UPDATED: 6 Nov 2025
Accurate intraoral scanning starts with clear margins, controlled moisture, and steady, consistent wand movement for precise digital impressions.
Digital dentistry has transformed how restorative work is planned and delivered. Intraoral scanning allows dentists to capture detailed, three-dimensional images that can be used to design and fabricate restorations with remarkable precision. Yet technology alone cannot guarantee accuracy. The quality of the digital impression still depends on the operator’s technique, attention to detail, and consistency.
Small errors in field control, movement, or scan path may not appear obvious on screen but can lead to subtle distortions that compromise fit once the restoration reaches the mouth. A crown that rocks, a splint that feels tight, or a contact that appears open often traces back to something as simple as a missed margin or a few seconds of moisture interference.
However, these problems are avoidable. With sound habits and structured scanning routines, dental professionals can produce accurate digital records that translate into restorations that require minimal adjustment.
This guide brings together practical tips drawn from real-world scan analysis and best-practice protocols to help you improve the consistency and reliability of every scan you take.
Common scanning issues to avoid
Most scanning inaccuracies fall into a few predictable categories. By understanding what goes wrong and why, dentists can recognise potential trouble spots before they cause downstream issues.
One of the most frequent problems is inadequate moisture control. Saliva, blood, or debris on the tooth surface scatters light and confuses the scanner’s optical sensors. Even a thin film can create small voids or blurred edges that distort the captured data. These irregularities may later appear as open margins or poor contacts once the restoration is seated. Effective moisture management before and during scanning is essential to avoid these errors.
A related challenge is insufficient retraction. If the gingiva or retraction cord is captured in the scan, the margin becomes difficult to read and reproduce accurately. This can lead to over- or under-milling and result in restorations that seat unevenly. Clear, consistent retraction ensures that the scanner records the true finish line of the preparation.
Another common cause of error is incorrect wand positioning. When the scanner is tilted or moved too quickly, areas on the mesial or palatal surfaces may be missed. The software attempts to “stitch” the data together, but these interpolations often reduce accuracy. In extreme cases, sections of the model may appear joined yet represent slightly different spatial planes.
Overscanning is another frequent pitfall. It may seem intuitive to make extra passes for more detail, but excessive rescanning can actually introduce distortion by creating conflicting data layers. The resulting mesh becomes rougher, and occlusal alignment can shift, causing discrepancies between arches.
Finally, bite mismatch occurs when the bite record does not represent true centric occlusion. The digital model may look correct, yet restorations or splints fit perfectly on the printed model while feeling high in the mouth. This is almost always the result of incomplete closure or a scan path that failed to overlap properly between arches.
Each of these issues arises from technique, not technology. Recognising the early signs of error, such as missing data bands, hazy margins, or sudden changes in texture, allows dental professionals to correct problems in real time rather than discovering them later.
How to minimise scanning errors
Once the common errors are understood, the next step is developing consistent habits that prevent them. The foundation of an accurate scan lies in creating stable, controlled conditions inside the mouth and maintaining a calm, deliberate scanning rhythm.
Lighting is a simple but often overlooked factor. Intraoral scanners are designed with their own calibrated light source, and additional illumination from operative lamps or headlamps can interfere with image capture. The best results come from dimming external lights and allowing the scanner’s internal system to control exposure and reflection.
Moisture management is equally critical. Before scanning, isolate the working field using cotton rolls, a rubber dam, or gentle suction. Even small amounts of gingival fluid can create bright spots or streaks on the digital model. If scanning takes longer than expected, pause to dry the area again. Maintaining dryness throughout the procedure ensures the optical sensor reads surface details accurately.
Movement technique also plays a major role. The wand should move smoothly and continuously, neither racing nor hesitating. Rapid or erratic motion interrupts data flow, while staying in one area for too long creates overlapping images that confuse the stitching algorithm. Think of the motion as painting with light. Use steady, even strokes that capture detail without redundancy.
Following a consistent scanning path further improves reliability. Start from the posterior region, move methodically forward along the occlusal surfaces, and then roll toward the lingual and buccal sides. Keeping the same route for every scan reduces missed data and ensures complete arch coverage. Consistency helps develop muscle memory, which in turn shortens scanning time and reduces errors caused by fatigue or variation.
While scanning, keep a close eye on the live image. Regularly inspect for voids, stitching seams, or colour anomalies that suggest incomplete data. Filling small gaps as you go saves significant time later and helps maintain the accuracy of the occlusal alignment.
