If you have experience in guided surgery, you know that the Dual Scan Protocol (DSP) is the industry standard for Fully Edentulous Surgical Guides. However, the Dual Scan Protocol can also be an inconvenience for many offices, as it requires the patient to have an existing well-fitting hard-relined denture. Before capturing the CBCT scans, the denture must be marked with radiographic markers. Even when executing the CBCT scans themselves, following the Dual Scan Protocol results in a higher incidence of errors in dental offices. Despite the extra steps and potential inconveniences, why is the Dual Scan Protocol still the ideal standard for fully edentulous guided surgery cases? In this article, we will highlight the crucial advantages of the Dual Scan Protocol to illustrate why it is vastly superior to a CBCT + Soft Tissue Model for your fully edentulous implant cases.
A Quick Look at Dual Scan Protocol (DSP)
- The Dual Scan Protocol is a CBCT Scanning Protocol for Fully Edentulous scenarios which provides an accurate and predictable capture of the patient’s soft tissue prior to implant treatment planning and surgical guide design. It enhances treatment planning by providing restorative information, which is critical for a restorative-based treatment plan.
- The Dual Scan Protocol can accomplish these things because it requires a well-fitting, hard-relined denture that accurately captures the patient’s soft tissues and current tooth positioning. When followed properly, the accurate denture fit translates to a well-fitting surgical guide.
Required Materials:
- Hard-relined Denture(s) with no soft-reline materials
- Intimate fit between acrylic and tissue
- Radiographic Markers
- Set of two (2) CBCT Scans
CBCT Scan #1: Denture + Markers Only
- Apply 6 radiographic markers to the cameo surface of the denture
- Place markers near the gingival margin on different axial slices
- Randomly place 3 on the facial and 3 on the lingual/palatal
*Do not place the markers on the intaglio surface of the denture*
- Orient the marked denture as it would sit in the patient’s mouth
- Position the denture into the FOV using a radiolucent object (sponge, foam block)
- Capture CBCT using Recommended Settings: 6cm – 8cm, 0.3 – 0.4 Voxel
Repeat steps for the opposing arch, if applicable
CBCT Scan #2: The patient wearing the denture(s) with markers
- Ensure that markers have not changed positions
- Do not use a bite stick. Have the patient bite in natural occlusion
- Capture CBCT using Recommended Settings: 6cm – 8cm, 0.3 – 0.4 Voxel
Upload CBCT Scans
Export the CBCT scans individually as multi-file DICOM files into appropriately named folders. Once zipped/compressed, they can then be imported into a treatment planning software for restoratively based treatment planning and guide design.
Restorative
Before surgical guide design can be considered, a sound treatment plan must be created. The variables to consider increase significantly when planning for a fully edentulous case compared with a partially edentulous case. This is where the Dual Scan Protocol shines by providing invaluable restorative information during the planning process. The captured denture scan is registered to the patient CBCT using the radiographic markers as registration points. This registration allows the planner to visualize both the patient anatomy and the prosthesis as it would sit in the mouth. With this information on hand, the planner can begin a restorative checklist:
Restorative Space:
Is there sufficient restorative space for the final prosthesis? With the Dual Scan Protocol, the answer to that question is easily answered. What is the distance from the incisal edge of the denture to the platform of the implant? Any deficiency in the space required immediately signals to the planner that sub-crestal placement and/or bone reduction may be a consideration.
Emergence:
How is the emergence of the implant in relation to the prosthesis? Anyone who has experience in 3D implant treatment planning knows that aligning the implant with the bone does not always result in the proper restorative emergence. In fact, the growth of digital implant planning and surgical guides is due to the need to differentiate ideal surgical angulation vs ideal restorative angulation. With the denture present in the scan, the planner can visually confirm how the implant emerges relative to the prosthesis, and emergence can be adjusted to ensure a viable and esthetic restoration.
The Design
The Dual Scan Protocol continues to impact the guided surgery workflow into the guide design step as well. The acquisition or absence of a Dual Scan Protocol directly affects the resulting guide design and the level of stability and accuracy. Here are some of the benefits the Dual Scan Protocol has for surgical guide design:
The designer can use the intaglio surface of the provided denture scan to design the surgical guide. This means that the resulting surgical guide will fit the patient exactly as the denture does. This is the primary reason a hard-reline is required during a Dual Scan Protocol. Any rocking, instability or space present in the denture fit will be translated into the guide design. Conversely, a snug, stable denture will yield an equally intimate and well-fitting surgical guide.
One of the challenges in delivering a tissue-borne surgical guide is confirming the correct orientation before securing it in place with anchor pins. Since there are no teeth to act as concrete landmarks, a tissue-borne surgical guide can easily be mispositioned on the flexible surface of the soft tissue, especially on a resorbed ridge.
In scenarios where the patient has minimal bone or a very thin ridge, a tissue-borne surgical guide that is mispositioned even as little as 2-3 degrees could result in disaster for the final implant placement. When the Dual Scan Protocol is executed correctly, this concern can be eliminated. The designer can incorporate the denture teeth into the surgical guide itself, allowing the patient to occlude onto it. This occlusion now confirms the guide is in the same orientation as the CBCT scan capture, prior to being fixated with anchor pins. The surgeon can then confidently proceed with surgery.
Dual Scan Protocol – Are there alternatives?
As an alternative scenario, a CBCT + Soft Tissue Model can yield an accurate, well-fitting surgical guide, and many surgeons have successfully used this workflow. However, as one can see, foregoing the Dual Scan Protocol leaves variables to chance. At Implant Concierge, implant treatment planning and surgical guide design are our specialties, and we truly believe the benefits of the Dual Scan Protocol vastly outweigh the minor inconveniences. If the best possible outcome for the patient is the goal, then the Dual Scan Protocol is most predictable modality for fully edentulous guided treatment.
If you are not able to execute the Dual Scan Protocol because your patient does not have a well-fitting, hard-relined denture, there are other protocols that can be followed.
Visit our website to learn more about those protocols or call us at 866-977-2228, and we would be happy to assist you and your team.