Computer-Assisted Dental Implant Placement Following Free Flap Reconstruction: Virtual Planning, CAD/CAM Templates, Dynamic Navigation and Augmented Reality

Abstract

Image-guided surgery, prosthetic-based virtual planning, 3D printing, and CAD/CAM technology are changing head and neck ablative and reconstructive surgical oncology. Due to quality-of-life improvement, dental implant rehabilitation could be considered in every patient treated with curative intent. Accurate implant placement is mandatory for prosthesis long-term stability and success in oncologic patients. We present a prospective study, with a novel workflow, comprising 11 patients reconstructed with free flaps and 56 osseointegrated implants placed in bone flaps or remnant jaws (iliac crest, fibula, radial forearm, anterolateral thigh). Starting from CT data and jaw plaster model scanning, virtual dental prosthesis was designed. Then prosthetically driven dental implacement was also virtually planned and transferred to the patient by means of intraoperative infrared optical navigation (first four patients), and a combination of conventional static teeth supported 3D-printed acrylic guide stent, intraoperative dynamic navigation, and augmented reality for final intraoperative verification (last 7 patients). Coronal, apical, and angular deviation between virtual surgical planning and final guided intraoperative position was measured on each implant. There is a clear learning curve for surgeons when applying guided methods. Initial only-navigated cases achieved low accuracy but were comparable to non-guided freehand positioning due to jig registration instability. Subsequent dynamic navigation cases combining highly stable acrylic static guides as reference and registration markers result in the highest accuracy with a 1–1.5-mm deviation at the insertion point. Smartphone-based augmented reality visualization is a valuable tool for intraoperative visualization and final verification, although it is still a difficult technique for guiding surgery. A fixed screw-retained ideal dental prosthesis was achieved in every case as virtually planned. Implant placement, the final step in free flap oncological reconstruction, could be accurately planned and placed with image-guided surgery, 3D printing, and CAD/CAM technology. The learning curve could be overcome with preclinical laboratory training, but virtually designed and 3D-printed tracer registration stability is crucial for accurate and predictable results. Applying these concepts to our difficult oncologic patient subgroup with deep anatomic alterations ended in comparable results as those reported in non-oncologic patients.

Learning Curve and Comparison of Dynamic Implant Placement Accuracy Using a Navigation System in Young Professionals

“…However, most surgeons still use conventional surgical templates, considering the cost and complexity of computer-aided guidance [ 28 ]. In many cases, this technique is adequate, but in some cases, it can have limitations [ 29 ]. Conventional surgical templates do not offer a solution for difficult anatomical conditions and insufficient field of view, so the surgeon must resort to the freehand technique [ 30 ].…”

Accuracy of Augmented Reality–Assisted Navigation in Dental Implant Surgery: Systematic Review and Meta-analysis

“…The characteristics of the included studies are summarized in Multimedia Appendix 1 [20][21][22][23][37][38][39][40][41][42][43][44][45][46][47]]. Among the 15 eligible studies, 5 studies [22,23,37,38] involved volunteers or patients, 2 studies were performed on cadavers [39][40][41], 5 studies [20,[42][43][44][45] involved plastic models, and 3 studies [21,46,47] used actual patient casts.…”

“…The characteristics of the included studies are summarized in Multimedia Appendix 1 [20][21][22][23][37][38][39][40][41][42][43][44][45][46][47]]. Among the 15 eligible studies, 5 studies [22,23,37,38] involved volunteers or patients, 2 studies were performed on cadavers [39][40][41], 5 studies [20,[42][43][44][45] involved plastic models, and 3 studies [21,46,47] used actual patient casts. Regarding the type of edentulous jaw, the number of mandibles (98/157, 62.4%) was higher than that of maxillary jaws (59/157, 37.6%), and the amount of partial edentulism (9/14, 64%) was higher than that of complete edentulism (5/14, 36%).…”

“…The number and type of edentulism were not reported in a previous study [23]. Regarding implant placements, 7 studies involved [22,[37][38][39][40][41]45] dental implants, 2 studies [21,47] used pins, and 4 studies [42][43][44]46] exploited drill channels to measure implant positional deviations. Two studies [20,23] did not clarify the number of implant placements.…”

Current Trends in the Reconstruction and Rehabilitation of Jaw following Ablative Surgery

“…The technology of AR has also been used to verify the location of dental implants inserted into the reconstructed jaw by augmenting the planned implant location and final prosthesis to the surgical field using a smartphone and a specially designed program. The alignment was still relying on the registration of a coded block attached to the surgical guide mounted onto the existing dentition [ 65 ]. The main difficulty of this process lies in the accurate and timely registration and tracking of the model to the real anatomy intraoperatively.…”