Finally, rely on your technique more than on software correction. Modern systems can automatically patch missing areas, but these generated surfaces are approximations. A clean, well-captured dataset always produces a better result than a digitally “repaired” one.
Best-practice scanning protocol
A structured, step-by-step workflow allows dentists to capture reliable digital impressions across different case types. Following the same process each time creates predictable results and helps the lab design restorations that require minimal chairside adjustment.
| Step 1: Scan the opposing arch | Begin with the wand flat on the occlusal surface and confirm the starting point on screen. Capture the occlusal anatomy first, then roll toward the lingual side before finishing on the buccal.
For a single-tooth case, a full-arch scan is typically unnecessary, but covering enough adjacent surfaces ensures accurate occlusal referencing. |
| Step 2: Scan the prepared tooth | Dry the preparation completely before beginning. Centre the tooth within the viewfinder, start from the occlusal surface to establish the margin line, and roll from lingual to buccal, then distal to mesial.
Review the live model as you work. If voids appear, rescan the affected area immediately rather than continuing with incomplete data. |
| Step 3 : Scan the preparation arch | Move across the occlusal surfaces of the arch, then roll the wand to capture lingual and buccal aspects. When scanning adjacent contacts, position the wand tip flat along the occlusal plane and angle it slightly to reach interproximal spaces.
Smooth rotation avoids stitching artefacts and ensures full surface capture. |
| Step 4: Capture the bite | Ask the patient to close completely in centric occlusion. Begin scanning within a previously captured zone to maintain orientation, then guide the wand slowly between arches in a wave-like motion.
Overlap both arches sufficiently so the software can align them precisely. |
| Step 5: Maintain isolation and retraction | Throughout each step, maintain isolation and retraction. A double-cord technique {where one cord remains in the sulcus during scanning) keeps margins exposed and prevents collapse of soft tissue. Combine this with suction or an air syringe to remove moisture.
And remember, the cleaner the field, the clearer the margin definition will be. |
| Step 6: Verify the scan | Before submitting the scan, perform a quick verification check. Ensure margins are crisp and uninterrupted, that the preparation is complete, and that occlusal clearance matches material requirements. Confirm that the bite scan shows full closure in centric and that the overall model has no voids when viewed from multiple angles.
Spending one or two minutes on this review can save hours later by preventing remakes or chairside adjustments. |
Preparation and margin design essentials
Even perfect scanning techniques cannot compensate for poor preparation and margin design. That’s because the clarity of the digital image depends on how well the preparation geometry allows light to reach the margins and internal surfaces.
Avoid feather-edge or knife-edge margins for full-coverage restorations. While they conserve tooth structure, they can cause over-contouring and distortion during milling. A visible chamfer provides a distinct boundary that scanners capture easily and that milling tools can reproduce accurately.
Keep preparation angles consistent. A taper of around four to eight degrees offers the best combination of retention and accessibility. Large variations create undercuts or loss of retention, while overly steep angles make the scan harder to interpret.
Round all incisal and occlusal edges to reduce stress points and improve optical readability. Sharp corners can appear jagged or fragmented in the digital model, which may lead to weak spots in the final restoration.
Check that there is adequate reduction. Most materials require 1 to 1.5 mm of occlusal clearance for posterior teeth and about 1 mm for anterior surfaces. Inadequate space is often visible in digital clearance tools as red areas. Adjust these before completing the scan rather than relying on laboratory compensation.
Finally, inspect for undercuts where opposing axial walls face in different directions. These may prevent full seating and complicate both scanning and manufacturing. A smooth, continuous taper ensures that every surface is visible to the scanner and that the restoration will seat without interference.
Good preparation design sets the foundation for an accurate digital impression. When margins are clear, surfaces are smooth, and reduction is adequate, the scanner can capture data precisely and the lab can replicate those details with confidence.
Final word
Consistency is the hallmark of high-quality digital work. The same disciplined attention to field control, movement, and preparation detail that produces a good conventional impression also determines the success of an intraoral scan. Accurate margins, clear occlusal data, and stable soft-tissue management depend on the dentist’s technique rather than the scanner’s brand or model.
By refining your workflow to include thorough drying, careful retraction, methodical scanning, and scan verification before each submission, you can eliminate most of the variables that cause misfits and remakes.
Every small improvement in scanning consistency contributes directly to better-fitting, longer-lasting restorations and a smoother experience for both dentist and patient.
Avant Dental is a full-service dental laboratory. To find out more about working with us, please email [email protected] or phone 1800 287 336.
This blog is part of our Intraoral Scanning blog series, designed to help dentists get more predictable results from digital workflows. Explore the full series below: