Three-dimensional printing the navigation template for precise percutaneous renal puncture to treat pyonephrosis on a porcine model and a patient ：a case report.

Objective: Percutaneous nephrolithotomy (PCNL) is the main method for pyonephrosis or lithotripsy in urology. However, it often comes with high risk, as the inaccurate puncture inevitably causes bleeding, intra- and post-operative complications. So, a new inter-disciplinary approach is needed to perform the puncture more accurately. Methods: 3 signs made of lead were marked onto the skin of the posterior side of the waist of a domestic pig or a patient, which was scanned by computed tomography (CT). Based on the CT images, the computer design and the 3D printing, a navigation template made of the transparent resin material is constructed. They were attached onto the surgical area on pig or patient according to the signs. During the PCNL, with this template, the puncture position, angle and depth were optimized in order to precisely enter the targeted renal pelvis or calices. Results: With the 3D navigation templates, 18G puncture needles were used to enter the renal pelvis upon performing the PCNL on a porcine model and a patient. On the porcine model, the urine outflow was observed with minimal complication. Post-operative CT scans revealed that the needle was located in the renal pelvis. For the patient case, the puncture point was designed to target the calix with stone. No obvious bleeding and complication was found in renal puncture with template. Conclusions: The navigation template was made with the combination of 3D printing, CT images and computer design. This template allows for accurate puncture of the renal pelvis or calix. Surgical improvement in kidney stones and pyonephrosis was observed in porcine model and patient case. In the future, prospective, trandomized, controlled clinical trials are needed to further confirm its advantage.

Impact of three-dimensional-printing technology guidance on surgical outcomes for retroperitoneal sarcoma: A propensity score-matched study.

BACKGROUND: The surgical treatment of retroperitoneal sarcoma (RPS) is highly challenging because of its complex anatomy. In this study, the authors compared the surgical outcomes of patients with RPS who underwent surgical resection guided by three-dimensional (3D) printing technology versus traditional imaging. METHODS: This retrospective study included 251 patients who underwent RPS resection guided by 3D-printing technology or traditional imaging from January 2019 to December 2022. The main outcome measures were operative time, intraoperative blood loss, postoperative complications, and hospital stay. RESULTS: In total, 251 patients were enrolled in the study: 46 received 3D-printed navigation, and 205 underwent traditional surgical methods. Propensity score matching yielded 44 patients in the 3D group and 82 patients in the control group. The patients' demographics and tumor characteristics were comparable in the matched cohorts. The 3D group had significantly shorter operative time (median, 186.5 minutes [interquartile range (IQR), 130.0-251.3 minutes] vs. 210.0 minutes [IQR, 150.8-277.3 minutes]; p = .04), less intraoperative blood loss (median, 300.0 mL [IQR, 100.0-575.0 mL] vs. 375.0 mL [IQR, 200.0-925.0 mL]; p = .02), shorter postoperative hospital stays (median, 11.0 days [IQR, 9.0-13.0 days] vs. 14.0 days [IQR, 10.8-18.3 days]; p = .02), and lower incidence rate of overall postoperative complications than the control group (18.1% vs. 36.6%; p = .03). There were no differences with regard to the intraoperative blood transfusion rate, the R0/R1 resection rate, 30-day mortality, or overall survival. CONCLUSIONS: Patients in the 3D group had favorable surgical outcomes compared with those in the control group. These results suggest that 3D-printing technology might overcome challenges in RPS surgical treatment. PLAIN LANGUAGE SUMMARY: The surgical treatment of retroperitoneal sarcoma (RPS) is highly challenging because of its complex anatomy. The purpose of this study was to investigate whether three-dimensional (3D) printing technology offers advantages over traditional two-dimensional imaging (such as computed tomography and magnetic resonance imaging) for guiding the surgical treatment of RPS. In a group of patients who had RPS, surgery guided by 3D-printing technology was associated with better surgical outcomes, including shorter operative time, decreased blood loss, shorter hospital stays, and fewer postoperative complications. These findings suggested that 3D-printing technology could help surgeons overcome challenges in the surgical treatment of RPS. 3D-printing technology has important prospects in the surgical treatment of RPS.

