Increasing the accuracy of mandibular reconstruction with free fibula flaps using functionalized selective laser-melted patient-specific implants: A retrospective multicenter analysis

Patient-specific Implants Improve Volumetric Surgical Accuracy Compared to Stock Reconstruction Plates in Modern Pardigm Virtual Surgical Planning of Fibular Free Flaps for Head and Neck Reconstruction

BACKGROUND

Virtual surgical planning (VSP) for composite microvascular free flaps has become standard of care for oncologic head and neck reconstruction. Controversy remains as to the use of three-dimensional (3D)-printed titanium patient-specific implants (PSIs) versus hand-bent stock reconstruction plates. Proponents of PSIs cite improved surgical accuracy, reduced operative times, and improved clinical outcomes. Detractors purport increased cost associated with PSIs and presumed equivalent accuracy with less expensive stock plates.

PURPOSE

The study purpose was to measure and compare the 3D-volumetric accuracy of PSI versus stock reconstruction plates among subjects undergoing VSP-guided mandibular fibular free flap reconstruction.

STUDY DESIGN, SETTING, SAMPLE

A retrospective cohort study of subjects undergoing VSP-guided fibular free flap reconstructions at Mayo Clinic between 2016 and 2023 was performed. Subjects were excluded for non-VSP guidance, midfacial reconstruction, nonfibular free flaps, and lack of requisite study variables.

PREDICTOR VARIABLE

The primary predictor was the type of reconstruction plate utilized (PSI vs stock plate).

MAIN OUTCOME VARIABLE

The main outcome was volumetric surgical accuracy of the final reconstruction compared to the preoperative surgical plan by root mean square error (RMSE) calculation. Lower RMSE values indicated a higher surgical accuracy.

COVARIATES

Covariates included age, sex, race, smoking status, American Society of Anesthesiologists Physical Status Classification System, Charlson Comorbidity Index, preoperative diagnosis, and number of fibular segments.

ANALYSES

Differences in surgical accuracy were assessed between preoperative and postoperative segmented scans using volumetric overlays from which RMSE values were calculated. Univariate and multivariate modeling of plate type to RMSE calculation was performed. Statistical significance set to P < .05.

RESULTS

Total of 130 subjects were identified, 105 PSI and 25 stock plates. Calculated mean RMSE in millimeters (mm) for stock plates was 1.46 (standard deviation: 0.33) and 1.15 (standard deviation: 0.36) for PSIs. Univariate modeling demonstrated a statistically significant difference in RMSE of 0.31 (95% confidence interval: 0.16-0.47) (P < .001) equating to a 21.2% (P < .001) improved volumetric surgical accuracy for PSIs. The association of improved volumetric accuracy with PSIs has been maintained in all multivariate models controlling for confounding.

CONCLUSION AND RELEVANCE

In modern era VSP-guided head and neck fibular free flap reconstruction, patient-specific 3D-printed titanium implants confer a statistically significant improvement in volumetric surgical accuracy over stock reconstruction plates.

In-and-out Technique: An In-house Efficient Predictive Hole Fabrication Workflow

Virtual surgical planning (VSP) and three-dimensional (3D) printing can increase precision and reduce surgical time in craniofacial reconstruction. However, the elevated cost and manufacturing time of outsourced workflows is increasing the development of in-house solutions. One of the main challenges in in-house workflows is to create cutting guides that hold plate position information. This is due to the fact that hospitals usually lack the infrastructure required to design and 3D print custom-made plates. Including plate-positioning information in resection guides is especially relevant in complex reconstructions and when tumor extension limits plate placement before resection. Current in-house workflows revolve around the idea of 3D scanning the bent plate's shape and to fuse it with the VSP. The goal of this article is to share our technique to transfer plate position information to resection guides. Our protocol uses a 3D model of the reconstruction as an intermediate step to transfer the plate position of a bent stock reconstruction plate to cutting guides. Two patients who required mandibular reconstruction with fibula flap are presented to illustrate the technique. This workflow requires a 3D-printed model of the desired outcome, cutting guides, and a stock plate. Results were satisfactory in terms of cutting location and angulation, plate adaptation and condylar position. This technique allows for a simple, safe, cheap, and quick alternative to add reconstruction plate information to cutting guides.

Bone regeneration in critical-size defects of the mandible using biomechanically adapted CAD/CAM hybrid scaffolds: An in vivo study in miniature pigs

The study aimed to analyze bone regeneration in critical-size defects using hybrid scaffolds biomechanically adapted to the specific defect and adding the growth factor rhBMP-2. For this animal study, ten minipigs underwent bilateral defects in the corpus mandibulae and were subsequently treated with novel cylindrical hybrid scaffolds. These scaffolds were designed digitally to suit the biomechanical requirements of the mandibular defect, utilizing finite element analysis. The scaffolds comprised zirconium dioxide-tricalcium phosphate (ZrO2-TCP) support struts and TCP foam ceramics. One scaffold in each animal was loaded with rhBMP-2 (100 μg/cm³), while the other served as an unloaded negative control. Fluorescent dyes were administered every 2 weeks, and computed tomography (CT) scans were conducted every 4 weeks. Euthanasia was performed after 3 months, and samples were collected for examination using micro-CT and histological evaluation of both hard and soft tissue. Intravital CT examinations revealed minor changes in radiographic density from 4 to 12 weeks postoperatively. In the group treated with rhBMP-2, radiographic density shifted from 2513 ± 128 (mean ± SD) to 2606 ± 115 Hounsfield units (HU), while the group without rhBMP-2 showed a change from 2430 ± 131 to 2601 ± 67 HU. Prior to implantation, the radiological density of samples measured 1508 ± 30 mg HA/cm³, whereas post-mortem densities were 1346 ± 71 mg HA/cm³ in the rhBMP-2 group and 1282 ± 91 mg HA/cm³ in the control group (p = 0.045), as indicated by micro-CT measurements. The histological assessment demonstrated successful ossification in all specimens. The newly formed bone area proportion was significantly greater in the rhBMP-2 group (48 ± 10%) compared with the control group without rhBMP-2 (42 ± 9%, p = 0.03). The mean area proportion of remaining TCP foam was 23 ± 8% with rhBMP-2 and 24 ± 10% without rhBMP-2. Successful bone regeneration was accomplished by implanting hybrid scaffolds into critical-size mandibular defects. Loading these scaffolds with rhBMP-2 led to enhanced bone regeneration and a uniform distribution of new bone formation within the hybrid scaffolds. Further studies are required to determine the adaptability of hybrid scaffolds for larger and potentially segmental defects in the maxillofacial region.

Biomechanical behavior of the three-dimensionally printed surgical plates for mandibular defect reconstruction: a finite element analysis

The aim of the study was to investigate the biomechanical behavior of three-dimensionally (3D)-printed surgical plates used for mandibular defect reconstruction, compare them with conventional surgical plates, and provide experimental evidence for their clinical application. Three-dimensional models were created for the normal mandible and for mandibular body defects reconstructed using free fibula and deep circumflex iliac artery flaps. Three-dimensional finite element models of reconstructed mandibles fixed using 3D-printed and conventional surgical plates were established. Vertical occlusal forces were applied to the remaining teeth and the displacement and Von Mises stress distributions were studied using finite element analysis. The normal and reconstructed mandibles had similar biomechanical behaviors. The displacement distributions for the surgical plates were similar, and the maximum total deformation occurred at the screw hole of the anterior segment of the surgical plates. However, there were differences in the Von Mises stress distributions for the surgical plates. In reconstructed mandibles fixed using 3D-printed surgical plates, the maximum equivalent Von Mises stress occurred at the screw hole of the posterior segment, while in those fixed using conventional surgical plates, the maximum equivalent Von Mises stress was at the screw hole of the anterior segment. In the mandible models reconstructed with the same free flap but fixed with different surgical plates, the plates had similar biomechanical behaviors. The biomechanical behavior of 3D-printed surgical plates was similar to conventional surgical plates, suggesting that 3D-printed surgical plates used to reconstruct mandibular body defects with vascularized autogenous bone grafts could lead to secure and stable fixation.

From bench to bedside - current clinical and translational challenges in fibula free flap reconstruction

Fibula free flaps (FFF) represent a working horse for different reconstructive scenarios in facial surgery. While FFF were initially established for mandible reconstruction, advancements in planning for microsurgical techniques have paved the way toward a broader spectrum of indications, including maxillary defects. Essential factors to improve patient outcomes following FFF include minimal donor site morbidity, adequate bone length, and dual blood supply. Yet, persisting clinical and translational challenges hamper the effectiveness of FFF. In the preoperative phase, virtual surgical planning and artificial intelligence tools carry untapped potential, while the intraoperative role of individualized surgical templates and bioprinted prostheses remains to be summarized. Further, the integration of novel flap monitoring technologies into postoperative patient management has been subject to translational and clinical research efforts. Overall, there is a paucity of studies condensing the body of knowledge on emerging technologies and techniques in FFF surgery. Herein, we aim to review current challenges and solution possibilities in FFF. This line of research may serve as a pocket guide on cutting-edge developments and facilitate future targeted research in FFF.

Biofabrication of engineered dento-alveolar tissue

Oral health is essential for a good overall health. Dento-alveolar conditions have a high prevalence, ranging from tooth decay periodontitis to alveolar bone resorption. However, oral tissues exhibit a limited regenerative capacity, and full recovery is challenging. Therefore, regenerative therapies for dento-alveolar tissue (e.g., alveolar bone, periodontal membrane, dentin-pulp complex) have gained much attention, and novel approaches have been proposed in recent decades. This review focuses on the cells, biomaterials and the biofabrication methods used to develop therapies for tooth root bioengineering. Examples of the techniques covered are the multitude of additive manufacturing techniques and bioprinting approaches used to create scaffolds or tissue constructs. Furthermore, biomaterials and stem cells utilized during biofabrication will also be described for different target tissues. As these new therapies gradually become a reality in the lab, the translation to the clinic is still minute, with a further need to overcome multiple challenges and broaden the clinical application of these alternatives.

Comparison of Laser-Sintered and Milled Patient-Specific Reconstruction Plates for Complications and Outcomes in Mandibular Defects-Comparative Analysis of a Single-Center Cohort

CAD/CAM-manufactured implants are increasingly becoming the standard in current therapy. The question of whether the manufacturing-related rougher surface of selective laser fusion plates compared to milled, smoother reconstruction plates leads to increased postoperative complications such as infections, plate exposure, and fistulas has not yet been determined. A retrospective analysis of 98 patients who underwent surgical treatment with either a selective laser fusion plate or a milled reconstruction plate at our hospital was performed. The only significant predictors of the revision risk were the operation time and use of antiresorptive medication. In the KLS Martin^® group, the risk of revision decreased by approximately 20% for each additional hour by which the operation time was increased (OR = 0.81). In the Depuy Synthes^® group, the risk of revision increased by approximately 11% with each additional hour of operative time (OR = 0.81 × 1.37 = 1.11). Both groups showed no significant differences in the number of necessary revision surgeries as well as inpatient complications. In summary, we can say that the assumption that additively manufactured reconstruction plates have a rougher surface due to selective laser melting and thus make plaque accumulation and revisions more likely has not been confirmed. Overall, it seems imperative to select further studies regarding the clinical outcome depending on the selected plate system.

The value of prebent reconstruction plates and in-house 3D printing

INTRODUCTION

Reconstruction plates, prebent on 3D printed models, are a cheap, quick, and safe solution to improve mandibular reconstruction procedures. The European Medical Device Regulation has changed recently and severely affects 3D printing in hospitals. Therefore, its legitimation must be discussed. This retrospective observational Case-Control Study aimed to evaluate the impact of prebent reconstruction plates on the condylar position in the temporomandibular joint after continuity resection of the mandible in oncological cases.

MATERIALS AND METHODS

We included patients who underwent segmental mandibular resection without exarticulation of the condyle or history of prior surgery. The patients were divided into groups with prebent plates on a stereolithographic model and intraoperatively bent reconstruction plates. The segmental defects were categorized using the Jewer Classification. Computed Tomography (CT) scans before and after surgery were analyzed using a standardized method to measure the metric movement of the condyles, as well as their angulation to reference planes to quantify positional changes (primary outcome measures). The influence of the defect location, according to the Jewer classification, was evaluated as a secondary outcome measure.

RESULTS

73 patients, including 33 with preformed reconstruction plates, were included. We could show significantly fewer rotational deviations in cases of prefabricated osteosynthesis in the coronal plane (p<0,001) and in the sagittal plane (p<0,027).

DISCUSSION

Using preformed reconstruction plates on 3D printed models improves the correct anatomical position of the condyle after mandibular resection. Especially Jewer-class-L defects seem to benefit from individualized reconstruction plates.

Patient-centred outcomes and dental implant placement in computer-aided free flap mandibular reconstruction: a systematic review and meta-analysis

Computerised surgical planning (CSP) and computer-aided design and manufacturing (CAD/CAM) have been demonstrated to increase surgical accuracy and reduce operative time in free flap mandibular reconstruction, but evidence is lacking as to their impact on patient-centred outcomes. Implant-supported dental prostheses, however, have been associated with improved quality of life outcomes following free flap mandibular reconstruction. We aim to review reported patient-centred outcomes in mandibular reconstruction with CSP and CAD/CAM and determine whether use of these technologies is associated with higher rates of dental implant placement following free flap mandibular reconstruction. On December 20, 2020, a systematic review and meta-analysis were conducted according to PRISMA guidelines for studies reporting quality of life, functional outcomes, and rates of dental implant placement in computer-aided free flap mandibular reconstruction. A random-effects meta-analysis was performed to compare dental implant placement rates between surgeries using CSP and those using conventional freehand techniques. A total of 767 articles were screened. Nine articles reporting patient-centred outcomes and 16 articles reporting dental implant outcomes were reviewed. Of those reporting dental implant outcomes, five articles, representing a total of 302 cases, were included in the meta-analysis. Use of CSP was associated with a significant increase in the likelihood of dental implant placement, with an odds ratio of 2.70 (95% CI 1.52 to 4.79, p = 0.0007). Standardised reporting methods and controlled studies are needed to further investigate the impact of CSP and CAD/CAM technologies on functional outcomes and patient-reported quality of life in free flap mandibular reconstruction. Use of CSP and CAD/CAM technologies is associated with higher rates of dental implant placement in patients undergoing free flap mandibular reconstruction when compared to conventional freehand techniques.

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

Simple Summary

The Maxilla and mandible provide skeletal support for of the middle and lower third of our faces, allowing for the normal functioning of breathing, chewing, swallowing, and speech. The ablative surgery of jaws in the past often led to serious disfigurement and disruption in form and function. However, with recent strides made in computer-assisted surgery and patient-specific implants, the individual functional reconstruction of the jaw is evolving rapidly and the prompt rehabilitation of both the masticatory function and aesthetics after jaw resection has been made possible. In the present review, the recent advancements in jaw reconstruction technology and future perspectives will be discussed.

Abstract

The reconstruction and rehabilitation of jaws following ablative surgery have been transformed in recent years by the development of computer-assisted surgery and virtual surgical planning. In this narrative literature review, we aim to discuss the current state-of-the-art jaw reconstruction, and to preview the potential future developments. The application of patient-specific implants and the “jaw-in-a-day technique” have made the fast restoration of jaws’ function and aesthetics possible. The improved efficiency of primary reconstructive surgery allows for the rehabilitation of neurosensory function following ablative surgery. Currently, a great deal of research has been conducted on augmented/mixed reality, artificial intelligence, virtual surgical planning for soft tissue reconstruction, and the rehabilitation of the stomatognathic system. This will lead to an even more exciting future for the functional reconstruction and rehabilitation of the jaw following ablative surgery.

Optimization of Vascular Supply in Free Flaps for Head and Neck Reconstruction: Analysis of a Young Team’s Experience

Background

For head and neck reconstructive procedures, free flap survival depends on microsurgical and anatomical choices besides multimodal clinical management. The aim of the present study is to identify relevant variables for flap survival in our initial consecutive series.

Methods

A single-center, novel reconstructive team consecutive surgical series was revised. The outcome was analyzed in terms of flap survival observing variables considered more relevant: flap type, recipient artery, vein(s), and graft interposition were discussed for facial thirds to be reconstructed. Statistical analysis was performed with Chi-square, Mann–Whitney, and Odds ratio.

