Printable oxygen-generating biodegradable scaffold for thicker tissue-engineered medical products.

BACKGROUND: Due to the increasing demand to generate thick and vascularized tissue-engineered constructs, novel strategies are currently being developed. An effective example is the fabrication of a 3D scaffold containing oxygen-releasing biomaterials to solve the limitations of gas diffusion and transport within transplanted tissues or devices. METHODS: In this study, we developed a biodegradable scaffold made of polycaprolactone (PCL) mixed with oxygen-generating calcium peroxide (CPO) to design new structures for regenerative tissue using a 3D printer capable of forming arbitrarily shapes. RESULTS AND CONCLUSION: When osteoblast progenitor cells (MC3T3-E1 cells) were cultured under hypoxic conditions on scaffolds fabricated with this technique, it was shown that cell death was reduced by the new scaffolds. Therefore, the results suggest that 3D-printed scaffolds made from biodegradable oxygen-releasing materials may be useful for tissue engineering and regeneration.

Pulmonary evaluation of whole-body inhalation exposure of polycarbonate (PC) filament 3D printer emissions in rats.

During fused filament fabrication (FFF) 3D printing with polycarbonate (PC) filament, a release of ultrafine particles (UFPs) and volatile organic compounds (VOCs) occurs. This study aimed to determine PC filament printing emission-induced toxicity in rats via whole-body inhalation exposure. Male Sprague Dawley rats were exposed to a single concentration (0.529 mg/m3, 40 nm mean diameter) of the 3D PC filament emissions in a time-course via whole body inhalation for 1, 4, 8, 15, and 30 days (4 hr/day, 4 days/week), and sacrificed 24 hr after the last exposure. Following exposures, rats were assessed for pulmonary and systemic responses. To determine pulmonary injury, total protein and lactate dehydrogenase (LDH) activity, surfactant proteins A and D, total as well as lavage fluid differential cells in bronchoalveolar lavage fluid (BALF) were examined, as well as histopathological analysis of lung and nasal passages was performed. To determine systemic injury, hematological differentials, and blood biomarkers of muscle, metabolic, renal, and hepatic functions were also measured. Results showed that inhalation exposure induced no marked pulmonary or systemic toxicity in rats. In conclusion, inhalation exposure of rats to a low concentration of PC filament emissions produced no significant pulmonary or systemic toxicity.

3D printing in pediatric neurosurgery: experimental study of a novel approach using biodegradable materials.

PURPOSE: 3D printing technologies have become an integral part of modern life, and the most routinely used materials in reconstructive surgery in children are biodegradable materials. The combination of these two technologies opens up new possibilities for the application of innovative methods in neurosurgery and a patient-centered approach in medical care. The aim of the study was to determine whether a physician without specialized programming and printing skills could independently create materials in a clinical setting for the treatment of patients. METHODS: We conducted a preclinical study on 15 male Balb-C mice. Cylindrical materials made of polylactic acid (PLA) plastic were 3D printed. Sterilization of the obtained material was performed using a cold plasma sterilizer with hydrogen peroxide vapor and its plasma. The sterile material was implanted subcutaneously into the mice for 30 days, followed by histological examination. Using open-source software for modeling and printing, plates and screws made of PLA plastic were manufactured. The produced components were tested in the biomedical laboratory of the institute. RESULTS: The histological material showed that no inflammatory changes were observed at the implantation site during the entire observation period. The cellular composition is mainly represented by macrophages and fibroblasts. There was a gradual resolution of the material and its replacement by native tissues. Research conducted to assess the effectiveness of material sterilization in a cold plasma sterilizer demonstrated its high bactericidal efficiency. CONCLUSION: The method we developed for obtaining biodegradable plates and fixation elements on a 3D printer is easy to use and has demonstrated safety in a preclinical study on an animal model.

Digital application of three-dimensional diagnosis and treatment with a virtual articulator.

