Orthodontic treatment starts, but certainly does not end with, the mounting of the braces. The use of braces can last months or beyond a year. During the process, the teeth are aligned and straightened using various kinds of forces. The braces archwire sequence, or the order in which archwires of various materials and sizes are applied, is based on what the orthodontic treatment is to accomplish at a particular point in time. In this explanation of the sequence, we highlight the materials used for archwires and their sizes, and how they contribute throughout the orthodontic treatment.
What Are Archwires?
The two rows of teeth in your mouth curve. Orthodontic archwires run the length of these dental arches, otherwise known as arcades. These archwires form a critical part of orthodontic treatment. In a system of braces, the brackets bond to the teeth. The orthodontic wires connect and anchor the brackets by running through the each of the bracket slots.
More significantly, the necessary force to correct the positions of the teeth comes courtesy of these wires. Ligatures, which come either in rubber or as stainless steel, secure the archwires to the brackets so that the force can be applied.
Different Types of Orthodontic Wires
Orthodontic wires are generally classified by the material that composes them. Generally, the types are:
- Nickel Titanium: These wires have a mix of 50 percent nickel and 50 percent titanium. With these elements come springiness and elasticity for the wires, resulting in an application of light continuous forces rather than short, abrupt ones. The materials that allow these to spring make them susceptible to breaking easily. Titanal or Orothonol contribute to the somewhat better fortification of the wires.
- Cobalt-Chromium: Wires of this mold have a blend of 40 percent cobalt, 20 percent chromium, 16 percent iron, and 15 percent nickel. High concentrations of cobalt and chromium provide stiffness to these wires. However, cobalt-chromium can have four levels, or tempers, of hardness based on heat treatment. This allows the orthodontist to bend wires into loops or V-shapes to anchor the brackets.
- Beta Titanium: This material exhibits characteristics of stainless steel and nickel titanium, but not fully. Therefore, beta titanium doesn’t have as much stiffness as stainless steel and lacks the flexibility of nickel titanium. Some orthodontists shy away from beta titanium because it causes more friction than other types of wires.
- Stainless Steel: Orthodontists began using this type of metal for wires in the 1930s. Its enduring popularity comes from the durability and resistance to rust. That latter property derives from the chromium that produces a film or protective coating over the stainless steel. Regular grade stainless steel breaks fairly infrequently, while the super grade version does not deform, or change in size, significantly.
Main Stages of Orthodontic Treatment
To understand braces archwire progression involves a review of the steps of the orthodontic treatment.
- Initial alignment. This begins as the first stage after the orthodontist mounts the brackets and installs the archwires. A low, constant pressure from the archwires breaks down bone on one side of a tooth and builds it on the other. The alignment becomes apparent in as short as three months.
- Leveling: Often occurring during the early part of orthodontic treatment, leveling the teeth creates a flat arch. The orthodontist may increase the strength of the orthodontic wires some to achieve this.
- Working: After these initial phases, the orthodontist will turn to further alignment of the teeth and correcting the overbite. This serves to fit the teeth together after the initial alignment. While cases can differ, the working period runs for twelve to eighteen months.
- Finishing: In the finishing stage, the orthodontist adjusts or fine tunes the details of the joinder of the teeth. Here, the emphasis lies in the facial and oral appearance of the patient.
- Settling: Normally, settling happens once the braces are removed. Depending on the treatment course, archwires do not come into play in this stage.
What Archwires Are Used When?
The braces archwire sequence considers the amount of force or elasticity needed at the various stages. The type of material used for the archwire has a major factor in the decision. Thus, as a general matter, orthodontists will use the nickel-titanium wires in the initial alignment and the leveling phases.
Some orthodontists may opt during leveling for heat-activated nickel-titanium, copper-based, or cobalt-chromium due to the ability to apply or withdraw heat to adjust the stiffness as necessary. When the patient needs more elasticity, especially for alignment, the adjustable wires get less heat or become cooler. More heat is applied to make these wires stiffer for use in leveling.
At the working stage of treatment, the orthodontist will want more stiffness. Traditionally, stainless steel was the choice and remains so for many orthodontists, including those who use the MBT system. The stainless steel can bend to almost any shape and generates fairly little friction. This absence of friction between the wires and the brackets benefits patients due to the closing of spaces in the working stage.
The finishing stage usually involves stainless steel or beta titanium. Normally, orthodontists do not use archwire for the settling phases in the Damon system or self-ligating bracket system. Orthodontists using MBT will apply braided stainless steel archwires at settling.
Factors to Consider in Braces Archwire Progression
Braces wire sizes also play a role in the braces archwire sequence. Specifically, as treatment progresses beyond the initial stage, the wires become thicker. Having wires with greater cross-section, or thickness, promotes more tightness.
For round wires, the radius measures the size. The sizes run at .014 in., .018 in., and .020 in. The rectangle versions normally come in either .016 in. long by .022 in width, and .019 inches long by .025 in width.
The braces archwire sequence progresses from elastic to stiffer and thinner to thicker as the patient accumulates time with the braces. The thickness and size affect the force applied to teeth as they align and have their bites corrected. Please share your thoughts about your orthodontist’s choice of braces archwire sequence.
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