Aesthetic nickel titanium wires--how much do they deliver?

Area of Science:

• Orthodontics
• Materials Science
• Biomaterials Engineering

Background:

• Nickel-titanium (Ni-Ti) wires are widely used in orthodontics due to their superelastic properties.
• Aesthetic coated Ni-Ti wires offer a cosmetic alternative to traditional metallic archwires.
• The mechanical properties, specifically force levels, of aesthetic wires may differ from regular Ni-Ti wires.

Purpose of the Study:

• To compare the force levels and mechanical properties of aesthetic Ni-Ti wires against regular Ni-Ti wires of identical dimensions.
• To evaluate the impact of coating on the superelastic behavior and recovery of Ni-Ti archwires.

Main Methods:

• Four manufacturers' aesthetic and regular superelastic Ni-Ti wires (0.016 × 0.022) were tested.
• A three-point bending test was employed to measure loading and unloading force values at various deflections.
• Scanning electron microscopy (SEM) assessed the coating thickness of aesthetic wires.

Main Results:

• A statistically significant decrease in force values was observed for aesthetic wires from manufacturers I, III, and IV compared to their regular counterparts (P < 0.001).
• No significant difference in force values was found for manufacturer II's aesthetic wires.
• Epoxy-coated wires from manufacturers I, III, and IV showed significantly reduced forces, while manufacturer II's coated wires exhibited comparable forces to regular Ni-Ti wires.

Conclusions:

• Aesthetic Ni-Ti wires exhibit reduced force levels compared to regular Ni-Ti wires, with variations among manufacturers.
• The choice of manufacturer is critical, as coating significantly impacts the force delivery of aesthetic Ni-Ti wires.
• Aesthetic wires from manufacturers I, II, and III demonstrated substantial recovery after deflection, indicating maintained superelasticity.