Post-processing of a 3D-printed denture base polymer: Impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity.

OBJECTIVES: To investigate the impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity of an additively manufactured denture base polymer. METHODS: The tested specimens were prepared by digital light processing (DLP). A centrifugation method (CENT) was used to remove the residual uncured resin. In addition, the specimens were post-processed with different post-rinsing solutions: isopropanol (IPA), ethanol (EtOH), and tripropylene glycol monomethyl ether (TPM), respectively. A commercial heat-polymerized polymethyl methacrylate was used as a reference (REF). First, the values of surface topography, arithmetical mean height (Sa), and root mean square height (Sq) were measured. Next, flexural strength (FS) and modulus were evaluated. Finally, cytotoxicity was assessed using an extract test. The data were statistically analyzed using a one-way analysis of variance, followed by Tukey's multiple comparison test for post-hoc analysis. RESULTS: The Sa value in the CENT group was lower than in the IPA, EtOH, TPM, and REF groups (p < 0.001). Moreover, the CENT group had lower Sq values than other groups (p < 0.001). The centrifugation method showed a higher FS value (80.92 ± 8.65 MPa) than the EtOH (61.71 ± 12.25 MPa, p < 0.001) and TPM (67.01 ± 9.751 MPa, p = 0.027), while affecting IPA (72.26 ± 8.80 MPa, p = 0.268) and REF (71.39 ± 10.44 MPa, p = 0.231). Also, the centrifugation method showed no evident cytotoxic effects. CONCLUSIONS: The surfaces treated with a centrifugation method were relatively smooth. Simultaneously, the flexural strength of denture base polymers was enhanced through centrifugation. Finally, no evident cytotoxic effects could be observed from different post-processing procedures. CLINICAL SIGNIFICANCE: The centrifugation method could optimize surface quality and flexural strength of DLP-printed denture base polymers without compromising cytocompatibility, offering an alternative to conventional rinsing post-processing.

Dimensional Stability of Additively Manufactured Dentate Maxillary Diagnostic Casts in Biobased Model Resin.

This study aimed to evaluate the dimensional stability of maxillary diagnostic casts fabricated from a biobased model resin, which consists of 50% renewable raw materials for sustainable production, a model resin, and stone, over one month. A master maxillary stone cast was digitized with a laboratory scanner to generate a reference file. This master cast was also scanned with an intraoral scanner to additively manufacture casts with a biobased model resin (BAM) and a model resin (AM). Polyvinylsiloxane impressions of the master cast were also made and poured in type III stone (CV) (n = 8). The same laboratory scanner was used to digitize each model one day (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4) after fabrication. Deviations from the reference file were calculated with an analysis software and analyzed with generalized linear model analysis (α = 0.05). The interaction between the material and the time point affected measured deviations (p < 0.001). Regardless of the time point, CV had the lowest and AM had the highest deviations (p < 0.001). BAM mostly had lower deviations at T0 and mostly had higher deviations at T4 (p ≤ 0.011). AM had the highest deviations at T4 and then at T3, whereas it had the lowest deviations at T0 (p ≤ 0.002). The measured deviations of CV increased after each time point (p < 0.001). BAM casts had deviations within the previously reported clinically acceptable thresholds over one month and had acceptable dimensional stability. Therefore, tested biobased resin may be a viable alternative for the sustainable manufacturing of maxillary diagnostic casts that are to be used clinically.

Positional accuracy of a single implant analog in additively manufactured casts in biobased model resin.

