Accuracy Assessment of Molded, Patient-Specific Polymethylmethacrylate Craniofacial Implants Compared to Their 3D Printed Originals

Advances in Three-Dimensional Printing for Craniomaxillofacial Trauma Reconstruction: A Systematic Review

Craniomaxillofacial (CMF) fractures present significant challenges for plastic surgeons due to their intricate nature. Conventional methods such as autologous bone grafts have limitations, necessitating advancements in reconstructive surgery techniques. This study reviewed the use of three-dimensional printing for CMF trauma reconstruction using human studies. A systematic search of PubMed, EMBASE, and Google Scholar was conducted in February 2024 for case reports, case series, and clinical trials related to CMF trauma reconstruction using three-dimensional printing technology. The authors' systematic review included 20 studies and a total of 170 participants with CMF bone defects. In general, the authors observed low bias risk in analyzed case reports and series, serious bias risk in nonrandomized controlled trials, and moderate bias risk in randomized controlled trials. The printed objects included CMF structure model prototypes, patient-specific implants, and other custom surgical devices. Studies reveal successful outcomes, including restored facial symmetry and function, restored orbital occlusion, resolved enophthalmos and diplopia, achieved cosmetically symmetrical lower face reconstruction, and precise fitting of surgical devices, enhancing patient and surgeon comfort. However, complications such as local infection, implant exposure, and persistent diplopia were reported. Three-dimensional printed devices reduced surgery time but increased preparation time and production costs. In-house production options could mitigate these time and cost expenditures. Three-dimensional printing holds potential in CMF trauma reconstruction, addressing both functional and esthetic restoration. Nevertheless, challenges persist in implementing this advanced technology in resource-limited environments.

Assessment of the accuracy of 3D printed medical models through reverse engineering

The dimensional accuracy of additively manufactured (3D printed) medical models can be affected by various parameters. Although different methods are used to evaluate the accuracy of additively manufactured models, this study focused on the investigation of the dimensional accuracy of the medical model based the combination of reverse engineering (RE) and additive manufacturing (AM) technologies. Human femur bone was constructed from CT images and manufactured, using Fortus 450mc Industrial material extrusion 3D Printer. The additive manufactured femur bone was subsequently 3D scanned using three distinct non-contact 3D scanners. MeshLab was used for mesh analysis, while VX Elements was used for post-processing of the point cloud. A combination of the VX Inspect environment and MeshLab was used to evaluate the scanning performance. The deviation of the 3D scanned 3D models from the reference mesh was determined using relative metrics and absolute measurements. The scanners reported deviations ranging from -0.375 mm to 0.388 mm, resulting in a total range of approximately 0.763 mm with average root mean square (RMS) deviation of 0.22 mm. The results indicate that the additively manufactured model, as measured by 3D scanning, has a mean deviation with an average range of approximately 0.46 mm and an average mean value of around 0.16 mm.

A Single Standard Polyvinyl Chloride 3D Skull Model to Create the Polymethyl Methacrylate Cranioplasty Flap: A Novel and Low-Cost Technique

BACKGROUND

 Although, cranioplasty is a commonly performed neurosurgical procedure worldwide, the cost of available cranioplasty implants is a major issue in a low-income country like India. The aims of this study were to introduce a novel and low-cost technique using a single standard three-dimensional (3D) skull model to guide the polymethyl methacrylate (PMMA) cranioplasty flap production and to evaluate the functional and cosmetic outcomes.

METHODS

 We retrospectively evaluated 47 cases of PMMA cranioplasty in the period from February 2019 to June 2022. A single standard 3D skull model was used to make the PMMA cranioplasty flaps. The overall cost of this PMMA implant was compared with that of other available cranioplasty implants. The functional and cosmetic outcomes were evaluated postoperatively.

RESULTS

 The mean age of our patients was 37.17 ± 13.83 years and the age range was 17 to 63 years. The primary cause of surgery was trauma in the majority of cases (n = 31, 65.96%). The mean operative time was 78.55 ± 19.82 minutes. The cosmetic results were very satisfying in 46 of 47 (97.87%) patients and moderately satisfying in 1 (2.12%) patient. Overall, there were three (6.38%) complications.

CONCLUSION

 Our technique provides excellent functional and cosmetic outcomes. The overall surgical cost of these PMMA implants was lower than that of the other available cranioplasty implants. This technique is currently the most cost-effective option for cranioplasty.

