Dental impressions at home

A home impression kit lets you make moulds of your upper and lower teeth so a lab can build your treatment plan and aligners. The steps are much the same in every kit: mix two putties until they are one colour, lay the putty in a tray, press the tray evenly onto your teeth until the putty reaches your gums, hold it still while it sets, and lift it off cleanly. The details, especially the timings, differ between kits, so follow the instructions in the kit you were sent. A good mould records every tooth and the gum line. A dentist still has to decide whether aligners are right for you.

Before you start

• Read or watch the kit's instructions all the way through first. The putty sets in minutes, so there is no time to look things up halfway.
• Check what is in the box. Count the trays and putty pots against the manual, and look for gloves, a return bag and a prepaid label.
• Try each tray for size, without putty. Your teeth should sit in the middle of the tray without pressing against the sides. If a tray is too small or tight, contact the company before you use any putty.
• Brush and floss, and wash your hands. Food left on the teeth can show up in the mould.
• Set up somewhere well lit, with a mirror, a timer and a towel. Drooling is normal.
• Practise if your kit includes practice putty. NewSmile includes some and suggests practising until you can capture the gum line and every tooth.

Two UK kits compared

Kits differ enough that a single set of timings would mislead. Here is how two UK companies describe theirs, as published on 22 October 2026. The NewSmile column describes its published kit instructions only. When we checked on 27 October 2026, NewSmile's UK aligners could not be ordered online and its impression kit link opened a retainer product, so ask before buying its kit for treatment.

Other kits may use different putty, different trays or a different number of moulds. If your instructions differ from anything here, follow your instructions.

Making each mould

1. Mix. Take one portion of each putty and knead them together until there are no streaks. Both kits list streaky, part-mixed putty as a common fault.
2. Shape and load. Roll the putty into a log and lay it along the tray, spreading it evenly with your thumbs.
3. Centre the tray. Use the mirror to line the tray up so your teeth sit as close to the middle of the putty as possible.
4. Press evenly. Press the tray onto your teeth evenly until you feel putty at your gums all the way round. NewSmile suggests thumbs on both sides at the back first, then moving to the front, and says to push rather than bite. Follow your own kit on this.
5. Hold still. Keep the tray steady for the time your kit gives, using a timer. Moving it while the putty sets smears the imprint.
6. Remove. Take the tray out once the time is up, as your kit describes.
7. Repeat for the other arch (your upper or lower teeth), and for any extra moulds your kit asks for.

If you gag

Gagging is common with impression trays. Dental nursing guidance suggests sitting upright with your head tilted slightly forward, so the putty flows towards the front of your mouth rather than your throat, and breathing slowly and deeply in through your nose. Distraction helps some people, and letting saliva drool rather than swallowing can too. These are practical tips rather than tested treatments: a 2019 Cochrane review found too little research to say which methods work best. If you cannot manage a tray at all, ask whether the company offers a scan at a partner practice instead.

What a usable mould looks like

Check each mould before it goes in the box. A usable one shows:

• every tooth clearly, including the back molars
• a clear edge of gum all the way round
• one clean imprint, not a double outline from pressing twice or moving
• putty of a single colour, without streaks
• teeth that have not pushed through to the plastic of the tray

The common faults are the opposite: a shallow mould that misses the gum line, a missing back tooth, a double or smeared imprint, streaky putty, or teeth showing through the plastic.

If you are unsure, photograph the mould and send it to the company before you post it.

Sending them back

Pack the moulds exactly as the instructions say; NewSmile asks for them back in the box they came in, with its prepaid label. Send the number of moulds your kit asks for, and any photos it needs: NewSmile also asks aligner customers for five photos of their teeth, taken with the mouth spreader, before it can make a preview. Keep proof of postage.

If the moulds cannot be used

If a mould is distorted, aligners made from it may not fit. The company should tell you if it cannot use your moulds and send material for a retake. Check before you buy whether a retake is free: Straight Teeth Direct sends a replacement kit free under its impressions guarantee, and NewSmile sends another kit, at a discounted price if you bought the kit on its own. Sending a mould you know is poor is one of the mistakes that affect clear aligner treatment.

The mould is a record, not an examination

A mould records the shape of your teeth. It does not show your gums' health, the roots of your teeth or the bone around them. The General Dental Council said in May 2021 that there is no effective substitute for a physical examination when deciding whether direct-to-consumer orthodontic treatment is suitable, and that you should be told the name of the dentist responsible. Straight Teeth Direct, for example, asks for recent X-rays and gum scores from your own dentist. Whether aligners suit your teeth is covered in what clear aligners can and cannot treat, and how remote and practice treatment compare is in Invisalign and at-home aligners in the UK.

What happens after your moulds arrive is covered in how at-home aligner treatment works in the UK, and what kits cost in what clear aligners cost in the UK.