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How Does Invisalign Work?

Invisalign is a system of clear, removable aligners that move teeth in small steps. This guide explains how it is planned, made and worn.

Key points

  • Invisalign is a brand of clear, removable, custom-made aligners that move teeth in small steps, one tray at a time.
  • A proper assessment, diagnosis and treatment plan is essential before aligner treatment starts.1
  • Trays are worn day and night, and taken out for meals, so the plan depends on your habits.1
  • A review of 22 studies found Invisalign a viable alternative to conventional treatment for mild to moderate problems in non-growing patients without extractions.2
  • Retainers are needed after aligner treatment so that the teeth keep their corrected positions.1

Invisalign is a brand of clear aligners, which are removable, custom-made plastic trays. You wear a series of them, and each moves the teeth a small distance before the next takes over.1 It is one of several aligner systems, and the principles are shared with others.

Step 1: an assessment

Every treatment starts with an examination. A proper orthodontic assessment, diagnosis and treatment plan is essential to successful aligner treatment, so aligners should not be started without an examination.1 Your dentist looks at your teeth, gums and bite, checks for decay and gum disease, takes X-rays and photographs, and asks what you would like to change. This is when you learn whether aligners suit your teeth.

Step 2: a scan or impression

An accurate impression or scan of your mouth is taken, and the aligners are custom-made from it.1 A scan is a digital image, taken with a small handheld camera, and many people find it more comfortable than impressions.

Step 3: a treatment plan

Software is used to plan how each tooth will move, stage by stage. You see the plan, and you are told if some movements may need other techniques.2 This is a chance to ask what the end result will look like, how many aligners are planned and how long treatment is expected to take.

Step 4: the aligners are made

The trays are produced from the plan. Each is slightly different from the last, so the teeth move gradually. Some teeth may have small tooth-coloured shapes bonded to them, called attachments, which give the aligners something to grip. Our article on Invisalign attachments explains them.

Step 5: wearing the aligners

You wear each aligner day and night, and take it out for meals.1 You usually change to the next tray after a set period, as your orthodontist directs. Habits that matter:

  • wear them for the hours advised, so the teeth keep moving as planned;
  • take them out to eat and drink anything except water;
  • brush your teeth before putting them back, and clean the aligners;
  • keep them in their case when they are out, so they are not lost.

Step 6: reviews

You see your dentist or orthodontist at intervals to check the movement and receive new sets of trays. Sometimes the plan needs adjusting, for example with a few extra aligners.

Step 7: retainers

After any aligner treatment, retainers are required so that the teeth keep their corrected positions.1 Your orthodontist will explain what to wear and for how long. See our article on why wear retainers after orthodontic treatment.

What the research says

A systematic review of 22 studies of Invisalign found that it is a viable alternative to conventional treatment for mild to moderate problems in people who have stopped growing and who do not need extractions, and that it can level, tip and turn most teeth predictably.2 It found limited effectiveness for widening the arch by moving teeth bodily, closing extraction spaces, correcting contacts between upper and lower teeth and larger front-to-back or vertical problems.2 Its authors say no clear clinical recommendations can be made apart from non-extraction treatment of mild to moderate problems in non-growing patients.2

A wider review of 11 studies of aligners in general found moderate-quality evidence of a worse occlusal result than with fixed braces, and concluded that the evidence does not support aligners as equally effective.5

Comfort and cleaning

Pain with Invisalign was lower than with fixed braces in the first days, and no different after that, up to three months.3 In a meta-analysis of 7 studies with 368 patients, plaque and bleeding scores were lower with Invisalign than with fixed braces, so the teeth appear easier to keep clean.4

Who may be suited

  • Adults whose teeth have finished growing and who have mild to moderate irregularity.2
  • People whose teeth can be lined up without extractions.2
  • People whose lifestyle or work makes visible fixed braces difficult.1
  • People who will wear the aligners full-time and attend their reviews.1

Who may need something else

People with severe crowding or complex tooth movements, or whose problem comes from the size or position of the jaws, may need braces or other techniques, as may people who find it hard to wear trays most of the day and night.1 Read our comparison of aligners and braces and our pages on Invisalign and clear aligners.

What a typical day looks like

Wearing aligners becomes routine after the first week.

  • Morning: take the aligners out, clean them, eat breakfast, brush your teeth, put them back.
  • During the day: keep them in except for meals and snacks. Drink water with them in, and take them out for anything else.
  • Evening: take them out for dinner, brush and floss, clean the aligners and put them back.
  • Night: wear them while you sleep.

Many people find it helps to set a reminder to put the aligners back after meals, because leaving them out is the commonest reason for treatment to slow.

Common early issues

  • Soreness. You may feel pressure for a day or two each time you start a new tray. Soreness after a new tray is common.3
  • A slight lisp. Your tongue needs a few days to adjust to the trays, and the lisp usually goes quickly.
  • Extra saliva. The mouth produces more saliva at first, and settles.
  • Trays that do not seat fully. Tell your dentist if a tray does not fit snugly, because small adjustments may be needed.

Looking after the aligners

  • Clean them every day with a soft brush and cool water.
  • Do not eat or drink anything but water with them in.
  • Store them in the case, not wrapped in a napkin, where they are easily thrown away.
  • Keep the earlier trays until your dentist says otherwise, in case you need to go back a step.