Virtual Reality Planning in Reconstructive Surgery for Orbital Prosthetic Rehabilitation Using ImmersiveTouch Platform: Preliminary Report

BACKGROUND/PURPOSE

Virtual reality (VR) is emerging as an effective and intuitive surgical planning and 3D visualization tool. Digital surgical planning is the gold standard for planning the placement of implants in maxillofacial prosthetics, but the field lacks a platform exclusively designed to perform the task. Virtual reality planning (VRP) specific for maxillofacial prosthetics offers the clinician improved control of the presurgical planning and the potential to limit the need to adapt other advanced segmentation software. Furthermore, the virtual plan can be directly translated to the patient through custom 3D printed (3DP) surgical guides and visual aids. To the best of our knowledge, this article outlines the development of the world's first virtual reality planning platform and workflow for pre-operatory planning within a VR environment for clinical use specific to facial prosthetics and anaplastology.

METHOD

The workflow was applied to managing 2 patients presenting with unilateral total exenteration and severe contracture enucleation, respectively (n=2). A cone-beam CT was acquired for each patient, and their data set was directly imported into the ImmersiveView Surgical Plan VR environment (ImmersiveTouch Inc, Chicago, IL). The clinicians virtually selected appropriately sized craniofacial implants and placed the implants in the desired orientation. Various measurement tools are available to aid in clinical decision-making. The ideal location of craniofacial implants was set according to an orbital and auricular prosthetic reconstruction. The resultant VR plan was exported for 3DP. The patients were evaluated preoperatively and postoperatively using the proposed VRP treatment. The workflow's data accuracy was validated postoperatively by comparing posterative CT data and the proposed VRP. Analysis was performed using Mimics software (Materialise, Leuven, Belgium).

RESULT

It takes, on average, 10 minutes to place 4 implants in the virtual reality space. The 3DP files resulting from VRP take ~2 hours to print and are constructed with a biocompatible resin appropriate for clinical use as surgical guides. Our user-friendly VRP workflow allows for an accurate simulation of surgical and nonsurgical procedures with an average displacement in XYZ of 0.6 mm and an SD of 0.3 mm. In addition, VRP is an excellent tool to simulate the craniofacial placement procedure and improves unsupervised self-learning teaching.

CONCLUSION

VRP is an exciting tool for training clinicians and students in complex surgical procedures. This study shows the promising applicability and efficiency of VR in clinical planning and management of facial rehabilitation. Patients allowed to interact with VR have been engaged, which would aid their treatment acceptance and patient education. A valuable advantage of surgical simulation is the reduced costs associated with renting instruments, buying implant dummies, and surgical hardware. The authors will explore VR to plan and treat surgical and nonsurgical reconstructive procedures and improve soft tissue manipulation. This study outlines the development of an original platform and workflow for segmentation, preoperative planning, and digital design within a VR environment and the clinical use in reconstructive surgery and anaplastology.

Breaking Barriers in Cranioplasty: 3D Printing in Low and Middle-Income Settings-Insights from Zenica, Bosnia and Herzegovina

Background and Objectives: Cranial defects pose significant challenges in low and middle-income countries (LIMCs), necessitating innovative and cost-effective craniofacial reconstruction strategies. The purpose of this study was to present the Bosnia and Herzegovina model, showcasing the potential of a multidisciplinary team and 3D-based technologies, particularly PMMA implants, to address cranial defects in a resource-limited setting. Materials and Methods: An observational, non-experimental prospective investigation involved three cases of cranioplasty at the Department of Neurosurgery, Cantonal Hospital Zenica, Bosnia and Herzegovina, between 2019 and 2023. The technical process included 3D imaging and modeling with MIMICS software (version 10.01), 3D printing of the prototype, mold construction and intraoperative modification for precise implant fitting. Results: The Bosnia and Herzegovina model demonstrated successful outcomes in cranioplasty, with PMMA implants proving cost-effective and efficient in addressing cranial defects. Intraoperative modification contributed to reduced costs and potential complications, while the multidisciplinary approach and 3D-based technologies facilitated accurate reconstruction. Conclusions: The Bosnia and Herzegovina model showcases a cost-effective and efficient approach for craniofacial reconstruction in LIMICs. Collaborative efforts, 3D-based technologies, and PMMA implants contribute to successful outcomes. Further research is needed to validate sustained benefits and enhance craniofacial reconstruction strategies in resource-constrained settings.