OBJECTIVE: The purpose of this article was to introduce a method for the digital application of three-dimensional (3D) diagnosis and treatment with a virtual articulator and 3D data. CLINICAL CONSIDERATION: With the use of cone-beam computed tomography (CBCT) and intraoral and facial scans, we can create a virtual articulator and evaluate the mandibular position in maximum intercuspation and centric-related occlusion for the patient with an unstable occlusion and temporomandibular disorders (TMD). Based on this, we treated a case using a digital mandibular position indicator (MPI) and fabricated a stabilization splint using a 3D printer. This approach eliminates the traditional impression or model mounting process and the analog face bow transfer. Furthermore, the design of the stabilization splint is accomplished using software. CONCLUSIONS: The approach outlined in this article offers the potential for a digital diagnosis and treatment process by seamlessly integrating CBCT, intraoral scans, and facial scans with a high degree of accuracy. This may enhance precision in diagnosis and treatment planning, especially for patients with complicated TMD, in addition to facilitating effective communication with orthodontic patients who require thorough attention. CLINICAL SIGNIFICANCE: Utilizing a virtual articulator and digital MPI for the occlusal evaluation of patients with TMD and unstable occlusion makes it possible to diagnose and analyze the occlusal condition accurately. This approach also allows for precision and efficiency in treatment.

Evaluation of digital and manual orthodontic diagnostic setups in non-extraction cases using ABO model grading system: an in-vitro study.

BACKGROUND: To evaluate the outcome quality of manual and digital orthodontic diagnostic setups in non-extraction cases according to the American Board of Orthodontics model grading system and to calculate the laboratory time needed for orthodontic diagnostic setup construction. METHODS: The sample consisted of 60 pretreatment models of non-extraction orthodontic cases with age ranges of 18-30. The study models were duplicated and scanned with 3Shape R-750 scanner. Digital and manual diagnostic setups were constructed according to their respective treatment plans. Digital diagnostic setups were 3D printed and then both manual and digital setups were assessed using the modified American Board of Orthodontics Cast Radiograph evaluation score (ABO CRE), which includes alignment, marginal ridge, buccolingual inclination, occlusal contacts, occlusal relationships, interproximal contacts, and overjet. The laboratory time needed for orthodontic setups was measured in minutes. RESULTS: The total ABO CRE score of the digital diagnostic setup group (5.93 ± 2.74) was significantly lower than that of the manual diagnostic setup group (13.08 ± 3.25). The manual diagnostic setup had significantly larger scores in marginal ridge, overjet, overbite, buccolingual inclination, occlusal relationship, and total scores (P < 0.01). However, the digital diagnostic setup had a statistically larger occlusal contacts score than the manual diagnostic setup (P < 0.01). There was no significant difference between the alignment and the interproximal contacts scores in either group. The manual diagnostic setup needed significantly longer laboratory time (187.8 ± 14.22) than the digital setup (93.08 ± 12.65) (P < 0.01). Comparison between broken teeth was performed by using the chi-square test which found no significant difference between different tooth types. CONCLUSIONS: Digital diagnostic setup is a reliable tool for orthodontic diagnostic setup construction providing excellent quality setup models. Manual diagnostic setup is time consuming with a technique-sensitive laboratory procedure.

Evaluation of a new 3D-printed tooth model allowing preoperative ICDAS assessment and caries removal.

