Efficacy and safety of 3-dimensional printing noncoplanar template (3D-PNCT)-assisted high-dose-rate interstitial brachytherapy (HDR-ISBT) for reirradiation of recurrent cervical cancer: a prospective cohort.

OBJECTIVE: This study aimed to investigate the efficacy and safety of 3-dimensional printing noncoplanar template (3D-PNCT)-assisted computed tomography (CT)-guided high-dose-rate interstitial brachytherapy (HDR-ISBT) for reirradiation of pelvic recurrent cervical carcinoma after external beam radiotherapy. METHODS: From January 2019 to August 2023, 45 eligible patients were enrolled in this prospective cohort. All patients underwent 3D-PNCT-assisted CT-guided HDR-ISBT with a prescribed dose of 4-7 Gy/fraction to the high-risk clinical target volume (HR-CTV) over 3-8 fractions, either for curative or palliative purposes. The primary endpoints were local progression-free survival (LPFS) and tumor response rate (TRR). The secondary outcome measures included overall survival (OS), toxicities, and symptom resolution. RESULTS: Forty-five patients received 261 fractions of 3D-PNCT-assisted HDR-ISBT. Twenty-nine patients had isolated pelvic recurrence, and 16 patients had simultaneous extra-pelvic or distant recurrences. The TRR was 66.7%. The 2- and 5-year LPFS rates were 30.0% and 25.7%, respectively. The median OS was 23.2 months, and 2- and 5-year OS rates were 49.5% and 34.0%, respectively. The multivariate analysis indicated that squamous cell carcinoma, radical surgery, recurrence-free interval≥12 months, tumor diameter, pelvic recurrence type, and HR-CTV D90≥45 Gy were independent factors influencing LPFS (all p<0.05). D100≥21 Gy, V100≥83%, and V150≥45% were associated with better LPFS (all p<0.05). Tumor diameter and metastasis were independent predictive factors for OS (all p<0.05). The pain relief rate was 66.7% (10/15). Grade 3-4 toxicities occurred in 20.0% of patients. CONCLUSION: 3D-PNCT-assisted HDR-ISBT for reirradiation of recurrent cervical cancer proved to be an effective and safe alternative to radical surgery.

Use of Three-dimensional Printing for Tibial Pilon Fracture Diagnosis and Treatment.

Objective To evaluate whether three-dimensional (3D) printing increases agreement in the classification of tibial pilon fractures. Methods Orthopedists and traumatologists reviewed radiographs, computed tomography scans with 3D reconstruction, and prototyping 3D printing, and classified the fractures based on the Rüedi-Allgöwer and Arbeitsgemeinschaft für Osteosynthesefragen (AO, Association for the Study of Internal Fixation) Foundation/Orthopedic Trauma Association (AO/OTA) classification systems. Next, data evaluation used Kappa agreement coefficients. Results The use of the 3D model did not improve agreement for tibial pilon fractures regarding the treatment proposed by the groups. Regarding the classification systems, the agreement only improved concerning the AO/OTA classification when the 3D model was used in the assessment by the foot and ankle specialists. Conclusion Although 3D printing is statistically relevant for surgeons specializing in foot and ankle, its values remain lower than optimal.

Mechanical and biological properties of polymer materials for oral appliances produced with additive 3D printing and subtractive CAD-CAM techniques compared to conventional methods: a systematic review and meta-analysis.

OBJECTIVES: The aim of this review was to analyze mechanical and biological properties of resin materials used with subtractive or additive techniques for oral appliances fabrication and compare them to those conventionally manufactured. MATERIALS AND METHODS: The protocol was registered online at Open Science Framework (OSF) registries ( https://osf.io/h5es3 ) and the study was based on the preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P). An electronic search was conducted on MEDLINE (via PubMed), Scopus, and Web of Science from 1 February 2022 to 1 May 2022. INCLUSION CRITERIA: in vitro and in vivo studies published in the last 10 years, with CAD-CAM or 3D printed resins for occlusal splints. Data considered homogenous were subjected to meta-analysis (95% confidence interval [CI]; α = 0.05) with Stata17 statistical software. Since all variables were continuous, the Hedge g measure was calculated. A fixed-effects model was used for I2 = 0%, while statistical analysis was conducted using a random-effects model with I2 > 0%. RESULTS: 13 studies were included after full-text reading. The mechanical properties most studied were wear, flexural strength, surface hardness and surface roughness, while only 1 study investigated biological properties, performing the XTT viability assay. For the meta-analysis, only surface roughness, volume loss, and flexural strength were selected. Considering surface roughness, the subtractive specimen had a lower average value compared to traditional ones (Hedge's g with 95% CI = -1.25[ -1.84, - 0.66]). No significant difference was detected in terms of volume loss (P > 0.05) between the groups (Hedge's g with 95% CI = -0.01 [-2.71, - 2.68]). While flexural strength was higher in the control group (Hedge's g with 95% CI = 2.32 [0.10-4.53]). CONCLUSION: 3D printed materials showed properties comparable to conventional resins, while milled splint materials have not shown better mechanical performance compared with conventional heat-cured acrylic resin. Polyetheretherketone (PEEK) have great potential and needs to be further investigated. Biological tests on oral cell populations are needed to confirm the long-term biocompatibility of these materials. CLINICAL RELEVANCE: The use of "mixed splints" combining different materials needs to be improved and evaluated in future research to take full advantage of different characteristics and properties.

Comparison of shock absorption capacities of three types of mouthguards: A comparative in vitro study.

BACKGROUND/AIM: 3D printing processes can be used to manufacture custom-made mouthguards for sports activities. Few studies have compared the impact performance of industrial-created mouthguards with that of custom-made mouthguards manufactured by thermoforming or 3D printing. The objective of this in vitro study was to compare the shock absorption capacities of custom-made mouthguards manufactured by 3D printing with industrial mouthguards and thermoformed ethylene vinyl acetate (EVA) mouthguards. MATERIALS AND METHODS: For each type of mouthguard, eight samples were produced. 3D-printed mouthguards were manufactured using digital light processing technology. Each mouthguard was subjected to an impact performance test defined by the standard AFNOR XP S72-427, which evaluate maximum deceleration and force transmitted during impact. The thickness of each mouthguard before and after a series of five impacts was measured at the impacted inter-incisal area. RESULTS: The mean maximum decelerations during impact ranged from 129 to 189 g for industrial mouthguards, 287 to 425 g for thermoformed EVA mouthguards, and 277 to 302 g for 3D-printed mouthguards. The mean reduction in mouthguard thickness at the impact zone after five tests was 1.2 mm for industrial mouthguards, 0.6 mm for 3D-printed mouthguards, and 2.2 mm for thermoformed EVA mouthguards. CONCLUSIONS: Custom-made 3D printed mouthguards showed slightly better shock absorption ability than thermoformed mouthguards with respect to the indicator proposed in XP S72-427. They seemed to combine the practical advantages of thermoformed mouthguards in sports with better shock absorption capacity and lower cost. Furthermore, they had the least thickness variation during the test, and their shock absorption capacity was the least affected by repeated mechanical tests. Other types of 3D-printing resin materials that will become available must continue to be tested for shock absorption to provide the best protection to users at low cost.

Visuospatial abilities and 3D-printed based learning.

PURPOSE: The use of 3D-printing in every field of medicine is expanding, notably as an educational tool. The aim of this study was to assess how visuospatial abilities (VSA) of students may impact learning helped with 3D-printed models. METHODS: Participants were undergraduate medical school students during their clinical rotation in oral and maxillofacial surgery in two French Universities. Students were included prospectively and consecutively from September 2021 to June 2023. First, a lecture about craniosynostosis was performed with the help of 3D-printed models of craniosynostotic skulls. Then, a mental rotation test (MRT) followed by a multiple-choice questions (MCQs) form about craniosynostosis presentations were submitted to the students. RESULTS: Forty undergraduate students were finally included. Median MRT score was 15 (10.75;21) and median score to the MCQs was 13 (11.75;14). There was a significantly weak correlation between the MRT-A score and the score to the MCQs (rs = 0.364; p = 0.022). A simple linear regression was calculated to predict the result to the MCQs on MRT-A score [ (F(1,39) = 281.248; p < 0.0001), with a R2 of 0.878 ]. CONCLUSION: This study showed that VSA has an impact on the recognition of complex clinical presentations, i.e. skulls with craniosynostosis. The correlation found between VSA and complex 3D shape recognition after learning aided with 3D-printed model is emphasizing the importance of VSA when using innovative technologies. Thus, VSA training should be envisioned during the curriculum.

Methodology for Preoperative Planning of Bone Deformities Using Three-dimensional Modeling Software.

Rapid prototyping technology, known as three-dimensional (3D) printing, and its use in the medical field are advancing. Studies on severe bone deformity treatment with 3D printing showed benefits in postoperative outcomes thanks to this technology. Even so, preoperative planning guidance for surgeons is lacking. This technical note describes a practical step-by-step guide to help surgeons use this technology to optimize the therapeutic plan with free license software and an intuitive interface. This study aims to organize the 3D modeling process using a preoperative computed tomography (CT) scan. This technology allows a deeper understanding of the case and its particularities, such as the direction, planes, and dimensions of the deformity. Planning considering these topics may reduce the surgical time and result in better functional outcomes by understanding the deformity and how to correct it. Associating planning via software with 3D printing can further enhance this therapeutic method.

