3D Printing: current use in facial plastic and reconstructive surgery

Surgical Medical Education via 3D Bioprinting: Modular System for Endovascular Training

There is currently a shift in surgical training from traditional methods to simulation-based approaches, recognizing the necessity of more effective and controlled learning environments. This study introduces a completely new 3D-printed modular system for endovascular surgery training (M-SET), developed to allow various difficulty levels. Its design was based on computed tomography angiographies from real patient data with femoro-popliteal lesions. The study aimed to explore the integration of simulation training via a 3D model into the surgical training curriculum and its effect on their performance. Our preliminary study included 12 volunteer trainees randomized 1:1 into the standard simulation (SS) group (3 stepwise difficulty training sessions) and the random simulation (RS) group (random difficulty of the M-SET). A senior surgeon evaluated and timed the final training session. Feedback reports were assessed through the Student Satisfaction and Self-Confidence in Learning Scale. The SS group completed the training sessions in about half time (23.13 ± 9.2 min vs. 44.6 ± 12.8 min). Trainees expressed high satisfaction with the training program supported by the M-SET. Our 3D-printed modular training model meets the current need for new endovascular training approaches, offering a customizable, accessible, and effective simulation-based educational program with the aim of reducing the time required to reach a high level of practical skills.

Patient-Specific Implant Customization for Treatment of Internal Orbital Fractures Using Office-Based Three-Dimensional Printing

OBJECTIVE

Three-dimensional (3D) modeling technology aids the reconstructive surgeon in designing and tailoring individualized implants for the reconstruction of complex craniofacial fractures. Three-dimensional modeling and printing have traditionally been outsourced to commercial vendors but can now be incorporated into both private and academic craniomaxillofacial practices. The goal of this report is to present a low-cost, standardized office-based workflow for restoring bony orbital volume in traumatic orbital fractures.

METHODS

Patients with internal orbital fractures requiring open repair were identified. After the virtual 3D models were created by iPlan 3.0 Cranial CMF software (Brainlab), the models were printed using an office-based 3D printer to shape and modify orbital plates to correctly fit the fracture defect. The accuracy of the anatomic reduction and the restored bony orbital volume measurements were determined using postoperative computed tomography images and iPlan software.

RESULTS

Nine patients fulfilled the inclusion criteria: 8 patients had unilateral fractures and 1 patient had bilateral fractures. Average image processing and print time were 1.5 hours and 3 hours, respectively. The cost of the 3D printer was $2500 and the average material cost to print a single orbital model was $2. When compared with the uninjured side, the mean preoperative orbital volume increase and percent difference were 2.7 ± 1.3 mL and 10.9 ± 5.3%, respectively. Postoperative absolute volume and percent volume difference between the orbits were -0.2 ± 0.4 mL and -0.8 ± 1.7%, respectively.

CONCLUSIONS

Office-based 3D printing can be routinely used in the repair of internal orbital fractures in an efficient and cost-effective manner to design the implant with satisfactory patient outcomes.

Sutures positioning technique enhances the predictability and concordance between preoperative simulation and actual outcomes in rhinoplasty

BACKGROUND

The predictability and concordance between simulated and actual outcomes in rhinoplasty are uncertain. Here, we introduce a suture positioning technique (SPT), a simple and low-cost method to minimize the gap between the simulated and actual outcomes of rhinoplasty.

METHODS

Seventy patients were enrolled in this study between January 2018 and January 2021. Preoperative simulations were performed using Adobe Photoshop. The control group underwent surgery using simulation and intuition. In the SPT group, sutures were used to assist in the preoperative identification of the ideal nasal tip position. The SPT effectiveness was tested by measuring the nasal parameters and using the patient's subjective satisfaction questionnaire at T1 (Time 1, immediately postoperatively) and T2 (Time 2, at least 1 year postoperatively).

RESULTS

The intraclass correlation coefficient test showed a satisfactory correlation between simulation and postoperative outcomes in both groups. However, the SPT group had a higher correlation than the control group, especially for the nasal length (16% higher at T1 and 15% higher at T2). The mean absolute difference (MAD) between the outcomes and simulation indicated that the MAD of nasal tip projection between T2 and simulation and MAD of nasal length between T1 (or T2) and simulation were statistically significant between groups. Additionally, the SPT group was more satisfied with the postoperative outcomes and were consistent with the preoperative simulation.

CONCLUSION

This study demonstrated the effectiveness of SPT in intraoperative quality control. This technique may be adopted by surgeons to achieve good concordance between simulated and actual surgical outcomes.

Viscoelastic Properties of Human Facial Skin and Comparisons with Facial Prosthetic Elastomers

Prosthesis discomfort and a lack of skin-like quality is a source of patient dissatisfaction with facial prostheses. To engineer skin-like replacements, knowledge of the differences between facial skin properties and those for prosthetic materials is essential. This project measured six viscoelastic properties (percent laxity, stiffness, elastic deformation, creep, absorbed energy, and percent elasticity) at six facial locations with a suction device in a human adult population equally stratified for age, sex, and race. The same properties were measured for eight facial prosthetic elastomers currently available for clinical usage. The results showed that the prosthetic materials were 1.8 to 6.4 times higher in stiffness, 2 to 4 times lower in absorbed energy, and 2.75 to 9 times lower in viscous creep than facial skin (p < 0.001). Clustering analyses determined that facial skin properties fell into three groups-those associated with body of ear, cheek, and remaining locations. This provides baseline information for designing future replacements for missing facial tissues.

The Feasibility of Computer Simulations and 3-Dimensional-Printed Resection Guides for Skin Cancer Resection

The surgical resection margin in skin cancer is traditionally determined by the lesion's surface boundary without 3-dimensional information. Computed tomography (CT) can offer additional information, such as tumor invasion and the exact cancer extent. This study aimed to demonstrate the clinical application of and to evaluate the safety and accuracy of resection guides for skin cancer treatment. This prospective randomized comparison of skin cancer resection with (guide group; n=34) or without (control group; n=28) resection guide use was conducted between February 2020 and November 2021. Patients with squamous cell carcinoma or basal cell carcinoma were included. In the guide group, based on CT images, the surgical margin was defined, and a 3-dimensional-printed resection guide was fabricated. The intraoperative frozen biopsy results and distance from tumor boundary to resection margin were measured. The margin involvement rates were 8.8% and 17.9% in the guide and control groups, respectively. The margin involvement rate was nonsignificantly higher in the control group as compared with the guide group ( P =0.393). The margin distances of squamous cell carcinoma were 2.3±0.8 and 3.4±1.6 mm ( P =0.01) and those of basal cell carcinoma were 2.8±1.0 and 4.7±3.2 mm in the guide and control groups, respectively ( P =0.015). Margin distance was significantly lower in the guide group than the control group. The resection guide demonstrated similar safety to traditional surgical excision but enabled the minimal removal of normal tissue by precisely estimating the tumor border on CT scans.

Porous biomaterials for tissue engineering: a review

The field of biomaterials has grown rapidly over the past decades. Within this field, porous biomaterials have played a remarkable role in: (i) enabling the manufacture of complex three-dimensional structures; (ii) recreating mechanical properties close to those of the host tissues; (iii) facilitating interconnected structures for the transport of macromolecules and cells; and (iv) behaving as biocompatible inserts, tailored to either interact or not with the host body. This review outlines a brief history of the development of biomaterials, before discussing current materials proposed for use as porous biomaterials and exploring the state-of-the-art in their manufacture. The wide clinical applications of these materials are extensively discussed, drawing on specific examples of how the porous features of such biomaterials impact their behaviours, as well as the advantages and challenges faced, for each class of the materials.

Surgical management of palatal teratoma (epignathus) with the use of virtual reconstruction and 3D models: a case report and literature review

Epignathus is a rare congenital orofacial teratoma that arises from the sphenoid region of the palate or the pharynx. It occurs in approximately 1:35,000 to 1:200,000 live births representing 2% to 9% of all teratomas. We present the case of a newborn of 39.4 weeks of gestation with a tumor that occupied the entire oral cavity. The patient was delivered by cesarean section. Oral resection was managed by pediatric surgery. Plastic surgery used virtual 3-dimensional models to establish the extension, and depth of the tumor. Bloc resection and reconstruction of the epignathus were performed. The mass was diagnosed as a mature teratoma associated with cleft lip and palate, nasoethmoidal meningocele that conditions hypertelorism, and a pseudomacrostoma. Tridimensional technology was applied to plan the surgical intervention. It contributed to a better understanding of the relationships between the tumor and the adjacent structures. This optimized the surgical approach and outcome.

Three-Dimensional printed instruments used in a Septoplasty: A new paradigm in Surgery

OBJECTIVE

Three-dimensional (3D) printing has been rapidly adopted by different surgical disciplines. It has shown itself to have improved outcomes in education, pre-operative planning, and reconstruction. However, using 3D printing to create surgical instruments is a niche within the literature that has not yet been fully explored. The authors present a study in which it is hypothesized that 3D printing surgical instruments can be utilized successfully within ENT surgery.

METHODS

As one of the most common ENT operations worldwide, a septoplasty was chosen as the procedure to provide proof of concept. For the septoplasty, five instruments were printed: a scalpel handle, needle holders, toothed forceps, a Cottle/Freer elevator, and a Killian's speculum. The entire set took 224 minutes on average to print, weighed 36 g, and only used approximately 86 pence ($1.20 USD) worth of polylactic acid plastic to create.

RESULTS

All steps in performing a septoplasty on a human cadaver with the 3D printed tools were possible and were undertaken successfully. This yielded a similar outcome to using stainless steel with the added benefit of there being a large reduction in cost and the ability for rapid customization according to the surgeon's preferences.

CONCLUSION

As technology and mainstream interest in 3D printing develops, the availability of more precise Computer-Aided Design software will allow for more complex designs of tools to be created. Currently, 3D printing has been shown to be a promising method from which future surgical tools can be fashioned to meet the complex, dynamic demands of surgery.

LEVEL OF EVIDENCE

N/A.

Three-Dimensional Printing for Preoperative Planning and Pedicle Screw Placement in Adult Spinal Deformity: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

This current systematic review seeks to identify current applications and surgical outcomes for 3-dimensional printing (3DP) in the treatment of adult spinal deformity.

METHODS

A comprehensive search of publications was conducted through literature databases using relevant keywords. Inclusion criteria consisted of original studies, studies with patients with adult spinal deformities, and studies focusing on the feasibility and/or utility of 3DP technologies in the planning or treatment of scoliosis and other spinal deformities. Exclusion criteria included studies with patients without adult spinal deformity, animal subjects, pediatric patients, reviews, and editorials.

RESULTS

Studies evaluating the effect of 3DP drill guide templates found higher screw placement accuracy in the 3DP cohort (96.9%), compared with non-3DP cohorts (81.5%, P < .001). Operative duration was significant decreased in 3DP cases (378 patients, 258 minutes) relative to non-3DP cases (301 patients,272 minutes, P < .05). The average deformity correction rate was 72.5% in 3DP cases (245 patients). There was no significant difference in perioperative blood loss between 3DP (924.6 mL, 252 patients) and non-3DP cases (935.6 mL, 177 patients, P = .058).

CONCLUSIONS

Three-dimensional printing is currently used for presurgical planning, patient and trainee communication and education, pre- and intraoperative guides, and screw drill guides in the treatment of scoliosis and other adult spinal deformities. In adult spinal deformity, the usage of 3DP guides is associated with increased screw accuracy and favorable deformity correction outcomes; however, average costs and production lead time are highly variable between studies.

Patient-specific Three-dimensional Bone Model for the Diagnosis and Treatment of Orthopedic Diseases of the Hip: Opinions of Orthopedic Surgeons on New Medical Technology

Purpose

To examine the perceptions and opinions of orthopedic surgeons on new medical technology for patient-specific three-dimensional (3D) bone models in the diagnosis and treatment of orthopedic diseases related to the hip joint.

