Courtesy of Arizona 3D Dental Lab
By: Michael Chiara
Includes scanning protocols for denture workflows, orthodontics, crown and bridge, and surgical planning, with both optical scanners and CBCT.
SCANNING PROTOCOLS FOR DENTURES
- Always do two bite scans on a full arch scan.
- There is a vertical slider on the left side of the scanning window in Medit Link that adjusts the scanning depth. The supplier recommends setting this at 16mm.
- When having difficulty scanning a model, use powder.
- Always check over the scan carefully to make sure there are no errors or insufficient data before letting the patient leave.
- Errors are usually visible as holes, extra data such as saliva blood, etc. on a crown prep, and areas where two parts of the scan do not match up exactly.
- Use an Optragate or equivalent product to keep patient’s cheeks out of the way.
SCENARIO 1 – PATIENT HAS ONE OR MORE EXISTING DENTURES
- Reline the denture with COE-SOFT or impression material.
- Scan the complete denture, including the intaglio surface.
- Scan the opposing arch or denture.
- Place the denture(s) into the patient’s mouth and do two bite scans.
SCENARIO 2 – SCANNING FOR AN IMMEDIATE DENTURE
- Scan both arches. On the arch(es) you are making the denture for, make sure to capture the full buccal vestibule and retromolar pads, tuberosities, palate, etc.
- Do two bite scans.
SCENARIO 3 – WAX BITE
- Scan both models, capturing the sides of the models.
- Put the wax bite in, then do at least one extensive bite scan, capturing the occlusal plane, centerline, and labial surface. It is extremely important to capture the sides of the models and any landmarks on the models that can be seen with the wax rims in place. The scanner may (will probably) have trouble matching this with the models. The important thing is to get a good scan of all the above-mentioned data. You might even want to scan it separately as a separate case or a pre-op scan. If you get a good enough bite scan, I can stitch the files in a different software.
SCANNING PROTOCOL FOR ORTHODONTIC CLEAR ALIGNERS
- Scan both arches, capturing enough of the gingiva to allow a bit of excess to trim after.
- Do two bite scans.
SCANNING PROTOCOL FOR CROWN PREPS
- Scan the prep and surrounding teeth. You can use HD mode for this.
- Scan the opposing arch.
- Get a bite scan.
- Verify the prep and margins are properly captured without any extraneous data/saliva/blood rendering the image unusable.
SCANNING PROTOCOLS FOR SURGICAL PLANNING
- For the mandible, place three cotton rolls between the jaw and the cheek and two between the jaw and the tongue.
- For the maxilla, place three cotton rolls between the jaw and the cheek.
- This give remarkably sharp images and makes planning far easier
- Make sure to capture enough data to be able to plan the case. For mandibular implants, almost the entire mandible should be in the image, including the mental foramen. For maxillary, the bottom of the sinus should be included.
- Do a scan of the arch(es) on which the surgery is going to be performed. You should scan at least a quadrant, even if only one implant is being placed. Capture at least a few millimeters of gingiva around the teeth and a bit extra at the implant site.
- If also planning immediate denture(s), follow the scanning protocol above. If there is existing dentition that will be extracted, the tech will do a virtual extraction, but it is a good idea to let him know how much you would like to open up the bite in the virtual articulator, since there is almost never enough restorative space in these cases.
- It is also possible to do a CBCT scan of a model or an impression and use this instead of an optical scan. These are extremely accurate. This is convenient if you don’t have your own optical scanner and saves the cost and time delay of shipping a model or impression.
If the patient has an existing denture, this can be used to create the surgical guide, and is far more accurate and useful than an optical scan of the edentulous ridge.
- Place at least 4 radiopaque beads on the denture, as far apart from each other as possible, and take a CBCT scan of them.
- Place the denture in the patient’s mouth (beads still present) and do the CBCT scan with the denture in situ.
- In lieu of beads, if you do not have them available you can do a reline with a radiopaque impression material, such as Green Mousse before scanning.