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CBCT Dual Scan Protocol: Step-By-Step Instructions

Taking a proper dual scan is difficult. 50%+ of submitted dual scans are incorrect.

It’s critical that all steps are followed – we are here to help.

A dual scan is the only way to fabricate a tissue supported edentulous, and in some cases partially edentulous, Pin Guide or surgical guide. The only way for the lab to see and work tissue is when we have the intaglio of the scan appliance seated and captured against the tissue, which comes from the dual scan.

Term

Definition

Dual Scan

Dual scan is when the office needs to take two scans, one with the patient wearing the scan appliance, and one of the appliance alone.

Scan Appliance

A scan appliance is usually the patient’s existing denture or a duplicate of the denture. There are do’s and don’t below, but suffice it to say that if you have a denture, and it fits (intimate with all tissues), and it is close to what the patient likes, and there’s no soft liner, then you have a scan appliance – just add the markers.

Markers

Markers are radiopaque beads or gutta percha that are added to the scan appliance for registration. If there are no markers, then you do not have a scan appliance. Markers can be purchased from ROE or can be ordered in bulk from www.suremark.com. You can order the 2.0 mm size from the ROE online store. The markers are placed on the scan appliance randomly on the pink or tooth area, labial or lingual, and even palatally – not on occlusal or intaglio. They must not move from their positions between the two/dual scans.

Scan Process

The scan process is to scan the patient wearing the denture/scan-appliance with the markers, in occlusion, just like they always wear their denture, with their chin on the chin rest. This is the first scan. The second scan is of the scan appliance by itself, on a piece of foam or a special scan table, not touching any metal or plastic. Be sure the scan captures 100% of the appliance.

Dual Scan Technique: Step-by-Step Guide

  1. Check the patient’s denture to ensure that it is NOT reinforced by any metal substructure. This will cause issues in the CBCT.
  2. Ensure that the existing denture fits well. Perform hard reline, or use Green Mousse to simulate relined intaglio surface. If there is space between the intaglio surface and the soft tissue, the guide will fit the same way and will lead to error.
  3. Place four to six radiopaque markers along the denture flange (available in ROE’s online store) approx. 5mm from the gingival margin.
  4. If using gutta-percha material, create a 1-mm-deep hole with a round bur and pack the hole with gutta-percha material. Ensure the material is flush with the denture’s or scan
    appliance’s surface.
  5. Single edentulous – records
    • Scan denture in the mouth in occlusion
    • Scan denture on foam
    • CHROME photo series
    • Bite registration
    • Opposing model or IOS Scan
  6. Double edentulous – records
    • Scan both dentures in the mouth, in occlusion
    • Individually scan both dentures resting on the foam
    • CHROME photo series
  7. Scan appliances must be placed on a foam block in the CBCT scanner or on the provided scan table. This will prevent the denture scan from merging with the base it sits upon. Ensure all surfaces of the denture are captured.
  8. When scanning the patient, ensure that the radiopaque markers positions remain the same as the previous scan. These markers act as constants across scans.
  9. Perform a second scan of the patient wearing the denture in full occlusion.
  10. Export all DICOM data from your CBCT and submit to ROE.

Dual Scan Material Requirements

  1. Patient’s well-fitting existing denture or an acrylic duplicate scan appliance. The denture must contain zero metal.
  2. Radiolucent bite registration material – Green Mousse
  3. Reline material (only needed if the existing prosthesis is mobile)
  4. Radiopaque stickers or gutta-percha material fiducial markers.
  5. Styrofoam or foam block

Dual Scan Technique: Typical Errors

Do’s
  1. Verify your scans before sending the patient home. It’s better to rescan vs reschedule with the patient
  2. Look for black voids between the tissue and the scan appliance. If there are gaps re-evaluate the methods and the fit.
  3. Ensure the denture is ideal for the patient and that it fits.
  4. Make sure that the patient is not wearing jewelry (may cause scatter) and stays very still through the scanning.
  5. Use scan markers. Cases without markers will not work.
  6. Capture a bite and opposing cast or IOS on single edentulous cases.
  7. Set Gantry tilt to none/ 0 degrees.
  8. Set slice thickness ≤ 0.4mm.
Dont’s
  1. Scan soft liners. They must be replaced with a hard reline or Green Mousse.
  2. Scan the appliance on plastic in the CBCT.
  3. Scan with the patient opened, biting on anything. Must be in a closed position on the chin rest.
  4. Add scan markers on the occlusion or intaglio.
  5. Send any edentulous arch tissue records (the dual scan is the only record of the edentulous arch).
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