Materials and Methods

A total of 75 doctors who were trained in orthopedic surgery or were current residents in the Republic of Korea were surveyed via questionnaires. Eight questions were included regarding the utility and current issues in the diagnosis and treatment of orthopedic disease using a customized 3D bone model made from s patient's computed tomography (CT) image. In addition to the questionnaire, the simple plain radiography and 3D CT image of the patient and 3D printed models of two actual patients were presented for comparison.

Results

An average of 92.7% of the orthopedic surgeons answered “very much” or “yes” to questions regarding the effectiveness of diagnosis, treatment, education, and simulation of surgery using the patient-specific 3D bone model. To the question, “Do you think you must have medical insurance to provide better medical services by using a new patient-specific 3D bone model medical technology for simulated surgery?” 93.3% of orthopedic surgeons answered either “very much” or “yes”.

Conclusion

Patient-specific 3D bone models of new medical technology can provide breakthrough support in the diagnosis, treatment, and education of orthopedic diseases in the field of hip joints. Therefore, it seems that efforts should be made to change governmental policy for coverage of patient-specific 3D bone modeling.

Patient-Specific Implants in Oculofacial Plastic Surgery

PURPOSE

To investigate how patient-specific implants (PSIs) are being utilized for periocular facial skeletal reconstruction. Specifically, to characterize indications for custom implants, areas of reconstruction, intraoperative variables impacting implant placement, as well as to report on postoperative outcomes.

MATERIALS AND METHODS

A retrospective chart review was performed for patients who received a PSI for periocular skeletal reconstruction between 2015 and 2019. Three independent academic centers were included in this study, which encompassed 4 different primary surgeons. Medical records, radiographic imaging, and operative reports were reviewed.

RESULTS

Eleven patients, 8 females and 3 males, ages ranging from 15 to 63 years old received PSIs. The average duration of follow up was 16 months ± 6.6 months (range: 9-30 months). The most common underlying etiology for reconstruction was prior trauma (54.5%) followed by benign tumor resection (18.2%). The most frequent area of reconstruction involved the inferior orbital rim and adjacent maxilla (63.6%). Implant materials included porous polyethylene, polyetheretherketone, and titanium. Six implants required intraoperative modification, most commonly accommodate critical neurovascular structures (66.6%) or improve contour (33.3%). Two postoperative complications were noted, both in the form of infection with 1 implant requiring removal.

CONCLUSIONS

Reconstruction of complex facial skeletal defects can be achieved by utilizing computer-assisted design software and 3D printing techniques to create PSIs. These implants represent the most customizable option for symmetric restoration of the facial skeleton by not only addressing structural deficits but also volumetric loss. This was particularly apparent in reconstruction of the orbital rim and midface. PSIs were found to be of most benefit in patients with prior trauma or complex skeletal defects after tumor resection.

Alternative Polyadenylation in Stem Cell Self-Renewal and Differentiation

Cellular function is shaped by transcriptional and post-transcriptional mechanisms, including alternative polyadenylation (APA). By directly controlling 3'- untranslated region (UTR) length and the selection of the last exon, APA regulates up to 70% of all cellular transcripts influencing RNA stability, output, and protein isoform expression. Cell-state-dependent 3'-UTR shortening has been identified as a hallmark of cellular proliferation. Hence, quiescent/dormant stem cells are characterized by long 3'-UTRs, whereas proliferative stem/progenitor cells exhibit 3'-UTR shortening. Here, the latest studies analyzing the role of APA in regulating stem cell state, self-renewal, differentiation, and metabolism are reviewed. The new role of APA in controlling stem cell fate opens novel potential therapeutic avenues in the field of regenerative medicine.

Three-Dimensional Printing in Cleft Care: A Systematic Review

OBJECTIVE

To determine the current applications of 3-dimensional (3D) printing in the care of patients with cleft lip and palate. We also reviewed 3D printing limitations, financial analysis, and future implications.

DESIGN

Retrospective systematic review.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were used by 3 independent reviewers. Articles were identified from Cochrane library, Ovid Medline, and Embase. Search terms included 3D printing, 3 dimensional printing, additive manufacturing, rapid prototyping, cleft lip, and cleft palate. Exclusion criteria included articles not in English, animal studies, reviews without original data, oral presentations, abstracts, opinion pieces, and articles without relevance to 3D printing or cleft lip and palate.

MAIN OUTCOME MEASURES

Primary outcome measure was the purpose of 3D printing in the care of patients with cleft lip and palate. Secondary outcome measures were cost analysis and clinical outcomes.

RESULTS

Eight-four articles were identified, and 39 met inclusion/exclusion criteria. Eleven studies used 3D printing models for nasoalveolar molding. Patient-specific implants were developed via 3D printing in 6 articles. Surgical planning was conducted via 3D printing in 8 studies. Eight articles utilized 3D printing for anatomic models/educational purposes. 3-Dimensional printed models were used for surgical simulation/training in 6 articles. Bioprinting was utilized in 4 studies. Secondary outcome of cost was addressed in 8 articles.

CONCLUSION

3-Dimensional printing for the care of patients with cleft lip and palate has several applications. Potential advantages of utilizing this technology are demonstrated; however, literature is largely descriptive in nature with few clinical outcome measures. Future direction should be aimed at standardized reporting to include clinical outcomes, cost, material, printing method, and results.

Surgical Management of Sinus Pericranii With Crouzon Syndrome

BACKGROUND

Sinus pericranii (SP) is a rare vascular malformation which connects the intracranial dural sinuses to the extracranial venous drainage system. Although the majority of SP cases are caused by trauma, some of them are congenital. Furthermore, a few SP cases have been reported in association with craniosynostosis. The authors' objective is to discuss the surgical management of SP with Crouzon's syndrome in children.

METHODS

Three-Dimensional reconstruction with enhanced CT scan was used for evaluate the condition of SP with Crouzon's syndrome in all 4 cases. Two cases with small single-hole defect on skull were only treated by cranioplasty with distraction osteogenesis. In the management of the other 2 SP patients with large skull defect, titanium mesh was used for compression of dilated venous sinus to inhabit filling and promote shrinking.

RESULT

Four cases of SP with Crouzon's syndrome were treated in the authors' department. With cranioplasty with distraction osteogenesis only, 2 patients with single-hole skull defect experienced SP spontaneous involution at 4 to 6 months postoperatively. With titanium mesh compression, SP with large skull defect shrank significantly without clinical recurrence, but long-term follow-up was still in need.

CONCLUSION

For small single-hole skull defect in SP patient with Crouzon's syndrome, the only application of cranioplasty for decreasing intracranial pressure can promote SP spontaneous involution. 3D printed titanium mesh compression renders a safe and efficient approach for SP with large skull defect. Long-time follow up and further accumulation of cases may establish the efficacy of the authors' management.

3D printing in neurosurgery education: a review

OBJECTIVES

The objectives of this manuscript were to review the literature concerning 3D printing of brain and cranial vault pathology and use these data to define the gaps in global utilization of 3D printing technology for neurosurgical education.

METHODS

Using specified criteria, literature searching was conducted to identify publications describing engineered neurosurgical simulators. Included in the study were manuscripts highlighting designs validated for neurosurgical skill transfer. Purely anatomical designs, lacking aspects of surgical simulation, were excluded. Eligible manuscripts were analyzed. Data on the types of simulators, representing the various modelled neurosurgical pathologies, were recorded. Authors' countries of affiliation were also recorded.

RESULTS

A total of thirty-six articles, representing ten countries in five continents were identified. Geographically, Africa as a continent was not represented in any of the publications. The simulation-modelling encompassed a variety of neurosurgical subspecialties including: vascular, skull base, ventriculoscopy / ventriculostomy, craniosynostosis, skull lesions / skull defects, intrinsic brain tumor and other. Finally, the vascular and skull base categories together accounted for over half (52.8 %) of the 3D printed simulated neurosurgical pathology.

CONCLUSIONS

Despite the growing body of literature supporting 3D printing in neurosurgical education, its full potential has not been maximized. Unexplored areas of 3D printing for neurosurgical simulation include models simulating the resection of intrinsic brain tumors or of epilepsy surgery lesions, as these require complex models to accurately simulate fine dissection techniques. 3D printed surgical phantoms offer an avenue for the advancement of global-surgery education initiatives.

Alloplastic Facial Implants

As the face ages, there is thinning of the epidermis, volume loss and rearrangement of the soft tissues, and malabsorption of the skeletal framework. It is essential to have a thorough understanding of the aging process for successful facial augmentation and rejuvenation. Alloplastic implants can be used to provide a long-lasting solution for augmentation of skeletal deficiencies, restoration of facial irregularities, and rejuvenation of the face. In this study, we describe the ideal implant characteristics along with the advantages and disadvantages of various implant materials. We also present techniques in nasal and premaxillary augmentation, midface augmentation, mandibular augmentation, and lip augmentation. Additionally, computer-aided design and manufacturing as well as bioprinting are emerging technologies with growing applications in facial plastic and reconstructive surgery. We discuss their role in the creation of patient-specific custom implants. The overall goal of facial rejuvenation is to address multiple aspects of the facial aging process including deficiencies in the skin, soft tissues, and skeletal framework. The use of alloplastic implants alone or synergistically with additional surgical procedures can restore a wide range of anatomical deficits that occur with age.

Realization of Circular Economy of 3D Printed Plastics: A Review

3D printing technology is a versatile technology. The waste of 3D printed plastic products is a matter of concern because of its impact on the circular economy. In this paper, we discuss the current status and problems of 3D printing, different methods of 3D printing, and applications of 3D printing. This paper focuses on the recycling and degradation of different 3D printing materials. The degradation, although it can be done without pollution, has restrictions on the type of material and time. Degradation using ionic liquids can yield pure monomers but is only applicable to esters. The reprocessing recycling methods can re-utilize the excellent properties of 3D printed materials many times but are limited by the number of repetitions of 3D printed materials. Although each has its drawbacks, the great potential of the recycling of 3D printed waste plastics is successfully demonstrated with examples. Various recycling approaches provide the additional possibility of utilizing 3D printing waste to achieve more efficient circular application.

Surgical training 2.0: A systematic approach reviewing the literature focusing on oral maxillofacial surgery - Part I

PURPOSE

Many technologies are emerging in the medical field. Having an overview of the technological arsenal available to train new surgeons seems very interesting to guide subsequent surgical training protocols.

METHODS

This article is a systematic approach reviewing new technologies in surgical training, in particular in oral and maxillofacial surgery. This review explores what new technologies can do compared to traditional methods in the field of surgical education. A structured literature search of PubMed was performed in adherence to PRISMA guidelines. The articles were selected when they fell within predefined inclusion criteria while respecting the key objectives of this systematic review. We looked at medical students and more specifically in surgery and analysed whether exposure to new technologies improved their surgical skills compared to traditional methods. Each technology is reviewed by highlighting its advantages and disadvantages and studying the feasibility of integration into current practice.

RESULTS

The results are encouraging. Indeed, all of these technologies make it possible to reduce the learning time, the operating times, the operating complications and increase the enthusiasm of the students compared to more conventional methods. The start-up cost, the complexity to develop new models, and the openness of mind necessary for the integration of these technologies are all obstacles to immediate development. The main limitations of this review are that many of the studies have been carried out on small numbers, they are not interested in acquiring knowledge or skills over the long term and obviously there is a publication bias.

CONCLUSION

Surgical education methods will probably change in the years to come, integrating these new technologies into the curriculum seems essential so as not to remain on the side. This first part therefore reviews, open field camera, telemedicine and 3D printing. This systematic review is registered on PROSPERO.