INTRODUCTION: Teaching caries lesion management with operative care requires tooth models with highly realistic anatomical detail and caries lesions that can be assessed using ICDAS. This study aimed to develop and evaluate a new 3D-printed teeth model for ICDAS assessment and caries removal for pre-clinical hands-on education. METHODS: Printable tooth with different layers for enamel, dentin and carious lesions was designed and tested by 31 dental students. They were asked to visually and radiologically assess the ICDAS severity of the simulated carious lesions, establish the therapeutic strategy according to CariesCare 4D, and perform a qualitative assessment of the models based on five-point Likert scale items. RESULTS: Concerning carious lesions, the texture was realistic, and the shade was adequate for 94% and 97% of the participants. Ninety per cent of the participants found the model adequate to perform an ICDAS visual assessment. Seventy-four per cent of the students found the hardness adequate. Concerning the difference in shade and the noticeable hardness difference between enamel and dentin, participants have mixed agreement with a proportion of 61% and 55%, respectively. All the participants agreed these 3D-printed models provide a good caries simulation, are suitable for hands-on operative dentistry courses, and that learning outcomes better than the standard model. CONCLUSION: The present work shows that rapid prototyping paves the way for customized educational models capable of supporting operative but also preoperative skills. 3D printing opens up new opportunities by reducing the gap between pre-clinical training and clinical reality in caries management, which can positively impact the quality of patient care.

3D-printed custom tray for maxillofacial implant assisted partial denture.

This technique presents a new fabrication workflow for a three-dimensional (3D) printed custom tray, which duplicates the morphology of the treatment denture for maxillofacial prostheses using an intraoral scanner, computer-aided design (CAD) software, and a 3D printer. A 70-year-old man underwent reconstruction of segmental mandibulectomy for mandibular osteoblastoma, followed by implant placement and secondary surgery. During the surgical treatment, a treatment denture was fabricated to restore oral function and determine the morphology of the definitive denture. To create the definitive denture with the same morphology as the treatment denture a custom tray was fabricated with the denture morphology after chairside adjustments. The oral cavity was scanned using an intraoral scanner, and the data acquired were imported into general-purpose CAD software, adjusted, and imported into a 3D printer to produce the custom tray. This was fitted into the patient's mouth without any issues, and closed tray impressions were made with impression caps for the locator attachments on the implant body. The morphology of the treatment denture was replicated in the definitive denture by making a silicon impression of the cameo surface at the fabrication of the cast after impression making. In this technique, the morphology of the treatment denture was transferred accurately to the definitive implant partial denture by leveraging existing digital technology. This method represents a practical approach for partial denture fabrication, including maxillofacial defects with complex denture configurations.

Analysis of ways to reduce potential health risk from ultrafine and fine particles emitted from 3D printers in the makerspace.

Due to the growing maker culture, maker spaces using multiple fused deposition modeling (FDM)-3D printers have spread around the world. However, the 3D printing process is known to cause the release of ultrafine and fine particles, which may have adverse health effects on occupants. Therefore, this experiment-based study was conducted on FDM-3D printers placed in an actual makerspace by the following three scenarios: the number of operating FDM-3D printers, ventilation, and measurement location to compare the concentrations of ultrafine and fine particles. In addition, the deposited dose in alveolar region for ultrafine and fine particles was predicted using a respiratory deposition model to analyze the potential health risk on occupants. As a result, the scenario-based comparison revealed that if the number of operating 3D printers is reduced by less than half, the potential health risk can be decreased by 34.1%, proper ventilation can reduce potential health risk by 55.5%, and working away from the 3D printer can also reduce potential health risk by up to 27.5%. This study analyzed the potential health risk of multiple FDM-3D printers on users in an actual makerspace, and proposed various improvement measures to reduce the potential health risk of ultrafine and fine particles.

Systematic ranking of filaments regarding their particulate emissions during fused filament fabrication 3D printing by means of a proposed standard test method.

The diversity of fused filament fabrication (FFF) filaments continues to grow rapidly as the popularity of FFF-3D desktop printers for the use as home fabrication devices has been greatly increased in the past decade. Potential harmful emissions and associated health risks when operating indoors have induced many emission studies. However, the lack of standardization of measurements impeded an objectifiable comparison of research findings. Therefore, we designed a chamber-based standard method, i.e., the strand printing method (SPM), which provides a standardized printing procedure and quantifies systematically the particle emission released from individual FFF-3D filaments under controlled conditions. Forty-four marketable filament products were tested. The total number of emitted particles (TP) varied by approximately four orders of magnitude (109  ≤ TP ≤ 1013 ), indicating that origin of polymers, manufacturer-specific additives, and undeclared impurities have a strong influence. Our results suggest that TP characterizes an individual filament product and particle emissions cannot be categorized by the polymer type (e.g., PLA or ABS) alone. The user's choice of a filament product is therefore decisive for the exposure to released particles during operation. Thus, choosing a filament product awarded for low emissions seems to be an easily achievable preemptive measure to prevent health hazards.

