Impact of 3D virtual planning on reconstruction of mandibular and maxillary surgical defects in head and neck oncology

Accuracy of augmented reality navigated surgery for placement of zygomatic implants: a human cadaver study

Purpose

Placement of zygomatic implants in the most optimal prosthetic position is considered challenging due to limited bone mass of the zygoma, limited visibility, length of the drilling path and proximity to critical anatomical structures. Augmented reality (AR) navigation can eliminate some of the disadvantages of surgical guides and conventional surgical navigation, while potentially improving accuracy. In this human cadaver study, we evaluated a developed AR navigation approach for placement of zygomatic implants after total maxillectomy.

Methods

The developed AR navigation interface connects a commercial navigation system with the Microsoft HoloLens. AR navigated surgery was performed to place 20 zygomatic implants using five human cadaver skulls after total maxillectomy. To determine accuracy, postoperative scans were virtually matched with preoperative three-dimensional virtual surgical planning, and distances in mm from entry-exit points and angular deviations were calculated as outcome measures. Results were compared with a previously conducted study in which zygomatic implants were positioned with 3D printed surgical guides.

Results

The mean entry point deviation was 2.43 ± 1.33 mm and a 3D angle deviation of 5.80 ± 4.12° (range 1.39-19.16°). The mean exit point deviation was 3.28 mm (±2.17). The abutment height deviation was on average 2.20 ± 1.35 mm. The accuracy of the abutment in the occlusal plane was 4.13 ± 2.53 mm. Surgical guides perform significantly better for the entry-point (P = 0.012) and 3D angle (P = 0.05); however, there is no significant difference in accuracy for the exit-point (P = 0.143) when using 3D printed drill guides or AR navigated surgery.

Conclusion

Despite the higher precision of surgical guides, AR navigation demonstrated acceptable accuracy, with potential for improvement and specialized applications. The study highlights the feasibility of AR navigation for zygomatic implant placement, offering an alternative to conventional methods.

A comparison of preoperative soft tissue contour versus bone accuracy as a predictor of quality of life outcomes in osseous free flap jaw reconstruction using occlusal-based virtual surgical planning

OBJECTIVES

Occlusal-based virtual surgical planning (VSP) prioritises the placement of endosseous dental implants, over replicating native bone contour. This may compromise facial aesthetics. This study aimed to compare function and health-related quality of life (HRQOL) following maxillomandibular reconstruction according to the ability to replicate preoperative soft-tissue contour and virtual plan.

MATERIALS AND METHODS

Patients who underwent occlusal based VSP osseous free flap reconstruction of the maxilla or mandible with high-resolution pre- and post-operative facial computerised tomography imaging and completed the FACE-Q questionnaire were retrospectively identified. Accuracy of reconstruction compared to preoperative soft tissue contour and virtual plan, was measured using 3DSlicer® and CloudCompare® in three dimensions. Random effects modelling determined the associations between bony and soft tissue accuracy and HRQOL/functional domains.

RESULTS

Twenty-two patients met the inclusion criteria. For mandibular and maxillary reconstructions, better soft tissue accuracy was associated with improved appearance (p = 0.048) and appearance distress (p = 0.034). For mandibular reconstructions, better soft tissue accuracy was associated with improved smile (p = 0.039) and smile distress (p = 0.031). For maxillary reconstructions, better bony accuracy was associated with improved appearance (p = 0.023) and drooling distress (p = 0.001). Unexpectedly, better bony accuracy was associated with worse eating and drinking (p = 0.015), oral competence (p = 0.005) and eating distress (p = 0.013) in mandibular reconstructions.

CONCLUSION

Whilst soft tissue accuracy was associated with better functional and HRQOL outcomes, bone accuracy was associated with worse oral function or distress in mandibular reconstruction. These results require validation but should be considered when performing occlusal-based VSP, which prioritises dental rehabilitation over replicating facial bony contour.

Guided placement of zygomatic implants in head and neck cancer patients: implant survival and patient outcomes at 1-3 years of follow-up

Zygomatic implants (ZI) are a valuable option for supporting an obturator prosthesis after maxillary resection. This study was performed to assess the clinical outcomes of a digitally validated guided technique for ZI placement, followed by immediate prosthetic obturation. The primary objective was to evaluate implant survival, while the secondary objective was to assess patient-reported quality of life post-rehabilitation. Twelve patients treated for head and neck cancer received a total of 36 ZI after ablative surgery. The mean duration of ZI follow-up was 30.1 months. The survival rate of ZI placed in non-irradiated patients was 100%, while it was 85% in irradiated patients. Patient-reported outcomes were evaluated using the Liverpool Oral Rehabilitation Questionnaire (LORQv3) and the University of Washington Quality of Life Questionnaire (UW-QOL v4). Most patients reported satisfactory outcomes in the oral function domain of the LORQv3 (mean score 17.7 ± 4.5; possible range 12-48, with lower scores indicating better outcomes). Regarding the UW-QOL v4, the swallowing and chewing domains had the highest scores (mean 97.5 ± 8.7 and 95.8 ± 14.4, respectively; maximum possible score of 100). In conclusion, this treatment approach improves function and quality of life after maxillary ablative surgery. However, irradiated patients showed a noticeable trend of higher implant failure, and this was influenced by tumour position and size impacting the radiation dose to the zygomatic bone.

Reconstructive flap surgery in head and neck cancer patients: an interdisciplinary view of the challenges encountered by radiation oncologists in postoperative radiotherapy

Background

Major advances have been made in reconstructive surgery in the last decades to reduce morbidity in head and neck cancer. Flaps are now present in 80% of patients with oral cavity cancer to cover anatomic, functional, and cosmetic needs. However, gaps in interdisciplinary innovation transfer from surgery to postoperative radiotherapy (poRT) remain challenging. We aimed to provide an interdisciplinary view of the challenges encountered by radiation oncologists in planning head and neck postoperative radiotherapy.

Methods

A systematic and critical review was conducted to address areas of optimization in surgery and radiology that may be relevant to poRT.

Results

Despite extensive surgical literature on flap techniques and salvage surgery, 13 retrospective series were identified, where flap outcomes were indirectly compared between surgery alone or poRT. These low-evidence studies suggest that radiotherapy accelerates flap atrophy, fibrosis, and osteoradionecrosis and deteriorates functional outcomes. Preliminary evidence suggests that tumor spread occurs at the flap-tissue junction rather than in the flaps. One prospective 15-patient study showed 31.3% vs. 39.2% flap volume reduction without or with poRT. In an international consensus, experts recognized the needs for optimized flap-sparing poRT against flap-related functional deterioration and bone damage. CT, MRI, and PET-CT modalities show potential for the delineation of the junction area between native tissues and flap for flap segmentation and to characterize flap-specific changes quantitatively and correlate them with patterns of relapse or complications.

Conclusion

Flap management in poRT is insufficiently documented, but poRT seems to damage flaps. Current gaps in knowledge underscore the need for prospective flap assessment and interdisciplinary trials investigating flap morbidity minimization by flap-sparing poRT planning.

Prefabricated fibula free flaps in reconstruction of maxillofacial defects: Two cases of transplanting a fractured fibula

BACKGROUND

The two-staged prefabricated vascularized fibula free flap is used in maxillofacial reconstruction. We describe the possible cause and management of two cases of fibula fracture after implant placement.

METHODS

The patients were treated with two-stage reconstruction with a prefabricated vascularized fibula free flap. Six dental implants were placed in both fibulas. Fibula fractures occurred during the osseointegration period before the second procedure. The reconstruction was continued as planned.

RESULTS

Both fibulas fractured in the distal segment, possibly due to a thinner cortex more distally. Harvesting of a fractured fibula flap is more difficult than normally due to callus formation and fibrosis. Both transplants became fully functional with extended healing and additional surgery.

CONCLUSION

The fracture apparently did not compromise the vascularisation of the fibula and proved still sufficient for successful harvest and transfer of the flap. The patient should be made aware that additional corrective surgery may be indicated.

Identifying Factors of Operative Efficiency in Head and Neck Free Flap Reconstruction

Importance

Head and neck oncological resection and reconstruction is a complex process that requires multidisciplinary collaboration and prolonged operative time. Numerous factors are associated with operative time, including a surgeon's experience, team familiarity, and the use of new technologies. It is paramount to evaluate the contribution of these factors and modalities on operative time to facilitate broad adoption of the most effective modalities and reduce complications associated with prolonged operative time.

Objective

To examine the association of head and neck cancer resection and reconstruction interventions with operative time.

Design, Setting, and Participants

This large cohort study included all patients who underwent head and neck oncologic resection and free flap-based reconstruction in Calgary (Alberta, Canada) between January 1, 2007, and March 31, 2020. Data were analyzed between November 2021 and May2022.

Interventions

The interventions that were implemented in the program were classified into team-based strategies and the introduction of new technology. Team-based strategies included introducing a standardized operative team, treatment centralization in a single institution, and introducing a microsurgery fellowship program. New technologies included use of venous coupler anastomosis and virtual surgical planning.

Main Outcomes and Measures

The primary outcome was mean operative time difference before and after the implementation of each modality. Secondary outcomes included returns to the operating room within 30 days, reasons for reoperation, returns to the emergency department or readmissions to hospital within 30 days, and 2-year and 5-year disease-specific survival. Multivariate regression analyses were performed to examine the association of each modality with operative time.

Results

A total of 578 patients (179 women [30.9%]; mean [SD] age, 60.8 [12.9] years) undergoing 590 procedures met inclusion criteria. During the study period, operative time progressively decreased and reached a 32% reduction during the final years of the study. A significant reduction was observed in mean operative time following the introduction of each intervention. However, a multivariate analysis revealed that team-based strategies, including the use of a standardized nursing team, treatment centralization, and a fellowship program, were significantly associated with a reduction in operative time.

Conclusions

The results of this cohort study suggest that among patients with head and neck cancer, use of team-based strategies was associated with significant decreases in operative time without an increase in complications.