Thickness Variations of Thermoformed and 3D-Printed Clear Aligners.

Objective: To assess thickness variations of thermoformed and 3D-printed clear aligners. Materials and Methods: Six different thermoplastic materials with different initial thicknesses were used for aligner thermoforming using Biostar® device (Biostar®, SCHEU-DENTAL GmbH, Iserlohn, Germany). Also, two different dental resins were used to create the printed aligners in three digitally designed thicknesses using IZZI Direct printer (3Dtech, Zagreb, Croatia). The aligners were measured using an electronic micrometer (ELECTRONIC UNIVERSAL MICROMETER, Schut Geometrical Metrology, Groningen, The Netherlands, accuracy: 0.001 mm) on a total of 20 points per aligner. Statistical analysis was performed using the JASP program (JASP, University of Amsterdam, Amsterdam, The Netherlands). Results: The difference between the thermoformed and printed groups was statistically significant. Significant differences between different thermoformed materials and between 3D-printed materials were found. The thickness of thermoformed aligners deviated more in the upper jaw, whereas the thickness of printed aligners deviated more in the lower jaw. Both differences were statistically significant. The greatest average deviation from the initial thickness was found in Duran 0.75; Erkodur 0.6; Erkoloc-Pro 1.0; IZZI 0.5; NextDent 0.6 and NextDent A 0.6. NextDent group had the lowest deviations for all teeth of both jaws, except for upper and lower first molar where NextDent A group was more accurate. Conclusions: Thermoformed aligners showed decreased values, while printed ones showed mostly increased values compared to the original material thickness. The highest mean deviation belonged to IZZI group, and the NextDent group had the lowest mean deviation. The thickness of both aligners was thinner at the edges compared to the thickness at cusps and fissures.

The role of 3D printing in chest wall reconstruction.

Technology is advancing fast, and chest wall surgery finds particular benefit in the broader availability of three-dimensional (3D) reconstruction and printing. An increasing number of reports are being published on the use of these resources in virtual 3D reconstructions of chest walls in computed tomography (CT) scans, virtual surgeries, 3D printing of real-size models for surgical planning, practice, and education, and of note, the manufacture of customized 3D printed implants, changing the fundamental conception from a surgery that fits all, to a surgery for each patient. In this review, we explore the evidence published on simple chest wall reconstruction, including the use of 3D technology to assist in the improvement of the repair of the most frequent chest wall deformities: pectus excavatum and carinatum. Current studies are oriented to the automatization and customization of transthoracic implants, as well as education on real-size models. Next, we investigate the implementation of 3D printing in the repair of complex chest wall reconstruction, comprised of infrequent chest wall deformities such as pectus arcuatum and Poland syndrome. These malformations are very heterogeneous resulting in a high degree of improvisation during the surgical repair. In this setting, 3D technology plays a role in the standardization of a process that contemplates customization, concepts that may seem contradictory. Finally, 3D printing with biocompatible materials is rapidly becoming the first choice for the reconstruction of wide chest wall oncological resections. In this work, we review the first and most important current publications on the subject.

Design of 3D printing osteotomy block for foot based on triply periodic minimal surface.

The ankle joint, which connects the lower limbs and the sole of the foot, is prone to sprain during walking and sports, which leads to ankle arthritis. Supratroleolar osteotomy is an ankle preserving operation for the treatment of ankle arthritis, in which the osteotomy is an important fixing and supporting part. In order to avoid stress shielding effect as much as possible, the osteotomy block is designed as a porous structure. In this study, the osteotomy block was designed based on three-period minimal surface, and the designed structure was manufactured by 3D printing. The mechanical properties of different structures were studied by mechanical test and finite element simulation. In mechanical tests, the Gyroid structure showed a progressive failure mechanism from bottom to bottom, while the Diamond structure showed a shear failure zone at 45° Angle, which was not conducive to energy absorption and was more prone to brittle fracture than the Gyroid structure. Therefore, the Gyroid structure is valuable for further research in the development of porous osteotomy.

New Scenarios for Training in Oral Radiology: Clinical Performance and Predoctoral Students' Perception of 3D-Printed Mannequins.