Prelaminated paramedian forehead flap for subtotal nasal reconstruction using three-dimensional printing

Nasal reconstruction following a total or subtotal resection presents a challenging clinical scenario. Ample external skin coverage is readily available using the paramedian forehead flap (PMFF), but restoring adequate internal lining of sufficient size and pliability is a major limitation. Intranasal mucosal flaps or free tissue transfer is often employed for this purpose, each with their own sets of limitations. Prelamination of the PMFF with a skin graft prior to transfer is a method to create a composite flap with both internal and external lining. Another challenge in subtotal nasal reconstruction centres around restoring adequate dimensions to the nose without an existing template to work from. Three-dimensional (3D) printing has become an increasingly popular tool in reconstructive surgery as it captures precise patient-specific dimensions to guide reconstruction. Herein, we describe a case of subtotal nasal reconstruction using a prelaminated PMFF using a patient-specific 3D printed model as a template for reconstruction.

A Review of 3D Printing in Dentistry: Technologies, Affecting Factors, and Applications

Three-dimensional (3D) printing technologies are advanced manufacturing technologies based on computer-aided design digital models to create personalized 3D objects automatically. They have been widely used in the industry, design, engineering, and manufacturing fields for nearly 30 years. Three-dimensional printing has many advantages in process engineering, with applications in dentistry ranging from the field of prosthodontics, oral and maxillofacial surgery, and oral implantology to orthodontics, endodontics, and periodontology. This review provides a practical and scientific overview of 3D printing technologies. First, it introduces current 3D printing technologies, including powder bed fusion, photopolymerization molding, and fused deposition modeling. Additionally, it introduces various factors affecting 3D printing metrics, such as mechanical properties and accuracy. The final section presents a summary of the clinical applications of 3D printing in dentistry, including manufacturing working models and main applications in the fields of prosthodontics, oral and maxillofacial surgery, and oral implantology. The 3D printing technologies have the advantages of high material utilization and the ability to manufacture a single complex geometry; nevertheless, they have the disadvantages of high cost and time-consuming postprocessing. The development of new materials and technologies will be the future trend of 3D printing in dentistry, and there is no denying that 3D printing will have a bright future.

Implications of Applying New Technology in Cosmetic and Reconstructive Facial Plastic Surgery

The field of facial plastic and reconstructive surgery is privy to a myriad of technological advancements. As innovation in areas such as imaging, computer applications, and biomaterials progresses at breakneck speed, the potential for clinical application is endless. This review of recent progress in the implementation of new technologies in facial plastic surgery highlights some of the most innovative and impactful developments in the past few years of literature. Patient-specific surgical modeling has become the gold standard for oncologic and posttraumatic reconstructive surgery, with demonstrated improvements in operative times, restoration of anatomical structure, and patient satisfaction. Similarly, reductions in revision rates with improvements in learner technical proficiency have been noted with the use of patient-specific models in free flap reconstruction. In the cosmetic realm, simulation-based rhinoplasty implants have drastically reduced operative times while concurrently raising patient postoperative ratings of cosmetic appearance. Intraoperative imaging has also seen recent expansion in its adoption driven largely by reports of eradication of postoperative imaging and secondary-often complicated-revision reconstructions. A burgeoning area likely to deliver many advances in years to come is the integration of bioprinting into reconstructive surgery. Although yet to clearly make the translational leap, the implications of easily generatable induced pluripotent stem cells in replacing autologous, cadaveric, or synthetic tissues in surgical reconstruction are remarkable.

The Impact of 3D Technology in Optimizing Midface Fracture Treatment-Focus on the Zygomatic Bone

PURPOSE

In the context of the ongoing development and expanding availability of 3-dimensional (3D) printing, there is increasing interest in designing simplified workflows that would encourage more medical practitioners to include 3D printing in their current practice. The purpose of this study is to present our experience regarding the use of 3D printing in the preoperative planning and management of acute midface trauma, an area less explored by existing studies.

METHODS

We performed a retrospective case series study including admitted patients who underwent surgical repair of midface fractures, in which 3D-printed stereolithic models were used preoperatively for shaping the osteosynthesis material. We recorded standard information about the patients, imaging method used, and type of midface fracture. We also logged the details and durations of each main step in the preoperative 3D printing workflow and documented the durations and outcomes of each surgical procedure.

RESULTS

We identified 29 cases of midface fractures that benefited of a preoperative stereolithic model. From the 2 main methods of obtaining the virtual model, mirroring and virtual fracture reduction, the longest duration was recorded in a case in which the later method was used. The longest stereolithic model printing time was found in a complex midface fracture case. All the prebent osteosynthesis material was used intraoperatively and fitted the reduced fracture sites, also serving as an intraoperative guide for correct fracture reduction. The particularities, benefits, as well as the possible challenges associated with the application of 3D printing in acute trauma cases are discussed.

CONCLUSIONS

Our 3D printing protocol was applicable and rendered favorable outcomes in the acute midface trauma setting. Proper understanding of the steps involved in achieving the stereolithic model is key for the adaptation of 3D printing to the current management of acute midface trauma.

Functional requirements for polymeric implant materials in head and neck surgery

BACKGROUND

The pharyngeal reconstruction is a challenging aspect after pharyngeal tumor resection. The pharyngeal passage has to be restored to enable oral alimentation and speech rehabilitation. Several techniques like local transposition of skin, mucosa and/or muscle, regional flaps and free vascularized flaps have been developed to reconstruct pharyngeal defects following surgery, in order to restore function and aesthetics. The reconstruction of the pharynx by degradable, multifunctional polymeric materials would be a novel therapeutical option in head and neck surgery.

MATERIALS AND METHODS

Samples of an ethylene-oxide sterilized polymer (diameter 10 mm, 200μm thick) were implanted for the reconstruction of a standardized defect of the gastric wall in rats in a prospective study. The stomach is a model for a "worst case" application site to test the stability of the implant material under extreme chemical, enzymatical, bacterial, and mechanical load.