Effect of experimental exposures to 3-D printer emissions on nasal allergen responses and lung diffusing capacity for inhaled carbon monoxide/nitric oxide in subjects with seasonal allergic rhinitis.

3-D printers are widely used. Based on previous findings, we hypothesized that their emissions could enhance allergen responsiveness and reduce lung diffusing capacity. Using a cross-over design, 28 young subjects with seasonal allergic rhinitis were exposed to 3-D printer emissions, either from polylactic acid (PLA) or from acrylonitrile butadiene styrene copolymer (ABS), for 2 h each. Ninety minutes later, nasal allergen challenges were performed, with secretions sampled after 1.5 h. Besides nasal functional and inflammatory responses, assessments included diffusing capacity. There was also an inclusion day without exposure. The exposures elicited slight reductions in lung diffusing capacity for inhaled nitric oxide (DLNO ) that were similar for PLA and ABS. Rhinomanometry showed the same allergen responses after both exposures. In nasal secretions, concentrations of interleukin 6 and tumor necrosis factor were slightly reduced after ABS exposure versus inclusion day, while that of interleukin 5 was slightly increased after PLA exposure versus inclusion.

Comparison of the decompressive effect of different surgical procedures for dysthyroid optic neuropathy using 3D printed models.

PURPOSE: To compare the decompressive effect around the optic nerve canal among 3 different decompression procedures (medial, balanced, and inferomedial) using 3D printed models. METHODS: In this experimental study, based on data obtained from 9 patients (18 sides) with dysthyroid optic neuropathy, a preoperative control model and 3 plaster decompression models were created using a 3D printer (total, 72 sides of 36 models). A pressure sensor was placed at the optic foramen, and the orbital space was filled with silicone. The surface of the silicone was pushed down directly, and changes in pressure were recorded at 2-mm increments of pushing. RESULTS: At 10 mm of pushing, there was significantly lower pressure in the medial (19,782.2 ± 4319.9 Pa, P = 0.001), balanced (19,448.3 ± 3767.4 Pa, P = 0.003), and inferomedial (15,855.8 ± 4000.7 Pa, P < 0.001) decompression models than in the control model (25,217.8 ± 6087.5 Pa). Overall, the statistical results for each 2-mm push were similar among the models up to 10 mm of pushing (P < 0.050). At each push, inferomedial decompression caused the greatest reduction in pressure (P < 0.050), whereas there was no significant difference in pressure between the medial and balanced decompression models (P > 0.050). CONCLUSION: All 3 commonly performed decompression procedures significantly reduced retrobulbar pressure. Because inferomedial decompression models obtained the greatest reduction in pressure on the optic nerve canal, inferomedial decompression should be considered the most reliable procedure for rescuing vision in dysthyroid optic neuropathy.

Nerve regeneration using the Bio 3D nerve conduit fabricated with spheroids.

Autologous nerve grafting is the gold standard method for peripheral nerve injury with defects. Artificial nerve conduits have been developed to prevent morbidity at the harvest site. However, the artificial conduit regeneration capacity is not sufficient. A Bio 3D printer is technology that creates three-dimensional tissue using only cells. Using this technology, a three-dimensional nerve conduit (Bio 3D nerve conduit) was created from several cell spheroids. We reported the first application of the Bio 3D nerve conduit for peripheral nerve injury. A Bio 3D nerve conduit that was created from several cells promotes peripheral nerve regeneration. The Bio 3D nerve conduit may be useful clinically to treat peripheral nerve defects.

