Digital impressions vs traditional impressions: what changes for the lab
A digital impression reaches the dental lab in minutes and needs no model poured. Here is what changes at intake and at the bench, and what stays the same.
By the Tusko team
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For a lab, the difference between a digital impression and a traditional one starts before any work does.
One arrives in minutes as a file. The other arrives a day or two later in a bag.
Everything after that follows. What the lab checks first, whether a model is made, and how a problem gets fixed all change with the route.
This guide follows both from the chair to the bench, and sets out what a lab and a practice each need to do differently.
Two routes to the same crown
Both routes capture the same thing: the shape of the prepared tooth, its neighbours and the bite.
| Step | Traditional | Digital |
|---|---|---|
| Capture | A tray of impression material sets in the mouth | A scanner records the teeth as a 3D file |
| Check at the chair | The dentist inspects the set impression | The dentist inspects the scan on screen |
| To the lab | Disinfected, bagged and collected by courier | Sent over a network |
| Arrival | The next day, or later | Minutes after sending |
| First job at the lab | Pour a model and trim the dies | Open the file |
| Design | On the model, or after scanning the model | On screen, from the scan |
Dr. Joel Gaudet, the dentist who founded Tusko, puts the case for scanning from the patient’s side:
“I knew the future of dentistry was not goopy impression material choking down the back of the throat. Everything had to be digital, with scanners.”
Dr. Joel Gaudet, Wave Dentistry
What the research says
Two studies are worth knowing, with their limits.
A 2014 study in BMC Oral Health took both kinds of impression from 24 volunteers.
The digital one took about four minutes in total, against about ten for the conventional one.
Every one of the 24 preferred the digital impression. The group was small and young, so read it as a signal about comfort and time, and no more.
A 2017 survey of 1,777 US dentists asked about remakes. Of the dentists who used only optical impressions, 89% reported remaking fewer than 2% of their crowns.
That was the lowest remake rate of any group in the survey. It records what dentists reported, and dentists who scan may differ in other ways too.
Neither study says a scan is always better. Together they suggest scanning is quicker for the patient, and that dentists who scan report few remakes.
What the two studies found
Three numbers from two studies. In a 2014 study of 24 volunteers, a digital impression took about 4 minutes in total and a conventional one about 10. In a 2017 survey of 1,777 US dentists, 89% of those who used only optical impressions reported remaking fewer than 2% of their crowns.
- A digital impression, in total
- About 4minutes
- BMC Oral Health, 2014, 24 volunteers
- A conventional impression, in total
- About 10minutes
- The same study
- Of dentists who used only optical impressions reported remaking fewer than 2% of crowns
- 89%
- A 2017 survey of 1,777 US dentists
What changes at intake
The largest change for a lab is timing. A digital case is on the screen while a traditional one is still at the practice.
The case can be checked the same hour. A technician can open the scan, look at the margin and ask a question before lunch.
A problem costs less. A rescan needs a short visit. A new impression needs the same visit, plus another courier run.
The Rx may not be with it. A scan sent from the scanner can arrive with a two-line note. The lab has to match it to a prescription that came another way.
Nothing physical arrives. There is no bag to put in a pan, so a digital case has to be given a place on the board deliberately.
That last point catches labs out. A lab whose whole system is built on pans can lose a case that never had one.
Give every scan a record and a slot the moment it arrives. Running a dental lab production board covers how.
What changes at the bench
Model work shrinks or disappears. There is nothing to pour, and no die to trim. If a dental model is needed, it is printed.
The margin is marked on screen. The technician traces it on the scan. Colour in the file helps to tell tooth from tissue.
Design comes first. With a scan, design starts at once. With a tray, it waits for the model.
The same file can be used again. A remake starts from the original scan, with no second impression, if the preparation has not changed.
Skills shift. Less plaster and more software. The eye for shape and contact is the same one.
Some work still wants a physical model. A technician layering ceramic by hand, or checking a long bridge, may print one for that purpose.
What each route gets wrong
Neither route is free of faults. They fail in different ways.
| Traditional | Digital | |
|---|---|---|
| At the margin | A pull or a bubble in the material | Tissue or fluid hiding the edge |
| Across the arch | Distortion as the material sets or travels | Small errors where the scanner joins its passes |
| The bite | A shifted bite record | Arches aligned wrongly in the software |
| In transit | A tray warped by heat or delay | A file sent to the wrong lab, or half a set |
| At the lab | A model that chips or is poured late | A file that will not open, or arrives without colour |
The digital column has one advantage. Many of its faults can be seen at the chair, on screen, before the patient leaves.
That only helps if someone looks. A scan sent without a check is no safer than a tray.
What stays the same
A scanner does not change what makes a good impression.
- The margin has to be visible. If tissue covers it, neither a scanner nor a tray will find it.
- The bite has to be right. Two perfect arches in the wrong relationship make a crown that is high.
- Shade still needs a photo. A scan’s colour is a guide to anatomy, and no guide to shade.
- The Rx still has to be complete. A fast file with a thin prescription is a fast question.
Our dental lab prescription checklist applies to both routes without change.
When a traditional impression is still used
Scanning has not replaced the tray everywhere, and a lab should expect to see both.
- A practice has no scanner, or its scanner is in use in another room
- The dentist prefers a tray for a particular kind of case
- Some removable work is still made from a conventional impression
- A scan could not capture an area, and a tray could
Treat this as normal. A lab that handles both well can serve every practice in its area.
Running both in one lab
The risk in a mixed lab is two systems. Scans live on a computer, trays live in pans, and nobody sees the whole day.
- One intake check. The same list for both: patient, teeth, restoration, material, shade, date, files or tray.
- One board. Print a slip for each scan and give it a pan, or use a board that shows both.
- One way to ask. A question about a scan goes to the practice the same way as a question about a tray.
- One confirmation. Tell the practice what arrived, whether that was a file or a bag.
For practices, the same holds in reverse. Label a tray so it can be tied to its Rx, and send a scan with its Rx attached.
How to send intraoral scans to a dental lab without losing files covers the digital half of that.
What to ask before you change
A practice moving to scans, or a lab starting to accept them, should settle five things together.
- Which scanners can the lab receive from directly?
- Which file format does it want, and does it want colour?
- How will the Rx travel with the scan?
- Does the lab’s turnaround differ for scans?
- Who confirms that each case arrived, and how?
STL vs PLY files covers the format question, and dental lab turnaround times covers the dates.
For the decision to bring more of the work inside the practice, see in-house dental lab vs outsourcing.
On Tusko, a scan and its Rx arrive at the lab as one case, with the photos and the date. See how it looks for labs and for practices.
Do digital impressions lead to fewer remakes?
One large survey points that way. Among 1,777 US dentists, those who used only optical impressions reported the lowest remake rates. It was a survey of what dentists reported, so it shows a link and not a cause.
Does a lab still need a model for a digital case?
Not always. Many single crowns are designed and made from the scan alone. A lab may print a model to check contacts or to layer ceramic, so ask yours what it does and when.
Can a lab accept both kinds of impression?
Yes, and many labs do. What matters is one intake routine for both, so a scan gets the same check and the same place on the board as a tray in a bag.
Does going digital shorten turnaround?
It removes the trip to the lab, which can save a day or more. The working days inside the lab depend on the product and the lab’s schedule, so ask whether its quoted times differ for scans.
Sources
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