Computer-assisted dental implant placement following free flap reconstruction: virtual planning, CAD/CAM templates, dynamic navigation and augmented reality

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.This work was supported by grant PI18/01625 (Ministerio de Ciencia e Innovación-Instituto de Salud Carlos III and European Regional Development Fund "Una manera de hacer Europa"). This study was also supported by Ticare® implants (Mozo-Grau, Valladolid, Spain). The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication

The application of virtual reality and augmented reality in oral & maxillofacial surgery

Background: Virtual reality is the science of creating a virtual environment for the assessment of various anatomical regions of the body for the diagnosis, planning and surgical training. Augmented reality is the superimposition of a 3D real environment specific to individual patient onto the surgical filed using semi-transparent glasses to augment the virtual scene.. The aim of this study is to provide an over view of the literature on the application of virtual and augmented reality in oral & maxillofacial surgery. Methods: We reviewed the literature and the existing database using Ovid MEDLINE search, Cochran Library and PubMed. All the studies in the English literature in the last 10 years, from 2009 to 2019 were included. Results: We identified 101 articles related the broad application of virtual reality in oral & maxillofacial surgery. These included the following: Eight systematic reviews, 4 expert reviews, 9 case reports, 5 retrospective surveys, 2 historical perspectives, 13 manuscripts on virtual education and training, 5 on haptic technology, 4 on augmented reality, 10 on image fusion, 41 articles on the prediction planning for orthognathic surgery and maxillofacial reconstruction. Dental implantology and orthognathic surgery are the most frequent applications of virtual reality and augmented reality. Virtual planning improved the accuracy of inserting dental implants using either a statistic guidance or dynamic navigation. In orthognathic surgery, prediction planning and intraoperative navigation are the main applications of virtual reality. Virtual reality has been utilised to improve the delivery of education and the quality of training in oral & maxillofacial surgery by creating a virtual environment of the surgical procedure. Haptic feedback provided an additional immersive reality to improve manual dexterity and improve clinical training. Conclusion: Virtual and augmented reality have contributed to the planning of maxillofacial procedures and surgery training. Few articles highlighted the importance of this technology in improving the quality of patients’ care. There are limited prospective randomized studies comparing the impact of virtual reality with the standard methods in delivering oral surgery education

Augmented reality for dental implantology: a pilot clinical report of two cases

Background: Despite the limited number of articles dedicated to its use, augmented reality (AR) is an emerging technology that has shown to have increasing applications in multiple different medical sectors. These include, but are not limited to, the Maxillo-facial and Dentistry disciplines of medicine. In these medical specialties, the focus of AR technology is to achieve a more visible surgical field during an operation. Currently, this goal is brought about by an accurate display of either static or dynamic diagnostic images via the use of a visor or specific glasses. The objective of this study is to evaluate the feasibility of using a virtual display for dynamic navigation via AR. The secondary outcome is to evaluate if the use of this technology could affect the accuracy of dynamic navigation. Case presentation: Two patients, both needing implant rehabilitation in the upper premolar area, were treated with flapless surgery. Prior to the procedure itself, the position of the implant was virtually planned and placed for each of the patients using their previous scans. This placement preparation contributed to a dynamic navigation system that was displayed on AR glasses. This, in turn, allowed for the use of a computer-aided/image-guided procedure to occur. Dedicated software for surface superimposition was then used to match the planned position of the implant and the real one obtained from the postoperative scan. Accuracies, using this procedure were evaluated by way of measuring the deviation between real and planned positions of the implants. For both surgeries it was possible to proceed using the AR technology as planned. The deviations for the first implant were 0.53\u2009mm at the entry point and 0.50\u2009mm at the apical point and for the second implant were 0.46\u2009mm at the entry point and 0.48\u2009mm at the apical point. The angular deviations were respectively 3.05\ub0 and 2.19\ub0. Conclusions: From the results of this pilot study, it seems that AR can be useful in dental implantology for displaying dynamic navigation systems. While this technology did not seem to noticeably affect the accuracy of the procedure, specific software applications should further optimize the results