RESULTS

Fundamental parameters investigated in this animal model were a local tight closure between the polymer and surrounding tissues, histological findings of tissue regeneration and systemic responses to inflammation. A tight anastomosis between the polymer and the adjacent stomach wall was found in all animals after polymer implantation (n = 42). Histologically, a regeneration with glandular epithelium was found in the polymer group. No differences in the systemic responses to inflammation were found between the polymer group (n = 42) and the control group (n = 21) with primary wound closure of the defect of the gastric wall.

CONCLUSIONS

A sufficient stability of the polymeric material is a requirement for the pharyngeal reconstruction with implant materials.

Regenerative medicine, organ bioengineering and transplantation

Background

Organ transplantation is predicted to increase as life expectancy and the incidence of chronic diseases rises. Regenerative medicine-inspired technologies challenge the efficacy of the current allograft transplantation model.

Methods

A literature review was conducted using the PubMed interface of MEDLINE from the National Library of Medicine. Results were examined for relevance to innovations of organ bioengineering to inform analysis of advances in regenerative medicine affecting organ transplantation. Data reports from the Scientific Registry of Transplant Recipient and Organ Procurement Transplantation Network from 2008 to 2019 of kidney, pancreas, liver, heart, lung and intestine transplants performed, and patients currently on waiting lists for respective organs, were reviewed to demonstrate the shortage and need for transplantable organs.

Results

Regenerative medicine technologies aim to repair and regenerate poorly functioning organs. One goal is to achieve an immunosuppression-free state to improve quality of life, reduce complications and toxicities, and eliminate the cost of lifelong antirejection therapy. Innovative strategies include decellularization to fabricate acellular scaffolds that will be used as a template for organ manufacturing, three-dimensional printing and interspecies blastocyst complementation. Induced pluripotent stem cells are an innovation in stem cell technology which mitigate both the ethical concerns associated with embryonic stem cells and the limitation of other progenitor cells, which lack pluripotency. Regenerative medicine technologies hold promise in a wide array of fields and applications, such as promoting regeneration of native cell lines, growth of new tissue or organs, modelling of disease states, and augmenting the viability of existing ex vivo transplanted organs.

Conclusion

The future of organ bioengineering relies on furthering understanding of organogenesis, in vivo regeneration, regenerative immunology and long-term monitoring of implanted bioengineered organs.

Cost Analysis for In-house versus Industry-printed Skull Models for Acute Midfacial Fractures

Industry-printed (IP) 3-dimensional (3D) models are commonly used for secondary midfacial reconstructive cases but not for acute cases due to their high cost and long turnaround time. We have begun using in-house (IH) printed models for complex unilateral midface trauma. We hypothesized that IH models would decrease cost and turnaround time, compared with IP models.

Osseous Transformation with Facial Feminization Surgery: Improved Anatomical Accuracy with Virtual Planning

BACKGROUND

Facial feminization surgery entails a series of surgical procedures that help the transwoman pass as their affirmed gender. Although virtual surgical planning, with intraoperative cutting guides, and custom plates have been shown to be helpful for craniomaxillofacial reconstruction, they have not yet been studied for facial feminization surgery. The authors used cadaveric analysis for morphologic typing and to demonstrate the utility of virtual surgical planning in facial feminization surgery procedures.

METHODS

Male cadaveric heads underwent morphologic typing analysis of the frontal brow, lateral brow, mandibular angle, and chin regions (n = 50). Subsequently, the cadavers were split into two groups: (1) virtual surgical planning intraoperative cutting guides and (2) no preoperative planning. Both groups underwent (1) anterior frontal sinus wall setback, (2) lateral supraorbital recontouring, (3) mandibular angle reduction, and (4) osseous genioplasty narrowing. Efficiency (measured as operative time), safety (determined by dural or nerve injury), and accuracy (scored with three-dimensional computed tomographic preoperative plan versus postoperative result) were compared between groups, with significance being p < 0.05.

RESULTS

For frontal brow and lateral lower face, morphologic type 3 (severe) predominated; for lateral brow and chin, type 2 (moderate) predominated. For frontal sinus wall setback, virtual surgical planning improved efficiency (19 minutes versus 44 minutes; p < 0.05), safety (100 percent versus 88 percent; p < 0.05; less intracranial entry), and accuracy (97 percent versus 79 percent; p < 0.05) compared with no preoperative planning. For mandibular angle reduction, virtual surgical planning improved safety (100 percent versus 88 percent; p < 0.05; less inferior alveolar nerve injury) and accuracy (95 percent versus 58 percent; p < 0.05).

CONCLUSIONS

Preoperative planning for facial feminization surgery is helpful to determine morphologic typing. Virtual surgical planning with the use of cutting guides/custom plates improved efficiency, safety, and accuracy when performing four key craniofacial techniques for facial feminization.

Clinical Application of a Patient-Specific, Three-Dimensional Printing Guide Based on Computer Simulation for Rhinoplasty

BACKGROUND

A practical application of three-dimensional printing technology has been considered a difficult area in rhinoplasty. However, the patient-specific three-dimensionally printed rhinoplasty guide based on the simulation program the authors developed could be a solution for minimizing the gap between simulation and actual surgical results. The aims of this study were to determine how a three-dimensional rhinoplasty guide based on three-dimensional simulation would link the patient to the surgeon to investigate its effectiveness.

METHODS

Fifty patients who underwent rhinoplasty between January of 2017 and February of 2018 were included in this study. The patients were consulted about the desired shape of their nose based on preoperative three-dimensional photography. The confirmed three-dimensional simulation was sent to a manufacturing company for three-dimensionally printed rhinoplasty guides. In the guide group, rhinoplasty was performed based on the three-dimensionally printed rhinoplasty guide, and in the control group, procedures were performed based on the surgeon's intuition.