Skull-Base Surgery-A Narrative Review on Current Approaches and Future Developments in Surgical Navigation

Surgical navigation technology combines patient imaging studies with intraoperative real-time data to improve surgical precision and patient outcomes. The navigation workflow can also include preoperative planning, which can reliably simulate the intended resection and reconstruction. The advantage of this approach in skull-base surgery is that it guides access into a complex three-dimensional area and orients tumors intraoperatively with regard to critical structures, such as the orbit, carotid artery and brain. This enhances a surgeon's capabilities to preserve normal anatomy while resecting tumors with adequate margins. The aim of this narrative review is to outline the state of the art and the future directions of surgical navigation in the skull base, focusing on the advantages and pitfalls of this technique. We will also present our group experience in this field, within the frame of the current research trends.

Three-Dimensional Innovations in Personalized Surgery

Due to the introduction of three-dimensional (3D) technology in surgery, it has become possible to preoperatively plan complex bone resections and reconstructions, (corrections and adjustments related to bones), from head to toe [...].

Digital Planning for Immediate Implants in Anterior Esthetic Area: Immediate Result and Follow-Up after 3 Years of Clinical Outcome-Case Report

In this case report, we demonstrate how the correct positioning of implants, associated with optimal gingival conditioning, and the correct choice of biomaterial can yield very predictable and fantastic aesthetic results.

OBJECTIVE

We aimed to use dental implants to rehabilitate the area of elements #11 and #21 in a satisfactory surgical and prosthetic manner, using guided surgery, connective tissue, nano-biomaterials, and a porcelain prosthesis.

CASE REPORT

A 32-year-old male patient presented with bone loss of elements #11 and #21, which was proven radiographically and clinically. Thus, oral rehabilitation with the use of dental implants was required. It was decided to proceed via digital planning with the DSD program (Digital smile design) and with the software Exoplan, (Smart Dent-Germany) whenever it was possible to plan immediate provisional and accurate dental implant positioning through reverse diagnostics (Software Exoplan, Smart Dent-German). The dental elements were extracted atraumatically; then, a guide was established, the implants were positioned, the prosthetic components were placed, the conjunctive tissue was removed from the palate and redirected to the vestibular wall of the implants, the nano-graft (Blue Bone^®) was conditioned in the gaps between the vestibular wall and the implants, and, finally, the cemented provision was installed.

RESULTS

After a 5-month accompaniment, an excellent remodeling of the tissues had been achieved by the implants; consequently, the final prosthetic stage could begin, which also achieved a remarkable aesthetic result.

CONCLUSIONS

This report demonstrates that the correct planning of dental implants, which is associated with appropriate soft tissue and bone manipulation, allows for the achievement of admirable clinical results.

Interdisciplinary challenges and aims of flap or graft reconstruction surgery of sinonasal cancers: What radiologists and radiation oncologists need to know

In sinonasal cancer surgery, a fundamental challenge is to understand the postoperative imaging changes after reconstruction. Misinterpretation of post-operative imaging may lead to a misdiagnosis of tumor recurrence. Because radiotherapy planning is based on imaging, there are many gaps in knowledge to be filled in the interpretation of postoperative imaging to properly define radiotherapy tumor volumes in the presence of flaps. On the other hand, radiotherapy may be responsible for tissue fibrosis or atrophy, the anatomy of the reconstructed region and the functional outcomes may change after radiotherapy compared to surgery alone. This narrative review illustrates the interdisciplinary aims and challenges of sinonasal reconstructive surgery using flaps or grafts. It is particularly relevant to radiologists and radiation oncologists, at a time when intensity modulated radiotherapy and proton therapy have the potential to further contribute to reduction of morbidity.

The effect of virtual reality on temporal bone anatomy evaluation and performance

PURPOSE

There is only limited data on the application of virtual reality (VR) for the evaluation of temporal bone anatomy. The aim of the present study was to compare the VR environment to traditional cross-sectional viewing of computed tomography images in a simulated preoperative planning setting in novice and expert surgeons.

METHODS

A novice (n = 5) and an expert group (n = 5), based on their otosurgery experience, were created. The participants were asked to identify 24 anatomical landmarks, perform 11 distance measurements between surgically relevant anatomical structures and 10 fiducial markers on five cadaver temporal bones in both VR environment and cross-sectional viewings in PACS interface. The data on performance time and user-experience (i.e., subjective validation) were collected.

RESULTS

The novice group made significantly more errors (p < 0.001) and with significantly longer performance time (p = 0.001) in cross-sectional viewing than the expert group. In the VR environment, there was no significant differences (errors and time) between the groups. The performance of novices improved faster in the VR. The novices showed significantly faster task performance (p = 0.003) and a trend towards fewer errors (p = 0.054) in VR compared to cross-sectional viewing. No such difference between the methods were observed in the expert group. The mean overall scores of user-experience were significantly higher for VR than cross-sectional viewing in both groups (p < 0.001).