OBJECTIVES: This study aimed to evaluate the impact of 3D-printed mannequins on the training of predoctoral students. METHODS: Two 3D-printed training models were developed: a traditional model that simulates a sound adult patient and a customized model with pathological and physiological changes (impacted third molar and edentulous region). Students accomplished their pre-clinical training divided into a control group (CG, n = 23), which had access to the traditional model, and a test group (TG, n = 20), which had access to both models. Afterward, they performed a full mouth series on patients and filled out a perception questionnaire. Radiographs were evaluated for technical parameters. Descriptive statistics and the Mann-Whitney test were used to compare the groups. RESULTS: Students provided positive feedback regarding the use of 3D printing. The TG reported a more realistic training experience than the CG (p = 0.037). Both groups demonstrated good clinical performance (CG = 7.41; TG = 7.52), and no significant differences were observed between them. CONCLUSIONS: 3D printing is an option for producing simulators for pre-clinical training in Oral Radiology, reducing student stress and increasing confidence during clinical care.

Partial Shoulder Arthroplasty Guided by Three-dimensional Prototyping.

Three-dimensional (3D) printing technology is a reality in medicine. In Orthopedics and Traumatology, 3D printing guides a precise and tailored surgical treatment. Understanding and disseminating its applicability, use, and outcomes can foster academicism and improve patient care. This is a report of a rare case of a female young adult patient with osteonecrosis of the humeral head due to avascular necrosis developed in early childhood. The treatment was tailored and optimized with 3D printing, which helped determine the steps for partial humeral arthroplasty.

A fully digital workflow for the design and manufacture of a class of metal orthodontic appliances.

Background: Traditional working procedures requires a lot of clinical processes and processing time. Methods: The orthodontic metal appliances were made by applying oral scanners, digital images, computer-aided design and computer-aided manufacturing (CAD-CAM) printers. Results: The computer digital technology simplified the manufacturing process for dental appliances and shorten the duration for clinical operation and technical processing. Conclusions: The technique described in this paper can guarantee the accuracy of orthodontic appliances and bring revolution the field. Clinical significance: The CAD-CAM technology provides a fully digital workflow for manufacturing metal orthodontic appliances, which saves a considerable amount of labor and material costs, and significantly reduces heavy metal pollution in the working environment of dental technicians.

Enhancing Hip Arthroplasty Outcomes: The Multifaceted Advantages, Limitations, and Future Directions of 3D Printing Technology.

In the evolving field of orthopedic surgery, the integration of three-dimensional printing (3D printing) has emerged as a transformative technology, particularly in addressing the rising incidence of degenerative joint diseases. The integration of 3D printing technology in hip arthroplasty offers substantial advantages throughout the surgical process. In preoperative planning, 3D models enable meticulous assessments, aiding in accurate implant selection and precise surgical strategies. Intraoperatively, the technology contributes to precise prosthesis design, reducing operation duration, X-ray exposures, and blood loss. Beyond surgery, 3D printing revolutionizes medical equipment production, imaging, and implant design, showcasing benefits such as enhanced osseointegration and reduced stress shielding with titanium cups. Challenges include a higher risk of postoperative infection due to the porous surfaces of 3D-printed implants, technical complexities in the printing process, and the need for skilled manpower. Despite these challenges, the evolving nature of 3D printing technologies underscores the importance of relying on existing orthopedic surgical practices while emphasizing the need for standardized guidelines to fully harness its potential in improving patient care.

Customizable, biocompatible implants for dorsal nasal augmentation: An in vivo pilot study of eight polylactic acid scaffold designs.

