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.

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.

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.

Use of individualized 3D-printed models of pancreatic cancer to improve surgeons' anatomic understanding and surgical planning.

OBJECTIVES: Three-dimensional (3D) printing has been increasingly used to create accurate patient-specific 3D-printed models from medical imaging data. We aimed to evaluate the utility of 3D-printed models in the localization and understanding of pancreatic cancer for surgeons before pancreatic surgery. METHODS: Between March and September 2021, we prospectively enrolled 10 patients with suspected pancreatic cancer who were scheduled for surgery. We created an individualized 3D-printed model from preoperative CT images. Six surgeons (three staff and three residents) evaluated the CT images before and after the presentation of the 3D-printed model using a 7-item questionnaire (understanding of anatomy and pancreatic cancer [Q1-4], preoperative planning [Q5], and education for trainees or patients [Q6-7]) on a 5-point scale. Survey scores on Q1-5 before and after the presentation of the 3D-printed model were compared. Q6-7 assessed the 3D-printed model's effects on education compared to CT. Subgroup analysis was performed between staff and residents. RESULTS: After the 3D-printed model presentation, survey scores improved in all five questions (before 3.90 vs. after 4.56, p < 0.001), with a mean improvement of 0.57‒0.93. Staff and resident scores improved after a 3D-printed model presentation (p < 0.05), except for Q4 in the resident group. The mean difference was higher among the staff than among the residents (staff: 0.50‒0.97 vs. residents: 0.27‒0.90). The scores of the 3D-printed model for education were high (trainees: 4.47 vs. patients: 4.60) compared to CT. CONCLUSION: The 3D-printed model of pancreatic cancer improved surgeons' understanding of individual patients' pancreatic cancer and surgical planning. CLINICAL RELEVANCE STATEMENT: The 3D-printed model of pancreatic cancer can be created using a preoperative CT image, which not only assists surgeons in surgical planning but also serves as a valuable educational resource for patients and students. KEY POINTS: • A personalized 3D-printed pancreatic cancer model provides more intuitive information than CT, allowing surgeons to better visualize the tumor's location and relationship to neighboring organs. • In particular, the survey score was higher among staff who performed the surgery than among residents. • Individual patient pancreatic cancer models have the potential to be used for personalized patient education as well as resident education.

[Percutaneous kyphoplasty assisted by three dimensional printing percutaneous guide plate for the treatment of osteoporotic vertebral compression fractures].

OBJECTIVE: To verify the safety of three dimensional printing percutaneous guide plate assisted percutaneous kyphoplasty(PKP) in the treatment of osteoporotic vertebral compression fractures(OVCFs). METHODS: The clinical data of 60 patients with OVCFs treated by PKP from November 2020 to August 2021 were retrospectively analyzed. There were 24 males and 36 females, aged from 72 to 86 years old with an average of (76.5±7.9) years. Routine percutaneous kyphoplasty was performed in 30 cases (conventional group) and three dimensional printing percutaneous guide plate assisted PKP was performed in 30 cases (guide plate group). Intraoperative pedicle puncture time (puncture needle to posterior vertebral body edge) and number of fluoroscopy, total operation time, total number of fluoroscopy, amount of bone cement injection, and complication (spinal canal leakage of bone cement) were observed. The visual analogue scale (VAS) and the anterior edge compression rate of the injured vertebra were compared before operation and 3 days after operation between two groups. RESULTS: All 60 patients were successfully operated without complication of spinal canal leakage of bone cement. In the guide plate group, the pedicle puncture time was(10.23±3.15) min and the number of fluoroscopy was(4.77±1.07) times, the total operation time was (33.83±4.21) min, the total number of fluoroscopy was(12.27±2.61) times;and in the conventional group, the pedicle puncture time was (22.83±3.09) min and the number of fluoroscopy was (10.93±1.62) times, the total operation time was(44.33±3.57) min, the total number of fluoroscopy was(19.20±2.67) times. There were statistically significant differences in the pedicle puncture time, intraoperative number of fluoroscopy, the total operation time, and the total number of fluoroscopy between the two groups(P<0.05). There was no significant difference in amount of bone cement injection between the two groups(P>0.05). There were no significant differences in VAS and the anterior edge compression rate of the injured vertebra at 3 days after operation between two groups(P>0.05). CONCLUSION: Three dimensional printing percutaneous guide plate assisted percutaneous kyphoplasty is safe and reliable, which can reduce the number of fluoroscopy, shorten the operation time, and decrease the radiation exposure of patients and medical staff, and conforms to the concept of precise orthopaedic management.