Three-dimensional printers applied for the production of beam blocks in total body irradiation treatment.

PURPOSE: Total body irradiation (TBI) in extended source surface distance (SSD) is a common treatment technique before hematopoietic stem cell transplant. The lungs are organs at risk, which often are treated with a lower dose than the whole body. METHODS: This can be achieved by the application of blocks. Three-dimensional (3D) printers are a modern tool to be used in the production process of these blocks. RESULTS: We demonstrate the applicability of a specific printer and printing material, describe the process, and evaluate the accuracy of the product. CONCLUSION: The blocks and apertures were found to be applicable in clinical routine.

Evaluation of Pulmonary Effects of 3-D Printer Emissions From Acrylonitrile Butadiene Styrene Using an Air-Liquid Interface Model of Primary Normal Human-Derived Bronchial Epithelial Cells.

This study investigated the inhalation toxicity of the emissions from 3-D printing with acrylonitrile butadiene styrene (ABS) filament using an air-liquid interface (ALI) in vitro model. Primary normal human-derived bronchial epithelial cells (NHBEs) were exposed to ABS filament emissions in an ALI for 4 hours. The mean and mode diameters of ABS emitted particles in the medium were 175 ± 24 and 153 ± 15 nm, respectively. The average particle deposition per surface area of the epithelium was 2.29 × 107 ± 1.47 × 107 particle/cm2, equivalent to an estimated average particle mass of 0.144 ± 0.042 µg/cm2. Results showed exposure of NHBEs to ABS emissions did not significantly affect epithelium integrity, ciliation, mucus production, nor induce cytotoxicity. At 24 hours after the exposure, significant increases in the pro-inflammatory markers IL-12p70, IL-13, IL-15, IFN-γ, TNF-α, IL-17A, VEGF, MCP-1, and MIP-1α were noted in the basolateral cell culture medium of ABS-exposed cells compared to non-exposed chamber control cells. Results obtained from this study correspond with those from our previous in vivo studies, indicating that the increase in inflammatory mediators occur without associated membrane damage. The combination of the exposure chamber and the ALI-based model is promising for assessing 3-D printer emission-induced toxicity.

Optical Strain Gauge Prototype Based on a High Sensitivity Balloon-like Interferometer and Additive Manufacturing.

An optical strain gauge based on a balloon-like interferometer structure formed by a bent standard single-mode fiber combined with a 3D printer piece has been presented and demonstrated, which can be used to measure displacement. The interferometer has a simple and compact size, easy fabrication, low cost, and is repeatable. The sensor is based on the interference between the core and cladding modes. This is caused by the fiber's curvature because when light propagates through the curved balloon-shaped interferometer region, a portion of it will be released from the core limitation and coupled to the cladding. The balloon has an axial displacement as a result of how the artwork was constructed. The sensor head is sandwiched between two cantilevers such that when there is a displacement, the dimension associated with the micro bend is altered. The sensor response as a function of displacement can be determined using wavelength shift or intensity change interrogation techniques. Therefore, this optical strain gauge is a good option for applications where structure displacement needs to be examined. The sensor presents a sensitivity of 55.014 nm for displacement measurements ranging from 0 to 10 mm and a strain sensitivity of 500.13 pm/µÏµ.

CAD-CAM Hollow Obturator Prosthesis: A Technical Report.

An obturator with a hollow bulb can decrease the overall weight of the prosthesis, stress on the underlying tissues, and patient discomfort. Although many techniques and materials have been proposed in the literature for hollowing the obturator prosthesis, they are often time consuming and technique sensitive. This proposed technique used an open-source software program to hollow a digital design of a solid obturator base from a commercially available software in one single convenient step. The hollowing process allowed precise control of prosthesis thickness at the hollow space area for desirable hermetic seal and prosthesis strength.