Results

A total of 118 free flaps were performed in 115 microsurgical procedures (93.9% for malignancies) on 109 patients, with a flap survival rate of 91.5%. For reconstruction of the middle and lower third of the face, the facial artery was privileged, because it was already transected during lymph node dissection in order to save the superior thyroid artery for further microsurgical needs. Flap failure was 50% venous. Double vein anastomosis was not related to flap survival. Deep venous drainage (as the internal jugular vein system) required fewer revisions. Half of the re-explorations saved the flap. Grafts were a risk for flap survival. Bony flaps were more critical.

Conclusion

At comparable reconstructive quality, flap choice should avoid a vascular graft. The facial artery is a preferable recipient vessel, since it saves other arteries both in the case of an arterial revision and in the case of recurrence, for further free flap reconstruction. For venous anastomosis, a deep venous recipient is safer, since it offers the possibility to choose the level of anastomosis optimizing the vascular pedicle geometry. A close postsurgical flap monitoring is advisable up to 7 days postoperatively to allow for timely flap salvage.

A Comparative Study on a Novel Fibula Malleolus Cap to Increase the Accuracy of Oncologic Jaw Reconstruction

OBJECTIVES

Although computer-assisted surgery using fibula flap has been widely applied for oncologic jaw reconstruction in recent years, the inaccurate positioning of the fibula harvest guide brings sliding and rotational errors, which leads to compromised accuracy in simultaneous implant placement and dental rehabilitation. This study aimed to develop a novel three-dimensional (3D)-printed patient-specific fibula malleolus cap to increase oncologic reconstruction accuracy.

METHODS

In this prospective comparative study with a recent historical control cohort, patients in need of oncologic jaw reconstruction with fibula free flaps were recruited. In the study group, the fibula was harvested with the guide of the malleolus cap, whereas in the control group, without the malleolus cap. Deviations of location and angulation of distal fibula osteotomies, jaw reconstruction segments, and simultaneous dental implants were compared.

RESULTS

Twenty patients were recruited, with 10 in each arm. The application of the malleolus cap significantly reduced the deviations in locations and angles of distal fibula osteotomies, from 9.5 to 4.1 mm and 25.3° to 8.7°. For the simultaneous dental implants placed in the fibula flaps, there was a significant increase in the accuracy of implant platform locations (the average deviation from 3.2 to 1.3 mm), apex locations (from 3.8 to 1.5 mm), and angles (from 11.3° to 4.6°). No significant difference was detected in the accuracy of fibula reconstruction segments.

CONCLUSIONS

We developed a novel fibula malleolus cap to overcome the sliding and rotational errors during fibula flap harvesting for oncologic jaw reconstruction, with increased accuracy in simultaneous dental implants. This is a step forward to achieve a satisfactory functional outcome of jaw reconstruction with dental rehabilitation.

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.

A New Strategy for Patient-Specific Implant-Borne Dental Rehabilitation in Patients With Extended Maxillary Defects

Purpose of the Study

Patients undergoing ablative tumor surgery of the midface are faced with functional and esthetic issues. Various reconstructive strategies, such as implant-borne obturator prostheses or microvascular tissue transfer, are currently available for dental rehabilitation. The present study shows the first follow-up of patients treated with patient-specific implants (IPS Implants^® Preprosthetic) for the rehabilitation of extended maxillary defects following ablative surgery.

Patients and Methods

All patients treated with patient specific implants due to postablative maxillary defects were included. 20 implants were placed in the 19 patients (bilateral implants were placed in one of the cases). In 65.75% of the cases, resection was performed due to squamous cell carcinoma. In addition to the primary stability, the clinical implant stability, soft tissue management, successful prosthodontic restoration, and complications were evaluated at a mean follow-up period of 26 months.

Results

All patient-specific implants showed primary stability and were clinically stable throughout the observation period. Definitive prosthodontic restorations were performed in all patients. No implant loosening was observed. Major complications occurred only in previously irradiated patients with insufficient soft tissue conditions (p = 0.058). Minor complications such as exposure of the underlying framework or mucositis were observed, but they never led to failure of restorations or implant loss.