OBJECTIVES: To evaluate the positional accuracy of implant analogs in biobased model resin by comparing them to that of implant analogs in model resin casts and conventional analogs in dental stone casts. METHODS: Polyvinylsiloxane impressions of a partially edentulous mandibular model with a single implant were made and poured in type IV dental stone. The same model was also digitized with an intraoral scanner and additively manufactured implant casts were fabricated in biobased model resin (FotoDent biobased model) and model resin (FotoDent model 2 beige-opaque) (n = 8). All casts and the model were digitized with a laboratory scanner, and the scan files were imported into a 3-dimensional analysis software (Geomagic Control X). The linear deviations of 2 standardized points on the scan body used during digitization were automatically calculated on x-, y-, and z-axes. Average deviations were used to define precision, and 1-way analysis of variance and Tukey HSD tests were used for statistical analyses (α = 0.05). RESULTS: Biobased model resin led to higher deviations than dental stone (all axes, P ≤ 0.031) and model resin (y-axis, P = 0.015). Biobased model resin resulted in the lowest precision of implant analog position (P ≤ 0.049). The difference in the positional accuracy of implant analogs of model resin and stone casts was nonsignificant (P ≥ 0.196). CONCLUSIONS: Implant analogs in biobased model resin casts mostly had lower positional accuracy, whereas those in model resin and stone casts had similar positional accuracy. Regardless of the material, analogs deviated more towards mesial, while buccal deviations in additively manufactured casts and lingual deviations in stone casts were more prominent.

A balance of biocompatibility and antibacterial capability of 3D printed PEEK implants with natural totarol coating.

OBJECTIVE: Polyetheretherketone (PEEK), a biomaterial with appropriate bone-like mechanical properties and excellent biocompatibility, is widely applied in cranio-maxillofacial and dental applications. However, the lack of antibacterial effect is an essential drawback of PEEK material and might lead to infection and osseointegration issues. This study aims to apply a natural antibacterial agent, totarol coating onto the 3D printed PEEK surface and find an optimized concentration with balanced cytocompatibility, osteogenesis, and antibacterial capability. METHODS: In this study, a natural antibacterial agent, totarol, was applied as a coating to fused filament fabrication (FFF) 3D printed PEEK surfaces at a series of increasing concentrations (1 mg/ml, 5 mg/ml, 10 mg/ml, 15 mg/ml, and 20 mg/ml). The samples were then evaluated for cytocompatibility with L929 fibroblast and SAOS-2 osteoblast using live/dead staining and CCK-8 assay. The antibacterial capability was assessed by crystal violet staining, live/dead staining, and scanning electron microscopy (SEM) utilizing the oral primary colonizer S. gordonii and isolates of mixed oral bacteria in a stirring system simulating the oral environment. The appropriate safe working concentration for totarol coating is selected based on the results of the cytocompatibility and antibacterial test. Subsequently, the influence on osteogenic differentiation was evaluated by alkaline phosphatase (ALP) and alizarin red staining (ARS) analysis of pre-osteoblasts. RESULTS: Our results showed that the optimal concentration of totarol solution for promising antibacterial coating was approximately 10 mg/ml. Such surfaces could play an excellent antibacterial role by inducing a contact-killing effect with an inhibitory effect against biofilm development without affecting the healing of soft and hard tissues around FFF 3D printed PEEK implants or abutments. SIGNIFICANCE: This study indicates that the totarol coated PEEK has an improved antibacterial effect with excellent biocompatibility providing great clinical potential as an orthopedic/dental implant/abutment material.

Three-Dimensional Printed Tooth Model with Root Canal Ledge: A Novel Educational Tool for Endodontic Training.

Ledge formation presents a significant challenge in endodontic treatment. Yet, there is still a lack of educational tooth models for hands-on practice. This study aimed to create and evaluate a tooth model for ledge management practice. A natural tooth with curved roots was collected for scientific use under ethics committee approval. Following initial root canal preparation, the tooth was scanned using micro-computed tomography (µCT) and 3D reconstructed. A K-file, created via computer-aided design (CAD), was partly inserted into the root canal wall of the 3D reconstructed tooth. By subtracting the K-file from the tooth, a tooth model with a root canal ledge was produced. The model was then 3D printed for a hands-on workshop. An eight-item Likert-scale questionnaire was administered to 20 postgraduate students and 10 endodontists to assess the model's quality and training effectiveness. In addition, the success rate of bypassing and correcting the root canal ledge was documented. The feedback from both the students and experts was positive, and the results of the Mann-Whitney U test indicated no statistically significant differences found between the two groups (p > 0.05). The success rate of the students and the experts was 85% and 100%, respectively. In future applications, this novel tooth model is expected to address the existing gap in endodontic education and provide benefits for dental practitioners.

Influence of additive manufacturing method and build angle on the accuracy of 3D-printed palatal plates.

OBJECTIVES: In this in vitro study, the effects of additive manufacturing (AM) methods and build angles on the trueness and precision of 3D-printed palatal plate orthodontic appliances for newborns and infants were examined. METHODS: Specimens were fabricated by different representative AM methods, including digital light processing (DLP), fused filament fabrication (FFF), and MultiJet printing (MJP). Three build angles (0°, 45°, and 90°) were used. After scanning, all specimens were analyzed using the 3D inspection software. The root mean square values were measured for trueness and precision. Color maps were created to detect deviations in samples. The data were statistically analyzed with a two-way ANOVA. RESULTS: The trueness and precision were statistically influenced by both AM methods and build angles (p < 0.05). Moreover, the root mean square values of the 45° DLP (0.0221 ± 0.0017 µm) and the 0° MJP (0.0217 ± 0.0014 µm) were significantly lower compared to those in other groups (p < 0.001). CONCLUSIONS: AM methods (DLP, FFF, and MJP) and build angles (0°, 45°, and 90°) significantly impacted the dimensional accuracy of additively manufactured palatal plate orthodontic appliances. Also, the 45° DLP and the 0° MJP were associated with the highest trueness and precision. CLINICAL SIGNIFICANCE: All tested AM methods with different build angles yielded clinically acceptable outcomes (within an acceptance range of ±300 µm for trueness), achieving the highest accuracy with a technology-specific suitable build angle.

Effects of layer thickness and build angle on the microbial adhesion of denture base polymers manufactured by digital light processing.

PURPOSE: To investigate the effects of printing-layer thickness and build angle on the surface characteristics and microbial adhesion of denture base polymers manufactured by digital light processing (DLP). METHODS: Specimens were additively manufactured using DLP. The specimens were printed with different printing-layer thicknesses (25, 50, and 100 µm) and build angles (0°, 45°, and 90°). Scanning electron microscopy was used to observe the surface topography, and the arithmetical mean heights (Sa) were measured. Moreover, the initial Candida albicans (C. albicans) adhesion to the specimens was evaluated using an adhesion test. Finally, two-way ANOVA and Tukey's multiple comparison tests were conducted. RESULTS: The results regarding the Sa values exhibited a statistically significant interaction (F (4, 45) = 90.77, P < 0.0001). The build angle has a significant impact on the surface topography. Furthermore, quantitative results revealed that the printing-layer thickness significantly affected C. albicans adhesion (F (2, 99) = 6.96, P = 0.0015). CONCLUSIONS: The surface roughness was significantly affected by the printing-layer thickness and the build angle. Additionally, the surface topography was mainly determined by the build angle. Furthermore, the adhesion of C. albicans to the DLP-printed denture surfaces was significantly affected by the printing-layer thickness but not by the build angle. Consequently, it is critical to decrease the thickness of the printing layer to produce digital dentures with optimal material properties.

Food Solutions and Cigarette Smoke-Dependent Changes in Color and Surface Texture of CAD/CAM Composite Resins-An In Vitro Study.