In Vitro and In Vivo Biological Assessments of 3D-Bioprinted Scaffolds for Dental Applications

Three-dimensional (3D) bioprinting is a unique combination of technological advances in 3D printing and tissue engineering. It has emerged as a promising approach to address the dilemma in current dental treatments faced by clinicians in order to repair or replace injured and diseased tissues. The exploration of 3D bioprinting technology provides high reproducibility and precise control of the bioink containing the desired cells and biomaterial over the architectural and dimensional features of the scaffolds in fabricating functional tissue constructs that are specific to the patient treatment need. In recent years, the dental applications of different 3D bioprinting techniques, types of novel bioinks, and the types of cells used have been extensively explored. Most of the findings noted significant challenges compared to the non-biological 3D printing approach in constructing the bioscaffolds that mimic native tissues. Hence, this review focuses solely on the implementation of 3D bioprinting techniques and strategies based on cell-laden bioinks. It discusses the in vitro applications of 3D-bioprinted scaffolds on cell viabilities, cell functionalities, differentiation ability, and expression of the markers as well as the in vivo evaluations of the implanted bioscaffolds on the animal models for bone, periodontal, dentin, and pulp tissue regeneration. Finally, it outlines some perspectives for future developments in dental applications.

Advances and Prospects in Materials for Craniofacial Bone Reconstruction

The craniofacial region is composed of 23 bones, which provide crucial function in keeping the normal position of brain and eyeballs, aesthetics of the craniofacial complex, facial movements, and visual function. Given the complex geometry and architecture, craniofacial bone defects not only affect the normal craniofacial structure but also may result in severe craniofacial dysfunction. Therefore, the exploration of rapid, precise, and effective reconstruction of craniofacial bone defects is urgent. Recently, developments in advanced bone tissue engineering bring new hope for the ideal reconstruction of the craniofacial bone defects. This report, presenting a first-time comprehensive review of recent advances of biomaterials in craniofacial bone tissue engineering, overviews the modification of traditional biomaterials and development of advanced biomaterials applying to craniofacial reconstruction. Challenges and perspectives of biomaterial development in craniofacial fields are discussed in the end.

Patient-Specific Implants in Maxillofacial Reconstruction - A Case Report

Rationale

The successful utilisation of three dimensional (3D) techniques in engineering a titanium patient specific implant (PSI) for a patient who underwent hemimaxillectomy following post COVID mucormycosis infection.

Patient Concerns

Issues related to problems associated with resection following mucormycosis, such as occlusal function, aesthetics and facial asymmetry.

Diagnosis

The patient affected by mucormycosis was left with Aramany class 1 and Cordeiro type II sub total maxillectomy defect.

Treatment

The patient was operated for mucormycosis followed by reconstruction with patient specific implant.

Outcome

Positive clinical outcomes, including improved facial symmetry, function and psychological well being with immediate replacement of the teeth, the benefits of which far outweigh the traditional approach.

Take away Lessons

The advances in the use of PSI by integration of 3D printing and computer aided design computer aided manufacturing (CAD-CAM) technology for extensive and challenging defects in the maxillofacial region have been highlighted in this case report.

Energy Consumption vs. Tensile Strength of Poly[methyl methacrylate] in Material Extrusion 3D Printing: The Impact of Six Control Settings

The energy efficiency of material extrusion additive manufacturing has a significant impact on the economics and environmental footprint of the process. Control parameters that ensure 3D-printed functional products of premium quality and mechanical strength are an established market-driven requirement. To accomplish multiple objectives is challenging, especially for multi-purpose industrial polymers, such as the Poly[methyl methacrylate]. The current paper explores the contribution of six generic control factors (infill density, raster deposition angle, nozzle temperature, print speed, layer thickness, and bed temperature) to the energy performance of Poly[methyl methacrylate] over its mechanical performance. A five-level L25 Taguchi orthogonal array was composed, with five replicas, involving 135 experiments. The 3D printing time and the electrical consumption were documented with the stopwatch approach. The tensile strength, modulus, and toughness were experimentally obtained. The raster deposition angle and the printing speed were the first and second most influential control parameters on tensile strength. Layer thickness and printing speed were the corresponding ones for the energy consumption. Quadratic regression model equations for each response metric over the six control parameters were compiled and validated. Thus, the best compromise between energy efficiency and mechanical strength is achievable, and a tool creates significant value for engineering applications.

Insights and trends review: the role of three-dimensional technology in upper extremity surgery

The use of three-dimensional (3-D) technology in upper extremity surgery has the potential to revolutionize the way that hand and upper limb procedures are planned and performed. 3-D technology can assist in the diagnosis and treatment of conditions, allowing virtual preoperative planning and surgical templating. 3-D printing can allow the production of patient-specific jigs, instruments and implants, allowing surgeons to plan and perform complex procedures with greater precision and accuracy. Previously, cost has been a barrier to the use of 3-D technology, which is now falling rapidly. This review article will discuss the current status of 3-D technology and printing, including its applications, ethics and challenges in hand and upper limb surgery. We have provided case examples to outline how clinicians can incorporate 3-D technology in their clinical practice for congenital deformities, management of acute fracture and malunion and arthroplasty.

Point-of-Care Virtual Surgical Planning and 3D Printing in Oral and Cranio-Maxillofacial Surgery: A Narrative Review

This paper provides an overview on the use of virtual surgical planning (VSP) and point-of-care 3D printing (POC 3DP) in oral and cranio-maxillofacial (CMF) surgery based on a literature review. The authors searched PubMed, Web of Science, and Embase to find papers published between January 2015 and February 2022 in English, which describe human applications of POC 3DP in CMF surgery, resulting in 63 articles being included. The main review findings were as follows: most used clinical applications were anatomical models and cutting guides; production took place in-house or as "in-house-outsourced" workflows; the surgeon alone was involved in POC 3DP in 36 papers; the use of free versus paid planning software was balanced (50.72% vs. 49.27%); average planning time was 4.44 h; overall operating time decreased and outcomes were favorable, though evidence-based studies were limited; and finally, the heterogenous cost reports made a comprehensive financial analysis difficult. Overall, the development of in-house 3D printed devices supports CMF surgery, and encouraging results indicate that the technology has matured considerably.

Subgaleal Effusion and Brain Midline Shift After Cranioplasty: A Retrospective Study Between Polyetheretherketone Cranioplasty and Titanium Cranioplasty After Decompressive Craniectomy

Cranioplasty with polyetheretherketone (PEEK) has recently shown better cerebral protection performance, improved brain function, and aesthetic contour compared with titanium mesh. However, whether patients undergoing PEEK cranioplasty tend to develop subgaleal effusions remains elusive. This retrospective study included patients who underwent cranioplasty with PEEK implants or titanium mesh after decompressive craniectomy between July 2017 and July 2020. Patient information, including general information, location, size of the defect, subgaleal depth, and brain midline shift was collected and statistically analyzed. There were 130 cases of cranioplasty, including 35 with PEEK implants and 95 with a titanium mesh. Patients who underwent cranioplasty with a PEEK implant had a higher subgaleal effusion rate than those who underwent cranioplasty with titanium mesh (85.71% vs. 53.68%, P < 0.001), while a midline shift >5 mm was more frequently observed in the PEEK group than in the titanium group (20% vs. 6.3%, P = 0.021). The PEEK material was the only factor associated with subgaleal effusion after cranioplasty (OR 5.589, P = 0.002). Logistic regression analysis further showed that age was a protective factor against midline shift in the PEEK cranioplasty group (OR 0.837, P = 0.029). Patients who underwent cranioplasty with PEEK implants were more likely to develop severe subgaleal effusion and significant brain midline shifts than those with titanium mesh implants.

Customized alloplastic cranioplasty of large bone defects by 3D-printed prefabricated mold template after posttraumatic decompressive craniectomy: A technical note

Background

Manufacturing of customized three-dimensional (3D)-printed cranioplastic implant after decompressive craniectomy has been introduced to overcome the difficulties of intraoperative implant molding. The authors present and discuss the technique, which consists of the prefabrication of silicone implant mold using additive manufacturing, also known as 3D printing, and polymethyl methacrylate (PMMA) implant casting.

Methods

To reconstruct a large bone defect sustained after decompressive craniectomy due to traumatic brain injury (TBI), a 3D-printed prefabricated mold template was used to create a customized PMMA implant for cranial vault repair in five consecutive patients.

Results

A superb restoration of the symmetrical contours and curvature of the cranium was achieved in all patients. The outcome was clinically and cosmetically favorable in all of them.

Conclusion

Customized alloplastic cranioplasty using 3D-printed prefabricated mold for casting PMMA implant is easy to perform technique for the restoration of cranial vault after a decompressive craniectomy following moderate-to-severe TBI. It is a valuable and modern technique to advance manufacturing of personalized prefabricated cranioplastic implants used for the reconstruction of large skull defects having complex geometry. It is a safe and cost-effective procedure having an excellent cosmetic outcome, which may considerably decrease expenses and time needed for cranial reconstructive surgery.