Augmentation of the nasal dorsum often requires implantation of structural material. Existing methods include autologous, cadaveric or alloplastic materials and injectable hydrogels. Each of these options is associated with considerable limitations. There is an ongoing need for precise and versatile implants that produce long-lasting craniofacial augmentation. Four separate polylactic acid (PLA) dorsal nasal implant designs were 3D-printed. Two implants had internal PLA rebar of differing porosities and two were designed as "shells" of differing porosities. Shell designs were implanted without infill or with either minced or zested processed decellularized ovine cartilage infill to serve as a "biologic rebar", yielding eight total treatment groups. Scaffolds were implanted heterotopically on rat dorsa (N = 4 implants per rat) for explant after 3, 6, and 12 months followed by volumetric, histopathologic, and biomechanical analysis. Low porosity implants with either minced cartilage or PLA rebar infill had superior volume retention across all timepoints. Overall, histopathologic and immunohistochemical analysis showed a resolving inflammatory response with an M1/M2 ratio consistently favoring tissue regeneration over the study course. However, xenograft cartilage showed areas of degradation and pro-inflammatory infiltrate contributing to volume and contour loss over time. Biomechanical analysis revealed all constructs had equilibrium and instantaneous moduli higher than human septal cartilage controls. Biocompatible, degradable polymer implants can induce healthy neotissue ingrowth resulting in guided soft tissue augmentation and offer a simple, customizable and clinically-translatable alternative to existing craniofacial soft tissue augmentation materials. PLA-only implants may be superior to combination PLA and xenograft implants due to contour irregularities associated with cartilage degradation.

Applications of physical and chemical treatments in plant-based gels for food 3D printing.

Extrusion-based three-dimensional (3D) printing has been extensively studied in the food manufacturing industry. This technology places particular emphasis on the rheological properties of the printing ink. Gel system is the most suitable ink system and benefits from the composition of plant raw materials and gel properties of multiple components; green, healthy aspects of the advantages of the development of plant-based gel system has achieved a great deal of attention. However, the relevant treatment technologies are still only at the laboratory stage. With a view toward encouraging further optimization of ink printing performance and advances in this field, in this review, we present a comprehensive overview of the application of diverse plant-based gel systems in 3D food printing and emphasize the utilization of different treatment methods to enhance the printability of these gel systems. The treatment technologies described in this review are categorized into three distinct groups, physical, chemical, and physicochemical synergistic treatments. We comprehensively assess the specific application of these technologies in various plant-based gel 3D printing systems and present valuable insights regarding the challenges and opportunities for further advances in this field.

Enhancing surgical planning for abdominal tumors in children through advanced 3D visualization techniques: a systematic review of future prospects.

Introduction: Preoperative three-dimensional (3D) reconstruction using sectional imaging is increasingly used in challenging pediatric cases to aid in surgical planning. Many case series have described various teams' experiences, discussing feasibility and realism, while emphasizing the technological potential for children. Nonetheless, general knowledge on this topic remains limited compared to the broader research landscape. The aim of this review was to explore the current devices and new opportunities provided by preoperative Computed Tomography (CT) scans or Magnetic Resonance Imaging (MRI). Methods: A systematic review was conducted to screen pediatric cases of abdominal and pelvic tumors with preoperative 3D reconstruction published between 2000 and 2023. Discussion: Surgical planning was facilitated through virtual reconstruction or 3D printing. Virtual reconstruction of complex tumors enables precise delineation of solid masses, formulation of dissection plans, and suggests dedicated vessel ligation, optimizing tissue preservation. Vascular mapping is particularly relevant for liver surgery, large neuroblastoma with imaging-defined risk factors (IDRFs), and tumors encasing major vessels, such as complex median retroperitoneal malignant masses. 3D printing can facilitate specific tissue preservation, now accessible with minimally invasive procedures like partial nephrectomy. The latest advancements enable neural plexus reconstruction to guide surgical nerve sparing, for example, hypogastric nerve modelling, typically adjacent to large pelvic tumors. New insights will soon incorporate nerve plexus images into anatomical segmentation reconstructions, facilitated by non-irradiating imaging modalities like MRI. Conclusion: Although not yet published in pediatric surgical procedures, the next anticipated advancement is augmented reality, enhancing real-time intraoperative guidance: the surgeon will use a robotic console overlaying functional and anatomical data onto a magnified surgical field, enhancing robotic precision in confined spaces.

[Construction of a novel tissue engineered meniscus scaffold based on low temperature deposition three-dimenisonal printing technology].

