Teeth shifting after orthodontic treatment can be a source of frustration. This phenomenon, known as orthodontic relapse, is a common occurrence, and it happens for understandable biological and behavioral reasons. While the goal of braces is to move teeth into ideal positions, the natural dynamics of the mouth mean that teeth are always subject to various forces that can lead to movement over time. Understanding these factors can help in maintaining the results of orthodontic treatment.
Common Reasons for Teeth Shifting
Teeth possess a natural tendency to return to their original positions even after being moved by braces, known as “orthodontic memory.” This is due to the periodontal ligaments, which are elastic fibers connecting the teeth to the jawbone. When teeth are moved during orthodontic treatment, these fibers are stretched and reorganized, but they retain a memory of their former position and exert a pull to revert to it. Without continued support, these fibers can cause teeth to drift back.
Beyond this inherent memory, teeth are subject to continuous movements throughout life. Daily actions such as chewing, swallowing, and even talking apply constant forces to the teeth. Over time, these pressures can contribute to gradual shifts in tooth alignment. The surrounding bone and gum tissues also need time to remodel and stabilize around the newly positioned teeth.
The Critical Role of Retainers
Retainers counteract the natural tendency of teeth to shift back, maintaining orthodontic results. After braces are removed, teeth are not yet firmly set in their new places, and the surrounding bone and soft tissues require time to adapt and solidify. Retainers provide the necessary support, holding teeth in their corrected positions while this biological stabilization occurs.
There are two main types of retainers: fixed and removable. Fixed retainers, also known as bonded or permanent retainers, consist of a thin wire custom-fitted and glued to the back surface of the teeth. These offer continuous support. However, they require careful cleaning to prevent plaque buildup and must be checked regularly by an orthodontist to ensure they remain properly bonded.
Removable retainers include: Hawley retainers and clear aligner-style retainers (Essix retainers). Hawley retainers are made of acrylic that fits against the roof of the mouth or along the tongue side of the lower arch, with a metal wire that wraps around the teeth. Clear Essix retainers are made from transparent plastic that fits snugly over the entire arch of teeth, making them less noticeable. Both removable types must be worn consistently as prescribed, often full-time initially and then transitioning to nighttime wear, to prevent teeth from drifting.
Other Factors Influencing Tooth Stability
While retainer wear is paramount, several other biological and behavioral factors can influence the long-term stability of teeth after braces. Natural growth and aging processes can lead to changes in facial and jaw structure throughout life. This ongoing development can affect tooth alignment.
Persistent oral habits also exert forces on teeth that can contribute to shifting. Habits such as tongue thrusting, where the tongue pushes against the front teeth during swallowing or speech, mouth breathing, teeth grinding (bruxism), and clenching can similarly impact tooth stability.
Dental health issues, such as gum disease, can also compromise tooth stability. Gum disease weakens the supporting tissues and bone around the teeth, making them more susceptible to movement. Maintaining good oral hygiene is therefore important for overall tooth stability. While wisdom teeth are often blamed for causing teeth to shift, modern research suggests their direct impact on front tooth crowding after orthodontic treatment is often minimal compared to other factors, though impacted wisdom teeth can still cause issues for adjacent teeth.
Addressing Relapse: Next Steps
If teeth have shifted after orthodontic treatment, the most effective first step is to consult with an orthodontist promptly. They can assess the extent of the relapse and determine the underlying causes. Early intervention can often lead to simpler solutions and prevent further movement.
For minor tooth movement, simply resuming consistent retainer wear, sometimes full-time for a period, may be sufficient to nudge teeth back into their correct positions. The orthodontist may provide a new or adjusted retainer to achieve this. If the shifting is more significant, other retreatment options are available.
Limited tooth movement can often be corrected with clear aligners, which are a series of removable, custom-made trays that gradually move teeth back into alignment. This can be a discreet and relatively quick option. In cases of more substantial relapse, a full course of traditional braces may be necessary again. While this might seem daunting, retreatment often takes less time than the original orthodontic treatment. Regardless of the retreatment approach, a renewed commitment to long-term retainer wear is crucial to prevent future relapse and maintain the achieved results.