CONCLUSION

In the VR environment, novices performed the anatomical evaluation of temporal bone faster and with fewer errors than in the traditional cross-sectional viewing, which supports its efficiency for the evaluation of complex anatomy.

Virtual Surgical Planning in Free Tissue Transfer for Orbito-Maxillary Reconstruction

Since its introduction, virtual surgical planning (VSP) has been rapidly adopted as a part of reconstructive surgeon's armamentarium. VSP allows reconstructive surgeons to simulate resection, plan osteotomies, and design custom plates. These unique advantages have been especially beneficial for head and neck reconstructive surgeons as there is small room for error and high technical demand in head and neck reconstruction. Despite its popularity, most surgeons have limited experience in using VSP for orbito-maxillary reconstruction as tumors that involve the midface are relatively rare compared with other head and neck oncologic defects. In our institution, we routinely use VSP for orbito-maxillary reconstruction using free fibula flap to provide support for orbit, to restore normal dental occlusion, and to restore midface projection. In this chapter, we will discuss the role of virtual surgical planning and our algorithmic approach of performing orbito-maxillary reconstruction using free tissue transfer.

Soft Tissue Dehiscence Associated with a Titanium Patient-Specific Implant: A Prosthetic Solution as an Alternative to Soft Tissue Grafting

Patients. This clinical report describes the detailed prosthodontic management of a 23-year-old male patient suffering from soft tissue complication following the placement of a 3d-printed titanium patient-specific implant. This implant was implemented simultaneously with the resection of a calcifying cystic odontogenic tumor related to the maxillary arch. Later, soft tissue dehiscence and implant exposure were encountered with subsequent food impaction, infection, and pus discharge. The treatment plan was to fabricate removable partial denture. The prosthesis was planned to be retained by bar and clip attachment on the patient-specific implant side, while on the other side, the removable prosthesis was allowed to engage two abutments with an embrasure clasp assembly in addition to covering the palatal tissues to offer protection for the soft tissue dehiscence against food impaction. Discussion. Soft tissue dehiscence and implant exposure are among the frequently reported complications associated with the patient-specific implant. The resulting infection complicates the prognosis of the implemented implant and necessitates, in some occasions, its removal. The selection of the removable prosthesis to cover soft tissue dehiscence was a conservative alternative to the implant removal as it protects the exposed titanium surface from food impaction while maintaining the implant functionality. Conclusion. Three-year follow-up showed complete resolution of the patient's complaints while fulfilling the patient's aesthetic and functional demands and indicates that the use of detachable overlay prosthesis could be one of the proposed treatment options.

How 3D Printing Is Reshaping Translational Research

"Translational Research" has traditionally been defined as taking basic scientific findings and developing new diagnostic tools, drugs, devices and treatment options for patients, that are translated into practice, reach the people and populations for whom they are intended and are implemented correctly. The implication is of a unidirectional flow from "the bench to bedside". The rapidly emergent field of additive manufacturing (3D printing) is contributing to a major shift in translational medical research. This includes the concept of bidirectional or reverse translation, early collaboration between clinicians, bio-engineers and basic scientists, and an increasingly entrepreneurial mindset. This coincides with, and is strongly complemented by, the rise of systems biology. The rapid pace at which this type of translational research can occur brings a variety of potential pitfalls and ethical concerns. Regulation surrounding implantable medical devices is struggling to keep up. 3D printing has opened the way for personalization which can make clinical outcomes hard to assess and risks putting the individual before the community. In some instances, novelty and hype has led to loss of transparency of outcomes with dire consequence. Collaboration with commercial partners has potential for conflict of interest. Nevertheless, 3D printing has dramatically changed the landscape of translational research. With early recognition and management of the potential risks, the benefits of reshaping the approach to translational research are enormous. This impact will extend into many other areas of biomedical research, re-establishing that science is more than a body of research. It is a way of thinking.

Aesthetical and Accuracy Outcomes of Reconstruction of Maxillary Defect by 3D Virtual Surgical Planning

Background

Reconstruction of maxillary defect resulting from trauma or oncology surgery is of great importance for patients with physical and psychological complications. The virtual surgical planning (VSP) and 3D printing technics had been used in recent years which simplified the surgical procedure and promoted success and accuracy. To assess the accuracy and outcome of VSP surgery, here we report our experience in maxillary reconstruction retrospectively.

Method

Patients who received maxillary defect reconstruction from 2013 to 2020 were analyzed retrospectively. These patients were divided into two groups. Group 1 received VSP and 3D printed guiding plates in the surgery, while group 2 underwent free-hand surgery (FHS). Patients with different vertical and horizontal defects were classified according to Brown and Shaw classification. Clinical information and postoperative complications of all patients were collected. For patients with unilateral maxillary defect, orbit volume, orbit height, and the contour of the reconstructed side were compared with the normal side.

