Relapse

Orthodontic relapse, in the AAO’s words

Orthodontic relapse is teeth moving out of their new positions once treatment is over. On its page about life after braces, dated September 16, 2026, the American Association of Orthodontists (AAO) says teeth can shift after braces are removed and gives the shift its name: “This is sometimes called orthodontic relapse, and it can happen because teeth naturally tend to move over time.”

Another AAO page, on whether retainers are needed, describes the pull: “Your teeth will attempt to return to their original positions after treatment, as no pressure is being applied to them.” The everyday way to say it is that the teeth shifted, or drifted back.

Why relapse happens is only partly known: Cochrane’s 2023 review of retention after braces notes in its background that what causes relapse is not fully understood.

Where relapse comes up: once active treatment ends

Relapse comes up at the point where treatment changes from moving teeth to holding them. The AAO’s Glossary of Orthodontic Terms says retainers, worn as prescribed, are a tool “to minimize unwanted tooth movement after active treatment ends,” and the AAO’s page on life after braces calls wearing a retainer as instructed “one of the most important ways to help limit unwanted movement.”

Minimize and help limit are the AAO’s own verbs, and neither one says a retainer keeps every tooth exactly where treatment left it.

The American Academy of Pediatric Dentistry (AAPD) names where relapse tends to show, in its guideline on the developing dentition: “Mandibular incisors have a high relapse rate in rotations and crowding.” Mandibular incisors are the lower front teeth.

Relapse, retention and the practice’s retainer sentence

Relapse is the reason retention follows active treatment, and the practice states the retainer’s job in a sentence of its own: A dental retainer is a custom-made appliance that maintains the position of your teeth after orthodontic treatment.

Why straightened teeth drift back, which kind of retainer suits a case and what published guidance says about wearing one are set out on the retainers page. Retention and fixed retainer, two neighboring words, are defined in the orthodontic glossary.