Biomechanical Evaluation of Patient-Specific Polymethylmethacrylate Cranial Implants for Virtual Surgical Planning: An In-Vitro Study

Cranioplasty with freehand-molded polymethylmethacrylate implants is based on decades of experience and is still frequently used in clinical practice. However, data confirming the fracture toughness and standard biomechanical tests are rare. This study aimed to determine the amount of force that could be applied to virtually planned, template-molded, patient-specific implants (n = 10) with an implant thickness of 3 mm, used in the treatment of a temporoparietal skull defect (91.87 cm2), until the implant cracks and finally breaks. Furthermore, the influence of the weight and porosity of the implant on its force resistance was investigated. The primary outcome showed that a high force was required to break the implant (mean and standard deviation 1484.6 ± 167.7 N), and this was very strongly correlated with implant weight (Pearson’s correlation coefficient 0.97; p < 0.001). Secondary outcomes were force application at the implant’s first, second, and third crack. Only a moderate correlation could be found between fracture force and the volume of porosities (Pearson’s correlation coefficient 0.59; p = 0.073). The present study demonstrates that an implant thickness of 3 mm for a temporoparietal skull defect can withstand sufficient force to protect the brain. Greater implant weight and, thus, higher material content increases thickness, resulting in more resistance. Porosities that occur during the described workflow do not seem to reduce resistance. Therefore, precise knowledge of the fracture force of polymethylmethacrylate cranial implants provides insight into brain injury prevention and serves as a reference for the virtual design process.

Customized cost-effective polymethylmethacrylate cranioplasty: a cosmetic comparison with other low-cost methods of cranioplasty

BACKGROUND

Intraoperative hand-moulded cranioplasty and polymethylmethacrylate (PMMA) prostheses made from bone impressions are economical but the cosmetic results are less than satisfactory. Commercially available customized prostheses perform better but are prohibitively expensive. We evaluate the performance of a locally developed, low-cost customized PMMA cranioplasty prosthesis.

OBJECTIVE

To compare the cosmetic outcome of 3 types of PMMA cranioplasty as well as with objective measurements on postoperative CT scans METHODS: This study includes 70 patients who underwent cranioplasty between March 2016 and June 2020. In this period, patients had their cranioplasty prostheses made by intra-operative hand moulding (HM), by using the removed bone as a template and making a bone impression (BI) or by 3D printing the prosthesis based on a CT scan. Cosmetic outcomes were assessed by the patient and the operating surgeon on an 8-point scale. The degree of measured anthropometric asymmetry was measured on a postoperative CT scan and correlated with the cosmetic outcome.

RESULTS

Our locally produced 3D-printed cranioplasty prostheses showed a statistically better performance in cosmetic scores when compared to the HM and BI (p value < 0.001). CT anthropometric measurements significantly correlated with cosmetic outcome (p value 0.01) CONCLUSION: Our 3D cranioplasty prostheses had better cosmetic outcomes than HM and BI prostheses, and our technique is able to produce them at 10% of the cost of the currently available commercial customized prostheses.

A Structured Approach for the Design and Manufacturing of Titanium Cranial Prostheses via Sheet Metal Forming

Currently, the growing need for highly customized implants has become one of the key aspects to increase the life expectancy and reduce time and costs for prolonged hospitalizations due to premature failures of implanted prostheses. According to the literature, several technological solutions are considered suitable to achieve the necessary geometrical complexity, from the conventional subtractive approaches to the more innovative additive solutions. In the case of cranial prostheses, which must guarantee a very good fitting of the region surrounding the implant in order to minimize micromotions and reduce infections, the need of a product characterized by high geometrical complexity combined with both strength and limited weight, has pushed the research towards the adoption of manufacturing processes able to improve the product’s quality but being fast and flexible enough. The attention has been thus focused in this paper on sheet metal forming processes and, namely on the Single Point Incremental Forming (SPIF) and the Superplastic Forming (SPF). In particular, the complete procedure to design and produce titanium cranial prostheses for in vivo tests is described: starting from Digital Imaging and COmmunications in Medicine (DICOM) images of the ovine animal, the design was conducted and the production process simulated to evaluate the process parameters and the production set up. The forming characteristics of the prostheses were finally evaluated in terms of thickness distributions and part’s geometry. The effectiveness of the proposed methodology has been finally assessed through the implantation of the manufactured prostheses in sheep.

[Features of modeling a polymer implant for closing a defect after decompressive craniotomy]

BACKGROUND

Individual polymer implants are widespread for bone reconstruction after decompressive craniectomy. Despite the availability of customized titanium products, various specialists and hospitals prefer polymer implants.

OBJECTIVE

To compare the methods of modeling and manufacturing the polymethylmethacrylate implants and identify the features affecting the quality of reconstruction.

MATERIAL AND METHODS

We analyzed 14 patients with extensive skull defects after installation of polymethyl methacrylate implants. Software used for modeling of individual implants by different specialists was compared.