Result

Thirty-four patients who achieved the criteria were analyzed, of which 20 patients underwent VSP surgery. There were primary and secondary reconstruction cases in both two groups. Vascularized iliac crest flap was used in three cases, and fibula flap was performed in the other cases. One flap collapse occurred in FHS group. Seven patients in VSP group received dental implants, while the number in FHS group was 0. In vertical class III cases, the differences in orbit height (ΔD) and orbit volume (ΔV) between normal side and reconstructed side were measured and compared in the two groups. The mean ΔD is 1.78 ± 1.33 mm in VSP group and 4.25 ± 0.95 mm in FHS group, while the mean ΔV is 2.04 ± 0.85 cm³ in VSP group and 3.25 ± 0.17 cm³ in FHS group. The alterations of orbit height and volume in VSP group were much smaller than that in FHS group with statistical significance. From the perspective of aesthetics, the color-gradient map indicates a more symmetric and smoother curve of post-operation appearance in VSP group.

Conclusion

Compared with traditional free-hand surgical technics, VSP and 3D printing guiding plates can allow for a more accurate maxillary reconstruction with improved aesthetics.

Mortality Within 30 Days After Head and Neck Free Flap Reconstruction: A Systematic Review

OBJECTIVE

The aim of this systematic review is to analyze the 30-day postoperative mortality in patients undergoing free flap reconstruction for head and neck cancer published in literature and to identify associated factors.

METHODS

The authors performed a literature search between January 1950 and February 2020 in PubMed, EMBASE, and Scopus, using a combination of Medical Subject Headings headings and text keywords related to head and neck cancer; microsurgery or free flap reconstruction; and 30-day mortality. Inclusion criteria were: original studies in English reporting on 30-day mortality after head and neck free flap reconstruction in adult population.

RESULTS

Thirty-one publications reported on a total of 13,447 patients who underwent head and neck free flap reconstruction. The published 30-day postoperative mortality ranged from 0% to 6.3%, with an average of 1.21%. A number of studies examined the association between mortality and body mass index, American Society of Anesthesiologists, and comorbidity score and age. One study found that underweight patients had significantly higher mortality. Two studies found no association between the American Society of Anesthesiologists score and 30-day postoperative mortality; however, 1 study reported significantly higher mortality with increased comorbidity score. Regarding association with age, 3 studies found significant higher mortality in older patients, while 5 studies found no difference.

CONCLUSIONS

The average 30-day postoperative mortality in patients undergoing head and neck free flap reconstruction is 1.21% and is; therefore, not negligible. Careful patient selection and preoperative optimization are essential in order to reduce mortality in head neck free flap reconstruction.

Immediate implant-retained prosthetic obturation after maxillectomy based on zygomatic implant placement by 3D-guided surgery: a cadaver study

Background

The aim of this study was to introduce a complete 3D workflow for immediate implant retained prosthetic rehabilitation following maxillectomy in cancer surgery. The workflow consists of a 3D virtual surgical planning for tumor resection, zygomatic implant placement, and for an implant-retained prosthetic-obturator to fit the planned outcome situation for immediate loading.

Materials and methods

In this study, 3D virtual surgical planning and resection of the maxilla, followed by guided placement of 10 zygomatic implants, using custom cutting and drill/placement-guides, was performed on 5 fresh frozen human cadavers. A preoperatively digitally designed and printed obturator prosthesis was placed and connected to the zygomatic implants. The accuracy of the implant positioning was obtained using 3D deviation analysis by merging the pre- and post-operative CT scan datasets.

Results

The preoperatively designed and manufactured obturator prostheses matched accurately the per-operative implant positions. All five obturators could be placed and fixated for immediate loading. The mean prosthetic point deviation on the cadavers was 1.03 ± 0.85 mm; the mean entry point deviation was 1.20 ± 0.62 mm; and the 3D angle deviation was 2.97 ± 1.44°.

Conclusions

It is possible to 3D plan and accurately execute the ablative surgery, placement of zygomatic implants, and immediate placement of an implant-retained obturator prosthesis with 3D virtual surgical planning.The next step is to apply the workflow in the operating room in patients planned for maxillectomy.

3D printing technology in healthcare: applications, regulatory understanding, IP repository and clinical trial status

Mass consumerization of three-dimensional (3D) printing innovation has revolutionised admittance of 3D-printing in an expansive scope of ventures. When utilised predominantly for industrial manufacturing, 3D-printing strategies have rapidly attained acquaintance in different parts of health care industry. 3D-printing is a moderately new technology that has discovered promising applications in the medication conveyance and clinical areas. This review intends to explore different parts of 3D- printing innovation concerning pharmaceutical and clinical applications. Review on pharmaceutical products like tablets, caplets, films, polypills, microdots, biodegradable patches, medical devices (uterine and subcutaneous), patient specific implants, cardiovascular stents, etc. and prosthetics/anatomical structures, surgical models, organs and tissues created utilising 3D-printing is being presented. In addition, the regulatory understanding and current IP and clinical trial status pertaining to 3D fabricated products/medical applications have also been funnelled, garnering information from different web portals of regulatory agencies and databases. It is additionally certain that for such new innovations, there would be difficulties and questions before these are acknowledged as protected and viable. The circumstance demands purposeful and wary endeavours to acquire regulations which would at last prompt the accomplishment of this progressive innovation, thus various regulatory challenges faced have been conscientiously discussed.