When Invisalign may not be the answer

Some problems are better handled with braces, and some need both. If your dentist explains that your problem needs more than aligners can do, it is a reason to listen, not a failure. The evidence supports Invisalign for mild to moderate problems in non-growing patients without extractions,2 and a proper orthodontic assessment, diagnosis and treatment plan is essential.1

What to do if an aligner is lost or broken

It happens to many people. If a tray is lost, cracked or no longer fits:

  1. Call the clinic and tell them which tray number you are on.
  2. Go back to your previous tray in the meantime, if it fits comfortably, and ask whether to wear it until a replacement is ready.
  3. Do not skip ahead to the next tray unless the clinic says so, since the teeth may not be ready for it.
  4. Keep the pieces of a broken tray and bring them if the clinic asks.
  5. Do not try to repair or reshape a tray yourself.

This is why you keep earlier trays until your dentist says otherwise. The clinic can order a replacement, and a short delay is less harmful than forcing a tray that does not fit.

Travelling and eating out with aligners

A little preparation makes aligners easy to live with.

  • Carry the case, a travel toothbrush, toothpaste and water for rinsing.
  • Take spare trays and the clinic's contact details on a trip.
  • Take the trays out for meals and put them in the case, not in a napkin.
  • Rinse your mouth or brush before putting the trays back, so food is not trapped against the teeth.
  • Drink only water with the trays in.
  • Pack the next set if you will be away when you are due to change.

If you will be away for a long time, ask your orthodontist how reviews can be handled, because most plans depend on regular checks.

What a refinement is

Teeth do not always move exactly as planned. If the final tray does not give the planned result, the dentist may take a new scan and plan a refinement, which is a further short series of trays to finish the movement. A refinement is a normal part of many plans and does not mean something has gone wrong, but it does add time. Ask at the start whether a refinement is likely in your case, how it is handled and who will see you for it.

Frequently asked questions

Can I eat with Invisalign in?

No. Aligners are taken out for meals, and worn day and night otherwise.1

Is it noticeable?

The trays are clear, so they are less obvious than braces, though small attachments may be visible.

Does it work for everyone?

No. Research supports it for mild to moderate problems that need no extractions in people who have stopped growing.2

Will my teeth stay straight afterwards?

Only with retainers, which are required after any aligner treatment.1

How many hours a day do I wear them?

Full-time, day and night, except at meals, as your orthodontist directs.1

What if I lose an aligner?

Contact your dentist. They may ask you to go back to the previous tray or order a replacement.

Can I drink coffee or tea with aligners in?

Take them out for anything other than water, because other drinks can stain the aligners and sit against your teeth.

Can I drink coffee or tea with aligners in?

Only water is advised with the trays in. Take them out for coffee, tea and other drinks, then brush or rinse before putting them back, since drinks can stain the trays and sit against the teeth.

How many hours a day must I wear them?

Aligners are worn day and night, except at meals, as the British Orthodontic Society leaflet describes. Your orthodontist will give you the hours that apply to your plan.1

About the author

Portrait of Dr Anupam Sinha

Dr Anupam Sinha, BDS, MDS – Orthodontics. BDS (2002), KLE Vishwanath Katti Institute of Dental Sciences, Belgaum. MDS in Orthodontics (2006), SDM College of Dental Sciences, Dharwad. His thesis work won a national research award in 2005, and he holds a certification in aesthetic dentistry. He sees patients at Orion Dental Clinic in Greater Kailash 1, South Delhi. Read the full profile of Dr Anupam Sinha.

Sources

  1. British Orthodontic Society. Clear aligners (patient information leaflet). https://www.bos.org.uk/Public-Patients/Patient-Information-Leaflets/Clear-Aligners
  2. Papadimitriou A, Mousoulea S, Gkantidis N, Kloukos D. Clinical effectiveness of Invisalign orthodontic treatment: a systematic review. Progress in Orthodontics, 2018;19(1):37. https://pubmed.ncbi.nlm.nih.gov/30264270/
  3. Cardoso PC, Espinosa DG, Mecenas P, Flores-Mir C, Normando D. Pain level between clear aligners and fixed appliances: a systematic review. Progress in Orthodontics, 2020;21(1):3. https://pubmed.ncbi.nlm.nih.gov/31956934/
  4. Lu H, Tang H, Zhou T, Kang N. Assessment of the periodontal health status in patients undergoing orthodontic treatment with fixed appliances and Invisalign system: a meta-analysis. Medicine (Baltimore), 2018;97(13):e0248. https://pubmed.ncbi.nlm.nih.gov/29595680/
  5. Papageorgiou SN, Koletsi D, Iliadi A, Peltomaki T, Eliades T. Treatment outcome with orthodontic aligners and fixed appliances: a systematic review with meta-analyses. European Journal of Orthodontics, 2020;42(3):331-343. https://pubmed.ncbi.nlm.nih.gov/31758191/

Medically reviewed by Dr Anupam Sinha, BDS, MDS – Orthodontics, on . General information for patients from Orion Dental Clinic, last updated 23 October 2026. It is not advice for one person, so ask a dentist what suits you. To report an error, contact us.