Finishing your aligners or braces feels like the finish line. Research suggests it's really the start of a second phase. Without a retainer, teeth tend to drift back towards where they started, and the risk doesn't fully go away with time.
Teeth move back without retention
The Cochrane review on this topic, updated in 2023, looked at 47 studies with 4,377 participants [1]. It confirms the basic point: without a period of retention after treatment, teeth tend to relapse towards their original positions [1].
What the review couldn't do is crown a single best type of retainer or schedule. The authors judged there wasn't enough high-quality evidence to recommend one approach over another, and called for longer, better-designed trials [1]. So the specific plan your orthodontist gives you is the one to follow.
Results can slip years later
Long term follow ups show change continues well after treatment ends:
- In one study of patients assessed 10 years after they stopped wearing retainers, the overall improvement from treatment fell from 73% at the end of treatment to 54% (measured on the PAR index). Those patients had worn retainers for an average of under two years [2].
- In another group of 42 patients followed for more than 10 years, most front teeth stayed acceptably aligned (81% upper, 88% lower). The authors credited fixed lower retainers with helping keep the lower front teeth stable [3].
Part of this is just ageing. Studies of people who never had orthodontic treatment show the lower front teeth naturally become more crowded over time, especially through the teenage years [4].
How many hours actually count?
People often think they wear their retainer more than they do. Studies that hide tiny temperature sensors inside retainers show this clearly:
- Patients told to wear clear retainers 20 to 22 hours a day actually averaged about 9 hours a day [5].
- In that study, those who averaged under 9 hours a day saw noticeably more crowding of the lower front teeth after a year (about 2.0 mm vs 0.9 mm). The authors suggested at least 9 hours a day as a working minimum, while noting their sample was small and not randomised [5].
- In a separate study, patients who knew their retainer was being monitored wore it for 16.3 hours a day on average, against 10.6 hours for those who didn't know [6].
The takeaway: the hours you think you're doing may not be the hours you're doing. A consistent nightly habit is easier to keep than a vague intention.
Making it a habit that lasts
- Follow your clinician's schedule. Some start with longer daily wear and step down to nights.
- Tie it to a routine. Retainer in straight after you brush your teeth at night.
- Keep it pleasant to wear. A retainer that smells or tastes stale is one you'll be tempted to skip. Clean it daily (see our guide to what the studies show about cleaning).
- Always use a case. Retainers wrapped in a napkin are the ones that get thrown away. A dedicated case keeps it safe when it's out.
- Check the fit. If your retainer suddenly feels tight, or doesn't seat, contact your orthodontist rather than forcing it.
This article is general information, not medical advice. Your orthodontist will set the retention plan that's right for you.
References
- Martin C, Littlewood SJ, Millett DT, et al. Retention procedures for stabilising tooth position after treatment with orthodontic braces. Cochrane Database Syst Rev. 2023;5:CD002283.
- Stability of anterior tooth alignment 10 years out of retention. J Orofac Orthop. 2017;78(4):275 to 283.
- Long-term incisor alignment in 42 patients at least 10 years after treatment. Angle Orthod. doi:10.2319/122315-881.1.
- Review of retention and natural arch changes. J Can Dent Assoc. Vol 64, issue 9.
- Evaluation of relapse with thermoplastic retainers equipped with microsensors. Angle Orthod. 2022;92(3):340 to 346.
- Hyun P, Preston CB, Al-Jewair TS, et al. Patient compliance with Hawley retainers fitted with the SMART sensor: a prospective clinical pilot study. Angle Orthod. 2015;85(2):263 to 269.