Effect of wall thickness of 3D-printed models on resisting deformation from thermal forming in-office aligners.

BACKGROUND: Fabricating clear aligners by thermoforming three-dimensional printed dental models requires a high degree of accuracy. It is unknown whether model thickness affects the accuracy when used to thermoform aligners. PURPOSE: This research utilizes three-dimensional printed models made with differing wall thicknesses to determine its effect on their ability to withstand deformation during aligner fabrication. METHODS: A total of 50 models of different wall thickness (10 each of 0.5, 1.0, 1.5, 2.0 mm, and solid) were printed using model resin (Model V2, Formlabs) on a low-force stereolithography printer (Form 3B, Formlabs). Aligners were then fabricated using a thermal pressure forming machine (Biostar V, Great Lakes Dental Technologies) utilizing 25 s cycles to adapt 0.030″ acrylic sheets (Invisacryl, Great Lakes Dental Technologies), then removed from the models and sprayed with a contrast powder (Optispray, Dentsply Sirona) to aid in scanning with an intraoral scanner (CEREC Primescan, Dentsply Sirona). Each aligner's data was then compared to the original file used for printing with 3D comparison software (Geomagic Control X, 3D Systems). RESULTS: The results show model thickness greater than or equal to 2.0 mm produced clinically acceptable results within the margin of error (0.3 mm). A total of 0.5 mm thickness failed to withstand thermal forming in 4 of the 10 trials. A total of 0.5 mm produced 27.56% of results in tolerance, 1.0 mm produced 75.66% of results in tolerance, 1.5 mm had 80.38% of results in tolerance, 86.82% of 2 mm models were in tolerance, and solid had 96.45% of results in tolerance. CONCLUSION: Hollow models of thicknesses 2.0 mm and solid models produced clinically acceptable aligners while utilizing less resin per unit compared to solid models, thus being more cost effective, time efficient and eco-friendly. Therefore, a recommendation can be made to print hollow models with a shell thickness of greater than 2.0 mm for aligner fabrication.

Research status and prospect of hydrogel preparation for artificial cornea / 中华实验眼科杂志

Currently, the dominating treatment of corneal blindness is corneal transplantation, but the shortage of corneal donors has been a major problem in corneal transplantation.Compared with the traditional preparation method of artificial cornea, with the emergence of new materials, new technologies and new commercial activities, hydrogel provides a new possibility for the preparation of artificial cornea.Hydrogel is similar to the equivalent of extracellular matrix, with high biocompatibility, low immunogenicity and other characteristics, so it has been popularized and applied in many industries.As an important material of regenerative medicine, hydrogel has shown a strong application prospect in pharmaceutical research, 3D cell culture, stem cell research, 3D printing bio-ink and other fields.The main materials used for generating hydrogels are hyaluronic acid, gelatin, sodium alginate, etc.A lot of researches on using hydrogels as materials combined with different 3D printing technologies to prepare artificial corneas have been carried out and certain technical and theoretical breakthroughs have been made.This article briefly reviewed the research progress of hydrogel combined with 3D printing in the preparation of artificial cornea.

3D printed metal augment or tibial prosthesis for reconstruction of large bone defects in total knee arthroplasty and revision surgery / 中华骨科杂志

