Orthodontic wires are metal alloy wires used with dental braces. The purpose of orthodontic wires is to provide the forces needed to move and align teeth during treatment. Bending the wire upon fitting it into the brackets produces these mechanical forces as the wire tries to unload the tension put on it. Several different materials are used to make these wires. The type and thickness of wire used varies according to the kind of and stage of treatment being conducted.
The oldest kind of material used to make orthodontic wires is stainless steel, which is very strong. Used since 1919, it is an extremely versatile and rust-proof metal that can be shaped and adjusted easily. Another material used to make these wires is nickel-titanium, which is even easier to shape and provides just the right forces needed for aligning crooked teeth during the early stages of orthodontic treatment. Heat-activated versions can be heated, reshaped, and used to move teeth when they bend back into shape upon cooling.
Beta-titanium wires can be deformed without going back to their original configuration. Their strength and elasticity ratings are somewhere in between steel and nickel-titanium, so these are good for use during the middle parts of orthodontic treatment with braces. Orthodontic wires also come in cobalt chromium nickel, which can be made harder by being heated.
It is important to consider the various properties of all of these wires in orthodontics. Elastic deflection, the ability for wires to be bent without being damaged or broken, is essential to the type of tooth movement the orthodontist wants to achieve. A low stiffness provides a more constant force for positioning teeth, while formability defines how well an arch wire can be configured into shapes, such as loops and coils, while maintaining its integrity.
Orthodontic wires can withstand a finite amount of force, the limit of which is determined by their resilience. It is also important for them to resist corrosion and not release toxins which could impact the health of the patient. Wire used to straighten teeth must also be able to tolerate soldering or welding and also cause the least amount of friction where it touches the bracket for optimal efficiency during treatment. Various orthodontic wires are used throughout orthodontic dental correction, and all materials and properties must be considered depending on treatment requirements of the case.
