DOCTOR ยท CLINICAL GUIDE
Troubleshooting impressions and scans
A quick good versus bad guide to the faults that get records rejected, and how to catch each one at the chair rather than after a collection has been arranged. Inspect every record before you send it.
IMPRESSION FAULTS
Common impression faults
On a PVS impression, look for air bubbles and voids in the material, double impressions, missing anatomy or teeth cut off at the ends, drag and push-through, and blended tooth and gingiva. Alginate material is always rejected, it distorts too much.
How to avoid
- Use PVS, never alginate, and the correct tray size with the rear molars covered
- Overflow both ends of the tray to capture the distal of the second molars, and the 8’s if present
- Capture 2 to 4mm of gingival margin all the way round
What gets it rejected
- Voids, bubbles, tears, drag or push-through
- A short tray with anatomy cut off at the ends
- Blended tooth and gingiva, or alginate material
SCAN FAULTS
Common scan faults
On a digital scan, watch for holes in the scan, missing anatomy or 8’s not captured, debris attached to anatomy, too little gingival margin captured, an edge-to-edge or inaccurate bite, and deformation from a poor scan sequence.
How to avoid
- Make sure all anatomy is visible, including at least half the 8’s if they are visible, with no holes in the scan
- Keep debris off the anatomy, and capture 2 to 4mm of gingival tissue
- Register an accurate bite in centric occlusion, never edge to edge, and follow a guided scan sequence
What gets it rejected
- Holes in the scan, or missing anatomy and uncaptured 8’s
- Debris attached to anatomy, which means a rescan
- An edge-to-edge bite, or deformation from a poor scan sequence
Not sure about a record?
Send it to us before you arrange a collection and we will help you get it right the first time.