Objective:To investigate the clinical efficacy of 3D printed metal augment or tibial prosthesis for reconstruction of large bone defects in total knee arthroplasty (TKA) and knee revision surgery.Methods:A total of 7 patients (7 knees) with TKA or knee revision who were admitted to the Department of Orthopaedics of the Second Affiliated Hospital of Zhejiang University School of Medicine with large bone defects from July 2018 to December 2023 were retrospectively analyzed, including 4 patients with TKA and 3 patients with knee revision. There were 3 males and 4 females, aged 58.7±7.6 years (range, 54-68 years), 3 patients with left knee and 4 patients with right knee. All the patients had bone defects in the knee joint (AORI type III), 2 cases had bone defects only in the femur, 4 cases had bone defects only in the tibia, and 1 case had bone defects in both the tibia and femur, which were treated with personalized reconstruction using 3D printing. Hip-knee-ankle angles, American Knee Society score (KSS) before and after surgery were compared, and postoperative complications were observed.Results:All patients successfully completed the operation, and the operation time was 189.3±35.5 min (range, 125-240 min). Complex TKA was performed in 4 cases with surgical times of 175, 195, 210, and 240 min, and revision surgery was performed in 3 cases with surgical times of 125, 180, and 200 min, respectively. Intraoperative blood loss was 114±24.4 ml (range, 100-150 ml). Five cases used 3D printed metal augment, and two used 3D printed one-piece tibial components. All patients were followed up for 2, 2, 5, 6, 7, 20, 57 months, respectively. The KSS of the five patients at 3 months postoperatively were 56, 61, 66, 56, and 56 points, respectively, greater than the preoperative scores of 35, 44, 36, 27, and 41 points. The KSS functional scores of the five patients at 3 months postoperatively were 45, 45, 45, 30, and 45 points, respectively, which were greater than the preoperative scores of 30, 30, 15, 20, and 20 points. The hip-knee-ankle angle was 181.8°±3.4° (range, 177.9° to 188.0°) at the final follow-up and 175.8°±12.4° (range, 153.3° to 192.1°) before surgery, with no significant difference ( t=-1.230, P=0.242). At the final follow-up, the 3D printed component was well integrated with the bone surface, the prosthesis was securely positioned, and the force lines of the lower limbs were normal. There were no postoperative complications such as poor wound healing, infection, fat liquefaction, nerve injury, deep vein thrombosis of lower limbs, knee joint stiffness, periprosthesis infection and loosening. Conclusion:Using 3D printed metal augment or tibial prosthesis to reconstruct the huge bone defect in TKA and revision has a satisfactory early clinical effect, satisfactory joint function and good surgical safety.

Evaluation of short-term effects on 3D printing patient-matched artificial vertebral body in clinical research and application / 中华骨科杂志

Objective:To evaluate the short-term efficacy and safety of 3D printing patient-matched artificial vertebral body in clinical research and application.Methods:A total of 12 patients with spinal tumors were enrolled 7 males (58.33%) and 5 females (41.67%), aged from 18 to 65 years old in The First Affiliated Hospital of Air Force military Medical University (hereinafter referred to as Xijing Hospital) and Peking University people's Hospital from September 2021 to July 2022. The spinal vertebra defect were restored by using 3D printing patient-matched artificial vertebral body after tumor resection. All patients who accepted TES and 3D printing patient-matched artificial vertebral body implantation were included according to the inclusion and exclusion criteria. The bone interface fusion was evaluated by the imaging fusion criteria of Brantigan and Steffee at 3 and 6 months after operation, the curative effect was evaluated by comparing Japanese Orthopaedic Association (JOA) score at 3 and 6 months after operation, visual analogue scale (VAS) 3 months after operation and intervertebral height at 3 and 6 months after operation with those before operation, and the safety was evaluated by adverse event recording.Results:All 12 patients completed the operation successfully, and the operation sites were thoracic vertebrae in 6 cases (50%), thoracolumbar in 3 cases (25%) and lumbar vertebrae in 3 cases (25%). All patients were followed up. The mean follow-up time was 23.92±3.23 months (range, 19-29 months). No tumor recurrence or metastasis was observed during this period. All patients were followed up at 15 days, 3 months and 6 months after operation. During the 6-month follow-up, X ray results showed that interface of bone and the vertebral body were fused in all of the 12 patients, and the effective rate of fusion was 100%. The 95% confidence interval is calculated to be (75.6%-100%). Six months after operation, the improvement rate of JOA score was excellent in 10 cases, good in 1 case, poor in 1 case, and the excellent and good rate was 91.66%. The preoperative VAS score was 4.08 ±2.47, and during the 3-month follow-up, the VAS score was improved to 1.83 ±1.59. Compared with the preoperative VAS score, the difference was statistically significant ( t=2.635, P=0.023). The intervertebral height before operation, 15 days after operation, 3 months after operation and 6 months after operation were 32.75 (25.94, 68.20), 41.09 (30.55, 70.20), 40.70 (30.23, 67.83) and 40.74 (30.23, 67.08), respectively, and there was no statistically significant difference (χ 2=0.768, P=0.857). No implant-related adverse events occurred after operation. Conclusion:The 3D printing patient-matched artificial vertebral body used in this study has satisfactory short-term efficacy and safety in the reconstruction of spinal stability after spinal tumor resection.

Application of three-dimensional printing technology in obstetrics / 中华围产医学杂志

Three-dimensional (3D) printing, also known as additive manufacturing, is a fabrication technology that constructs three-dimensional objects by successive addition of materials. In recent years, the advancements in 3D printing technology, reductions in material costs, development of biomaterials, and improvements in cell culture techniques allow the application of 3D printing in the clinical medical fields, such as orthopedics, dentistry, and urinary surgery, to develop rapidly. Obstetrics, focusing on both theory and practice, is an emerging application field for 3D printing technology. 3D printing has been used in obstetrics for fetal and maternal diseases, such as prenatal diagnosis of fetal abnormalities and preoperative planning for placental implantation disorders. Additionally, 3D printing can simulate surgical scenarios and enable the targeted training for doctors. This review aims to provide a summary of the latest developments in the clinical application of 3D printing in obstetrics.

Influence of fabrication method on the marginal fit of temporary restorations

Abstract Computer-aided manufacturing (CAM) technology allows the use of different manufacturing techniques. This in vitro study aimed to evaluate the marginal fit of temporary restorations manufactured using conventional chairside methods, milling, and three-dimensional printing. Fifteen 3-element temporary restorations specimens were produced and categorized into three groups: non-digital, obtained using the conventional chairside method (GC); milled (GM); and three-dimensionally printed (GP). Marginal fit was assessed using scanning electron microscopy (SEM) performed under two conditions: one with only the central screw tightened, and the other with all three screws tightened. Horizontal misfit values were categorized as over-, equal-, and under-extended and qualitatively analyzed. Statistical analysis was performed using the Tukey-Kramer test (α=0.05). In the vertical assessment, three-dimensionally printed restorations demonstrated greater misfit than restorations obtained by milling and the conventional chairside method (P<0.05). In the horizontal assessment, the misfit in the GP group was significantly higher than that in the GM and GC groups. Restorations obtained using the conventional chairside method and milled provisional restorations showed more favorable results than three-dimensionally printed restorations.

Methodology for Preoperative Planning of Bone Deformities Using Three-dimensional Modeling Software / Metodologia para planejamento pré-operatório de deformidades ósseas utilizando software de modelagem tridimensional

Abstract Rapid prototyping technology, known as three-dimensional (3D) printing, and its use in the medical field are advancing. Studies on severe bone deformity treatment with 3D printing showed benefits in postoperative outcomes thanks to this technology. Even so, preoperative planning guidance for surgeons is lacking. This technical note describes a practical step-by-step guide to help surgeons use this technology to optimize the therapeutic plan with free license software and an intuitive interface. This study aims to organize the 3D modeling process using a preoperative computed tomography (CT) scan. This technology allows a deeper understanding of the case and its particularities, such as the direction, planes, and dimensions of the deformity. Planning considering these topics may reduce the surgical time and result in better functional outcomes by understanding the deformity and how to correct it. Associating planning via software with 3D printing can further enhance this therapeutic method.

Resumo Observa-se o avanço da tecnologia de prototipagem rápida, conhecida como impressão tridimensional (3D) e seu uso na área médica. Existem estudos a respeito do tratamento de deformidades ósseas graves com impressão 3D, os quais mostram benefícios no resultado pós-operatório às custas do uso da tecnologia em questão. Ainda assim, nota-se a escassez quando o assunto é disponibilizar ao cirurgião orientações para planejamento pré-operatório. O objetivo desta nota técnica é descrever um passo-a-passo prático para auxiliar cirurgiões a utilizarem a tecnologia como ferramenta para otimizar o plano terapêutico, dispondo de um programa de licença gratuita e de interface intuitiva. Este é um estudo que visa a organização do processo de modelagem 3D, no qual foi utilizado um exame de tomografia computadorizada (TC) pré-operatória. Com esta tecnologia, é possível uma compreensão mais profunda do caso e suas particularidades como direção, planos e dimensões das deformidades. Acredita-se que um planejamento que leve em consideração tais tópicos gera redução do tempo cirúrgico e melhores resultados funcionais devido ao entendimento da deformidade e maneiras de correção. Associar o planejamento via software com a impressão 3D pode potencializar ainda mais na elaboração do método terapêutico.

Development and mechanical-functional validation of 3D-printed laparoscopic forceps / Desenvolvimento e validação mecânico-funcional de pinça laparoscópica impressa em 3 dimensões

ABSTRACT Introduction: 3-dimensional printing has enabled the development of unique and affordable additive manufacturing, including the prototyping and production of surgical forceps. Objective: demonstrate the development, 3D printing and mechanical-functional validation of a laparoscopic grasping forceps. Methods: the clamp was designed using a computer program and printed in 3 dimensions with polylactic acid (PLA) filament and added 5 screws for better leverage. Size and weight measurements were carried out, as well as mechanicalfunctional grip and rotation tests in the laboratory with a validated simulator. Results: Called "Easylap", the clamp weighed 48 grams, measured 43cm and was printed in 8 pieces, taking an average of 12 hours to produce. It allowed the simulation of the functional characteristics of laparoscopic pressure forceps, in addition to the rotation and rack locking mechanism. However, its strength is reduced due to the material used. Conclusion: It is possible to develop plastic laparoscopic grasping forceps through 3-dimensional printing.

RESUMO Introdução: a impressão em 3 dimensões permitiu o desenvolvimento de manufaturas aditivas únicas e acessíveis, inclusive na prototipagem e produção de pinças cirúrgicas. Objetivo: Demonstrar o desenvolvimento, a impressão em 3D e a validação mecânico-funcional de pinça laparoscópica do tipo apreensão. Métodos: a pinça foi desenhada em programa de computador e impressa em 3 dimensões com filamento de ácido poliláctico (PLA) e acrescida de 5 parafusos para melhor efeito de alavanca. Foram realizadas aferições de tamanho e peso, bem como testes mecânicos-funcionais de preensão e rotação em laboratório com simulador validado. Resultados: denominada "Easylap", a pinça pesou 48 gramas, mediu 43 cm e foi impressa em 8 peças, levando em média 12 horas para sua produção. Ela permitiu a simulação das características funcionais de pinça laparoscópicas de apreensão, além de mecanismo de rotação e travamento por cremalheira. Porém sua força é reduzida devido ao material utilizado. Conclusão: é possível desenvolver pinça laparoscópica plástica de apreensão através de impressão em 3 dimensões.

Analysis of the Mechanical Behavior of Porcine Graft Fixation in a Polyurethane Block Using a 3D-printed PLA Interference Screw.

Objective The interest in using 3D printing in the healthcare field has grown over the years, given its advantages and potential in the rapid manufacturing of personalized devices and implants with complex geometries. Thus, the aim of the present study was to compare the mechanical fixation behavior of a 3D-printed interference screw, produced by fused deposition modeling of polylactic acid (PLA) filament, with that of a titanium interference screw. Methods Eight deep flexor porcine tendons, approximately 8 mm wide and 9 cm long, were used as graft and fixed to a 40 pounds-per-cubic-foot (PCF) polyurethane block at each of its extremities. One group was fixed only with titanium interference screws (group 1) and the other only with 3D-printed PLA screws (BR 20 2021 018283-6 U2) (group 2). The tests were conducted using an EMIC DL 10000 electromechanical universal testing machine in axial traction mode. Results Group 1 (titanium) obtained peak force of 200 ± 7 N, with mean graft deformation of 8 ± 2 mm, and group 2 (PLA) obtained peak force of 300 ± 30 N, and mean graft deformation of 7 ± 3 mm. Both the titanium and PLA screws provided good graft fixation in the polyurethane block, with no slippage or apparent deformation. In all the samples, the test culminated in graft rupture, with around 20 mm of deformation in relation to the initial length. Conclusion The 3D-printed PLA screw provided good fixation, similar to that of its titanium counterpart, producing satisfactory and promising results.

Analysis of the Mechanical Behavior of Porcine Graft Fixation in a Polyurethane Block Using a 3D-printed PLA Interference Screw / Análise do comportamento mecânico da fixação do enxerto suíno em um bloco de poliuretano usando um parafuso de interferência PLA impresso em 3D

Abstract Objective The interest in using 3D printing in the healthcare field has grown over the years, given its advantages and potential in the rapid manufacturing of personalized devices and implants with complex geometries. Thus, the aim of the present study was to compare the mechanical fixation behavior of a 3D-printed interference screw, produced by fused deposition modeling of polylactic acid (PLA) filament, with that of a titanium interference screw. Methods Eight deep flexor porcine tendons, approximately 8 mm wide and 9 cm long, were used as graft and fixed to a 40 pounds-per-cubic-foot (PCF) polyurethane block at each of its extremities. One group was fixed only with titanium interference screws (group 1) and the other only with 3D-printed PLA screws (BR 20 2021 018283-6 U2) (group 2). The tests were conducted using an EMIC DL 10000 electromechanical universal testing machine in axial traction mode. Results Group 1 (titanium) obtained peak force of 200 ± 7 N, with mean graft deformation of 8 ± 2 mm, and group 2 (PLA) obtained peak force of 300 ± 30 N, and mean graft deformation of 7 ± 3 mm. Both the titanium and PLA screws provided good graft fixation in the polyurethane block, with no slippage or apparent deformation. In all the samples, the test culminated in graft rupture, with around 20 mm of deformation in relation to the initial length. Conclusion The 3D-printed PLA screw provided good fixation, similar to that of its titanium counterpart, producing satisfactory and promising results.

Resumo Objetivo O interesse em utilizar a impressão 3D na área da saúde tem crescido ao longo dos anos, dadas as suas vantagens e o seu potencial na rápida fabricação de dispositivos e implantes personalizados com geometrias complexas. Assim, o objetivo do presente estudo foi comparar o comportamento de fixação mecânica de um parafuso de interferência impresso em 3D, produzido pela modelagem fundida de deposição do filamento de ácido polilático (PLA), com o de um parafuso de interferência de titânio. Métodos Oito tendões suínos flexores profundos, de aproximadamente 8 mm de largura e 9 cm de comprimento, foram utilizados como enxerto e fixados em um bloco de poliuretano de 40 PCF em cada uma de suas extremidades. Um grupo foi fixado apenas com parafusos de interferência de titânio (grupo 1) e o outro apenas com parafusos PLA impressos em 3D (BR 20 2021 018283-6 U2) (grupo 2). Os testes foram realizados utilizando uma máquina de teste universal eletromecânica EMIC DL 10.000 no modo de tração axial. Resultados O grupo 1 (titânio) obteve força máxima de 200 ± 7 N com deformação média do enxerto de 8 ± 2 mm, e a força máxima do grupo 2 (PLA) foi de 300 ± 30 N e deformação média do enxerto de 7 ± 3 mm. Ambos os parafusos de titânio e PLA forneceram boa fixação de enxerto no bloco de poliuretano, sem deslizamento ou deformação aparente. Em todas as amostras o teste culminou na ruptura do enxerto, com cerca de 20 mm de deformação em relação ao comprimento inicial. Conclusão O parafuso PLA impresso em 3D proporcionou boa fixação, semelhante à de sua contraparte de titânio, produzindo resultados satisfatórios e promissores.

Fratura idiopática de mandíbula atrófica / Idiopathic fracture of atrophic jaw / Fractura idiopática de mandíbula atrófica

Objetivo: Discorrer sobre o tratamento cirúrgico de uma fratura idiopática de mandíbula atrófica. Relato de caso: Idosa compareceu à emergência de um hospital referência em traumas na Paraíba relatando dificuldade ao se alimentar, impossibilidade de uso da prótese dentaria, sintomatologia dolorosa em região mandibular direita com processo infeccioso ativo, sem histórico de trauma direto em face. Ao exame tomográfico constatou-se fratura em mandíbula atrófica com presença de dente incluso na região. Diante do quadro, optou-se por iniciar antibioticoterapia empírica e planejou-se tratamento cirúrgico de reconstrução mandibular com sistema load-sharing, tendo auxílio de biomodelo para conformação prévia da placa. Conclusão: O correto planejamento e escolha do sistema de fixação são fundamentais para o sucesso do tratamento. O uso de biomodelo com pré modelagem de placa mostrou-se positivo por otimizar o tempo cirúrgico, reduzindo os riscos inerentes ao procedimento nesta faixa etária e a utilização de sistema capaz de suportar a carga sofrida na estrutura óssea comprometida nestes casos é mandatório... (AU)

Objective: to discuss the surgical treatment of an idiopathic fracture of the atrophic mandible. Case report: elderly woman attended the emergency department of the Emergency and Trauma Hospital Dom Luiz Gonzaga Fernandes, in Campina Grande, Brazil. The patient reported pain on eating and inability to use her denture as painful symptoms in the right mandibular region with active fistula, without any records of facial trauma. Tomographic examination revealed an atrophic mandibular fracture with an impacted tooth in the region. The following procedures were performed: antibiotic therapy, surgical fixation using a 2.4mm pre-molded plate, shaped using a biomodel, and fistulectomy. Conclusion: Thus, to plan accordingly aiming to minimize the surgical time and its associate damage and the use of appropriate fixation systems capable of supporting the load on the compromised bone are essential to a successful treatment, specially with elderly patients due their general health condition and preexistent comorbities... (AU)

Objetivo: Discutir sobre el tratamiento quirúrgico de una fractura idiopática de la mandíbula atrófica. Caso clínico: Anciana compareció al servicio de urgencias del Hospital de Emergencia y Trauma de Campina Grande Dom Luiz Gonzaga Fernandes, PB, relatando dificultad para alimentarse, imposibilidad de uso de prótesis dental, sintomatología dolorosa en la región mandibular derecha con fístula activa, sin antecedentes de traumatismo directo en la cara. El examen tomográfico presentó una fractura mandibular atrófica con presencia de un diente incluido en la región. Como resultado se realizó antibioticoterapia, procedimiento de fijación quirúrgica con una placa de 2,4 mm premoldeada en biomodelo y fistulectomía. Conclusión: De esta forma, el correcto planeamiento para minimizar el tiempo quirúrgico y los daños asociados, principalmente en los ancianos por su estado general de salud y comorbilidades preexistentes, la utilización de sistemas de fijación adecuados capaces de soportar la carga sufrida en los huesos comprometidos, es fundamental para el éxito del tratamiento... (AU)

Trueness of cone-beam computed tomography-derived skull models fabricated by different technology-based three-dimensional printers.