RESULTS

The intraclass correlation coefficient test for comparing the simulated and postoperative measurements showed higher correlation in the three-dimensional printing guide group: higher correlation 11.3 percent in nasal tip projection, 21.6 percent in dorsum height, and 9.8 percent in nasolabial angle. The postoperative result of the nasal dorsum had a statistically significant difference between the two groups (p < 0.05).

CONCLUSIONS

This study demonstrated the usefulness of the three-dimensionally-printed rhinoplasty guide, which delivers the preoperative simulated image in the actual clinical practice of rhinoplasty. This approach could cause a paradigm shift in simulation-based rhinoplasty.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Assessment of a Patient-Specific, 3-Dimensionally Printed Endoscopic Sinus and Skull Base Surgical Model

Importance

Three-dimensional (3D) printing is an emerging tool in the creation of anatomical models for simulation and preoperative planning. Its use in sinus and skull base surgery has been limited because of difficulty in replicating the details of sinus anatomy.

Objective

To describe the development of 3D-printed sinus and skull base models for use in endoscopic skull base surgery.

Design, Setting, and Participants

In this single-center study performed from April 1, 2017, through June 1, 2017, a total of 7 otolaryngology residents and 2 attending physicians at a tertiary academic center were recruited to evaluate the procedural anatomical accuracy and haptic feedback of the printed model.

Interventions

A 3D model of sinus and skull base anatomy with high-resolution, 3D printed material (VeroWhite) was printed using a 3D printer. Anatomical accuracy was assessed by comparing a computed tomogram of the original patient with that of the 3D model across set anatomical landmarks (eg, depth of cribriform plate). Image-guided navigation was also used to evaluate accuracy of 13 surgical landmarks. Likert scale questionnaires (1 indicating strongly disagree; 2, disagree; 3, neutral; 4, agree; and 5, strongly agree) were administered to 9 study participants who each performed sinus and skull base dissections on the 3D-printed model to evaluate anatomical accuracy and haptic feedback.

Main Outcomes and Measures

Main outcomes of the study include objective anatomical accuracy through imaging and navigation and haptic evaluation by the study participants.

Results

Seven otolaryngology residents (3 postgraduate year [PGY]-5 residents, 2 PGY-4 residents, 1 PGY-3 resident, and 1 PGY-2 resident) and 2 attending physicians evaluated the haptic feedback of the 3D model. Computed tomographic comparison demonstrated a less than 5% difference between patient and 3D model measurements. Image-guided navigation confirmed accuracy of 13 landmarks to within 1 mm. Likert scores were a mean (SD) of 4.00 (0.71) for overall procedural anatomical accuracy and 4.67 (0.5) for haptic feedback.

Conclusions and Relevance

This study shows that high-resolution, 3D-printed sinus and skull base models can be generated with anatomical and haptic accuracy. This technology has the potential to be useful in surgical training and preoperative planning and as a supplemental or alternative simulation or training platform to cadaveric dissection.

Personalized 3D-printed endoprostheses for limb sparing in dogs: Modeling and in vitro testing

Osteosarcoma is the most common type of bone cancer in dogs, treatable by amputation or limb-sparing surgery. For the latter, commercially available plate - endoprosthesis assemblies require contouring, to be adapted to the patient's bone geometry, and lead to sub-optimal results. The use of additively-manufactured personalized endoprostheses and cutting guides for distal radius limb-sparing surgery in dogs presents a promising alternative. Specialized software is used for the bone structure reconstruction from the patient's CT scans and for the design of endoprostheses and cutting guides. The prostheses are manufactured from a titanium alloy using a laser powder bed fusion system, while the cutting guides are manufactured from an ABS plastic using a fused deposition modeling system. A finite element model of an instrumented limb was developed and validated using experimental testing of a cadaveric limb implanted with a personalized endoprosthesis. Personalized endoprostheses and cutting guides can reduce limb sparing surgery time by 25-50% and may reduce the risk of implant failure. The numerical model was validated using the kinematics and force-displacement diagrams of the implant-limb construct. The model indicated that a modulus of elasticity of an implant material ranging from 25 to 50 GPa would improve the stress distribution within the implant. The results of the current study will allow optimization of the design of the personal implants in both veterinary and human patients.

Imaging-Based 3-Dimensional Printing for Improved Maxillofacial Presurgical Planning: A Single Center Case Series

Purpose

3-D printing is an increasingly widespread technology that allows physical models to be constructed based on cross-sectional medical imaging data. We sought to develop a pipeline for production of 3-dimensional (3-D) models for presurgical planning and assess the value of these models for surgeons and patients.

Methods

In this institutional review board–approved, single-center case series, participating surgeons identified cases for 3-D model printing, and after obtaining patient consent, a 3-D model was produced for each of the 7 participating patients based on preoperative cross-sectional imaging. Each model was given to the surgeon to use during the surgical consent discussion and preoperative planning. Patients and surgeons completed questionnaires evaluating the quality and usefulness of the models.

Results

The 3-D models improved surgeon confidence in their operative approach, influencing the choice of operative approach in the majority of cases. Patients and surgeons reported that the model improved patient comprehension of the surgery during the consent discussion, including risks and benefits of the surgery. Model production time was as little as 4 days, and the average per-model cost was $350.

Conclusions

3-D printed models are useful presurgical tools from both surgeon and patient perspectives. Development of local hospital-based 3-D printing capabilities enables model production with rapid turnaround and modest cost, representing a value-added service for radiologists to offer their surgical colleagues.

Augmented Reality, Surgical Navigation, and 3D Printing for Transcanal Endoscopic Approach to the Petrous Apex

Otolaryngologists increasingly use patient-specific 3-dimensional (3D)–printed anatomic physical models for preoperative planning. However, few reports describe concomitant use with virtual models. Herein, we aim to (1) use a 3D-printed patient-specific physical model with lateral skull base navigation for preoperative planning, (2) review anatomy virtually via augmented reality (AR), and (3) compare physical and virtual models to intraoperative findings in a challenging case of a symptomatic petrous apex cyst. Computed tomography (CT) imaging was manually segmented to generate 3D models. AR facilitated virtual surgical planning. Navigation was then coupled to 3D-printed anatomy to simulate surgery using an endoscopic approach. Intraoperative findings were comparable to simulation. Virtual and physical models adequately addressed details of endoscopic surgery, including avoidance of critical structures. Complex lateral skull base cases may be optimized by surgical planning via 3D-printed simulation with navigation. Future studies will address whether simulation can improve patient outcomes.