Imaging-based navigation technologies in head and neck surgery

PURPOSE OF REVIEW

Image guided navigation has had significant impact in head and neck surgery, and has been most prolific in endonasal surgeries. Although conventional image guidance involves static computed tomography (CT) images attained in the preoperative setting, the continual evolution of surgical navigation technologies is fast expanding to incorporate both real-time data and bioinformation that allows for improved precision in surgical guidance. With the rapid advances in technologies, this article allows for a timely review of the current and developing techniques in surgical navigation for head and neck surgery.

RECENT FINDINGS

Current advances for cross-sectional-based image-guided surgery include fusion of CT with other imaging modalities (e.g., magnetic resonance imaging and positron emission tomography) as well as the uptake in intraoperative real-time 'on the table' imaging (e.g., cone-beam CT). These advances, together with the integration of virtual/augmented reality, enable potential enhancements in surgical navigation. In addition to the advances in radiological imaging, the development of optical modalities such as fluorescence and spectroscopy techniques further allows the assimilation of biological data to improve navigation particularly for head and neck surgery.

SUMMARY

The steady development of radiological and optical imaging techniques shows great promise in changing the paradigm of head and neck surgery.

Accuracy of Computer-Assisted Surgery in Maxillary Reconstruction: A Systematic Review

Computer-assisted surgery (CAS) in maxillary reconstruction has proven its value regarding more predictable postoperative results. However, the accuracy evaluation methods differ between studies, and no meta-analysis has been performed yet. A systematic review was performed in the PubMed, Embase, and Cochrane Library databases, using a Patient, Intervention, Comparison and Outcome (PICO) method: (P) patients in need of maxillary reconstruction using free osteocutaneous tissue transfer, (I) reconstructed according to a virtual plan in CAS software, (C) compared to the actual postoperative result, and (O) postoperatively measured by a quantitative accuracy assessment) search strategy, and was reported according to the PRISMA statement. We reviewed all of the studies that quantitatively assessed the accuracy of maxillary reconstructions using CAS. Twelve studies matched the inclusion criteria, reporting 67 maxillary reconstructions. All of the included studies compared postoperative 3D models to preoperative 3D models (revised to the virtual plan). The postoperative accuracy measurements mainly focused on the position of the fibular bony segments. Only approximate comparisons of postoperative accuracy between studies were feasible because of small differences in the postoperative measurement methods; the accuracy of the bony segment positioning ranged between 0.44 mm and 7.8 mm, and between 2.90° and 6.96°. A postoperative evaluation guideline to create uniformity in evaluation methods needs to be considered so as to allow for valid comparisons of postoperative results and to facilitate meta-analyses in the future. With the proper validation of the postoperative results, future research might explore more definitive evidence regarding the management and superiority of CAS in maxillary and midface reconstruction.

The use of 3D virtual surgical planning and computer aided design in reconstruction of maxillary surgical defects

PURPOSE OF REVIEW

The present review describes the latest development of 3D virtual surgical planning (VSP) and computer aided design (CAD) for reconstruction of maxillary defects with an aim of fully prosthetic rehabilitation. The purpose is to give an overview of different methods that use CAD in maxillary reconstruction in patients with head and neck cancer.

RECENT FINDINGS

3D VSP enables preoperative planning of resection margins and osteotomies. The current 3D VSP workflow is expanded with multimodal imaging, merging decision supportive information. Development of more personalized implants is possible using CAD, individualized virtual muscle modelling and topology optimization. Meanwhile the translation of the 3D VSP towards surgery is improved by techniques like intraoperative imaging and augmented reality. Recent improvements of preoperative 3D VSP enables surgical reconstruction and/or prosthetic rehabilitation of the surgical defect in one combined procedure.

SUMMARY

With the use of 3D VSP and CAD, ablation surgery, reconstructive surgery, and prosthetic rehabilitation can be planned preoperatively. Many reconstruction possibilities exist and a choice depends on patient characteristics, tumour location and experience of the surgeon. The overall objective in patients with maxillary defects is to follow a prosthetic-driven reconstruction with the aim to restore facial form, oral function, and do so in accordance with the individual needs of the patient.

Virtual reality improves the accuracy of simulated preoperative planning in temporal bones: a feasibility and validation study

PURPOSE

Consumer-grade virtual reality (VR) has recently enabled various medical applications, but more evidence supporting their validity is needed. We investigated the accuracy of simulated surgical planning in a VR environment (VR) with temporal bones and compared it to conventional cross-sectional image viewing in picture archiving and communication system (PACS) interface.

METHODS

Five experienced otologic surgeons measured significant anatomic structures and fiducials on five fresh-frozen cadaveric temporal bones in VR and cross-sectional viewing. Primary image data were acquired by computed tomography. In total, 275 anatomical landmark measurements and 250 measurements of the distance between fiducials were obtained with both methods. Distance measurements between the fiducials were confirmed by physical measurement obtained by Vernier caliper. The experts evaluated the subjective validity of both methods on a 5-point Likert scale qualitative survey.

