An orthodontic retainer is a device that holds your teeth in position after they have been moved by some method, typically braces. The use of retainers is important because it allows the gums to adjust to changes in the structure of the surrounding bone. Retainers must be custom-made to fit each person and are usually composed of plastic or metal wires. The most common types of retainers include Hawley retainers, vacuum-formed retainers, pressure-formed retainers and fixed retainers.
A Hawley retainer is the most well-known retainer. It consists of a wire that wraps around the six upper front teeth, which have the greatest act on a person’s smile. This wire is anchored to a plastic arch that lies against the wearer’s upper palate. The primary advantage of a Hawley retainer is that the wire can be adjusted periodically to induce small movements of the teeth, thus fine tuning the treatment provided by braces.
A vacuum-formed retainer is composed of a clear, plastic material such as polyvinylchloride or polypropylene, and typically has a thickness of less than 0.03 inches. It may fit over all the teeth or only the front teeth. A VFR prevents the upper and lower teeth from touching, which some orthodontists consider necessary for proper positioning of the teeth. The primary advantages of VFRs are that they are less expensive, easier to wear and harder to detect than Hawley retainers. The primary disadvantage of these retainers is that they break more easily.
A pressure-formed retainer is made with a pressure-molding machine that shapes the retainer according to the orthodontist’s specifications. This process typically involves pressures of up to 90 psi, whereas the manufacture or VFRs only use pressures of about 15 psi. A PFR must therefore be composed of a stronger plastic such as polyurethane, which provides a better definition of the gum line. PFRs are significantly more expensive than VFRs.
A fixed retainer is composed of a wire that is bonded to the inside of the patient’s lower teeth. The primary difference between this retainer and other types of retainers is that fixed retainers can’t be removed by the patient. Fixed retainers are typically used when the previous treatment has caused large changes in the patient’s teeth. They usually remain on the teeth for at least a year and may stay in place permanently. Fixed retainers require additional care to prevent the accumulation of tartar on the tooth surfaces that are covered by the retainer.