A scan is the foundation of every digital aligner case. When it is clean, planning moves quickly. When it is not, the case can stall for days while the team asks for a new scan, repairs the model or guesses at missing areas.

The good news is that most scan problems are easy to prevent. Here are eight common intraoral scanning mistakes, what they cause and how to avoid them. Always follow the manufacturer’s guidance for your own scanner, since methods differ between systems.

Mistake 1: Scanning in a wet or crowded field

Saliva, blood and a moving tongue or cheek can distort the scan or leave gaps. Wet surfaces may also reflect light and confuse the scanner.

How to avoid it: isolate and dry the area as well as you can, use cheek retractors, and ask the patient to keep the tongue still. Scan the toughest areas first while the field is clean.

Mistake 2: Scanning too fast

Moving the scanner quickly can break the stitching of images, which leads to distorted or incomplete areas.

How to avoid it: use a slow, steady pace and keep the scanner at the recommended distance. Watch the live image, and slow down whenever the software loses tracking.

Mistake 3: Missing the back teeth and gum margins

Distal surfaces of the last molars, interproximal areas and the gum margins are the most common places for gaps. Missing data here can cause poor aligner fit or an incorrect model.

How to avoid it: follow a consistent scanning path, and make sure you capture occlusal, buccal and lingual surfaces for the whole arch. Review each arch on screen for holes before moving on.

Mistake 4: A poor bite registration

If the patient does not bite in a natural, stable position, the upper and lower arches will not line up correctly. This affects the setup and the final bite.

How to avoid it: guide the patient into their usual closure, check that they are not biting on soft tissue or a loose restoration, and compare the digital bite with what you see in the mouth. Repeat the bite scan if there is any doubt.

Mistake 5: Leaving plaque, calculus or debris on the teeth

Deposits and debris change the surface the scanner records. The model may then show shapes that are not real, which can affect attachments and fit.

How to avoid it: clean the teeth before scanning, and remove any excess material, cement or loose restorations that should not be in the model.

Mistake 6: Not managing soft tissue and gum margins

Swollen or bleeding gums and soft tissue folds can hide the edge of the tooth and make margins unclear.

How to avoid it: treat gum problems before the scan if possible, and use retraction methods where needed so the margin is visible to the scanner.

Mistake 7: Skipping calibration and equipment care

A scanner with a dirty tip, fogged mirror or missed calibration can produce poor results, even when your technique is correct.

How to avoid it: follow the maintenance steps for your scanner, such as cleaning, using clean tips and calibrating when required. Keep your software up to date.

Mistake 8: Not checking before you send

Many delays start here. Scans are sent without a final check, with missing areas, the wrong bite, unclear case details or files in the wrong format.

How to avoid it: use a short pre-send checklist (below), and make sure files are named clearly and complete before they leave your clinic.

Your 60-second pre-send checklist

Check	Done
Both arches scanned fully, with no holes or gaps
Distal surfaces of the last molars captured
Gum margins visible and clear
Bite registration matches the patient’s natural bite
Teeth clean, with no debris or loose material
No obvious distortion, doubled surfaces or stitching errors
Files in an accepted format and named clearly
Prescription and case notes attached

What happens when a scan is not good enough

When a scan has problems, the planning team usually has three options. They can try to repair small gaps in the model, ask you for a new scan, or plan around the problem with extra risk. Repairing gaps is possible for small defects, as explained in our guide to Meshmixer for aligner models, but it cannot replace missing anatomy. A new scan is often the fastest and safest choice.

A clean scan also makes later checks easier. See our guide to aligner QC service and our 6-step digital aligner workflow to see how scan quality connects to the whole process.

Building a scanning routine in your clinic

A few simple habits will improve scan quality across your whole team:

1. Assign one trained person to own scanning quality, or train everyone on the same method.
2. Use a written scanning path so no area is forgotten.
3. Review every scan on screen before the patient leaves.
4. Keep a short list of the rescans you needed and why, and learn from the patterns.
5. Ask for feedback from your planning partner when a scan caused a problem.

Frequently asked questions

What is the most common intraoral scanning mistake? Missing areas, especially the back teeth and gum margins, along with poor bite registration.

Can a planner fix a bad scan? Small defects can sometimes be repaired, but large gaps or distortions usually need a new scan.

Do I need powder to scan? That depends on your scanner. Many modern scanners do not need it, so follow the manufacturer’s instructions.

Is an impression better than a scan? Not necessarily. A good scan is faster to send and easy to check on screen, but a high-quality impression that is digitized can also work.

How can I tell if the bite registration is wrong? If the arches do not seat the way they do in the mouth, or you see unexpected gaps or collisions between the teeth, repeat the bite scan.

Need help with a difficult scan?

If you are unsure whether a scan is good enough, send it to us before you commit to a case. Contact OrthoAlign Solution and we will help you check it. Add your own details here about accepted file formats and how to send scans, so readers know exactly what to do.