RESULTS

A strong correlation based on intraclass coefficient was found between the methods on both the anatomical (r > 0.900) and fiducial measurements (r > 0.916). Two-tailed paired t-test and Bland-Altman plots demonstrated high equivalences between the VR and cross-sectional viewing with mean differences of 1.9% (p = 0.396) and 0.472 mm (p = 0.065) for anatomical and fiducial measurements, respectively. Gross measurement errors due to the misidentification of fiducials occurred more frequently in the cross-sectional viewing. The mean face and content validity rating for VR were significantly better compared to cross-sectional viewing (total mean score 4.11 vs 3.39, p < 0.001).

CONCLUSION

Our study supports good accuracy and reliability of VR environment for simulated surgical planning in temporal bones compared to conventional cross-sectional visualization.

Usefulness of a template-based anterolateral thigh flap for reconstruction of head and neck defects

BACKGROUND

One of the challenges in head and neck reconstruction is to have an adequate understanding of the three-dimensionalities of the defects created after resections due to the high variability of clinical scenarios. Consequently, it is essential to design the flap to match the requirements of the defect in order to facilitate the insetting and to achieve a successful outcome. The anterolateral thigh flap (ALT) is a robust and versatile flap commonly used in head and neck reconstruction. In this study the authors use a hand-made template as a tool to customize ALT flaps and its variations to fit more accurately the different shapes, volume, and components of the resulting defects. The aim of this study is to describe in detail this surgical approach and present the clinical experience in 100 consecutive cases using a template-based ALT flaps in head and neck reconstruction.

METHODS

A retrospective review was performed on all microvascular head and neck reconstruction cases between January 2013 and December 2017 in our institution where a template-based ALT flap design was performed. We describe in detail the surgical technique used and present the clinical outcomes. In addition, we analyzed the use of different designs of the ALT flaps including different flap components in relation to the location of the defect.

RESULTS

One hundred reconstructions for head and neck defects were performed in 97 patients. Seven types of ALT free flaps were performed: fasciocutaneous (46%), suprafascial (8%), adipofascial (9%), vastus lateralis muscle (3%), composite fasciocutaneous/adipofascial (9%), chimeric flaps (21%), and vascularized nerve grafts (4%). Oropharyngeal and periauricular defects were mostly reconstructed with fasciocutanoues design. In more complex three-dimensional defects such as skull base or midface defects, a chimeric flap was selected. In all cases the used of template facilitated the insetting of the free flap. The total flap loss was 2%.

CONCLUSIONS

Customization of ALT flaps using intraoperative templates is a useful method for flap design which facilitates fitting of the flap to a variety of defects in head and neck reconstruction.

Prosthodontic rehabilitation of head and neck cancer patients-Challenges and new developments

Head and neck cancer treatment can severely alter oral function and aesthetics, and reduce quality of life. The role of maxillofacial prosthodontists in multidisciplinary treatment of head and neck cancer patients is essential when it comes to oral rehabilitation and its planning. This role should preferably start on the day of first intake. Maxillofacial prosthodontists should be involved in the care pathway to shape and outline the prosthetic and dental rehabilitation in line with the reconstructive surgical options. With the progress of three‐dimensional technology, the pretreatment insight in overall prognosis and possibilities of surgical and/or prosthetic rehabilitation has tremendously increased. This increased insight has helped to improve quality of cancer care. This expert review addresses the involvement of maxillofacial prosthodontists in treatment planning, highlighting prosthodontic rehabilitation of head and neck cancer patients from start to finish.

What is the optimal timing for implant placement in oral cancer patients? A scoping literature review

BACKGROUND

Oral cancer patients can benefit from dental implant placement. Traditionally, implants are placed after completing oncologic treatment (secondary implant placement). Implant placement during ablative surgery (primary placement) in oral cancer patients seems beneficial in terms of early start of oral rehabilitation and limiting additional surgical interventions. Guidelines on the ideal timing of implant placement in oral cancer patients are missing.

OBJECTIVE

To perform a scoping literature review on studies examining the timing of dental implant placement in oral cancer patients and propose a clinical practice recommendations guideline.

METHODS

A literature search for studies dealing with primary and/or secondary implant placement in MEDLINE was conducted (last search December 27, 2019). The primary outcome was 5-year implant survival.

RESULTS

Sixteen out of 808 studies were considered eligible. Both primary and secondary implant placement showed acceptable overall implant survival ratios with a higher pooled 5-year implant survival rate for primary implant placement 92.8% (95% CI: 87.1%-98.5%) than secondary placed implants (86.4%, 95% CI: 77.0%-95.8%). Primary implant placement is accompanied by earlier prosthetic rehabilitation after tumor surgery.

CONCLUSION

Patients with oral cancer greatly benefit from, preferably primary placed, dental implants in their prosthetic rehabilitation. The combination of tumor surgery with implant placement in native mandibular bone should be provided as standard care.

