routine fluoride application affected the mechanical properties of orthodontic archwires containing titanium, 38 which was further explained in another study as being a factor of hydrogen embrittlement of the alloy 36 . On the other hand, a study tested the effect of mechanical brushing on the surface wear of StSt wires.…”

Evaluation of a Hypersensitivity Inhibitor Containing a Novel Monomer That Induces Remineralization—A Case Series in Pediatric Patients

“…While demineralization prevention using fluoride may be considered, there is no clear evidence of its effectiveness [ 57 ]. Furthermore, acidulated phosphate fluoride reduces Ni-Ti strength [ 58 ]. Therefore, new approaches are required.…”