Technology, precision, clinical applications and comparison with traditional impressions — everything you need to know
A digital impression is the three-dimensional recording of a patient's oral anatomy — teeth, gums, arches and occlusion — captured with an intraoral scanner (IOS) in place of traditional impression materials (alginate, silicone, polyvinyl siloxane). The result is a digital file in STL or PLY format that can be sent instantly to the lab, processed by CAD software or sent to a CAD/CAM milling machine.
The transition from traditional to digital impressions is one of the most significant changes in dental practice over the last twenty years, comparable in impact to the introduction of digital radiology. It's not a matter of technical preference, but a structural change in the workflow that affects efficiency, quality and patient satisfaction.
The intraoral scanner projects structured light (or laser) onto the surface of the teeth and captures thousands of frames per second while the clinician moves the wand inside the mouth. Acquisition software processes the data in real time and reconstructs the 3D geometry of the arch, displaying it on screen as the scan progresses.
There are three main acquisition technologies:
| Parameter | Traditional | Digital (IOS) |
|---|---|---|
| Patient comfort | Low — material in the mouth, risk of nausea | High — only a lightweight wand, no material |
| Chair time | 10–20 min (impression + setting time) | 2–5 min |
| Single-tooth precision | ±30–80 µm | ±5–20 µm (premium systems) |
| Full-arch precision | ±50–100 µm | ±10–30 µm (premium systems) |
| Transport errors | Frequent (deformation, temperature) | None |
| Cost per impression | €3–10 (materials) | €0 (only scanner amortization) |
| Transmission to the lab | Physical shipping (1–3 days) | Instant digital transfer |
| Archiving | Physical model (space, deterioration) | Digital file (unlimited, retrievable) |
| CAD/CAM integration | Requires scanning the physical model | Direct, no intermediate steps |
| Learning curve | None | 4–8 weeks to full proficiency |
This is the application with the highest ROI and the shortest learning curve. Scanning the prepared abutment, the opposing arch and the wax occlusion completely replaces the silicone impression. With a chairside CAD/CAM system, the crown is ready the same day.
IOS scanning is now the preferred method for planning clear aligners (Invisalign, F22, Spark). It eliminates plaster models, reduces set-up time and enables digital treatment simulations to show the patient.
The IOS scan, merged with the CBCT volume via software such as coDiagnostiX or Implant Studio, enables three-dimensional implant planning and the production of 3D-printed surgical guides with positioning precision < 1 mm.
Digital scanning allows a patient's situation to be compared over time: abrasion, erosion, orthodontic progression. Files are archived and can be reviewed years later with overlaid comparison.
Digital impressions for removable prosthetics are still evolving, but systems like Medit and 3Shape already support the complete workflow for implant-bar-supported full dentures.
The learning curve is real but manageable. Most clinicians reach good proficiency within 4–8 weeks of daily use. The critical stages are:
Manufacturers offer on-site training and online tutorials. Many authorized resellers include training sessions with the purchase.
The dental lab needs to be equipped to receive and work with digital files. Before buying an IOS scanner, check that your reference lab accepts STL files and has CAD software. If the lab still works in analog, consider making the transition or find digital labs in your area — the market has become heavily digitalized over the past five years.
Find intraoral scanners on the DentLink marketplace: 3Shape TRIOS, Carestream, Medit, Primescan and more. Save 40–60% compared to new.
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