Relationship between friction force and orthodontic force at the leveling stage using a coated wire

Area of Science:

• Orthodontics
• Biomaterials Science
• Dental Mechanics

Background:

• The efficiency of orthodontic leveling is influenced by the interplay between applied force and friction between archwires and brackets.
• Understanding this relationship is crucial for optimizing treatment outcomes during the alignment phase.

Purpose of the Study:

• To investigate the relationship between force and friction in small-diameter esthetic nickel-titanium (Ni-Ti) wires.
• To determine how wire properties and displacement affect friction during simulated orthodontic movement.

Main Methods:

• Tested five esthetic Ni-Ti wires (coated and plated) and two plain Ni-Ti wires (0.012 and 0.014 inches).
• Utilized a three-point bending test (ISO 15841) and a custom dental arch model with simulated linguoversion.
• Measured forces and friction at displacements of 0.5, 1.0, 2.0, and 3.0 mm.

Main Results:

• At displacements < 1.0 mm, unloading bending forces exceeded friction forces.
• At displacements > 2.0 mm, friction forces surpassed unloading bending forces, suggesting potential arch expansion.
• Martensitic 0.014-inch Ni-Ti wires exhibited significantly higher friction than other tested wires.

Conclusions:

• For orthodontic displacements exceeding 1.0 mm, selecting an archwire with the lowest possible friction is recommended.
• Minimizing friction is key to efficient wire sliding and leveling in orthodontics.