A study model, a dental impression and a digital intraoral scan all capture the same basic thing, the exact shape of your teeth and bite, but they are used for different purposes and kept under different rules, which is worth understanding the next time your dentist reaches for a tray of putty or a small wand-shaped scanner. This guide is the sibling to our articles on X-ray ownership and records transfer, but it covers the physical and digital shape record rather than the radiograph.
Key takeaways
- A study model is a plaster or 3D-printed cast of your teeth, used mainly to plan treatment and to compare your bite over time.
- A dental impression is the putty or tray-based process used to capture that shape before it becomes a model, an appliance, a denture or a crown.
- A digital intraoral scan does the same job as an impression without the tray, using a small camera-like wand, and produces a file rather than a physical object.
- Study models and scans are used for diagnosis, treatment planning, monitoring change over time and making an appliance, not just one single purpose.
- Practices generally keep this kind of record as part of your file for as long as they keep your clinical notes, following the same retention principles used for X-rays.
- This article is about your teeth's physical shape record. For the ownership and access rules around X-rays specifically, see our guide to who owns your dental X-rays.
What a study model is actually for
A study model used to almost always mean a plaster cast, poured from a putty impression, then trimmed and kept as a physical object on a shelf or in a drawer. Today it is just as likely to be a 3D-printed model produced from a digital file, but the purpose has not changed. A study model lets a dentist look at your bite from angles that are hard to see directly in your mouth, hold it in their hands, and compare it against an earlier model taken months or years before.
This comparison function is genuinely useful in a few common situations. Orthodontic treatment relies on before and after models to show how teeth have moved. Monitoring wear from teeth grinding often uses models taken a year or two apart to see whether flat spots on the teeth are getting more pronounced. Planning a full mouth rehabilitation or a significant bite change usually starts with a set of models mounted on a device called an articulator, which recreates how your jaw actually opens and closes, something a flat photo cannot show.
Impressions: the process behind the model
An impression is the step that comes before a model exists. A tray filled with a putty-like material is seated over your teeth for a minute or two while it sets, capturing every groove and edge in reverse. That impression is then used to pour a model, sent to a dental laboratory to make a crown, denture or mouthguard, or scanned itself to create a digital file.
Impressions are still used for some appliances and in some clinical situations where a digital scanner cannot easily reach, such as a mouth with very limited opening, or for certain denture work. They have a long track record and remain a reliable option, even as scanning has become more common for everyday use.
Digital scans: the same shape, a different capture method
A digital intraoral scan uses a small hand-held wand that is moved over your teeth, building up a 3D digital model on a screen in real time rather than needing a tray of material to set. For many patients this is more comfortable, particularly anyone who has ever found a full impression tray uncomfortable to hold in place.
The output is a digital file rather than a physical object, which brings a few practical advantages. It can be emailed directly to a dental laboratory without anything needing to be posted or couriered. It can be enlarged on screen to check detail that is hard to see on a small plaster model. And because it is a file, a copy exists indefinitely without the storage space a growing shelf of plaster models would eventually need.
Digital scans for planning appliances such as a nightguard for teeth grinding, retainers, or clear aligners are now common, and the file itself can also be compared over time in the same way an older set of plaster models would have been, by overlaying an earlier scan against a current one to measure how much a tooth has moved or worn.
What each record is actually used for
- Diagnosis and treatment planning. A dentist studies the model or scan alongside your clinical examination and X-rays to work out the best approach to a filling, crown, denture or orthodontic plan.
- Monitoring change over time. Comparing a current model or scan against an earlier one shows tooth wear, movement or the progress of an orthodontic plan in a way a verbal description cannot.
- Making an appliance. A model, impression or scan is what a dental laboratory actually works from to build a crown, bridge, denture, mouthguard, splint or retainer that fits your mouth precisely.
- Communicating with a laboratory or specialist. A digital file or physical model is often the clearest way to show a technician or another practitioner exactly what your teeth look like, more precise than a written description alone.
How long a practice keeps these records
Retention expectations for this kind of record generally follow the same broad principle used for the rest of your clinical file, including X-rays: a health record is typically kept for at least seven years from your last visit if you are an adult, and until you turn 25 if the record was created while you were under 18. This is the same benchmark set out in the Dental Board of Australia's Code of Conduct and reflected in NSW health record-keeping guidance.
In practice, digital scan files are simple to retain well beyond that minimum, since a file takes up negligible storage space compared to a physical model. Physical plaster models and study casts take up actual shelf space, so some practices retain the digital record of a case (a scan, or a scanned copy of an older physical model) for the long term, while a physical model itself may eventually be returned to the patient, disposed of, or replaced by its digital equivalent once the treatment it was made for is complete and stable.
Comparing the three records at a glance
| Record type | What it is | Main use | Format kept |
|---|---|---|---|
| Study model | Plaster or 3D-printed cast of your teeth | Bite analysis, comparing change over time | Physical object, or digital file if scanned |
| Dental impression | Putty-based capture used to create a model or send to a laboratory | The step before a model, crown, denture or appliance exists | Usually not kept itself, once the model or item is made |
| Digital intraoral scan | Wand-based 3D digital capture | Same purposes as a model, plus faster laboratory communication | Digital file, easily retained long term |
Can you ask for a copy of your own models or scan?
Yes. In the same way you have a right to request a copy of your X-rays, you can ask for a copy of a digital scan file or, where relevant, arrangements around a physical study model. A digital file is straightforward to provide as a copy without losing the original. A physical plaster model is a single physical object, so a practice may photograph it, offer a 3D-printed duplicate, or discuss what is practical, rather than there necessarily being an easy duplicate on hand the way there is for a digital file. Our guide to changing dentists and transferring records covers the practical process if you are moving your whole file to a new practice.
Frequently asked questions
What is the difference between a dental impression and a study model?
An impression is the process of capturing the shape of your teeth in a putty-like material. A study model is the plaster or 3D-printed cast made from that impression, or from a digital scan, once the shape has been captured.
Why would my dentist want a scan if nothing seems wrong?
Scans and models are not only used to fix a problem. They are also used to track change over time, such as wear from grinding or gradual tooth movement, which is easier to see by comparing images than by relying on memory.
Do I own my study models or scan file?
The practice generally holds the record as part of your clinical file, in the same way it holds your X-rays and notes, while you have a right to access and request a copy of the information. Our guide to dental X-ray types covers how a similar principle applies to radiographs.
Is a digital scan more accurate than a traditional impression?
Both can produce accurate results when done well. A digital scan is generally more comfortable for many patients and gives an instant on-screen result, while a traditional impression remains a reliable option, particularly for certain appliances or situations where scanning is harder to use.
How long does a practice keep my scan or model on file?
Records are generally retained for at least seven years from your last visit as an adult, or until age 25 if the record was created while you were under 18, following the same principle used for the rest of your clinical file.
Can I take my study models with me if I change dentists?
You can request a copy of the record. For a digital scan this is usually straightforward. For a physical model, discuss with the practice what is practical, since it is a single physical object rather than an easily duplicated file. Our guide to understanding your dental treatment plan covers what other documentation is usually part of your file.
If you are curious about what records your own file includes, or want a copy for a second opinion or a new dentist, the team at Lumi Dental can talk you through what is held and how to request it. Current new patient offers are listed on our current deals page.
This article is general information about dental records in Australia and does not replace advice from the practice that currently holds your file.