RESULTS

Satisfactory reconstruction result was obtained in all cases. There were no infectious complications. The authors outlined certain important aspects for modeling of individual polymer products: local use of anatomical thickness of the implant, leaving safe spaces, prevention of temporal retraction, template-based resection before reconstruction.

CONCLUSION

To date, skull defect closure with polymeric materials remains relevant, and even has certain advantages over customized titanium products.

Patient specific Polymethyl methacrylate customised cranioplasty using 3D printed silicone moulds: Technical note

INTRODUCTION

Cranioplasty after decompressive craniectomy can be performed with several techniques and materials. With the common use of 3D printing, custom cranioplasty can be produced at affordable cost. Aim of this technical note is to describe our technique for producing patient specific Polymethyl methacrylate (PMMA) cranioplasty using 3D printed silicone moulds.

MATERIALS AND METHODS

We enrolled seven patients from January 2020 to June 2021 who required surgery for cranioplasty. The 3D printing was used to produce silicone moulds for defining the exact shape of the PMMA cranioplasty, according to the CT scan of the patient.

RESULTS

We performed seven procedures. The mean time of the surgery was 80 min. All cranioplasties perfectly matched the patient specific anatomy. No complications occurred.

CONCLUSIONS

Using 3D printed patient specific silicone moulds and PMMA resulted to be effective, with affordable costs and ensuring a good cosmetic result.

Quality control methods in musculoskeletal tissue engineering: from imaging to biosensors

Tissue engineering is rapidly progressing toward clinical application. In the musculoskeletal field, there has been an increasing necessity for bone and cartilage replacement. Despite the promising translational potential of tissue engineering approaches, careful attention should be given to the quality of developed constructs to increase the real applicability to patients. After a general introduction to musculoskeletal tissue engineering, this narrative review aims to offer an overview of methods, starting from classical techniques, such as gene expression analysis and histology, to less common methods, such as Raman spectroscopy, microcomputed tomography, and biosensors, that can be employed to assess the quality of constructs in terms of viability, morphology, or matrix deposition. A particular emphasis is given to standards and good practices (GXP), which can be applicable in different sectors. Moreover, a classification of the methods into destructive, noninvasive, or conservative based on the possible further development of a preimplant quality monitoring system is proposed. Biosensors in musculoskeletal tissue engineering have not yet been used but have been proposed as a novel technology that can be exploited with numerous advantages, including minimal invasiveness, making them suitable for the development of preimplant quality control systems.

Sinus Lift and Implant Insertion on 3D-Printed Polymeric Maxillary Models: Ex Vivo Training for In Vivo Surgical Procedures

Background and Objectives: The aim of this study is to demonstrate the increased efficiency achieved by dental practitioners when carrying out an ex vivo training process on 3D-printed maxillaries before performing in vivo surgery. Materials and Methods: This developed ex vivo procedure comprises the following phases: (i) scanning the area of interest for surgery; (ii) obtaining a 3D virtual model of this area using Cone Beam Computed Tomography (CBCT); (iii) obtaining a 3D-printed model (based on the virtual one), on which (iv) the dental practitioner simulates/rehearses ex vivo (most of) the surgery protocol; (v) assess with a new CBCT the 3D model after simulation. The technical steps of sinus augmentation and implant insertion could be performed on the corresponding 3D-printed hemi-maxillaries prior to the real in vivo surgery. Two study groups were considered, with forty patients divided as follows: Group 1 comprises twenty patients on which the developed simulation and rehearsal procedure was applied; Group 2 is a control one which comprises twenty patients on which similar surgery was performed without this procedure (considered in order to compare operative times without and with rehearsals). Results: Following the ex vivo training/rehearsal, an optimal surgery protocol was developed for each considered case. The results of the surgery on patients were compared with the results obtained after rehearsals on 3D-printed models. The performed quantitative assessment proved that, using the proposed training procedure, the results of the in vivo surgery are not significantly different (p = 0.089) with regard to the ex vivo simulation for both the mezio-distal position of the implant and the distance from the ridge margin to sinus window. On the contrary, the operative time of Group 1 was reduced significantly (p = 0.001), with an average of 20% with regard to in vivo procedures performed without rehearsals (on the control Group 2). Conclusions: The study demonstrated that the use of 3D-printed models can be beneficial to dental surgeon practitioners, as well as to students who must be trained before performing clinical treatments.