Conclusions

Treatment of postablative maxillary defects with patient-specific implants offers a safe alternative with predictable results for full and rapid dental rehabilitation, avoiding time-consuming augmentation procedures and additional donor-site morbidity.

Comparison of the Accuracy and Clinical Parameters of Patient-Specific and Conventionally Bended Plates for Mandibular Reconstruction

Objectives

This retrospective study compared two mandibular reconstruction procedures-conventional reconstruction plates (CR) and patient-specific implants (PSI)-and evaluated their accuracy of reconstruction and clinical outcome.

Methods

Overall, 94 patients had undergone mandibular reconstruction with CR (n = 48) and PSI (n = 46). Six detectable and replicable anatomical reference points, identified via computer tomography, were used for defining the mandibular dimensions. The accuracy of reconstruction was assessed using pre- and postoperative differences.

Results

In the CR group, the largest difference was at the lateral point of the condyle mandibulae (D2) -1.56 mm (SD = 3.8). In the PSI group, the largest difference between preoperative and postoperative measurement was shown at the processus coronoid (D5) with +1.86 mm (SD = 6.0). Significant differences within the groups in pre- and postoperative measurements were identified at the gonion (D6) [t(56) = -2.217; p = .031 <.05]. In the CR group, the difference was 1.5 (SD = 3.9) and in the PSI group -1.04 (SD = 4.9). CR did not demonstrate a higher risk of plate fractures and post-operative complications compared to PSI.

Conclusion

For reconstructing mandibular defects, CR and PSI are eligible. In each case, the advantages and disadvantages of these approaches must be assessed. The functional and esthetic outcome of mandibular reconstruction significantly improves with the experience of the surgeon in conducting microvascular grafts and familiarity with computer-assisted surgery. Interoperator variability can be reduced, and training of younger surgeons involved in planning can be reaching better outcomes in the future.

Mechanical properties of three-dimensionally printed titanium plates used in jaw reconstruction: preliminary study

The aim of this study was to compare the mechanical properties of three-dimensionally (3D)-printed and conventional surgical plates used for the repair of maxillary or mandibular defects under the same experimental conditions, and to provide experimental evidence for the future application and clinical trial of 3D-printed individualized surgical plates. For the experimental group, two groups of surgical plates with thicknesses of 2.0 mm and 2.5 mm were designed and 3D-printed by electron beam melting, using Ti-6Al-4V as raw material. Conventional commercially available surgical plates with the same thickness were adopted as the control group. A Vickers hardness tester and universal testing machine were used to measure the mechanical properties of the plates (hardness, bending strength, tensile strength, and yield strength). The mechanical properties of 3D-printed surgical plates were significantly better than those of conventional surgical plates of the same thickness (P < 0.001). Comparing the surgical plates of different thickness, the 2.5 mm-thick plates had the highest bending strength in the experimental group (P < 0.001) and the best hardness (P < 0.001), bending strength (P = 0.001), tensile strength (P = 0.001), and yield strength (P = 0.001) in the control group. No statistical difference was found between the two kinds of plates in the experimental group in terms of hardness (P = 0.060), tensile strength (P = 0.096), and yield strength (P = 0.496). The 3D-printed surgical plates have better mechanical properties than the conventional ones.

The Learning Curve of Computer-Assisted Free Flap Jaw Reconstruction Surgery Using 3D-Printed Patient-Specific Plates: A Cumulative Sum Analysis

Background

Computer-assisted jaw reconstruction (CAJR) has benefits in reducing operation time and improving reconstruction accuracy, compared to conventional freehand jaw reconstruction. However, no information is available regarding learning curves in CAJR with the use of 3D-printed patient-specific surgical plates (PSSP). The purpose of this study was to assess surgical outcomes and learning curve for the first 58 consecutive CAJR using 3D-printed PSSP performed by a single surgical team in a single institution.

Methods

In a prospective study, consecutive patients who underwent free flap CAJR using 3D-printed PSSP were included. The determination of proficiency, based on the cumulative sum of surgical success (no major adjustment of 3D-printed PSSP, flap survival) passing the acceptable boundary line of cumulative sum analysis, was the primary outcome. To find out any potential factors influencing the learning curve, baseline characteristics of patients were compared before and after proficiency achievement. Secondary outcomes included inflexion points of the total operation time, blood loss, length of hospital stay, and bone graft deviation, measured by the cumulative sum analysis.