Safety of resection margins in CAD/CAM-guided primarily reconstructed oral squamous cell carcinoma-a retrospective case series

OBJECTIVES

After resection of malignancies of the jaws, CAD/CAM procedures have become standard for primary bony reconstruction. Even so, these techniques may limit surgical resection safety. Therefore, the aim of the study was to examine osseous as well as soft tissue resection margins after CAD/CAM-guided tumor resections and reconstructions.

METHODS

A retrospective analysis of patients treated with oral squamous cell carcinoma (OSCC) from 2014 to 2019 was performed. Inclusion criteria were CAD/CAM-guided osseous resection and primary reconstruction. Evaluation was performed for histological confirmed resection margins (hard and soft tissue) as well as recurrence of the disease related to the resection status.

RESULTS

In 46 patients, bony resection margins were classified: tumor free (R0 41/46), microscopical invasion (R1 1/46), and close margin (R0 < 4 mm 4/46) respectively for soft tissue 29/46 tumor free (R0), 7/46 close margin (R0 < 4 mm), 5/46 R1, and 4/46 could not be further determined (Rx). Fourteen patients (14/46) showed recurrent disease (2/46 locoregional) without association with the bony resection margin status. Recurrence occurred predominantly (13/46) in high-staged tumor patients. R1/close margin/Rx resection of the soft tissue resulted in a significant earlier recurrence when compared with R0 resection.

CONCLUSION

CAD/CAM procedure allows safe tumor resection with the profit of a guided and accurate reconstruction. In contrast to positive soft tissue margins, positive bony resection margins did not increase recurrence parameters.

The application of 3D-printed titanium mesh in maxillary tumor patients undergoing total maxillectomy

OBJECTIVE

To evaluate the clinical outcomes of reconstruction of maxillary class III defect using 3D-printed titanium mesh.

METHODS

Twelve patients with maxillary class III defect from April 2015 to December 2016 were retrospectively studied. A 3D individualized maxillary stereo model based on mirror images of the unaffected maxilla was obtained to fabricate an anatomically adapted titanium mesh using computer-assisted design and manufacture. The individual titanium mesh was inserted into the maxillary class III defect after total maxillectomy. The incidence of postoperative complications was evaluated. The postoperative orbital volume and protrusion degree of eye were measured.

RESULTS

All patients were satisfied with their postoperative facial symmetry, without developing diplopia or endophthalmos. The postoperative orbital volumes were 26.41 ± 0.52 mL on the affected side and 26.55 ± 0.45 mL on the unaffected side. The postoperative protrusion degrees of affected and unaffected eyes were 16.21 ± 0.48 and 16.82 ± 0.79 mm, respectively. Titanium mesh exposure was observed in 2 patients and mild limitation of mouth opening was observed in 4 patients who underwent postoperative radiotherapy.

CONCLUSION

Reconstruction of maxillary class III defect with 3D-printed titanium mesh can achieve successful clinical outcomes, which recovered orbital volume and protrusion degree of eye. Twelve patients with maxillary class III defect were satisfied with their postoperative facial symmetry, without developing diplopia or endophthalmos. We investigated that reconstruction of maxillary class III defect with 3D-printed titanium mesh can achieve successful clinical outcomes.

3D Printing-Encompassing the Facets of Dentistry

This narrative review presents an overview on the currently available 3D printing technologies and their utilization in experimental, clinical and educational facets, from the perspective of different specialties of dentistry, including oral and maxillofacial surgery, orthodontics, endodontics, prosthodontics, and periodontics. It covers research and innovation, treatment modalities, education and training, employing the rapidly developing 3D printing process. Research-oriented advancement in 3D printing in dentistry is witnessed by the rising number of publications on this topic. Visualization of treatment outcomes makes it a promising clinical tool. Educational programs utilizing 3D-printed models stimulate training of dental skills in students and trainees. 3D printing has enormous potential to ameliorate oral health care in research, clinical treatment, and education in dentistry.

Accuracy of computer-assisted surgery in mandibular reconstruction: A systematic review

Computer-assisted surgery (CAS) for mandibular reconstruction was developed to improve conventional treatment methods. In the past years, many different software programs have entered the market, offering numerous approaches for preoperative planning and postoperative evaluation of the CAS process of mandibular reconstruction. In this systematic review, we reviewed planning and evaluation methods in studies that quantitatively assessed accuracy of mandibular reconstruction performed with CAS. We included 42 studies describing 413 mandibular reconstructions planned and evaluated using CAS. The commonest software was Proplan/Surgicase CMF (55%). In most cases, the postoperative virtual 3-dimensional model was compared to the preoperative 3-dimensional model, revised to the virtual plan (64%). The commonest landmark for accuracy measurements was the condyle (54%). Accuracy deviations ranged between 0 mm and 12.5 mm and between 0.9° and 17.5°. Because of a lack of uniformity in planning (e.g., image acquisition, mandibular resection size) and evaluation methodologies, the ability to compare postoperative outcomes was limited; meta-analysis was not performed. A practical and simple guideline for standardizing planning and evaluation methods needs to be considered to allow valid comparisons of postoperative results and facilitate meta-analysis in the future.