Quantitative Assessment of Point-of-Care 3D-Printed Patient-Specific Polyetheretherketone (PEEK) Cranial Implants

Recent advancements in medical imaging, virtual surgical planning (VSP), and three-dimensional (3D) printing have potentially changed how today's craniomaxillofacial surgeons use patient information for customized treatments. Over the years, polyetheretherketone (PEEK) has emerged as the biomaterial of choice to reconstruct craniofacial defects. With advancements in additive manufacturing (AM) systems, prospects for the point-of-care (POC) 3D printing of PEEK patient-specific implants (PSIs) have emerged. Consequently, investigating the clinical reliability of POC-manufactured PEEK implants has become a necessary endeavor. Therefore, this paper aims to provide a quantitative assessment of POC-manufactured, 3D-printed PEEK PSIs for cranial reconstruction through characterization of the geometrical, morphological, and biomechanical aspects of the in-hospital 3D-printed PEEK cranial implants. The study results revealed that the printed customized cranial implants had high dimensional accuracy and repeatability, displaying clinically acceptable morphologic similarity concerning fit and contours continuity. From a biomechanical standpoint, it was noticed that the tested implants had variable peak load values with discrete fracture patterns and failed at a mean (SD) peak load of 798.38 ± 211.45 N. In conclusion, the results of this preclinical study are in line with cranial implant expectations; however, specific attributes have scope for further improvements.

Cubik system: maximizing possibilities of in-house computer-guided surgery for complex craniofacial reconstruction

Craniofacial reconstruction represents a major challenge due to the complex anatomical morphology. Although implant production has often been outsourced to external companies, in-house planning and manufacturing has developed in many centres. This note introduces a conceptualized modular mould system to perform any desired craniofacial reconstruction, named 'Cubik', inspired by the famous Rubik's cube. A sophisticated virtual process is described that simulates realistic cranio-orbital resections, and the workflow to create multi-component moulds in order to achieve intraoperatively moulded implants is presented. The description focuses on the appropriate definition of interfaces between the subdivision surfaces of the planned implant, which is the key element to successful design and function of the moulds during surgery and is the peculiarity of the Cubik system. The use of Cubik does not prolong the overall duration of surgery, and it appears to be a very versatile tool, allowing personalized implants with different morphology to be created, which are suitable to cover every potential defect of the skull and the orbital region. This study extends the potential of in-house production, allowing highly accurate implantable craniofacial implants to be fabricated, and in the future this might represent a solution to achieve in-house replacement of other segments of the facial skeleton.

Thickness accuracy of virtually designed patient-specific implants for large neurocranial defects

The combination of computer‐aided design (CAD) techniques based on computed tomography (CT) data to generate patient‐specific implants is in use for decades. However, persisting disadvantages are complicated design procedures and rigid reconstruction protocols, for example, for tailored implants mimicking the patient‐specific thickness distribution of missing cranial bone. In this study we used two different approaches, CAD‐ versus thin‐plate spline (TPS)‐based implants, to reconstruct extensive unilateral and bilateral cranial defects in three clinical cases. We used CT data of three complete human crania that were virtually damaged according to the missing regions in the clinical cases. In total, we carried out 132 virtual reconstructions and quantified accuracy from the original to the generated implant and deviations in the resulting implant thickness as root‐mean‐square error (RMSE). Reconstructions using TPS showed an RMSE of 0.08–0.18 mm in relation to geometric accuracy. CAD‐based implants showed an RMSE of 0.50–1.25 mm. RMSE in relation to implant thickness was between 0.63 and 0.70 mm (TPS) while values for CAD‐based implants were significantly higher (0.63–1.67 mm). While both approaches provide implants showing a high accuracy, the TPS‐based approach additionally provides implants that accurately reproduce the patient‐specific thickness distribution of the affected cranial region.

Design and Additive Manufacturing of a Biomimetic Customized Cranial Implant Based on Voronoi Diagram

Reconstruction of cranial defects is an arduous task for craniomaxillofacial surgeons. Additive manufacturing (AM) or three-dimensional (3D) printing of titanium patient-specific implants (PSIs) made its way into cranioplasty, improving the clinical outcomes in complex surgical procedures. There has been a significant interest within the medical community in redesigning implants based on natural analogies. This paper proposes a workflow to create a biomimetic patient-specific cranial prosthesis with an interconnected strut macrostructure mimicking bone trabeculae. The method implements an interactive generative design approach based on the Voronoi diagram or tessellations. Furthermore, the quasi-self-supporting fabrication feasibility of the biomimetic, lightweight titanium cranial prosthesis design is assessed using Selective Laser Melting (SLM) technology.

