Common Mistakes in Intraoral Scanning

An intraoral scanner is a tool – like any tool, it requires a procedure. Even the latest 3Shape or CEREC won't capture what the clinician doesn't present. The technician in the laboratory works based on what they received – if the data is incomplete or erroneous, the work will reflect that.

Underscanned Preparation Margin

This is the most common error. The preparation margin is the line where the tooth ends and the crown begins. If the margin is hidden subgingivally, the technician cannot see it – and without this information, they design the crown by guesswork.

Result: the crown either doesn't fit perfectly (poor adaptation) or is too long and impinges on the gingiva.

How to avoid this: Before scanning, use gingival retraction – retraction cord and epinephrine paste (Expasyl, Racestyptine). Allow 5–10 minutes for the paste to act, then scan.

Lack of Full Antagonist Scan

Without an antagonist scan, the technician lacks data on the occlusal relationship.

Result: the technician designs the crown according to average anatomical parameters. Upon delivery – occlusal interference, patient discomfort.

How to avoid this: Always scan both arches. Add an occlusal scan – the technician receives a complete occlusal map.

Image Stitching Artifacts

The scanner creates a scan by combining successive frames into a single image. Sometimes at the transitions between frames, errors appear: double contours, geometric shifts, unnatural transitions.

How to avoid this: Observe the screen during scanning. Double lines or geometric jumps at the margins require rescanning that area.

Insufficient Gingival Retraction

Paste applied for 2 minutes, quickly removed, immediate scanning. The gingiva did not have time to retract.

How to avoid this: The action time of retraction paste is a minimum of 5–8 minutes. Before scanning, remove the paste with a stream of water and air, wait until bleeding stops.

What are the most common mistakes in intraoral scanning?

The four most common: underscanned preparation margin, missing antagonist scan, image stitching artifacts, and too short retraction paste application time.

How to expose the preparation margin before scanning?

Apply epinephrine retraction paste a minimum of 5–8 minutes before scanning. The gingiva should be dry and retracted by at least 0.3–0.5 mm above the preparation line.

What to do if artifacts are visible on the scanner screen?

Rescan the affected area. For systematic problems, contact the scanner service.

Do I always need to scan both arches?

Yes, for any fixed prosthetic work. Lack of an antagonist scan increases the risk of occlusal errors upon delivery.