Objective: To investigate the construction of a novel tissue engineered meniscus scaffold based on low temperature deposition three-dimenisonal (3D) printing technology and evaluate its biocompatibility. Methods: The fresh pig meniscus was decellularized by improved physicochemical method to obtain decellularized meniscus matrix homogenate. Gross observation, HE staining, and DAPI staining were used to observe the decellularization effect. Toluidine blue staining, safranin O staining, and sirius red staining were used to evaluate the retention of mucopolysaccharide and collagen. Then, the decellularized meniscus matrix bioink was prepared, and the new tissue engineered meniscus scaffold was prepared by low temperature deposition 3D printing technology. Scanning electron microscopy was used to observe the microstructure. After co-culture with adipose-derived stem cells, the cell compatibility of the scaffolds was observed by cell counting kit 8 (CCK-8), and the cell activity and morphology were observed by dead/live cell staining and cytoskeleton staining. The inflammatory cell infiltration and degradation of the scaffolds were evaluated by subcutaneous experiment in rats. Results: The decellularized meniscus matrix homogenate appeared as a transparent gel. DAPI and histological staining showed that the immunogenic nucleic acids were effectively removed and the active components of mucopolysaccharide and collagen were remained. The new tissue engineered meniscus scaffolds was constructed by low temperature deposition 3D printing technology and it had macroporous-microporous microstructures under scanning electron microscopy. CCK-8 test showed that the scaffolds had good cell compatibility. Dead/live cell staining showed that the scaffold could effectively maintain cell viability (>90%). Cytoskeleton staining showed that the scaffolds were benefit for cell adhesion and spreading. After 1 week of subcutaneous implantation of the scaffolds in rats, there was a mild inflammatory response, but no significant inflammatory response was observed after 3 weeks, and the scaffolds gradually degraded. Conclusion: The novel tissue engineered meniscus scaffold constructed by low temperature deposition 3D printing technology has a graded macroporous-microporous microstructure and good cytocompatibility, which is conducive to cell adhesion and growth, laying the foundation for the in vivo research of tissue engineered meniscus scaffolds in the next step.

Three-dimensional replica of the temporal bone in the teaching of human anatomy.

PURPOSE: The current study proposes the comparison of the visualization and identification of anatomical details between natural human temporal bone, its respective copy from three-dimensional printing, and the virtual model obtained from CBCT. METHODS: The sample consisted of undergraduate students in Dentistry (Group UE, n = 22), Postgraduate students in Radiology and Imaging (Group P-RI, n = 20), and Postgraduate students in Forensic Odontology (Group P-FO, n = 24). All participants attended a theoretical class on specialized anatomy of the temporal bone and subsequently performed the markings of 10 determined structures. RESULTS: The number of correct identifications was similar in natural bone and printed three-dimensional models in all groups (p > 0.05). The virtual model showed a significantly lower number of correct structures (p < 0.05) in the 3 groups. In general, there were significantly higher percentages of accurate answers among postgraduate students compared to undergraduate students. Most graduate students believed that the printed three-dimensional model could be used to teach anatomy in place of natural bone, while undergraduate students disagreed or were unsure (p < 0.05). Regarding the virtual tomographic image, in all groups, students disagreed or were not sure that its use would be beneficial in replacing natural bone. CONCLUSION: Three-dimensional and virtual models can be used as auxiliary tools in teaching anatomy, complementing practical learning with natural bones.

Effect of thickness on the translucency of machinable and printable ceramic-glass polymer materials.

OBJECTIVES: To assess the translucency of machinable and printable ceramic-glass polymer materials with different thicknesses. METHODS: Five ceramic-glass polymer materials were tested: one 3D-printable material, Permanent Crown resin (3D), two machinable materials available at low translucency (LT) and high translucency (HT) levels, VITA Enamic (VE) HT/LT, and Cerasmart 270 (CS) HT/LT. A total of 100 specimens were produced across 10 subgroups (n = 10) with thicknesses of 1 mm and 1.5 mm. The colour coordinates of the specimens were measured against black and white backgrounds using a spectrophotometer. Translucency was quantified using the Relative Translucency Parameter (RTP), calculated via the CIEDE2000 formula. A two-way ANOVA followed by post-hoc tests with Bonferroni correction (α = 0.05) was used for statistical analysis. RESULTS: The RTP for both thicknesses were ranked as follows: CSHT > VEHT > CSLT > 3D > VELT. The RTP of the 3D was lower than that of the HT machinable materials (CSHT and VEHT) for both thicknesses (p < 0.05). No significant difference was observed between the RTP of 3D and CSLT at 1.5 mm (p = 1.000); however, at 1 mm, the RTP of the 3D was lower than that of the CSLT (p < 0.05). Notably, the 3D showed the least translucency difference with a 0.5 mm increase in thickness. CONCLUSIONS: Printable ceramic-glass polymer materials demonstrated lower translucency than HT machinable ceramic-glass polymer materials. Both the thickness and type significantly influenced the translucency of the LT machinable counterparts compared to the printable ceramic-glass polymer material. CLINICAL SIGNIFICANCE: Printable ceramic-glass polymer resins may be a suitable option for minimally invasive procedures, especially when attempting to mask undesirable-coloured abutments. When selecting HT machinable ceramic-glass polymers, clinicians should pay greater attention to the abutment colour and thickness of the restorative material.