Digital approach for the rehabilitation of the edentulous maxilla with pterygoid and standard implants: The static and dynamic computer-aided protocols

A full-arch rehabilitation of the edentulous upper jaw without grafting procedures exploits the residual alveolar or the basal bone, with the necessity of long implants placed with a particular orientation. The precision in planning and placing the fixtures is fundamental to avoid clinical problems and to allow an acceptable connection with the prosthesis. The computer-aided implantology resulted in more accuracy than the traditional one, with a high standard of correspondence between the virtual project and the real outcome. This paper reports about the two different digital protocols, static and dynamic, as support to implant-borne prosthetic rehabilitation of edentulous maxillae. Two pterygoid and two/four anterior standard implants were seated in both cases by two different operators, without flap raising, and immediately loaded. This approach avoided the posterior cantilever by-passing the maxillary sinus and was adequately planned and realized without any surgical or prosthetic error. The two digital flow-charts were described step by step, underlining each other’s advantages and drawbacks compared to a free-hand approach

Image-Guided Robotic Dental Implantation With Natural-Root-Formed Implants

Dental implantation is now recognized as the standard of the care for tooth replacement. Although many studies show high short term survival rates greater than 95%, long term studies (\u3e 5 years) have shown success rates as low as 41.9%. Reasons affecting the long term success rates might include surgical factors such as limited accuracy of implant placement, lack of spacing controls, and overheating during the placement. In this dissertation, a comprehensive solution for improving the outcome of current dental implantation is presented, which includes computer-aided preoperative planning for better visualization of patient-specific information and automated robotic site-preparation for superior placement and orientation accuracy. Surgical planning is generated using patient-specific three-dimensional (3D) models which are reconstructed from Cone-beam CT images. An innovative image-guided robotic site-preparation system for implants insertion is designed and implemented. The preoperative plan of the implant insertion is transferred into intra-operative operations of the robot using a two-step registration procedure with the help of a Coordinate Measurement Machine (CMM). The natural-root implants mimic the root structure of natural teeth and were proved by Finite Element Method (FEM) to provide superior stress distribution than current cylinder-shape implants. However, due to their complicated geometry, manual site-preparation for these implants cannot be accomplished. Our innovative image-guided robotic implantation system provides the possibility of using this advanced type of implant. Phantom experiments with patient-specific jaw models were performed to evaluate the accuracy of positioning and orientation. Fiducial Registration Error (FRE) values less than 0.20 mm and final Target Registration Error (TRE) values after the two-step registration of 0.36±0.13 mm (N=5) were achieved. Orientation error was 1.99±1.27° (N=14). Robotic milling of the natural-root implant shape with single- and double-root was also tested, and the results proved that their complicated volumes can be removed as designed by the robot. The milling time for single- and double-root shape was 177 s and 1522 s, respectively

Image calibration and registration in cone-beam computed tomogram for measuring the accuracy of computer-aided implant surgery

Medical radiography is the use of radiation to “see through” a human body without breaching its integrity (surface). With computed tomography (CT)/cone beam computed tomography (CBCT), three-dimensional (3D) imaging can be produced. These imagings not only facilitate disease diagnosis but also enable computer-aided surgical planning/navigation. In dentistry, the common method for transfer of the virtual surgical planning to the patient (reality) is the use of surgical stent either with a preloaded planning (static) like a channel or a real time surgical navigation (dynamic) after registration with fiducial markers (RF). This paper describes using the corner of a cube as a radiopaque fiducial marker on an acrylic (plastic) stent, this RF allows robust calibration and registration of Cartesian (x, y, z)- coordinates for linking up the patient (reality) and the imaging (virtuality) and hence the surgical planning can be transferred in either static or dynamic way. The accuracy of computer-aided implant surgery was measured with reference to coordinates. In our preliminary model surgery, a dental implant was planned virtually and placed with preloaded surgical guide. The deviation of the placed implant apex from the planning was x=+0.56mm [more right], y=- 0.05mm [deeper], z=-0.26mm [more lingual]) which was within clinically 2mm safety range. For comparison with the virtual planning, the physically placed implant was CT/CBCT scanned and errors may be introduced. The difference of the actual implant apex to the virtual apex was x=0.00mm, y=+0.21mm [shallower], z=-1.35mm [more lingual] and this should be brought in mind when interpret the results

