Why do teeth shift after braces or Invisalign, and can they move years later?

What keeps teeth moving after treatment

Braces and aligners both move teeth by force, so the bone and soft tissues around the teeth need time to stabilize around the new alignment, the AAO explains. The causes of relapse are not fully understood, a 2023 Cochrane review of retention after braces (opens in a new tab) says, but are felt to relate to the recoil of fibers holding the teeth in the jaw bone, pressure from the lips, cheeks and tongue, further growth and the way the teeth meet. The AAO adds the bone side: tooth movement is the result of a lifelong natural process called bone remodeling, and everyday forces such as biting and chewing make teeth drift in the direction of that force.

The ligament fibers that pull newly moved teeth back toward their old positions are the subject of a paragraph on retainers and retention. Carvalho & Roth Orthodontics treats retention as part of treatment: "Following through with your retention plan is just as important as completing active treatment," its retention page says.

Your braces just came off and your teeth feel odd

Teeth commonly feel smooth or slightly different right after braces come off, the AAO says, and they can sometimes feel a little loose while the bone and tissues around them adjust. The AAO also describes a settling-in period right after treatment ends, when teeth are particularly prone to moving back, often because constant force is no longer holding them. That stretch is no time for a break from the retainer: the AAO calls the early retention period especially important. If a tooth feels very loose, painful or just not right, the AAO’s next step is to "contact your orthodontist so they can take a look."

Your retainer stayed out for a while

Time without a retainer can show up as a fit problem: after an extended period without wear, the AAO says, a retainer may feel tight when it goes back in or no longer fit at all. That can mean the teeth have begun to move, the retainer has changed, or both, which is why the AAO says to contact your orthodontist rather than forcing it into place. Reading a snug, half-seated or stuck retainer gets its own page: when a retainer does not fit.

What happens without a retainer at all has a short answer in the practice’s orthodontics FAQ. If the retainer is lost or broken rather than tight, what to do if you break or lose your retainer walks through the replacement.

Years later, your front teeth are crowding again

Crowding that develops over the years is not limited to people who had braces: in a 1983 study of people with untreated normal bites, in the American Journal of Orthodontics, incisor irregularity increased from childhood into early adulthood, changes similar in nature to, though smaller than, those after retention in treated cases. Among treated patients whose treatment included premolar extractions, a 1988 study in the American Journal of Orthodontics and Dentofacial Orthopedics found that crowding of the lower front teeth kept increasing long after retention ended, and the cases responded "in a diverse unpredictable manner," with no apparent predictors of future success in the pretreatment records or the treated results. A 2018 study in the same journal followed people with normal bites from adolescence into late adulthood and found that incisor crowding increased.

Waiting to see is the wrong response, because the AAO advises telling your orthodontist as soon as you start noticing significant tooth movement. If the teeth have moved past what a retainer can hold, why some people need braces a second time is answered in can you get braces twice.

Retention is part of the treatment plan

No retainer can promise that teeth never move again. A 2023 Cochrane review says there is no recognized duration for wearing retainers, that wearing a removable retainer as prescribed is required to maintain the correction, and that some clinicians retain for longer periods, sometimes indefinitely. The AAO, for its part, says a retainer is typically necessary for a lifetime, though the frequency of wear may decrease over time. How long and how often you wear yours is your orthodontist’s call rather than a general schedule, as the AAO advises. At Carvalho & Roth Orthodontics, the retainer options are reviewed with you at your final appointment.