Results

From December 2016 to November 2020, 58 consecutive cases underwent surgery performed by a single surgical team. The overall surgical success rate was 94.8% (55/58). A three-stage learning curve of primary outcome was observed. The proficiency was achieved after 23 cases. The proportions of advanced tumor staging and concomitant surgery after obtaining proficiency were significantly higher than those before achieving proficiency (p = 0.046 and p < 0.001, respectively). Mean values of operation time, intraoperative blood loss, length of hospital stay, and bone graft deviation were 532.5 ± 119.2 min, 1,006.8 ± 547.2 ml, 16.1 ± 6.3 days, and 0.9 ± 1.2 mm, respectively. Two trends of learning curve were observed in the CUSUM analyses of total operation time, length of hospital stay, and bone graft deviation, in which the first and second inflexion points occurred between 8 and 17 cases and between 43 and 46 cases, respectively.

Conclusion

Our results revealed a three-stage learning curve of CAJR with the use of PSSP, including initial learning, plateau, and overlearning. Based on CUSUM analysis, the surgical proficiency was achieved after 23 cases, and total operation time, length of hospital stay, and bone graft deviation stabilized after 8–17 cases.

Printed titanium implants in UK craniomaxillofacial surgery. Part II: perceived performance (outcomes, logistics, and costs)

This second part explores perceptions and understanding of clinical performance, turnaround, and costs for printed titanium implants or plates in common procedures, evaluating both 'in-house' and 'outsourced' CAD-CAM pathways. A cross-sectional study, supported by the British Association of Oral and Maxillofacial Surgeons (BAOMS) and a national trainee-led recruitment team, was conducted over 14 weeks. A total of 132 participants took part (demographic data is reported in Part I). For fibular-flap mandibular reconstruction, most participants (69% - 91%) perceived printed titanium as superior to intraoperatively or preoperatively hand-bent plates for surgical duration, accuracy, dental restorability, and aesthetics. There was less agreement about complications and plate-failure risks. Most perceived printed plates to be superior to traditional wafer-based maxillary osteotomy for surgical duration (61%) and maxillary positioning (60%). For orbital floor repair, most perceived improvements in surgical duration (83%, especially higher-volume operators p=0.009), precision (84%), and ease of placement (69%). Rarely (less than 5%) was any outcome rated inferior to traditional techniques for any procedure. Perceived turnaround times and costs were variable, but the greatest consensus was for two-segment fibular-flap reconstructions and orbital floor repair. Industry estimates were generally consistent between two company representatives, but manufacturing-only costs differed when using in-house (departmental) designers. Costs and turnaround times are questionable barriers since few understand 'real-world' figures. Designing in-house can dramatically alter costs. Improved accuracy and surgical duration are common themes but biomechanical benefits are less-well understood. This study paints a picture of the potentially routine applications and benefits of printed titanium, capacity for uptake, understanding amongst surgeons, and areas for improvement.

Titanium Alloy Cutting Guides in Craniomaxillofacial Surgery-A Minimally Invasive Alternative to Synthetic Polymer Guides

PURPOSE

Historically, synthetic polymers, such as polyamide, have been the predominate material used for patient-specific cutting guides in 3-dimensionally guided craniomaxillofacial surgery. The physical properties of polyamide result in guides that are bulky and difficult to place within the confines of the facial soft tissue envelope, requiring larger incisions with resultant morbidity. Despite their utility, we found the need for wider exposure simply for guide placement was unacceptable. The purpose of the present study was to evaluate our experience with the newly marketed titanium alloy cutting guides.

MATERIALS AND METHODS

We conducted a retrospective cohort study of patients who had undergone either segmental mandibulectomy or maxillectomy using patient-specific titanium alloy cutting guides from May to December 2019. The primary outcome variable was the need for an extended-access cervical incision or a transfacial incision for either maxillectomy or segmental mandibulectomy in patients with benign disorders. The secondary outcome variables included the need for a transfacial incision in patients with malignant pathology requiring either maxillectomy or composite oromandibular resection and the final histopathologic bone margin status.