Mechanical properties, cytotoxicity, and protein adsorption of three-dimensionally printable hybrid resin containing zwitterionic polymer and silicate-based composites for dental restorations.

OBJECTIVE: To evaluate the mechanical and biological properties of three-dimensionally (3D) printable resins filled with 2-methacryloyloxyethyl phosphorylcholine (MPC) and silicate-based composites and compare with those of a commercially available 3D-printable resin for definitive restorations. METHODS: A group of 3D-printable hybrid resins (HRs) filled with 6 wt% MPC and three different compositions of silicate-based composites (barium silicate to zirconium silicate ratios: 1.50:1 for HR1, 0.67:1 for HR2, and 0.25:1 for HR3) were prepared. The HR groups were compared with the commercially available unfilled 3D-printable resin (CR) marketed for definitive restorations in terms of flexural strength and modulus, fracture toughness, surface roughness, Vickers hardness, light transmittance (all, n = 15), cytotoxicity, and protein adsorption (both, n = 3). All data were analyzed by using non-parametric Kruskal-Wallis and Dunn's tests (α=0.05). RESULTS: The HR groups had significantly higher flexural strength, modulus, fracture toughness, and hardness values than the CR (P < 0.001). HR3 had the highest surface roughness and light transmittance among the groups (P ≤ 0.006). None of tested resins showed cytotoxicity. Both HR2 and HR3 showed significantly lower protein adsorption than the CR, with a difference of approximately 60% (P ≤ 0.026). CONCLUSION: Both HR2 and HR3 exhibited superior mechanical properties (flexural strength, flexural modulus, fracture toughness, and Vickers hardness), light transmittance, and protein-repellent activity than the CR, with no impact on cytotoxicity. CLINICAL SIGNIFICANCE: The MPC/silicate-based composite-filled resins may be a suitable alternative for definitive restorations, given their higher mechanical properties and promising biological properties to prevent microbial adhesion and subsequent biofilm formation, as well as their non-cytotoxic properties.

THREE-DIMENSIONAL PRINTING IN SPINAL SURGERY: UPDATE AND SYSTEMATIC REVIEW / IMPRESSÃO 3D EM CIRURGIA DA COLUNA VERTEBRAL: ATUALIZAÇÃO E REVISÃO SISTEMÁTICA

Introduction: Three-dimensional printing is considered the "third industrial revolution". It was developed as a promising innovation for many areas, including medicine. There are many ways to use 3D printing in spinal surgery: patient and healthcare professional education, preoperative applications such as surgical planning and intraoperative applications. Objective: To carry out an update and systematic review on the use of 3DP in spinal surgery. Method: A systematic literature review was conducted using the PubMed database in January 2024, using the terms "spine surgery" and "3D printing". Articles published between 2014 and 2024 and only clinical trials were selected. Articles that were not in English or Spanish were excluded. This review followed the Preferred Reported Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline. Result: After screening and evaluation, 10 articles were included. Regarding the diseases studied, the majority were deformities (n = 3) and trauma (n = 3), followed by degenerative diseases (n = 2). Two articles dealt with surgical technique. Six studied the creation of personalized guides for inserting screws; 2 were about education, 1 related to educating patients about their disease and the other to teaching residents surgical technique; 2 other articles addressed surgical planning, where biomodels were printed to study anatomy and surgical programming. Conclusion: Three-dimensional printing biomodels and personalized guides for screw implants are useful for use in spinal surgery. The use of this technology has enabled patient and medical team education, as well as optimizing preoperative planning and reducing surgical time and radiation exposure in spinal surgery.

Introdução: A impressão tridimensional é considerada a "terceira revolução industrial". Foi desenvolvida como inovação promissora para muitas áreas, incluindo a medicina. Há muitas maneiras de usar a impressão 3D em cirurgia da coluna vertebral: educação de pacientes e profissionais de saúde, aplicações pré-operatórias, como planejamento cirúrgico e aplicações intraoperatórias. Objetivo: Realizar atualização e revisão sistemática sobre o uso do 3DP em cirurgia da coluna vertebral. Método: Foi realizada revisão sistemática da literatura na base de dados PubMed em janeiro de 2024, utilizando os termos "spine surgery" e "3D printing". Foram selecionados artigos publicados entre 2014 e 2024 e apenas como ensaios clínicos. Foram excluídos aqueles que não estivessem em inglês ou espanhol. Esta revisão seguiu a diretriz Preferred Reported Items for Systematic Reviews and Meta-Analysis (PRISMA). Resultado: Após triagem e avaliação, foram incluídos 10 artigos. Em relação às doenças estudadas, a maioria foi de deformidades (n = 3) e traumas (n = 3), seguidas das doenças degenerativas (n = 2). Dois artigos trataram da técnica cirúrgica. Seis estudaram a criação de guias personalizadas para inserção de parafusos; 2 eram sobre educação, 1 relacionado à educação dos pacientes sobre sua doença e outro ao ensino da técnica cirúrgica aos residentes; outros 2 artigos abordaram planejamento cirúrgico, onde foram impressos biomodelos para estudo de anatomia e programação cirúrgica. Conclusão: Biomodelos de impressão tridimensional e guias personalizados para implantes de parafusos são úteis para uso em cirurgia da coluna vertebral. O uso dessa tecnologia possibilitou a educação do paciente e da equipe médica, além de otimizar o planejamento pré-operatório e reduzir o tempo cirúrgico e a exposição à radiação em operações de coluna.

CUSTOMIZED BIOMODEL OF THE CERVICAL SPINE FOR LABORATORY LAMINOPLASTY TRAINING / BIOMODELO PERSONALIZADO DA COLUNA CERVICAL PARA TREINAMENTO DE LAMINOPLASTIA EM LABORATÓRIO

Background: Additive manufacturing has been developed as a promising innovation for many areas, including medicine. There are many ways to use it in spine surgeries and the use of biomodels in the laboratory to study and training of cervical laminoplasty has not yet been reported in the literature. Objective: To evaluate the use of a biomodel of the cervical spine for surgical training of laminoplasty. Method: This is an experimental study. Were printed 10 identical biomodels of the cervical spine based on CT and MRI scans of a patient diagnosed with spondylotic cervical myelopathy. The additive manufacturing method used was fused deposition modeling and the raw material chosen was polyatic acid. The sample was divided into 2 groups: control (n = 5; the biomodels were submitted to CT scanning) and open-door (n = 5; the biomodels were submitted to open-door laminoplasty and postoperative CT). The area and anteroposterior diameter of the vertebral canal were measured on CT scans. Result: The time for printing each piece was 12 h. During the surgical procedure, the support of the biomodels was sufficient to keep them static. The use of drill was feasible; however, continuous irrigation was mandatory to prevents the heating of the plastic material. The raw material used allowed the CT study of the biomodels. It was observed an increase the dimensions of the vertebral canal in 24,80% (0.62 cm2) in the area and 24,88% (3.12 mm) in the anteroposterior diameter. Conclusion: The cervical spine biomodels can be used for laminoplasty training, even using thermosensitive material such as PLA. The use of continuous irrigation is essential during the use of the drill.

Introdução: A manufatura aditiva tem se desenvolvido como inovação promissora para muitas áreas, incluindo a medicina. Existem muitas maneiras de utilizá-la em operações de coluna, e o uso de biomodelos em laboratório para estudo e treinamento de laminoplastia cervical ainda não foi relatado na literatura. Objetivo: Avaliar a utilização de um biomodelo da coluna cervical para treinamento cirúrgico de laminoplastia. Método: Trata-se de estudo experimental. Foram impressos 10 biomodelos idênticos da coluna cervical baseados em exames de tomografia computadorizada e ressonância magnética de um paciente com diagnóstico de mielopatia cervical espondilótica. O método de manufatura aditiva utilizado foi a modelagem por deposição fundida e a matéria-prima escolhida foi o ácido poliático. A amostra foi distribuída em 2 grupos: controle (n = 5; os biomodelos foram submetidos à tomografia computadorizada) e open-door (n = 5; os biomodelos foram submetidos à laminoplastia open-door e tomografia pós-operatória). A área e o diâmetro anteroposterior do canal vertebral foram medidos na tomografia. Resultado: O tempo de impressão de cada peça foi de 12 h. Durante o procedimento, o suporte utilizado para fixar o biomodelo foi suficiente para mantê-los estáticos. O uso de broca mostrou-se viável; porém, a irrigação contínua foi mandatória para evitar o aquecimento do material plástico. A matéria-prima utilizada permitiu o estudo tomográfico dos biomodelos. Observou-se aumento das dimensões do canal vertebral em 24,80% (0,62 cm2) na área e 24,88% (3,12 mm) no diâmetro anteroposterior. Conclusão: Os biomodelos da coluna cervical podem ser utilizados para o treinamento de laminoplastias, mesmo utilizando material termossensível. O uso de irrigação contínua é essencial durante o uso da broca.

Accuracy of 3D Printed Model Acquired from Different Types of Intra Oral Scanners and 3D Printers.

Objective: The aim of this study was to verify the influence of different types of intraoral scanners and 3D printers on the accuracy of printed models in comparison to plaster models obtained from conventional impressions. Material and Methods: A dental study model was used as the reference model and was molded with polyvinyl siloxane to produce the plaster models which were scanned by a reference scanner. Two types of intraoral scanners and digital files were printed by two types of 3D printers. To measure the accuracy (trueness and precision) amongst the groups, the datasets were superimposed via a best-fit alignment method utilizing a 3D analysis program (Geomagic Verify; 3D Systems). The trueness of the complete arch was evaluated by superimposing the STL file data of the reference model with STL file data obtained from other scanners. The precision of the complete arch was evaluated by superimposing the scan data within each group. The quantitative values were automatically calculated by the 3D analysis program based on the root mean square (RMS). Results: It was observed that all the tested combinations of the scanner and 3D printer showed variation from reference which was nonsignificant. However, Trios 4 intraoral scanner and Formlabs 3D printer was the combination that showed the best trueness and precision values. Conclusions: It was concluded that the accuracy of printed and plaster models was impaired due to the trueness of the models. The type of printer influenced the accuracy of the printed models, while the type of scanner did not. The standardization of the method of obtaining printed models must be carried out to provide the production of quality models. However, there will be differences between the technologies.

Optimization Course of Titanium Nitride Nanofiller Loading in High-Density Polyethylene: Interpretation of Reinforcement Effects and Performance in Material Extrusion 3D Printing.

In this study, titanium nitride (TiN) was selected as an additive to a high-density polyethylene (HDPE) matrix material, and four different nanocomposites were created with TiN loadings of 2.0-8.0 wt. % and a 2 wt. % increase step between them. The mixtures were made, followed by the fabrication of the respective filaments (through a thermomechanical extrusion process) and 3D-printed specimens (using the material extrusion (MEX) technique). The manufactured specimens were subjected to mechanical, thermal, rheological, structural, and morphological testing. Their results were compared with those obtained after conducting the same assessments on unfilled HDPE samples, which were used as the control samples. The mechanical response of the samples improved when correlated with that of the unfilled HDPE. The tensile strength improved by 24.3%, and the flexural strength improved by 26.5% (composite with 6.0 wt. % TiN content). The dimensional deviation and porosity of the samples were assessed with micro-computed tomography and indicated great results for porosity improvement, achieved with 6.0 wt. % TiN content in the composite. TiN has proven to be an effective filler for HDPE polymers, enabling the manufacture of parts with improved mechanical properties and quality.