Utility of three-dimensional models in resident education on simple and complex intracardiac congenital heart defects

OBJECTIVE

Applications of three-dimensional (3D) printed models in medicine include preprocedure planning, patient education, and clinical training. Reproducing complex anatomy as a 3D printed model can be useful for understanding congenital heart defects (CHD). We hypothesized that using 3D printed models during didactic sessions with resident physicians will improve trainees' understanding of CHD.

DESIGN AND INTERVENTION

We performed a prospective, randomized educational intervention for teaching pediatric and pediatric/emergency medicine residents about simple (ventricular septal defect [VSD]) and moderately complex (tetralogy of Fallot [ToF]) CHD. Residents were divided into two groups: intervention and control. Each group completed a subjective survey about their comfort with the anatomy, evaluation, and treatment of VSD and ToF and took an objective test on VSD and ToF. They separately received the same 20 min lecture, including projected two-dimensional digital images of VSD and ToF; the intervention group was given 3D printed models created using the same imaging data. After the lecture, the groups repeated the survey and test questions.

RESULTS

Twenty-six residents participated in the VSD session, 34 in the ToF. There were no differences in demographics between control and intervention groups. All residents had higher subjective comfort with VSD and ToF after the lectures. There was no difference in baseline test scores for VSD or ToF groups. The control group scored higher on the VSD postlecture test. The intervention group scored higher on the ToF postlecture test.

CONCLUSION

Incorporation of 3D printed models into lectures about CHD imparts a greater acute level of understanding, both subjective and objective, for pediatric and combined pediatric/emergency medicine residents. There does not seem to be an added benefit for understanding ventricular septal defects, but there is for tetralogy of Fallot, likely due to increased complexity of the lesion and difficulty visualizing spatial relationships in CHD with multiple components.

Virtual Functional Endoscopic Sinus Surgery Simulation with 3D-Printed Models for Mixed-Reality Nasal Endoscopy

The surgeon's knowledge of a patient's individual anatomy is critical in skull base surgery. Trainees and experienced surgeons can benefit from surgical simulation; however, current models are expensive and impractical for widespread use. In this study, we report a next-generation mixed-reality surgical simulator. We segmented critical anatomic structures for 3-dimensional (3D) models to develop a modular teaching tool. We then developed a navigation tracking system utilizing a 3D-printed endoscope as a trackable virtual-reality (VR) controller and validated the accuracy on VR and 3D-printed skull models within 1 cm. We combined VR and augmented-reality visual cues with our 3D physical model to simulate sinus endoscopy and highlight segmented structures in real time. This report provides evidence that a mixed-reality simulator combining VR and 3D-printed models is feasible and may prove useful as an educational tool that is low cost and customizable.

Optimization of 3D Print Material for the Recreation of Patient-Specific Temporal Bone Models

Objective:

Identify the 3D printed material that most accurately recreates the visual, tactile, and kinesthetic properties of human temporal bone

Subjects and Methods:

Fifteen study participants with an average of 3.6 years of postgraduate training and 56.5 temporal bone (TB) procedures participated. Each participant performed a mastoidectomy on human cadaveric TB and five 3D printed TBs of different materials. After drilling each unique material, participants completed surveys to assess each model’s appearance and physical likeness on a Likert scale from 0 to 10 (0 = poorly representative, 10 = completely life-like). The 3D models were acquired by computed tomography (CT) imaging and segmented using 3D Slicer software.

Results:

Polyethylene terephthalate (PETG) had the highest average survey response for haptic feedback (HF) and appearance, scoring 8.3 (SD = 1.7) and 7.6 (SD = 1.5), respectively. The remaining plastics scored as follows for HF and appearance: polylactic acid (PLA) averaged 7.4 and 7.6, acrylonitrile butadiene styrene (ABS) 7.1 and 7.2, polycarbonate (PC) 7.4 and 3.9, and nylon 5.6 and 6.7.

Conclusion:

A PETG 3D printed temporal bone models performed the best for realistic appearance and HF as compared with PLA, ABS, PC, and nylon. The PLA and ABS were reliable alternatives that also performed well with both measures.

Three-dimensional Printed Surgical Simulator for Kirschner Wire Placement in Hand Fractures

Supplemental Digital Content is available in the text.

Closed reduction and percutaneous pinning (CRPP) of hand fractures can be a deceptively challenging procedure that requires significant hands-on time to teach and learn. We created a realistic three-dimensional simulator that can be used for teaching junior residents the CRPP. Computer-aided design and computer-aided manufacturing (CAD/CAM) software was used to create a three-dimensional hand model incorporating several common hand fractures: Bennett’s fracture, transverse fifth metacarpal neck, and transverse second proximal phalanx. Three-dimensional printing was used to create molds in which the bones and soft tissue were poured. A polyurethane foam was utilized for the bones with iron incorporated to render them radiopaque, whereas silicone of varying viscosities was used for the soft tissues. Five plastic surgery residents and 5 consultants evaluated the model. Individuals then completed an anonymous 12-question survey evaluating the model based on realism, educational utility, and overall usefulness. Survey responses obtained from both residents and consultants were strongly in favor of the simulator. Average realism was graded as 4.48/5 by residents and 4.68/5 by consultants. Average educational utility was graded as 5/5 by residents and 4.95/5 by consultants. Average overall usefulness was graded as 5/5 by both groups. We created an anatomically accurate and realistic simulator for CRPP of hand fractures that was low cost and easily reproducible. Initial feedback was encouraging in regard to realism, educational utility, and overall usefulness.