Colour stability of 3D-Printed orthodontic brackets using filled resins.

OBJECTIVE: To determine the effect of common beverages and accelerated aging on the colour stability of filled resins, which could potentially be used for fabrication of 3D-printed orthodontic brackets. MATERIALS AND METHODS: GR-17.1 (shades A1, A2, and A3), and GR-10 Guide resins (pro3dure medical, Eden Prairie, MN) were printed on an Asiga MAX UV printer into discs 2 mm thick, with a diameter of 10 mm, and then post-print processed as per manufacturer's instructions. Discs were immersed in 5 mL of coffee, tea, red wine, or distilled water for 7 days. Another group was subjected to accelerated aging in accordance with ISO Standard 4892-2. Ten samples were produced per resin, per treatment condition. Colour measurements were taken on the discs before and after treatment using a spectrophotometer against white and black reference tiles to assess colour and translucency differences with the CIEDE2000 colour difference formula. RESULTS: While initial colour of the printed resin discs was acceptable, all resin groups underwent significant colour change during the experiment. Red wine and coffee produced the greatest colour and translucency change, followed by tea, with accelerated aging producing the least change in colour and translucency. CONCLUSION: The 3D-printed resins tested underwent significant changes in colour and translucency following exposure to endogenous and exogenous sources of staining, which may affect their acceptability for fabrication of aesthetic orthodontic brackets.

Effect of slice thickness of 3D printer in fabrication of surgical guide on the accuracy of dental implant placement.

Introduction This study aimed to assess the effect of slice thickness of 3D printer in fabrication of surgical guide (SG) on the accuracy of dental implant placement. Materials and Methods After preparation of two dry human mandibles, Cone-beam computed tomography (CBCT) scans were obtained, and the location and direction of implants in the edentulous ridge of the mandible were identified using Romexis software. Data in STL format were transferred to a 3D printer and two SGs with 50 µm and 100 µm thicknesses were fabricated for each mandible. Drilling was performed using two SGs. The pre- and post-intervention CBCT scans were superimposed to measure the magnitude of differences. The two groups were compared using the Mann-Whitney U test. Results No significant difference was noted in SGs with 50 and 100 µm thicknesses in the coronal and apical regions of the implants or the depth of drilling. However, the difference in angular deviation was statistically significant. Conclusion Considering the higher accuracy of SGs with 50 µm thickness (despite the presence of a significant difference in AD between the SGs with different thicknesses), it is recommended to use a SG with 50 µm thickness in cases where anatomical limitations exist.

Effectiveness in Sterilization of Objects Produced by 3D Printing with Polylactic Acid Material: Comparison Between Autoclave and Ethylene Oxide Methods / Eficácia na esterilização de objetos produzidos pela impressão 3D com material ácido polilático: Comparação entre os métodos autoclave e óxido de etileno

Abstract 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.

Resumo Objetivo Devido à popularidade da tecnologia 3D, cirurgiões podem criar guias cirúrgicos específicos e esterilizá-los nas suas instituições. O objetivo do presente estudo é comparar a eficácia dos métodos de esterilização por autoclave e óxido de etileno (OE) de objetos produzidos pela impressão 3D com material ácido polilático (PLA, na sigla em inglês). Métodos Quarenta objetos em formato cúbico foram impressos com material de PLA. Vinte eram sólidos e 20 eram ocos (impressos com pouco enchimento interno). Vinte objetos (10 sólidos e 10 ocos) foram esterilizados em autoclave, formando o Grupo 1. Os demais (10 sólidos e 10 ocos) foram esterilizados em OE, compondo o Grupo 2. Após a esterilização, os objetos foram armazenados e encaminhados para cultura. Objetos ocos de ambos os grupos foram quebrados durante a semeadura, comunicando o espaço morto com o meio de cultura. Os resultados obtidos foram analisados estatisticamente (teste exato de Fisher e análise de resíduo). Resultados No grupo 1 (autoclave) houve crescimento bacteriano em 50% dos objetos sólidos e em 30% dos objetos ocos. No grupo 2 (OE) o crescimento ocorreu em 20% dos objetos ocos, com ausência de crescimento bacteriano nos objetos sólidos (100% de amostras negativas). A bactéria isolada nos casos positivos foi Staphylococcus Gram positivo não produtor de coagulase. Conclusões A esterilização tanto em autoclave quanto pelo OE não foi eficaz para objetos impressos no formato oco. Objetos sólidos esterilizados em autoclave não demonstraram 100% de amostras negativas, não sendo seguro no presente ensaio. Ausência completa de contaminação ocorreu apenas com objetos sólidos esterilizados pelo OE, sendo a combinação recomendada pelos autores.

Application of 3D Printing Technology in the Treatment of Hoffa's Fracture Nonunion / Aplicação da tecnologia de impressão 3D no tratamento da pseudartrose da fratura de Hoffa

Abstract 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.

Resumo Objetivo Avaliar uma proposta de processo de impressão tridimensional (3D) de um biomodelo preparado com o auxílio da tecnologia de modelagem por deposição de material fundido (fused deposition modeling, FDM, em inglês) a partir de imagens de tomografia computadorizada (TC) de um indivíduo com pseudartrose de fratura coronal do côndilo femoral (fratura de Hoffa). Materiais e Métodos Para tanto, utilizamos imagens de TC, que permitem estudar a reconstrução volumétrica 3D do modelo anatômico, além da arquitetura e geometria óssea de sítios de anatomia complexa, como as articulações. Também permite o planejamento cirúrgico virtual (PCV) em um programa de desenho assistido por computador (computer-aided design, CAD, em inglês). Essa tecnologia possibilita a impressão de modelos anatômicos em escala real que podem ser utilizados em simulações cirúrgicas para o treinamento e a escolha do melhor posicionamento do implante de acordo com o PCV. Na avaliação radiográfica da osteossíntese da pseudartrose de Hoffa, verificou-se a posição do implante no modelo anatômico impresso em 3D e no joelho do paciente. Resultados O modelo anatômico impresso em 3D apresentou características geométricas e morfológicas semelhantes às do osso real. O posicionamento dos implantes em relação à linha de pseudartrose e pontos anatômicos foram bastante precisos na comparação do joelho do paciente com o modelo anatômico impresso em 3D. Conclusão A utilização do modelo anatômico virtual e do modelo anatômico impresso em 3D com a tecnologia de manufatura aditiva (MA) foi eficaz e auxiliou o planejamento e a realização do tratamento cirúrgico da pseudartrose da fratura de Hoffa. Desta forma, foi bastante preciso na reprodutibilidade do planejamento cirúrgico tanto virtual quanto no modelo anatômico impresso em 3D.

Desenvolvimento de dentes decíduos artificiais para práticas laboratoriais em Odontopediatria / Desarrollo de dientes temporales artificiales para prácticas de laboratorio en Odontopediatría / Development of artificial primary teeth for laboratory practices in Pediatric Dentistry

Na formação em Odontologia os acadêmicos realizam treinos pré-clínicos para aperfeiçoar suas técnicas. O objetivo deste estudo é relatar a experiência de produção de dentes decíduos artificiais por impressão tridimensional (3D), com baixo custo, para práticas laboratoriais acadêmicas em Odontopediatria. Partiu-se de uma pesquisa laboratorial e experimental, tendo sido realizada uma revisão bibliográfica para obtenção dos dados. A obtenção das imagens 3D se deu a partir da biblioteca gratuita de dentes permanentes Brenner e edição no programa Meshmixer para incorporação das características de dentes decíduos, seguida de impressão 3D utilizando estereolitografia. Posteriormente, foram preenchidos os condutos radiculares com cera 7 e poliacetato de vinila (PVA)vermelha. Foi realizada também a pintura do cemento e da coroa, com tinta de esmalte marrom e branca, respectivamente. As duas resinas exibiram fidelidade anatômica externa, entretanto, para viabilidade do uso na Endodontia, foi analisada a anatomia interna, imagem radiográfica, tempo de impressão, custo de produção e custo/benefício. A combinação de resina Anycubic para a representação dos tecidos mineralizados com cera 7 para simulação da polpa possibilitou a adequada reprodução da anatomia interna de dentes decíduos (AU).

En la formación en Odontología, los alumnos realizan una formación preclínica para mejorar sus técnicas. El objetivo de este estudio es relatar la experiencia de producción de dientes temporales artificiales por impresión tridimensional (3D), a bajo costo,para prácticas académicas de laboratorio en Odontopediatría. Se inició con una investigación de laboratorio y experimental, habiéndose realizado una revisión bibliográfica para la obtención de los datos. Las imágenes 3D se obtuvieran de la biblioteca gratuita de dientes permanentes de Brenner y se editó en el programa Meshmixer para incorporar las características de los dientes temporales, seguida de una impresión 3D mediante estereolitografía. Posteriormente se obturaron los conductos radiculares con cera7 y acetato de polivinilo rojo (PVA). El cemento y la corona también se pintaron con pintura de esmalte marrón y blanco, respectivamente. Las dos resinas exhibieron fidelidad anatómica externa, sin embargo, para la factibilidad de uso en Endodoncia se analizó la anatomía interna, imagen radiográfica, tiempo de impresión, costo de producción y costo/beneficio. La combinación de la resina Anycubic para la representación de tejidos mineralizados con la cera 7 para la simulación de la pulpa permitió reproduciradecuadamente la anatomía interna de los dientes temporales (AU).

During Dentistry training, students undertake pre-clinical training to improve their techniques. The objective of this study is to report the experience of producing artificial deciduous teeth using three-dimensional (3D) printing, at low cost, for academic laboratory practices in Pediatric Dentistry. The starting point was laboratory and experimental research, and a bibliographic review was carried out to obtain data. The 3D images were obtained from the free Brenner permanent teeth library and edited in the Meshmixer program to incorporate the characteristics of deciduous teeth, followed by 3D printing using stereolithography. Subsequently, the root canals were filled with wax 7 and red polyvinyl acetate (PVA). The cementum and crown were also painted with brown and white enamel paint, respectively. The two resins exhibited external anatomical fidelity, however, for feasibility of use in Endodontics, the internal anatomy, radiographic image, printing time, production cost and cost/benefit were analyzed. The combination of Anycubic resin to represent mineralized tissues with wax 7 to simulate the pulp made it possible to adequately reproduce the internal anatomy of deciduous teeth (AU).

Low-cost and open-source three-dimensional (3D) printing in neurosurgery: A pilot experiment using direct drive modification to produce multi-material neuroanatomical models.

BACKGROUND: 3-dimensional (3D) printing carries a genuine potential for pre-operative planning in neurosurgery. Entry-level 3D printers offer practicality in low resource settings, but are often limited by the range of filament materials as well as the capability of open-source segmentation software. OBJECTIVE: We intended to demonstrate that 3D printing of neuroanatomical structures is possible using an entry-level 3D printer equipped with the direct drive (DD) modification, which supported flexible filaments, with the models segmented using an open-source software. METHODS: A DD system was installed onto the Ender 3 Pro printer. An attempt to print neurosurgical models using a low-cost 3D printer was conducted, where four patient-based neuroanatomical models were printed: skull base-vasculature, skull base-tumour, cervical spine, and ventricular system. The results were discussed and compared to similar endeavours in past literature. RESULTS: Although DD installation was challenging and led to vibration and longer print time, which ultimately warranted an inferior printing speed, DD system enabled the printing with thermoplastic polyurethane (TPU), a versatile elastomer; in addition to producing equal amount of detail to those printed with high-end printers and advanced image segmentation software. Fitting the frame well, changing infill type, and avoiding warping and stringing will improve print quality with the DD system. CONCLUSION: 3D printing with entry-level 3D printers equipped with DD system has been proven to be a reliable way of accurately reproducing patient-specific neuroanatomical constructs. Follow-up studies are necessary to implement 3D printing for neurosurgical planning in low-resource settings.

Minimal invasiveness at dental implant placement: A systematic review with meta-analyses on flapless fully guided surgery.

Flapless and fully guided implant placement has the potential to maximize efficacy outcomes and at the same time to minimize surgical invasiveness. The aim of the current systematic review was to answer the following PICO question: "In adult human subjects undergoing dental implant placement (P), is minimally invasive flapless computer-aided fully guided (either dynamic or static computer-aided implant placement (sCAIP)) (I) superior to flapped conventional (free-handed implant placement (FHIP) or cast-based/drill partially guided implant placement (dPGIP)) surgery (C), in terms of efficacy, patient morbidity, long-term prognosis, and costs (O)?" Randomized clinical trials (RCTs) fulfilling specific inclusion criteria established to answer the PICO question were included. Two review authors independently searched for eligible studies, screened the titles and abstracts, performed full-text analysis, extracted the data from the published reports, and performed the risk of bias assessment. In cases of disagreement, a third review author took the final decision during ad hoc consensus meetings. The study results were summarized using random effects meta-analyses, which were based (wherever possible) on individual patient data (IPD). A total of 10 manuscripts reporting on five RCTs, involving a total of 124 participants and 449 implants, and comparing flapless sCAIP with flapped FHIP/cast-based partially guided implant placement (cPGIP), were included. There was no RCT analyzing flapless dynamic computer-aided implant placement (dCAIP) or flapped dPGIP. Intergroup meta-analyses indicated less depth deviation (difference in means (MD) = -0.28 mm; 95% confidence interval (CI): -0.59 to 0.03; moderate certainty), angular deviation (MD = -3.88 degrees; 95% CI: -7.00 to -0.77; high certainty), coronal (MD = -0.6 mm; 95% CI: -1.21 to 0.01; low certainty) and apical (MD = -0.75 mm; 95% CI: -1.43 to -0.07; moderate certainty) three-dimensional bodily deviations, postoperative pain (MD = -17.09 mm on the visual analogue scale (VAS); 95% CI: -33.38 to -0.80; low certainty), postoperative swelling (MD = -6.59 mm on the VAS; 95% CI: -19.03 to 5.85; very low certainty), intraoperative discomfort (MD = -9.36 mm on the VAS; 95% CI: -17.10 to -1.61) and surgery duration (MD = -24.28 minutes; 95% CI: -28.62 to -19.95) in flapless sCAIP than in flapped FHIP/cPGIP. Despite being more accurate than flapped FHIP/cPGIP, flapless sCAIP still resulted in deviations with respect to the planned position (intragroup meta-analytic means: 0.76 mm in depth, 2.57 degrees in angular, 1.43 mm in coronal, and 1.68 in apical three-dimensional bodily position). Moreover, flapless sCAIP presented a 12% group-specific intraoperative complication rate, resulting in an inability to place the implant with this protocol in 7% of cases. Evidence regarding more clinically relevant outcomes of efficacy (implant survival and success, prosthetically and biologically correct positioning), long-term prognosis, and costs, is currently scarce. When the objective is to guarantee minimal invasiveness at implant placement, clinicians could consider the use of flapless sCAIP. A proper case selection and consideration of a safety margin are, however, suggested.