Overview of In-Hospital 3D Printing and Practical Applications in Hand Surgery

Three-dimensional (3D) printing is spreading in hand surgery. There is an increasing number of practical applications like the training of junior hand surgeons, patient education, preoperative planning, and 3D printing of customized casts, customized surgical guides, implants, and prostheses. Some high-quality studies highlight the value for surgeons, but there is still a lack of high-level evidence for improved clinical endpoints and hence actual impact on the patient's outcome. This article provides an overview over the latest applications of 3D printing in hand surgery and practical experience of implementing them into daily clinical routine.

Evaluation of implant properties, safety profile and clinical efficacy of patient-specific acrylic prosthesis in cranioplasty using 3D binderjet printed cranium model: A pilot study

There exists a significant demand to develop patient-specific prosthesis in reconstruction of cranial vaults after decompressive craniectomy. we report here, the outcomes of an unicentric pilot study on acrylic cranial prosthesis fabricated using a 3D printed cranium model with its clinically relevant mechanical properties.

METHODS

The semi-crystalline polymethyl methacrylate (PMMA) implants, shaped to the cranial defects of 3D printed cranium model, were implanted in 10 patients (mean age, 40.8 ± 14.8 years). A binderjet 3D printer was used to create patient-specific mould and PMMA was casted to fabricate prosthesis which was analyzed for microstructure and properties. Patients were followed up for allergy, infection and cosmesis for a period of 6 months.

RESULTS

As-cast PMMA flap exhibited hardness of 15.8 ± 0.24Hv, tensile strength of 30.7 ± 3.9 MPa and elastic modulus of 1.5 ± 0.1 GPa. 3D microstructure of the semi-crystalline acrylic implant revealed 2.5-15 µm spherical isolated pores. The mean area of the calvarial defect in craniectomy patients was 94.7 ± 17.4 cm². We achieved a cranial index of symmetry (CIS -%) of 94.5 ± 3.9, while the average post-operative Glasgow outcome scale (GOS) score recorded was 4.2 ± 0.9.

CONCLUSIONS

3D printing based patient-specific design and fabrication of acrylic cranioplasty implant is safe and achieves acceptable cosmetic and clinical outcomes in patients with decompressive craniectomy. Our study ensured clinically acceptable structural and mechanical properties of implanted PMMA, suggesting that a low cost 3D printer based PMMA flap is an affordable option for cranioplasty in resource constrained settings.

Customized Cost-Effective Polymethyl-Methacrylate Cranioplasty Implant Using Three-Dimensional Printer

There is no doubt that many synthetic materials used in cranioplasty have given good result regarding patient's calvarial shape. However, the use of these materials is costly to the patient and requires complex intraoperative process. There has been a long history regarding the use of acrylic bone cement called as polymethyl-methacrylate (PMMA) as an implant due to its desirable properties. Here, we present three cases of simple, cost effective manually sculpted calvarial defect using three-dimensional (3D) printer. Sharing the achievement and challenges, we want to focus that the 3D customized implant of PMMA can be used as bone substitute.

Quality Characteristics and Clinical Relevance of In-House 3D-Printed Customized Polyetheretherketone (PEEK) Implants for Craniofacial Reconstruction

Additive manufacturing (AM) of patient-specific implants (PSIs) is gradually moving towards in-house or point-of-care (POC) manufacturing. Polyetheretherketone (PEEK) has been used in cranioplasty cases as a reliable alternative to other alloplastic materials. As only a few fused filament fabrication (FFF) printers are suitable for in-house manufacturing, the quality characteristics of the implants fabricated by FFF technology are still under investigated. This paper aimed to investigate PEEK PSIs fabricated in-house for craniofacial reconstruction, discussing the key challenges during the FFF printing process. Two exemplary cases of class III (Group 1) and class IV (Group 2) craniofacial defects were selected for the fabrication of PEEK PSIs. Taguchi’s L9 orthogonal array was selected for the following nonthermal printing process parameters, i.e., layer thickness, infill rate, number of shells, and infill pattern, and an assessment of the dimensional accuracy of the fabricated implants was made. The root mean square (RMS) values revealed higher deviations in Group 1 PSIs (0.790 mm) compared to Group 2 PSIs (0.241 mm). Horizontal lines, or the characteristic FFF stair-stepping effect, were more perceptible across the surface of Group 1 PSIs. Although Group 2 PSIs revealed no discoloration, Group 1 PSIs displayed different zones of crystallinity. These results suggest that the dimensional accuracy of PSIs were within the clinically acceptable range; however, attention must be paid towards a requirement of optimum thermal management during the printing process to fabricate implants of uniform crystallinity.