BACKGROUND: Three-dimensional (3D) printing is a novel innovation in the field of craniomaxillofacial surgery, however, a lack of evidence exists related to the comparison of the trueness of skull models fabricated using different technology-based printers belonging to different cost segments. METHODS: A study was performed to investigate the trueness of cone-beam computed tomography-derived skull models fabricated using different technology based on low-, medium-, and high-cost 3D printers. Following the segmentation of a patient's skull, the model was printed by: (i) a low-cost fused filament fabrication printer; (ii) a medium-cost stereolithography printer; and (iii) a high-cost material jetting printer. The fabricated models were later scanned by industrial computed tomography and superimposed onto the original reference virtual model by applying surface-based registration. A part comparison color-coded analysis was conducted for assessing the difference between the reference and scanned models. A one-way analysis of variance (ANOVA) with Bonferroni correction was applied for statistical analysis. RESULTS: The model printed with the low-cost fused filament fabrication printer showed the highest mean absolute error ([Formula: see text]), whereas both medium-cost stereolithography-based and the high-cost material jetting models had an overall similar dimensional error of [Formula: see text] and [Formula: see text], respectively. Overall, the models printed with medium- and high-cost printers showed a significantly ([Formula: see text]) lower error compared to the low-cost printer. CONCLUSIONS: Both stereolithography and material jetting based printers, belonging to the medium- and high-cost market segment, were able to replicate the skeletal anatomy with optimal trueness, which might be suitable for patient-specific treatment planning tasks in craniomaxillofacial surgery. In contrast, the low-cost fused filament fabrication printer could serve as a cost-effective alternative for anatomical education, and/or patient communication.

Application of 3D Printing Technology in the Treatment of Hoffa's Fracture Nonunion.

Objective To evaluate a proposed three-dimensional (3D) printing process of a biomodel developed with the aid of fused deposition modeling (FDM) technology based on computed tomography (CT) scans of an individual with nonunion of a coronal femoral condyle fracture (Hoffa's fracture). Materials and Methods Thus, we used CT scans, which enable the evaluation of the 3D volumetric reconstruction of the anatomical model, as well as of the architecture and bone geometry of sites with complex anatomy, such as the joints. In addition, it enables the development of the virtual surgical planning (VSP) in a computer-aided design (CAD) software. This technology makes it possible to print full-scale anatomical models that can be used in surgical simulations for training and in the choice of the best placement of the implant according to the VSP. In the radiographic evaluation of the osteosynthesis of the Hoffa's fracture nonunion, we assessed the position of the implant in the 3D-printed anatomical model and in the patient's knee. Results The 3D-printed anatomical model showed geometric and morphological characteristics similar to those of the actual bone. The position of the implants in relation to the nonunion line and anatomical landmarks showed great accuracy in the comparison of the patient's knee with the 3D-printed anatomical model. Conclusion The use of the virtual anatomical model and the 3D-printed anatomical model with the additive manufacturing (AM) technology proved to be effective and useful in planning and performing the surgical treatment of Hoffa's fracture nonunion. Thus, it showed great accuracy in the reproducibility of the virtual surgical planning and the 3D-printed anatomical model.

Effectiveness in Sterilization of Objects Produced by 3D Printing with Polylactic Acid Material: Comparison Between Autoclave and Ethylene Oxide Methods.

Objective Due to the popularity of 3D technology, surgeons can create specific surgical guides and sterilize them in their institutions. The aim of the present study is to compare the efficacy of the autoclave and ethylene oxide (EO) sterilization methods for objects produced by 3D printing with polylactic acid (PLA) material. Methods Forty cubic-shaped objects were printed with PLA material. Twenty were solid and 20 were hollow (printed with little internal filling). Twenty objects (10 solid and 10 hollow) were sterilized in autoclave, forming Group 1. The others (10 solid and 10 hollow) were sterilized in EO, composing Group 2. After sterilization, they were stored and referred to culture. Hollow objects of both groups were broken during sowing, communicating the dead space with the culture medium. The results obtained were statistically analyzed (Fisher exact test and residue analysis). Results In group 1 (autoclave), there was bacterial growth in 50% of solid objects and in 30% of hollow objects. In group 2 (EO), growth occurred in 20% of hollow objects, with no bacterial growth in solid objects (100% of negative samples). The bacteria isolated in the positive cases was non-coagulase-producing Staphylococcus Gram positive. Conclusions Sterilization by both autoclave and EO was not effective for hollow printed objects. Solid objects sterilized by autoclave did not demonstrate 100% of negative samples and were not safe in the present assay. Complete absence of contamination occurred only with solid objects sterilized by EO, which is the combination recommended by the authors.