Digital treatment planning protocols, introduction
- Virtual placement of implants allows to identify and fully use available bone volume, to plan bone augmentation and to optimize implant placement
- Since anatomical structures are revealed damage to nerves and vessels can be better prevented
- Prosthetically and anatomically driven: Predictable position and orientation of implants, taking into account all available bone and the prosthetic demands
- If CBCT technology is available, radiation involved remains limited
- Favors communication among clinical team members and patient
Creation of 3D images for software planning
Spiral or Cone Beam CT (CBCT) data sets of the patient jaw bones and of the scan template are transcoded by a specific software to produce three-dimensional (3-D) images of the jaw bones and thickness of the mucosa. Software planning can be made in a full 3-D data set or rather in 2-D and then recalculated to produce 3-D images. Planning in full 3-D mode allows to choose any viewpoint in the virtual reality, avoids recalculations of the data set and renders planning more intuitively, since it is similar to the real world.
Anatomical structures and safety zones
The images reveal height, width and trabecular/cortical structure of available bone allowing for optimal implant placement. Mucosa thickness, location of the maxillary sinuses, mandibular canal, mental foramen and incisive canal all have to be considered in the planning. A safety zone towards anatomical structures should be respected since deviations from anatomical reality can occur during imaging, software data transformation and surgery. Those deviations can add up and become clinically relevant. The clinician should clearly elaborate with the commercial company involved how large this safety zone should be, based on the maximum deviation observed in their clinical reports.
If bone augmentation has to be performed, some planning softwares allow to line out the needed bone subtitute block or the subperiosteal membrane to maintain the bone substitute material.
Prosthesis and implants positions planning
The radiological template helps to visualize the optimal prosthetic outcome. First fo all the position of the restoration is chosen and the supporting implants are planned accordingly, when the available bone allows for it. Matching the position and inclination of implants towards the prosthesis is a major advantage of 3-D planning both biomechanically and esthetically.
Softwares which integrate the extraoral face scan allow to further optimize esthetics.
Surgical guides or mental navigation
CAD/CAM-processed surgical guides are easily obtained from the same image data set. While a bone-supported drill guide is an option, presently mostly mucosally-supported guides are fabricated for flapless surgery because of the limited postoperative discomfort. One can opt for guided pilot drilling or for fully guided surgery. Even when no drill guides are fabricated, the visual transfer of the planning to the operative field improves precision of reproducing the planning and reduces surgery time.
Communication among team members and with patients
The treatment planning can be shared through the internet among the team members including the laboratory technician allowing for interactive and interdisciplinary planning. The data set of the planned prosthesis can be used for its preoperative manufacturing through the CAD/CAM technology. It can also be sent to an expert for a second opinion. The treatment planning can be shown to the patient, even fusing the radiological data with clinical images to improve understanding of what is at stake and improve acceptance through 3D visualization.