The retention phase is the required final stage of comprehensive orthodontic treatment. This period is an active continuation of the process that moved the teeth into their new positions. The purpose of this phase is to maintain the alignment and bite correction achieved by the braces. By holding the teeth steady, the retainer allows surrounding biological structures to stabilize, securing the results of the treatment long term.
The Biology of Tooth Relapse
The tendency for straightened teeth to shift back toward their original positions is a natural biological process known as orthodontic relapse. This movement is driven by the “memory” stored within the tissues that support the tooth. Teeth are held in the jawbone by the periodontal ligament (PDL), a network of fibers connecting the tooth root to the alveolar bone.
During treatment, the PDL is constantly stretched and compressed, triggering the resorption and formation of bone. When braces are removed, the ligament and surrounding gingival fibers are still under tension and try to pull the teeth back to their initial alignment. The alveolar bone, remodeled during movement, requires a significant period to fully reorganize and secure the new tooth placement. The retainer acts as a passive scaffold, resisting these forces until the bone fully matures around the roots.
Types of Retainers and Their Function
Hawley Retainers
One common removable option is the Hawley retainer. It uses a custom-fitted acrylic plate that rests against the palate or floor of the mouth, combined with a wire that spans the front of the teeth. The wire can be adjusted slightly to fine-tune alignment or accommodate minor settling.
Essix Retainers
Another popular removable option is the Essix retainer, a clear, vacuum-formed plastic appliance that snaps snugly over the entire arch of the teeth. This type is favored for its near-invisibility and comfort. However, its thin plastic construction can wear down over time, especially for individuals who clench or grind their teeth.
Fixed Retainers
A third option is the fixed, or permanent, retainer. This consists of a thin, braided wire bonded directly to the tongue-side surface of the front teeth, typically from canine to canine. This non-removable appliance passively holds the alignment twenty-four hours a day and is often recommended for patients who had significant crowding or spacing. A fixed retainer requires meticulous hygiene to prevent plaque and calculus buildup around the wire.
Retainer Wear Schedule and Duration
The transition from active treatment to the retention phase involves a gradual reduction in wear time. Initially, full-time wear is mandatory (approximately 22 hours per day), only removed for eating and brushing. This intense phase, which typically lasts three to twelve months, allows the periodontal ligaments and bone to begin stabilizing the new tooth positions.
Following this initial period, the orthodontist instructs a transition to a reduced schedule, most often nightly wear. While frequency decreases, retention duration is generally considered indefinite. Teeth naturally continue to shift throughout life due to chewing, aging, and growth, even after the bone has stabilized. Consistent nightly wear helps counteract these long-term movements.
What Happens Without Consistent Retention
Failing to wear the retainer as directed allows relapse mechanisms to take effect immediately, leading to a loss of alignment. The most common consequence is the return of dental crowding or the re-emergence of spaces between teeth. The bite relationship can also shift, potentially leading to discomfort or functional issues.
If a retainer is left out too long, the teeth move to the point where the appliance no longer fits comfortably. Attempting to force a tight retainer back into place can cause pain or damage the appliance. In cases of substantial relapse, the only solution is often re-treatment, which requires additional time and financial commitment.
Retainer Care
Protecting the retention device is important for long-term success. Removable retainers should always be stored in their protective case when not in the mouth, as they can easily be lost or damaged. Exposure to high heat, such as leaving a retainer in a hot car, will warp the plastic, rendering the appliance useless. Regular cleaning with a toothbrush and mild soap or a specialized cleanser is necessary to prevent the buildup of plaque and odor-causing bacteria.