A Step-By-Step Workflow
Following is a simplified step-by-step workflow for an edentulous implant case, within a digital workflow.
In today’s world, it is possible to do virtually all major steps of implant prosthetic work in a digital workflow. However, it is usually carried out drifting in and out of a truly digital workflow, and we are still reliant on the traditional procedures in many instances.
Each clinician should make workflow decisions based on patient needs and practice efficiency for each case individually.
Digital Workflow Procedures for Edentulous Implant Cases
1. Create an ideal denture set-up, either from the current denture or new set-up.
The initial steps in a digital workflow for an edentulous case are essentially the same as a conventional workflow.
There are two possible starting places for any given edentulous implant case. In either situation, the goal of the initial sequence of records is to establish the desired vertical, smile line, tooth position, occlusion, and phonetics.
If the current denture meets the essential element that you will desire in the final prosthetic, you can make a duplicate denture that will be used for articulation and as the scanning guide.
This requires bite block and set-up try-ins. Digital options to record the bite and set-up are on the horizon, but not something that we are recommending at this time.
In both cases, it is important to take a PVS to reline impression in the duplicate denture or new denture set-up.
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2. Fabricate CT Scanning Appliance. (Figure 3)
Once an ideal denture set-up is established it is then used as the basis for a CT scanning appliance.
Important design elements for the CT Scanning Appliance:
After you pour the stone base make a base extending about 10 mm beyond the buccal peripheral of the scanning appliance.
Now, add radio-opaque composite dots around the base's ledge.
Optically scan the appliance with the stone base prior to separation, and optically scan the model after separation.
3. The CT Scanning Appointment
Perform the scan with the CT scanning appliance in the mouth. (Figure 6)
4. Surgical Planning
Merge the CT scan, the .stl of the appliance, the .stl of the model, and the .stl of the model with the appliance in place in an implant planning software.
5. Guided Surgery Appliance Design
After the surgical plan is completed the guided surgery appliance can be designed and exported to a .stl file for printing. (Figure 7)
6A. Surgical Appointment
Use the guided surgery appliance to perform a fully guided surgery, including implant delivery. (Figure 9)
6B. Surgical Appointment - Immediate Provisionalization
Conversion denture can be pre-fabricated using the digital implant planning software in a few different ways: Figure 10
A model with guide pins incorporated in a printed model can be used as a guide to cut holes in the prosthetic to be delivered. The conversion appliance can be derived from previous denture or a new denture. (The new denture could be printed or milled or conventional processing.)
Digitally fabricate a denture with screw access holes pre-designed into denture via the surgical guide plan, and using the CT scanning appliance as a template.
The titanium cylinders are seated, and then the prosthetic is placed over the top and tacked down. The prosthetic is removed and perfected for delivery during the surgical appointment.
7. Digital impression appointment for PMMA provisional prosthetic
8. PMMA provisional designed and fabricated (Figure 12)
The lab merges the scan body .stl, the model scan, and the appliance scan within the design software. Once the digital merge is complete the PMMA prosthetic can be perfected and milled.
It should be noted that intra-oral full arch impressions using digital scan bodies are not 100% dimensionally accurate. Full arch prosthetics that are fabricated from an intra-oral scan are not guaranteed for fit. In these cases, it is always best to deliver a PMMA provisional that is cemented to the titanium cylinders in the mouth. This will reduce the potential for fit problems. Once the PMMA provisional is delivered and the patient has lived with it for a period of time, the PMMA provisional can be used to scan and copy mill the final prosthetic restoration.
9. Final restoration delivery
Final restorations can be fabricated from a scan and copy mill of the tested and approved provisional can be delivered in a variety of materials for the final restoration.
The digital workflow is a rapidly changing environment. In this article we have reviewed certain steps; however, there are other workflows. It is always best to consult with Burbank Dental Lab prior to beginning a workflow on a complex case to assure that the current procedures used will assure you and your patient of the best results.
Burbank Dental Lab has the technology to assist you in the process of creating full arch prosthetics and the expertise to partner with you in the success of your cases.