If you are about to start orthodontic treatment, you will almost certainly need impressions or a digital scan of your teeth. These records are used to plan your treatment, fabricate appliances, and track your progress. You may have heard the words "iTero scan" or "digital impressions" and wondered how they differ from traditional putty impressions — or you may simply be wondering what to expect at your scan appointment. This guide explains everything clearly. Key takeaway Digital scans (such as those taken with an iTero or Trios scanner) are now the standard in most UK orthodontic practices. They are faster, more comfortable, and more accurate than traditional putty impressions. If you have a strong gag reflex or are anxious about impressions, ask your practice whether a digital scan is available. Accurate three-dimensional records of your teeth are essential for orthodontic treatment planning. They are used to study models — physical or virtual replicas of your upper and lower arches that allow your orthodontist to measure crowding, spacing, bite relationships, and the positions of individual teeth before any treatment begins. Impressions or scans are also needed to fabricate custom appliances such as clear aligners, retainers, expansion appliances, and bite registration devices. You may need scans or impressions at the start of treatment, at key review points, and at debond (when the appliances are removed) to make your retainers. Traditional impressions use a viscous material (alginate or polyvinylsiloxane, commonly called "putty") that is loaded into a U-shaped tray and pressed over the upper and lower teeth. The material sets in 60–90 seconds, during which time you need to remain still with your mouth open. Once removed, the impression leaves a negative mould of the teeth, which is then filled with dental stone to create a plaster model. Traditional impressions are effective and still used in some practices, particularly for certain appliance types. However, they have well-known drawbacks: the material tastes unpleasant, the set time feels long, and the process can trigger a gag reflex in patients who are sensitive. Plaster models can also be broken and are bulky to store. Intraoral scanners capture three-dimensional images of your teeth using a small wand-shaped camera that is moved around the inside of your mouth. The scanner captures thousands of images per second and stitches them together into a full 3D digital model in real time. Popular scanner brands in UK orthodontic practices include iTero (widely used with Invisalign), Trios (3Shape), and Cerec Primescan. The process typically takes 3–8 minutes per arch, depending on the scanner and the clinician's experience. There is no material in your mouth, no taste, and no set time to wait. You can breathe, swallow, and move your tongue normally (within limits) during the scan. The digital file can be sent electronically to a laboratory for appliance fabrication or loaded into treatment planning software immediately. 3–8 min Typical time to scan a full arch digitally 0.1mm Accuracy of leading intraoral scanners — more precise than traditional impressions 60s How long a putty impression typically takes to set Research consistently shows that leading intraoral scanners produce impressions that are at least as accurate as traditional putty, and in many cases more so — particularly for full-arch records. Digital scans eliminate the risk of distortion caused by removing the tray from the mouth before the material has fully set, and they cannot be damaged in transit to a laboratory. For clear aligner treatment planning, digital scans are actually preferred by most aligner manufacturers, including Align Technology (Invisalign), because they integrate directly with the digital planning software. Important If you know you have a strong gag reflex, tell your practice when booking your records appointment. A digital scan is significantly more comfortable for most gag reflex sufferers because nothing is pushed to the back of the mouth. If a practice only offers putty impressions, ask whether an alternative can be accommodated. A digital scan appointment is typically relaxed and straightforward. The clinician will: Ready to explore your treatment options? Start with a free virtual assessment — no scan required to begin. Get started → Digital scanning equipment is expensive, and its availability on the NHS varies by practice. Some NHS orthodontic practices have invested in digital scanning technology; others still use traditional impressions. Private practices are more likely to offer digital scanning as a routine option, often at no additional charge. If this matters to you, ask specifically when booking your initial consultation. Learn more about NHS orthodontic eligibility and typical treatment costs. Begin Your Orthodontic Journey Today A free virtual assessment from Virtual Consultant Online is the easiest first step — no impressions, no scan, no clinic visit required to get started.Why Are Impressions or Scans Needed?
Traditional Putty Impressions: How They Work
Digital Scans (Intraoral Scanners): How They Work
Which Is More Accurate?
What to Expect at a Digital Scan Appointment
Are Digital Scans Available on the NHS?
Digital Impressions vs Putty Impressions: What to Expect at Your Scan Appointment
Published · 5 min read · by Virtual Consultant Online
Ask you to sit back in the chair and open your mouth comfortably — not as wide as for a traditional impression
Move the scanner wand slowly around your lower arch first, then your upper arch
Take a "biting" scan where you close into your natural bite to record how your upper and lower teeth meet
Review the scan on screen to check for any gaps that need to be re-scanned (this is quick and painless)
In some cases, show you a 3D preview of your teeth and even a simulation of your predicted treatment outcome
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References
BOS information on clinical records in orthodontics including impressions, photographs, and X-rays.
British Orthodontic SocietyNHS overview of orthodontic treatment, including what patients can expect from the initial assessment and records process.
NHSNICE clinical guidance relevant to orthodontic records and treatment planning standards in the UK.
NICEBOS information on clinical records in orthodontics including impressions, photographs, and X-rays.
British Orthodontic SocietyNHS overview of orthodontic treatment, including what patients can expect from the initial assessment and records process.
NHSNICE clinical guidance relevant to orthodontic records and treatment planning standards in the UK.
NICE