Percutaneous kyphoplasty assisted by three dimensional printing percutaneous guide plate for the treatment of osteoporotic vertebral compression fractures / 中国骨伤

OBJECTIVE@#To verify the safety of three dimensional printing percutaneous guide plate assisted percutaneous kyphoplasty(PKP) in the treatment of osteoporotic vertebral compression fractures(OVCFs).@*METHODS@#The clinical data of 60 patients with OVCFs treated by PKP from November 2020 to August 2021 were retrospectively analyzed. There were 24 males and 36 females, aged from 72 to 86 years old with an average of (76.5±7.9) years. Routine percutaneous kyphoplasty was performed in 30 cases (conventional group) and three dimensional printing percutaneous guide plate assisted PKP was performed in 30 cases (guide plate group). Intraoperative pedicle puncture time (puncture needle to posterior vertebral body edge) and number of fluoroscopy, total operation time, total number of fluoroscopy, amount of bone cement injection, and complication (spinal canal leakage of bone cement) were observed. The visual analogue scale (VAS) and the anterior edge compression rate of the injured vertebra were compared before operation and 3 days after operation between two groups.@*RESULTS@#All 60 patients were successfully operated without complication of spinal canal leakage of bone cement. In the guide plate group, the pedicle puncture time was(10.23±3.15) min and the number of fluoroscopy was(4.77±1.07) times, the total operation time was (33.83±4.21) min, the total number of fluoroscopy was(12.27±2.61) times;and in the conventional group, the pedicle puncture time was (22.83±3.09) min and the number of fluoroscopy was (10.93±1.62) times, the total operation time was(44.33±3.57) min, the total number of fluoroscopy was(19.20±2.67) times. There were statistically significant differences in the pedicle puncture time, intraoperative number of fluoroscopy, the total operation time, and the total number of fluoroscopy between the two groups(P<0.05). There was no significant difference in amount of bone cement injection between the two groups(P>0.05). There were no significant differences in VAS and the anterior edge compression rate of the injured vertebra at 3 days after operation between two groups(P>0.05).@*CONCLUSION@#Three dimensional printing percutaneous guide plate assisted percutaneous kyphoplasty is safe and reliable, which can reduce the number of fluoroscopy, shorten the operation time, and decrease the radiation exposure of patients and medical staff, and conforms to the concept of precise orthopaedic management.

Biomechanical evaluation of four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs

ABSTRACT Purpose: This study compared, through biomechanical evaluation under ventral flexion load, four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs. Methods: In total, 28 identical atlantoaxial joint models were created by digital printing from computed tomography images of a dog, and the specimens were divided into four groups of seven. In each group, a different technique for ventral stabilization of the atlantoaxial joint was performed: transarticular lag screws, polyaxial screws, multiple screws and bone cement (polymethylmethacrylate-PMMA), and atlantoaxial plate. After the stabilization technique, biomechanical evaluation was performed under ventral flexion load, both with a predefined constant load and with a gradually increasing load until stabilization failure. Results: All specimens, regardless of stabilization technique, were able to support the predefined load without failing. However, the PMMA method provided significant more rigidity (p ≤ 0.05) and also best resisted the gradual increase in load, supporting a significantly higher maximum force (p ≤ 0.05). There was no statistical difference in flexural strength between the transarticular lag screws and plate groups. The polyaxial screws method was significantly less resistant to loading (p ≤ 0.05) than the other groups. Conclusions: The PMMA technique had biomechanical advantages in ventral atlantoaxial stabilization over the other evaluated methods.