Orthodontic treatment is only fully completed with the retention phase. A retainer is a custom-made appliance designed to hold teeth steady in their corrected alignment after braces are removed. This device is a mandatory part of the overall treatment plan, ensuring the long-term stability of the achieved smile. Neglecting to wear this appliance as prescribed can lead to noticeable changes in tooth positioning, undoing the time and financial investment of the straightening process.
Orthodontic Relapse and Shifting Teeth
The most immediate consequence of failing to wear a retainer is orthodontic relapse—the natural tendency of teeth to drift back toward their original, pre-treatment positions. This movement can begin quickly, with shifting sometimes reported within just a few days or weeks of discontinued retainer use.
Relapse commonly manifests as the reopening of spaces closed during treatment. Frequent signs include new or worsening crowding on the lower front teeth, or the rotation of individual teeth. The speed of shifting depends on the severity of the original alignment issue, with complex cases often showing movement sooner.
Retainers are generally either removable (like clear plastic trays or Hawley appliances) or fixed (a thin wire bonded to the back of the front teeth). The absence of a removable retainer allows the teeth to move freely, while a break in a fixed retainer can cause the teeth on either side of the break to shift. Once shifting begins, the misalignment can also affect the alignment of the upper and lower jaws, changing how the teeth fit together when the mouth is closed.
Why Teeth Naturally Want to Move Back
The need for a retainer is rooted in the biology of how teeth are held in the jawbone. Each tooth is suspended within the jaw by thousands of microscopic fibers called the periodontal ligament. These elastic ligaments have a “memory” that tries to pull the teeth back to their previous locations, similar to a stretched rubber band.
Orthodontic movement works by slowly breaking down and rebuilding the bone surrounding the tooth root, allowing the tooth to slide into its new spot. This process of alveolar bone remodeling is slow and takes time to fully stabilize the teeth in their new positions. If the retainer is not worn consistently, the ligaments and soft tissues exert pressure that encourages the teeth to move before the bone fully hardens around the new roots.
Aging naturally causes minor changes in the facial structure and dental arch, which contributes to teeth shifting. Even individuals who have never had braces experience some degree of movement over time. The retainer is necessary to counteract these ongoing biological and age-related pressures, protecting the alignment achieved during treatment.
Correcting Teeth That Have Already Shifted
If teeth have already moved due to non-compliance, the first action should be an immediate consultation with an orthodontist to assess the severity of the change. In cases where the movement is very slight, the original removable retainer may still fit, even if it feels tight. For minor relapse, wearing the existing retainer full-time for a period may be sufficient to gently guide the teeth back into place.
If shifting is pronounced, the old retainer will likely no longer fit without excessive force, and attempting to force it can damage the teeth or the appliance. The orthodontist will need to take new impressions to create a new retainer. This new retainer holds the teeth in their current, slightly shifted position to prevent further movement and might be designed as an active retainer for minor corrections.
For moderate degrees of shifting, a limited course of orthodontic treatment is often recommended. This could involve using clear aligners or partial braces for a few months to realign only the teeth that have moved. This targeted approach is faster and less expensive than a full retreatment. If the relapse is severe and the original bite problems have returned, a patient may require a full second round of comprehensive orthodontic therapy to restore the proper alignment and bite.