Digital Scans and Crowns Not Fitting

Let’s be honest, digital dentistry has revolutionised how we work. Intraoral scanners (IO Scans) have made impressions faster, cleaner, and in many cases, more accurate than traditional putty impressions. But with this transformation comes a new set of challenges, especially when crowns don’t seat the way we expect.

At Bremadent Dental Laboratory we see it, we solve it, and we want to help you minimise remakes, save chairtime and keep patients smiling.

The Old Days vs The Digital Era
Once upon a time a dentist took a PVS or alginate impression. That physical impression went to the laboratory. On rare occasions if something was off both dentist and technician blamed the impression, leaving a fairly narrow pool of suspects. Now in a digital workflow the suspect list has exploded. You have the dentist, the intraoral scanner, scanning technique, CAD software, scanning strategy, internet transfer, lab technician, scanner software versions, email systems, even the patient’s ability to stay still, all potential points where tiny inaccuracies can lead to a crown that doesn’t fit quite right.

With digital scans everything is more traceable which is good but it also means that pinpointing why a crown doesn’t fit can feel like tracing a spiderweb of digital and human steps, each of which must be correct for success.

Why Digital Scans Can Lead to Crown Fit Issues
Digital impressions sound simple: point, scan, send. But the reality is that IO scanners are optical devices that capture millions of data points, stitch them together and rely on algorithms to create a 3D model. These systems cannot see through tissues, fluid or shadows and they require precision from the operator to get it right.

This is where a common issue often begins. A huge number of dentists do not use retraction cord routinely when preparing cases for digital scanning. A digital intraoral scan does not penetrate below the gingival margin. It acts like a photo, capturing exactly what is visible to the scanner. If the preparation margin is subgingival or hidden under soft tissue the scanner will not record that margin accurately. The scan simply cannot record what it can’t see. This can lead to crowns with open margins, poor fit, light contacts or gaps cervically.

Crowns not fitting digitally often come down to small errors early in the scan that get magnified downstream in CAD and manufacture. These errors typically include:
Bullet list
• Incomplete margin capture because the finish line is obscured by tissue, blood, saliva or poor retraction.
• Scanning artefacts from shiny surfaces, wet areas or inconsistent scanning technique.
• Undercuts, sharp edges and poorly prepared margins that digital systems struggle to recognise accurately.
• Bite registered too early or incompletely leading to occlusal misfit.
• Overscanning or going back over areas too many times leading to stitching errors in the scan.
• Long span bridges with more stitching errors accumulating making the scan less accurate.
• Software differences, updates and incompatibilities between scanner and lab CAD systems.

It’s Not Just the Scanner, It’s the Workflow
Let’s think of the digital crown workflow like a relay race. If one runner fumbles the baton the whole team slows down. In digital dentistry the runners are:
Bullet list
• Dentist prep quality and tissue management including use of retraction cord where appropriate
• Scanning operator skill yes even dentists and nurses need training
• Intraoral scanner hardware and software version
• Scanning strategy and technique
• Data transfer method internet, cloud or email
• Lab reception and interpretation of the digital files
• CAD design parameters including margin thickness and contact strength
• Milling or printing parameters
• Technician review at the laboratory

Each handoff between these steps introduces opportunities for tiny distortions, inconsistencies or misinterpretations. That is why some practices find crowns from one scanner fit perfectly and others need tweaks. It is not always the lab’s fault and it is not always the dentist’s.

Common Clinical Signs of Digital Scan Issues
When a crown comes back and doesn’t fit properly it usually presents as:
Bullet list
• High occlusion
• Open or light contacts
• Crowns that feel tight in one area and loose in another
• Marginal gaps or poor seating cervically
• Premature contacts

These symptoms often trace back to scanning errors, poor margin exposure during scan capture, preparation issues or communication breakdowns in the digital workflow.

Solutions That Work Practical Tips for Practice & Lab
The good news is most issues are solvable with a few simple workflow adjustments that reduce errors early and keep digital data clean and accurate.

1) Train and Standardise Scanning Technique
Digital scanners are only as accurate as the person using them. Clearly see the margins, plan your scan path and use a consistent scanning pattern. Avoid overscanning and keep smooth even motion. Wrong or inconsistent scanning habits lead to stitching artefacts and inaccurate models.

2) Improve Soft Tissue Management
Always ensure excellent retraction and moisture control around margins. Retract with cords where necessary. A digital scan will not magically see under soft tissue so if your margins are subgingival consider placing retraction cord before scanning to expose the finish line. Seeing the margin clearly makes a massive difference in scan accuracy.

3) Review Preparations Before Scanning
Sharp edges, undercuts, or inconsistent tapers make life harder for both scanners and CAD. Milling burs used in labs cannot perfectly replicate very sharp or thin edges, which means the CAD/CAM software will either round off these areas or create tiny inaccuracies. This not only affects fit but also creates weak points in the restoration where thick and thin sections meet, increasing the risk of chipping or fracture. Aim for smooth walls and clear chamfer or shoulder margins. This improves scanning accuracy, CAD design, and ultimately the strength and longevity of the restoration.

4) Confirm Complete Bite Registration
Incomplete interocclusal data is a major reason for occlusal misfit. Capture a full stable bite scan ideally on both sides and confirm it before sending.

5) Choose the Right Scanner Settings and Software Versions
Scanner manufacturers often update software with improved stitching algorithms and bug fixes. Make sure your scanner and lab CAD systems are on compatible versions and communicate if there have been recent updates.

6) Communicate Contact and Margin Preferences With Your Lab
Not all scanners produce the same data density or contact definition. Let your lab know if you want heavier or lighter contacts for particular materials or tooth types. Be descriptive about what you are seeing clinically. Small notes save big adjustments later.

7) Collaborate Early With the Lab
If a scan looks unusual chairside don’t just send it blindly. Get in touch. Your Bremadent team can review most scans quickly, offer feedback and often catch potential issues before fabrication.

8) When in Doubt Capture a Second Scan or Use a Hybrid Workflow
For tricky cases or deep margins a quick supplementary scan or even a PVS impression can give your lab extra data to work with. A hybrid digital and analogue approach still reduces overall remake risk.

Digital Isn’t Perfect But It Is Better
Digital impressions are here to stay because they work. In many studies they outperform traditional impressions for short span restorations when done correctly and reduce remake rates dramatically. The key is mastering the workflow not assuming the technology will do all the work for you. At Bremadent Dental Laboratory we see the results of both excellent and could do better digital scans. When practices invest in quality scanning habits and communication crowns fit first time adjustments are minimal and patients are happier.

You’re Not Alone
If you are struggling with crown fit in your digital workflow reach out. Our experience with practices across London and beyond means we have seen nearly every scenario and have practical real world solutions that save you time, money and chair adjustments.

We provide a trusted laboratory service delivering consistent quality, saving chairside time, and supporting predictable patient outcomes.

📞: 0208 520 8528 

 📧: [email protected] 

📍: 25A St James Street, London, E17 7PJ