We received a remake dental case from a dental office today. The office said that the crown was with open margin. This time, we have received X-ray and new scans to remake the crown.

1. Checking X-ray

Xray of the dental crown

Xray of the dental crown

We immediately began investigation. We could see that the distal margin of the crown was open on X-ray. So we located the first-time scans and compare them with new scans. Let’s check what we found out.

2. Checking the first-time digital scan

unclear margin for dental crown

unclear margin for dental crown

We can see that the first-time scan was with poor margin. The margins were covered a lot by the gum tissue. We could not clearly determine where the margin was. Therefore, we made this crown based on our experience. Please note that we normally try not to ask for new scans, because doctors are pretty busy. It is also troublesome for dentists to call back patients for new scans.

3. Checking the new digital scan

Clear margin for dental crown

Clear margin for dental crown

Now let’s look at the new scan. The margin is very clear this time. The dentist cleaned blood and saliva. We believe the dentist used gum retraction cord before oral scanning. Now we can see that the distal margin of the new scan is a lot deeper than that of the first-time scan. This explains why the distal margin of the old crown was open.

4. Printing 3D models

3D printed models

The grey color 3D printed model is working model, while the oringe one is study model.

We printed working model with one brand of printer, and printed study model with another brand of printer. Our crown should perfectly seat on both working models and study models. This means that if one brand of printer is having a problem with precision, we will immediately know. It makes sure that the our 3D models are precise, and it also makes sure that our crowns are with precise margins.

5. Checking new margin

full zirconia crowns

Full zirconia crowns

As we can see, the margin of the full zirconia crown is perfect on the working model and the study model.