This article defines Dandy quality scanning standards for crowns and bridges.
What is a Quality Scan
- HD Scans
- The Margin
- Contacts
- Clearance
- Point of Insertion
HD Scans - in Chairside
- When reviewing your scan before submission, please ensure that in the review step, the scans are being reviewed in HD. These are the scans the lab will use to create the restoration.
The Margin
A good margin is one that is clearly visible without surrounding tissue or cord covering it.
What is a good vs. bad scan of the margin?
- Good: The finish line of the prepped surface is fully visible, and not touched by surrounding tissue.
- This is best seen in stone colour.
- Bad: Margin has no clear definition when viewed in stone
- Bad: Tissue overlaps visible margin line
- If you notice an area where tissue or retraction cord/paste is on that margin, trim and rescan that area on the prep scan step.
- When rescanning the margin, ensure there is no saliva, blood, tissue or cord covering the margin. Be sure to clean and dry the area thoroughly as well.
- Sometimes, if there are large amounts of blood, it may be best to allow the tissue some time to heal and bring the patient back in a few days for a final scan. Simply click "save and close" in the top left corner of chairside until you are ready to rescan. Scans will be saved for 45 days. If scanning after that, you will need to rescan everything.
Contacts
Good contacts are crucial to ensure the restoration fits between adjacent teeth with little to no adjustments.
What is a good vs bad scan of contacts?
- Good: contacts are fully captured, and do not have missing areas
- Good: Adjacent contacts are smooth, without divots or burr slips.
- Bad: Missing contact areas in scan
- Bad: Adjacent contacts are bumpy, have undercuts, or have visible imperfections.
- These areas can be hard to capture. Going in with the scanner vertically on the buccal and lingual areas, and slowly rolling it left to right, can help us capture the scan data we need.
Bite
A good bite is crucial to seating crowns with little to no occlusal adjustment.
What is a good vs. bad bite scan?
Good: Properly aligned bite matches the patient's mouth
Good: Properly aligned bite shows accurate wear patterns
Bad: Bite does not reflect the patient's mouth
Bad: Bite scans show discrepancies in wear patterns
Prep
A good prep scan is crucial to restoring both a strong and aesthetic restoration.
What is a good vs. bad prep scan?
Good: Axial wall and occlusal clearance have enough space for material thickness
Good: Prep is free of sharp edges
Bad: Prepped wall does not accommodate material thickness for aesthetic restoration
Bad: Prepped occlusal does not accommodate material thickness for strength.
Path of Insertion
Good: From a single occlusal viewpoint, all margins are visible and are not covered by adjacent contact teeth.
Bad: A single unit crown has contacts overhanging the visible prepped margin
Bad: A bridge restoration shows prep abutments overhanging visible margins.
- Ensure that, for single-unit cases, the margin does not fall into an undercut. If the margin is in an undercut when the case is submitted, it will result in the lab flagging the scans
- For bridge cases, you want to be able to see all margins from the same point of view. If you do not, please adjust and rescan.
- Use the "undercut" tool on the bottom toolbar to double-check once the margins have been traced.
- This tool is great for visualising whether the margin is in an undercut. Make sure to adjust the point of insertion and check that all margins are completely green with no red.
Instructions for Use
- Global IFU - Bridge (Polymer)
- Global IFU - Bridge (Metal - Ceramic)
- Global IFU - Bridge (Ceramic)
- Global IFU - Crown (Polymer)
- Global IFU - Crown (Metal)
- Global IFU - Crown (Metal-Ceramic)
- Global IFU - Crown (Ceramic)
- Global IFU - Inlay - Metal
- Global IFU - Inlay - Ceramic
- Global IFU - Veneer