Dental Impressions: Digital vs Traditional Techniques

What research actually says about the accuracy comparison between intraoral scanners and traditional silicone impressions: where digital technology already excels, and where conventional impressions still remain the more reliable choice.

The intraoral scanner captures a three-dimensional model of the patient's mouth through optical sensors, typically based on structured light, in a process that usually takes less than two minutes and requires no physical impression material. Compared to a traditional silicone impression, the most immediately noticeable advantage for patients is comfort: no more need to hold the mouth open for a long time with a tray loaded with material, which significantly reduces discomfort, especially in patients with a pronounced gag reflex or in children.

On the front of clinical accuracy, however, the scientific literature offers a more nuanced picture than the marketing around new technologies suggests. A literature review published in Doctor OS highlights that optical impression accuracy is clinically satisfactory and comparable to conventional impressions for single restorations or fixed partial dentures of up to 4-5 units. For more extensive rehabilitations — fixed partial dentures with more than 5 units, or full-arch prostheses on natural teeth or implants — studies instead indicate a still-measurable superiority of traditional impressions, which accumulate less error over the extent of the scan.

An analysis published in Odontoiatria33 adds a relevant technical detail: for single-tooth scanning or sectional impressions of an implant abutment, digital technique accuracy is comparable to that obtained with a polyether impression material; for full-arch scanning, however, studies still indicate a superiority of traditional impressions. Interestingly, according to the same analysis, digital scan accuracy seems to depend more on the sequence and movement with which the operator performs the scan than on the scanner system itself: scanning the arch through multiple progressive passes, for example, partially compensates for the reading errors that would accumulate in a single continuous pass.

This picture suggests a more useful practical conclusion than an absolute verdict for or against digital: the choice between digital and traditional impressions should be made case by case, based on the extent of the rehabilitation to be performed, rather than as a once-and-for-all matter of principle adopted in the practice. It's no coincidence that the most recent hybrid protocols — for example in building complete dentures — deliberately combine traditional impressions for the steps where they remain more accurate with subsequent digitization to leverage workflow speed in later phases.

On Oralzon you'll find both traditional silicone and polyether impression materials for every clinical indication, as well as consumables compatible with the main intraoral scanning systems.