State of the art in additive manufacturing and its possible chemical and particle hazards-review.

Additive manufacturing, enabling rapid prototyping and so-called on-demand production, has become a common method of creating parts or whole devices. On a 3D printer, real objects are produced layer by layer, thus creating extraordinary possibilities as to the number of applications for this type of devices. The opportunities offered by this technique seem to be pushing new boundaries when it comes to both the use of 3D printing in practice and new materials from which the 3D objects can be printed. However, the question arises whether, at the same time, this solution is safe enough to be used without limitations, wherever and by everyone. According to the scientific reports, three-dimensional printing can pose a threat to the user, not only in terms of physical or mechanical hazards, but also through the potential emissions of chemical substances and fine particles. Thus, the presented publication collects information on the additive manufacturing, different techniques, and ways of printing with application of diverse raw materials. It presents an overview of the last 5 years' publications focusing on 3D printing, especially regarding the potential chemical and particle emission resulting from the use of such printers in both the working environment and private spaces.

Prevention through design: insights from computational fluid dynamics modeling to predict exposure to ultrafine particles from 3D printing.

Fused filament fabrication (FFF) 3D printers are increasingly used in industrial, academic, military, and residential sectors, yet their emissions and associated user exposure scenarios are not fully described. Characterization of potential user exposure and environmental releases requires robust investigation. During operation, common FFF 3D printers emit varying amounts of ultrafine particles (UFPs) depending upon feedstock material and operation procedures. Volatile organic compounds associated with these emissions exhibit distinct odors; however, the UFP portion is largely imperceptible by humans. This investigation presents straightforward computational modeling as well as experimental validation to provide actionable insights for the proactive design of lower exposure spaces where 3D printers may be used. Specifically, data suggest that forced clean airflows may create lower exposure spaces, and that computational modeling might be employed to predict these spaces with reasonable accuracy to assist with room design. The configuration and positioning of room air ventilation diffusers may be a key factor in identifying lower exposure spaces. A workflow of measuring emissions during a printing process in an ANSI/CAN/UL 2904 environmental chamber was used to provide data for computational fluid dynamics (CFD) modeling of a 6 m2 room. Measurements of the particle concentrations in a Class 1000 clean room of identical geometry were found to pass the Hanna test for agreement between model and experimental data, validating the findings.

Development of breast phantoms using a 3D printer and glandular dose evaluation.

In this study, breast phantoms were fabricated by emulating glandular and adipose tissues separately using a three-dimensional (3D) printer. In addition, direct and quantitative glandular dose evaluations were performed. A quantitative method was developed to evaluate the glandular and adipose tissues separately when performing glandular dose evaluations. The variables used for glandular dose evaluation were breast thickness, glandular tissue ratio, and additional filter materials. The values obtained using a Monte Carlo simulation and those measured using a glass dosimeter were compared and analyzed. The analysis showed that as the glandular tissue ratio increased, the dose decreased by approximately 10%, which is not a significant variation. The comparison revealed that the simulated values of the glandular dose were approximately 15% higher than the measured values. The use of silver and rhodium filters resulted in a mean simulated dose of 1.00 mGy and 0.72 mGy, respectively, while the corresponding mean measured values were 0.89 mGy ± 0.03 mGy and 0.62 mGy ± 0.02 mGy. The mean glandular dose can be reliably evaluated by comparing the simulated and measured values.

Simple Duplication Technique of Complete Denture Using an Intraoral Scanner.

Various techniques have been applied to the fabrication of duplicate dentures. In this new method, after scanning the cameo and intaglio surfaces of the complete denture using an intraoral scanner, the two images were superimposed on the interocclusal image. The linear gap between cameo and intaglio surfaces was filled using free downloadable CAD software. The superimposed image was subsequently used as data for fabricating the duplicate complete denture with a 3D printer. Using the intraoral scanner, duplication of complete dentures could be performed without needing any complicated processes, laboratory scanners, or advanced CAD software.