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General Information

In order to understand the role of wires in orthodontics, let’s imagine that orthodontic treatment is like driving a car from Point A to Point B. The tooth is the car that needs to be moved from point A (crooked teeth) to point B (a beautiful smile). To have a smooth and easy trip, everything needs to be coordinated:


  1. Tooth: The car: It moves from point A to B.
  2. Wires: The engine of the car. It generates the force necessary to move the tooth.
  3. Brackets/Braces: Tires of the car. They transfer the force from the wire (engine) so that the tooth (car) can move.
  4. Color ties: Parts that connect the tires to the engine.
  5. Regular dental cleaning and check-up: Oil change and maintenance.
  6. Dr. Amin Movahhedian and Dr. Hamed Vaziri: The drivers. 

From the information above, it is clear that brackets do not move the teeth. They are a part of the system necessary for tooth movement. The actual “engine” that generates the force is the wires and other accessories such as rubber bands and power chains.

Now that you know about the role of wires in orthodontics; let’s get a little bit more specific about the physics and characteristics of each wire.

Orthodontic archwires are used to generate the force necessary for tooth movement. Depending on the stage of treatment these wires are used to move the teeth or maintain them in a certain spot and prevent them from any undesirable movement.

Orthodontic wires are classified based on different properties, materials, shape of the cross section, and overall forms.

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Nickel-Titanium (NiTi)

  • It’s an alloy of Nickel and Titanium
  • This material was first developed for the space program in 1959. 
  • This wire has a tendency to go back to its original shape.
  • Superelasticity: This wire generates almost the same amount of force regardless of the amount of deflection.
  • Cannot be bent easily.
  • Usually used in the initial stages of treatment.

Copper NiTi

  • Similar to NiTi wires but with the addition of Copper in the alloy.
  • Adding Copper makes the wire react to different temperatures. 
  • It is more flexible in lower temperatures and stiffer in higher temperatures. 
  • It’s easier to place in the brackets on severely crowded teeth.

Beta Titanium

  • Also known as TMA wires.
  • First introduced in early 1980.
  • Has properties between Stainless Steel and NiTi.
  • It is not as stiff as stainless steel and not as flexible as NiTi.
  • It can be bent easier than stainless steel wire.
  • It has the highest friction with braces that makes it the last choice for space closure.

Stainless Steel

  • Stiff wire.
  • It can be bent to any desirable shape.
  • Minimal friction with braces makes it ideal for space closure.
  • Its moldability and strength make it a material of choice to fabricate appliances such as a Nance or Forsus. 

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Cross Section

If all of the other features are the same, wires will act differently if the cross section is not the same. There are a few different common shapes of cross sections, the following are the most common ones:

1. Round: These wires are usually more flexible.
2. Rectangular: These wires are generally stiffer.

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  • It is usually referred to the dimension of the cross section.
  • The measurement unit is in inches. 
  • Round wires are measured by their radius. So one number represents their size. 
  • .014, .018, .020 are common sizes for round wires.
  • Rectangular wires are represented by two sets of numbers, one for the length and another one for the width. 
  • .016x .022, .019 x .025 are common sizes for rectangular wires.

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Arch Form 

Since every individual has a unique dental arch shape, orthodontic wires are made in different arch forms. Below are some of the most common ones are oval,
standard and square.

AvA Orthodontics & Invisalign


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