Augmented reality in clinical dental training and education

Dentistry is a profession that requires coordinated motor skills in addition to acquired knowledge for ideal execution of any treatment plan for patients. Learning experiences have been modified over a period of time for students as well as for the healthcare providers. Conventional pre-clinical training employed the use of cadavers, but financial, ethical and supervisory constraints have become a major shortcoming. With the adaptation of technology in dentistry, pre-clinical training has now employed simulation. It provides the opportunity for students to develop psychomotor skills for procedures by practising pre-clinical, standardised learning competencies before they engage in patient-management. Simulation involves computer-aided learning, augmented reality and virtual reality, which are largely taking over pre-clinical teaching. Augmented reality is commonly being employed in maxillofacial, restorative, tooth morphology learning and mastering technique for administering local anaesthesia in dentistry. Virtual reality is being employed particularly in pre-treatment implant planning and dental education for students. Use of haptic technology, like robotics, is also gaining popularity, and facilitates a two-way communication between the user and the environment to better simulate the clinical setting for learning purposes

Dynamic Navigation: Paving The Way for Accurate Implant Placement

Dental implants have become one of the most accepted treatments for the replacement of missing teeth over the last decade. Conventional or static guided approaches are almost arbitrary approach that are heavily dependent on the clinician’s experience. Over the past several years, computer-aided implant placement (CAIP) protocols, which are based on digital workflows aimed at maximizing implant placement accuracy, have expanded the landscape of existing surgical options. The development of the dynamic navigation systems for placing dental implants is paving a way to overcome their drawbacks and provide reproduces the virtual implant position directly from computerized tomographic data and allows intra-operative changes of the implant position

Dynamic navigation for zygomatic implant placement: a randomized clinical study comparing the flapless versus the conventional approach

Objectives: The assessment of the accuracy of flapless placement of zygomatic implants in edentulous maxilla using dynamic navigation. Methods: A randomized controlled trial was carried out on 20 patients. Patients were randomized into two groups, the flapless (Group 1; n=10) and the conventional (Group 2; n=10). In each case two zygomatic implants were inserted under local anaesthesia, one on the right and one on the left side guided by a dynamic navigation system. The surgical procedure was identical in the two groups except for the reflection of the mucoperiosteal flap which was eliminated in the flapless cases. Postoperative CBCT scans were used to assess the accuracy of the placement of zygomatic implants. Results: Osseointegration was achieved for all the implants except one case in the flapless group, it was successfully replaced after 4 months. Statistically significant accuracy in the position of the zygomatic implants in the flapless group when compared to the conventional one, this was measured at the apex and the entry points of the implants (p < 0.01). The average error of apical deviation was about 5mm, 3mm shift of the coronal entry point, angular deviation was 6 degrees, and 2mm vertical apical disparity was detected between the planned and the achieved surgical position. Perforation of the Schneiderian membrane was noted in three cases, one in flapless group and two in the conventional group. Conclusions: Flapless placement of zygomatic implants guided by dynamic navigation offered satisfactory safety and accuracy. Clinical Significance: This is the first clinical trial to prove the feasibility and accuracy of flapless placement of zygomatic implant with minimal morbidity. The study highlights the innovative reflection of the Schneiderian membrane under guided surgical navigation. The procedure can be performed under local anaesthesia which offers clinical and financial advantages. Adequate training on the use of dynamic navigation is mandatory before its use in clinical cases

Image overlay surgery based on augmented reality : a systematic review

Acknowledgements We thank the staff of the Medical Library of the University of Aberdeen for their advice and Prof. Jennifer Cleland and Dr Jenny Gregory for discussion and support. This work was funded by the Roland Sutton Academic Trust (0053/R/17) and an Elphinstone PhD Scholarship from the University of Aberdeen.Postprin