CBCT Scanning Tips For Surgical Guides
As A General Rule, These Are The Guidelines For Scanning Patients:
- Teeth must be apart.
- Ideally a full arch scan to be completed to ensure enough common stitching points to make reference between the dicom files and the impression or intra oral scan.
- High quality silicone impression putty wash capturing as much detail of the hard and soft tissue as possible.
- Intra oral scans to capture as much soft tissue as possible especially if planning on full arch cases.
Clinical Scenarios
Mildly restored dentition
Take full arch CBCT scanNormal putty wash silicone impression or intra oral scanBite
Heavily Restored Dentition And Limited Number Of Remaining Teeth 5 Or Less
Silicone impression + Bite
A. Place 6-8 radiographic markers on the outside of impression tray.
B. Replace the impression scan back into the patients mouth.
C. Scan the patient with the impression in the mouth in the CBCT scanner.
D. Immediately remove the impression and place only the impression into the CBCT scanner and scan. You will then have 2 data sets. The dicom of the patient with impression in the mouth and one of the impression only.
Edentulous Patient
The ideal prosthetic envelope is required to plan appropriate implant position.
This is best done by providing all the stages up to the denture try in stage. Ideally the denture try in base should be fabricated from a stable material such as triad.
The future fit of your surgical guide will be as good as the fitting surface of your try in.
Alternatively if the patient currently has a well fitting denture to utilise this as the prosthetic envelope. If it is poorly fitting consider relining with silicone or hard acrylic for the purpose of scanning.
Steps:
The denture try is verified and ensured the fitting surface is suitable.
Radiographic markers are placed on the buccal flanges and the palatal aspect of the denture (approx. 8-10)
The patient is positioned into the scanner by means of a chin rest.
Ensure the patient is in ICP in their dentures.
The patient is scanned in the CBCT scanner.
The dentures are then removed and the dentures scanned in the scanner one at a time.
You will then have 2 data sets for a single arch case. Dicom file of the patient with dentures in situ and a dicom file of the denture only.
Prepared by: Dr. David Veige DD, BDS, MJDF (RCS Eng.) MSc. Implantology
Useful Videos:
Generating an STL Model from a CBCT Scan of an Impression: