4D polycarbonates via stereolithography as scaffolds for soft tissue repair.

3D printing has emerged as one of the most promising tools to overcome the processing and morphological limitations of traditional tissue engineering scaffold design. However, there is a need for improved minimally invasive, void-filling materials to provide mechanical support, biocompatibility, and surface erosion characteristics to ensure consistent tissue support during the healing process. Herein, soft, elastomeric aliphatic polycarbonate-based materials were designed to undergo photopolymerization into supportive soft tissue engineering scaffolds. The 4D nature of the printed scaffolds is manifested in their shape memory properties, which allows them to fill model soft tissue voids without deforming the surrounding material. In vivo, adipocyte lobules were found to infiltrate the surface-eroding scaffold within 2 months, and neovascularization was observed over the same time. Notably, reduced collagen capsule thickness indicates that these scaffolds are highly promising for adipose tissue engineering and repair.

Custo-benefício de diferentes impressoras 3D na Ortodontia / Cost-benefit of different 3d printers in orthodontics

Ao escolher uma impressora 3D para modelos odontológicos, a relação custo-benefício deve ser avaliada. Os modelos impressos devem ser acurados, precisos e eficientes quanto ao tempo, assim como financeiramente acessíveis. O objetivo deste estudo é comparar a acurácia, precisão, custo e tempo necessário para a preparação e impressão de modelos usando diferentes tecnologias: duas impressoras DLP (Digital Light Processing) e uma FFF (Fused Filament Fabrication) comparadas ao padrão-ouro (PolyJet). Para realização deste estudo, foram selecionados 10 escaneamentos de 5 pacientes, contendo a arcada superior e inferior. Todos os 10 modelos foram impressos usando a seguinte combinação de tecnologias: (1) DLP Moonray (MR), (2) DLP Anycubic (AC) (3) DLP Moonray com utilização de resina da Anycubic (MRA), (4) filamento UpMini 2 (FFF) e (5) PolyJet Eden 500 da Objet (PJ). Um dos modelos virtuais foi impresso adicionalmente quatro vezes consecutivas em cada impressora, de forma a permitir a avaliação da precisão destas. O arquivo .STL original de cada modelo foi superposto com o escaneamento do seu respectivo modelo impresso, gerando mapas de cores que permitiram o cálculo de RMS (média quadrática) para a comparação de ambos. Além deste método, foram realizadas medidas lineares através de um paquímetro digital em 8 variáveis diferentes: distância inter-caninos (DIC), distância inter-molares (DIM), plano ântero-posterior bilateralmente (PAP-D e PAP-E), plano vertical bilateralmente (PV-D e PV-E) e plano misto bilateralmente (PM-D e PM-E). O teste Shapiro-Wilk mostrou que os dados não eram normalmente distribuídos. O teste de Friedman com o post hoc de Bonferroni foi utilizado para verificar se havia diferenças entre os valores obtidos para as variáveis avaliadas. Uma diferença acima de 0,4 mm foi considerada clinicamente significante para as medidas lineares. Observou-se diferenças clínica e estatisticamente significantes (p < 0,05) para as seguintes comparações: PV-D e PV-E entre MR e MRA (p=0,00), PV-D entre FFF e MR (p=0,01), e PV-E entre FFF e MR (p=0,00). Já para o RMS, ocorreram diferenças estatisticamente significantes entre: AC e MR (p=0,00); AC e MRA (p=0,00); FFF e MR (p=0,01) e PJ e MR (p=0,01). Para as diferenças no RMS, nenhum valor esteve acima do considerado clinicamente significante (0,25 mm). Quando avaliada a precisão dos modelos pelas medidas lineares, observou-se diferença estatisticamente significativa apenas na variável PV-D entre FFF e AC (p=0,00). A mesma diferença foi vista para os valores de RMS em: AC e MR (p=0,02) e AC e MRA (p=0,04). As impressoras produziram resultados de qualidade similares, embora a Moonray com a resina da Anycubic tenha mostrado perda de acurácia e a Anycubic tenha problema de consistência no plano vertical. Dentre elas, a impressão em PolyJet foi considerada o método mais rápido, porém com o custo muito elevado. A impressão em FFF apresenta um custo baixo da impressora e dos insumos, no entanto com o tempo de impressão consideravelmente mais elevado. Em ambas as impressoras DLP houve um equilíbrio, resultando em um bom custo-benefício(AU)

