Predictability in Full-Arch Implant Reconstruction

Effie Habsha, DDS, MSc (EH): Digital technology has positively impacted many facets of dentistry. In implant dentistry and, more specifically, full-arch reconstructions, we can now very predictably compile all of a patient's clinical data to create a virtual patient, which subsequently allows us to plan the patient's prosthesis in advance of surgery and in conjunction with planning implant placement. We have a very sophisticated way of treatment planning cases that captures ideal implant positions by merging data from cone-beam computed tomography (CBCT) scans, intraoral scans, and photographs. For a patient with terminal dentition, we can incorporate those combined datasets, retain approximately three teeth in order to position a 3D printed surgical guide, and achieve ideal implant placement. We also now have software that can incorporate the patient's smile design and select the most appropriate teeth from extensive tooth libraries, so we can mill a very esthetic provisional prosthesis in conjunction with the surgical plan and then walk into the surgery with it. The clinician can then use the surgical guide to place the implants in a flapless fashion and, if appropriate, immediately load the implants with the prefabricated prosthesis. In this manner, we are able to achieve instant patient rehabilitation after extraction with a prosthesis that is extremely accurate. We know that it fits passively because we pick it up intraorally. The patient wears the provisional prosthesis for the duration of healing, and as the tissues change and evolve, we can modify it as needed. Ultimately, we also now have the technology to acquire a digital scan of the edentulous arch after healing. There are several ways to do this, but my preferred method involves using horizontal scan gauges, rather than the typical vertical ones, which enable us to use a regular intraoral scanner without photogrammetry to scan a patient's soft tissue, the abutments, and the provisional prosthesis, and then layer all of those files together to make either a second provisional prosthesis or a definitive prosthesis. Every step of a modern digital full-arch treatment protocol incorporates digital technology that enhances accuracy as well as efficiency in terms of patient care.

ID: Why are the horizontal scan gauges significant?

EH: They enable a scanning workflow that was specifically designed to decrease scanning inaccuracy in the areas between implants. On horizontal scan gauges, there are more surfaces for the scanner to catch when compared with conventional scan bodies. This streamlines the scanning protocol and ultimately decreases scanning error.

ID: Most of the individual technologies that you described have existed for some time, so why did it take until recently to capitalize on the virtual patient concept and workflow?

EH: They existed, but they were not optimized for the treatment of edentulous patients. Merging the various datasets in software applications was not easy or smooth. The newest software applications that are available really make a difference. The one that I use allows for the integration of all of the virtual patient data-CBCT scans, photographs, STL files, and surgical guide files-in one cloud-based platform. Rather than pulling from multiple sources, you pool it into one software application, which is extremely useful. Therefore, the development of better, more all-inclusive software that does not require clinicians to piece together information from different programs has been the differentiator on the diagnostic level. On the restorative level, the acquisition of scans for full-arch implant treatment has not been very predictable in the past. There are other ways to do it, but the method involving horizontal scan gauges that I described is a lot more efficient. I have been performing guided implant surgeries for full-arch rehabilitations for many years, and in the past, any time we were transitioning a denture patient to a fixed prosthesis, we were essentially converting the patient's complete denture, which is very time-consuming and sometimes inaccurate because it can be offset and negatively alter the occlusion, among other issues. Now, the latest technology allows us to have the prosthesis made in advance based on the pre-extraction records, and the occlusion and accuracy are excellent. Overall, the current technology is just enabling us to put all of the pieces together in a way that is more cohesive than in the past.

ID: When you consider the end result, what is the total impact? Can you quantify the time and money that are saved?

EH: There are a lot of benefits, many of which are patient-centric, most importantly, but there are certainly also clinician-specific benefits. From a patient standpoint, a person can come in, have his or her teeth extracted, and leave with a prosthesis after relatively minimally invasive surgery that does not require significant bone reduction. The entire surgical protocol is a lot more streamlined and a lot less invasive than it was with conventional methods. Furthermore, having the added benefit of a prosthetic guide, which coincides with the surgical guide, allows us to position a prosthesis very efficiently, decreasing the treatment time involved. That is beneficial to the patient, of course, but the dentist's productivity also increases dramatically. Subsequent to that, the treatment can involve fewer appointments, fewer postoperative adjustments, and fewer remakes of provisional prostheses. In addition, having the plan created in advance and using digital technology across the workflow results in improvement in the esthetics and overall fit of restorations.

ID: Do these technologies increase the capabilities of general dentists to provide full-arch implant treatment, even if they are still a part of a multidisciplinary team?

EH: One cannot generalize the skill levels of individual dentists; however, there are excellent general dentists who are skilled enough to provide this level of care. What I can say is that having the best tools at your disposal allows you to optimize the accuracy of treatment planning and also to maximize collaboration with other members of the team, such as the oral surgeon and the laboratory technician. Ultimately, you need to have the restorative knowledge and skills, and of course the surgical and prosthetic knowledge and skills, to properly treatment plan and to execute, but having these technologies available where they were not before provides more predictability and reduces the potential for error. Where we are today regarding full-arch implant treatment is a more advanced place than where we were in the past, even just 1 or 2 years ago.