RESULTS

Of the 21 included patients, 11 had undergone maxillectomy (1 of 2) or segmental mandibulectomy (9 of 9) for benign disorders, with 91% (10 of 11) having undergone titanium alloy guide placement and resection entirely transorally without the need for an extended cervical or a transfacial incision. For 10 of the 11 patients undergoing immediate reconstruction with vascularized bone flaps, transcervical access was limited to small 1.5- to 2.5-cm incisions for target vessel access and microvascular anastomosis. None of the 10 patients with a malignant disorder requiring either maxillectomy or composite oromandibular resection required a transfacial incision. The bone margins, as determined by histopathologic analysis, were negative for 100% of the patients.

CONCLUSIONS

Patient-specific titanium alloy cutting guides represent a viable alternative to traditional synthetic polymer guides. Their superior properties permit easier intraoral placement, decreasing the need for cutaneous incisions and excessive periosteal stripping.

Full-Digital Workflow for Fabricating a Custom-Made Direct Metal Laser Sintering (DMLS) Mandibular Implant: A Case Report

Direct Laser Metal Sintering (DLMS) is an additive manufacturing (AM) technique that is capable of manufacturing metal parts according to a three-dimensional (3D) design made using computer-assisted-design (CAD) software, thanks to a powerful laser beam that melts selectively micro-powder layers, one on top of the other, until the desired object is generated. With DMLS, it is now possible to fabricate custom-made titanium implants for oral and maxillofacial applications. We present the case of a 67-year-old woman diagnosed with a squamous cell carcinoma of the mandible. The patient underwent subtotal mandibular resection; conventional reconstruction procedures failed to rehabilitate the function of the mandible. A prosthesis replacing the resected mandible was designed and fabricated using a digital workflow. The extensive bone defect was rehabilitated with a prosthesis replacing the mandibular bone and supporting a morse-taper dental prosthesis. The masticatory function was reestablished.

Recent advance in patient-specific 3D printing templates in mandibular reconstruction

Patient-specific 3D printing template is used in mandibular defect reconstruction with multiple deficiencies. During the operation, the template can accurately transfer the preoperative design, assisting surgeons to complete the surgery with high efficiency and accuracy. The template design has been continuously improved to obtain good application for miscellaneous classification and description. This review attempted to preliminarily analyse and summarise recent advancements in personalized 3D printing templates in mandibular reconstruction from the aspects of functional classification, existing problems, improved strategies and post-surgery evaluation by reviewing studies and through our combined clinical work and experience on hundreds of reconstruction surgeries.

Review of surgical resection and reconstruction in head and neck cancer. Traditional versus current concepts

This review summarizes the development of head and neck cancer resection and reconstruction. The developments in the treatment of cancer patients are reflected in their surgical outcomes, in addition to functional and aesthetic improvements. New technologies, such as surgical simulation and planning, minimally invasive surgery, and microsurgery have been added to the field to improve surgical resection of the tumor and reconstruction. The field is still growing to optimize the management of head and neck cancer.

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.

Craniomaxillofacial patient-specific CAD/CAM implants based on cone-beam tomography data - A feasibility study

Customized implants have simplified surgical procedures and have improved patient outcome in craniomaxillofacial surgery. Traditionally, patient-specific data is gathered by conventional computed tomography (CT). However, cone-beam CT (CBCT) can generate a 3D reconstruction of the area of interest with a lower dose of radiation at reduced cost. In this study, we investigated the feasibility of using CBCT data to design and generate customized implants for patients requiring craniomaxillofacial reconstruction. We used CBCT to generate 62 implants for 51 consecutive patients admitted to our department between January 2015 and December 2017. The indications for reconstruction and types of reconstruction were very variable. In all cases, the implants were well fitted and no implant-related complications were detected. Pre-surgical planning was faster and more efficient as we did not have to consult a radiologist. Although CBCT data is more difficult to process than conventional CT data for the implant provider, the clinical advantages are pronounced and we now use CBCT as standard in our department. In conclusion, we have shown that using CBCT to design and manufacture customized implants for reconstruction of the craniomaxillofacial area is feasible and recommend this approach to other departments.