When choosing a 3D printer for dental models, cost-benefit should be evaluated. Printed models should be accurate, precise and time efficient, as well as financially accessible. The aim of this study is to compare the accuracy, precision, cost and time required for preparation and printing using different technologies: two DLP (Digital Light Processing) printers, and one FFF (Fused Filament Fabrication) compared to the gold standard (PolyJet). For this study, it was selected 10 intraoral scans of 5 patients. All 10 models were printed as follows: (1) DLP printer Moonray (MR), (2) DLP printer Anycubic (AC) (3) DLP printer Moonray with Anycubic resin (MRA), (4) filament printer UpMini 2 (FFF) and (5) PolyJet printer Objet eden500 (PJ). One of the virtual models was additionally printed four consecutive times on each printer to allow consistency assessment. The original .STL file of each model was superimposed by scanning its respective printed model, generating color maps that allowed the RMS (root mean square) calculation for the comparison of both models. In addition, linear measurements were performed using a digital caliper on 8 different variables: inter-canine distance (ICD), inter-molar distance (IMD), bilateral anteroposterior plane (APP-R and APP-L), bilateral vertical plane (VP-R and VP-L) and bilateral mixed plan (MP-R and MP-L). The Shapiro-Wilk test showed that the data was not normally distributed. Friedman's test with Bonferroni's post hoc test was used to verify if there were differences between the evaluated variables. A difference above 0.4 mm was considered clinically significant for linear measurements. Clinically and statistically significant differences (p <0.05) were observed for the following comparisons: VP-R and VP-L between MR and MRA (p = 0.00), VP-R between FFF and MR (p = 0.01), VP-L between FFF and MR (p = 0.00). For RMS, there were statistically significant differences between: AC and MR (p = 0.00); AC and MRA (p = 0.00); FFF and MR (p = 0.01) and PJ and MR (p = 0.00). For the differences in RMS, no value was above the clinical significancy threshold (0.25mm). When the consistency of the models by the linear measurements was evaluated, a statistically significant difference was observed only in the VP-R variable between FFF and AC (p = 0.00). The same difference was seen for the RMS values in: AC and MR (p = 0.02) and AC and MRA (p = 0.04). The printers produced similar quality results, although Moonray with Anycubic resin showed loss of accuracy and Anycubic has a consistency problem in vertical plane. Among them, PolyJet printing was considered the fastest one, but with the highest cost. FFF printing has a low printer and filament cost, but with considerably longer printing times. In both DLP printers there was a balance, resulting in a good cost-benefit(AU)

Optical stereolithography of antifouling zwitterionic hydrogels.

This paper reports the rapid 3D printing of tough (toughness, UT, up to 141.6 kJ m-3), highly solvated (φwater∼ 60 v/o), and antifouling hybrid hydrogels for potential uses in biomedical, smart materials, and sensor applications, using a zwitterionic photochemistry compatible with stereolithography (SLA). A Design of Experiments (DOE) framework was used for systematically investigating the multivariate photochemistry of SLA generally and, specifically, to determine an aqueous SLA system with an additional zwitterionic acrylate, which significantly increases the gelation rate, and the resilience of the resulting hybrid hydrogels relative to an equivalent non-ionic polyacrylamide hydrogel. Specifically, the resulting zwitterionic hybrid hydrogels (Z-gels) can be tuned over a large range of ultimate strains, ca. 0.5 < γult < 5.0, and elastic moduli, ca. 10 < E < 1000 kPa, while also demonstrating a high resilience under cyclic tensile loading. Importantly, unlike traditional chemistry, increasing the elastic modulus of the Z-gels does not necessarily reduce the ultimate strain. Moreover, the Z-gels can be rapidly printed using a desktop commercial SLA 3D printer, with relatively low photoirradiation dosages of visible light (135 to 675 mJ cm-2 per 50-100 µm layer). Compared with the counterpart polyacrylamide hydrogels, the Z-gels have greater antifouling properties and exhibit 58.2% less absorption of bovine serum albumin.

Feasibility of Clinician-Facilitated Three-Dimensional Printing of Synthetic Cranioplasty Flaps.

BACKGROUND: Integration of three-dimensional (3D) printing and stereolithography into clinical practice is in its nascence, and concepts may be esoteric to the practicing neurosurgeon. Currently, creation of 3D printed implants involves recruitment of offsite third parties. We explored a range of 3D scanning and stereolithographic techniques to create patient-specific synthetic implants using an onsite, clinician-facilitated approach. METHODS: We simulated bilateral craniectomies in a single cadaveric specimen. We devised 3 methods of creating stereolithographically viable virtual models from removed bone. First, we used preoperative and postoperative computed tomography scanner-derived bony window models from which the flap was extracted. Second, we used an entry-level 3D light scanner to scan and render models of the individual bone pieces. Third, we used an arm-mounted, 3D laser scanner to create virtual models using a real-time approach. RESULTS: Flaps were printed from the computed tomography scanner and laser scanner models only in a ultraviolet-cured polymer. The light scanner did not produce suitable virtual models for printing. The computed tomography scanner-derived models required extensive postfabrication modification to fit the existing defects. The laser scanner models assumed good fit within the defects without any modification. CONCLUSIONS: The methods presented varying levels of complexity in acquisition and model rendering. Each technique required hardware at varying in price points from $0 to approximately $100,000. The laser scanner models produced the best quality parts, which had near-perfect fit with the original defects. Potential neurosurgical applications of this technology are discussed.