PURPOSE: To investigate the discoloration and surface properties of four CAD/CAM composite resins following storage in various food solutions and exposure to cigarette smoke. MATERIALS AND METHODS: A total of 74 specimens (N = 370) were prepared for five materials: Brilliant Crios (BC), Cerasmart (GC), Lava Ultimate (LU), Shofu Block HC (SH), and Sonic Fill 2 (SO). Discoloration (ΔE) was investigated with a spectrophotometer. Measurements were taken before immersion in storage media (carrot juice, curry, cigarette smoke, red wine, energy drink, and distilled water), after 2 weeks of immersion, and after manual polishing of the specimens following immersion. The average surface roughness (Ra) was measured with a profilometer. Qualitative surface observation was performed with scanning electron microscopy (SEM). Data were analyzed using Kolmogorov-Smirnov test, Mann-Whitney U test, and one-way ANOVA with Tukey post hoc test. RESULTS: The highest influence on ΔE after immersion was observed for storage medium (ηηP2 = 0.878, P < .001), followed by the interaction between storage medium and material (ηP2 = 0.770, P < .001) and material (ηP2 = 0.306, P < .001). For ΔE after polishing, the highest influence was indicated by the interaction between material and medium (ηP2 = 0.554, P < .001), followed by medium (ηP2 = 0.244, P < .001) and material (ηP2 = 0.196, P < .001). Immersion in carrot juice led to the highest color change (ΔE: 8.0 to 10.4), whereas the lowest values were recorded in distilled water (ΔE: 2.0 to 2.4). Carrot juice and the energy drink caused the highest Ra values (0.120 µm to 0.355 µm). SEM pictures indicated a loss of the organic matrix after manual polishing. CONCLUSION: The different materials reacted dissimilarly to the various storage media in terms of discoloration. Surface roughness increased after immersion or polishing. Neither discoloration nor surface roughness could be reset to default by manual polishing. Int J Prosthodont 2023;36:194-202. doi: 10.11607/ijp.6950.

Trueness and precision of skin surface reproduction in digital workflows for facial prosthesis fabrication.

STATEMENT OF PROBLEM: How much skin surface details of facial prostheses can be transferred throughout the digital production chain has not been quantified. PURPOSE: The purpose of this in vitro study was to quantify the amount of skin surface details transferred from the prosthesis virtual design through the prototype printing with various additive manufacturing (AM) methods to the definitive silicone prosthesis with an indirect mold-making approach. MATERIAL AND METHODS: Twelve test blocks with embossed wrinkles of 0.05 to 0.8 mm and 12 test blocks with applied earlobe skin structures were printed with stereolithography (SLA), direct light processing (DLP), and PolyJet methods (n=4). DLP and SLA prototype specimens were duplicated in wax. All specimens were then transferred into medical-grade silicone. Rz values of the wrinkle test blocks and the root mean square error (RMSE) of the earlobe test blocks were evaluated by laser topography to determine the trueness and precision of each stage. RESULTS: For the earlobe test blocks, the PolyJet method had superior trueness and precision of the final skin surface reproduction. The SLA method showed the poorest trueness, and the DLP method, the lowest precision. For the wrinkle test blocks, the PolyJet method had the best wrinkle profile reproduction level, followed by DLP and SLA. CONCLUSIONS: The indirect mold-making approach of facial prostheses manufacturing may be associated with 7% of skin surface profile loss with SLA, up to 20% with DLP, and no detail loss with PolyJet.

Rapid Additive Manufacturing of a Superlight Obturator for Large Oronasal Fistula in Pediatric Patient.

This study developed a novel digital workflow to fabricate a 3D printed hollow obturator for the prosthetic reconstruction of palatal fistula. It will provide cleft surgeons and therapists a choice for treating children with large palatal fistula before the appropriate age for surgical reconstruction. Laryngoscope, 133:1507-1512, 2023.

Adhesive Property of 3D-Printed PEEK Abutments: Effects of Surface Treatment and Temporary Crown Material on Shear Bond Strength.

Three-dimensionally printed polyetheretherketone (PEEK) materials are promising for fabricating customized dental abutments. This study aimed to investigate the adhesive property of a 3D-printed PEEK material. The effects of surface treatment and temporary crown materials on shear bond strength were evaluated. A total of 108 PEEK discs were 3D printed by fused-filament fabrication. Surface treatments, including sandblasting, abrasive paper grinding, and CO2 laser ablation, were applied to the PEEK discs, with the untreated specimens set as the control. Afterward, the surface topographies of each group were investigated by scanning electron microscopy (SEM, n = 1) and roughness measurements (n = 7). After preparing the bonding specimens with three temporary crown materials (Artificial teeth resin (ATR), 3M™ Filtek™ Supreme Flowable Restorative (FR), and Cool Temp NATURAL (CTN)), the shear bond strength was measured (n = 6), and the failure modes were analyzed by microscopy and SEM. The results showed that ATR exhibited a significantly higher shear bond strength compared to FR and CTN (p < 0.01), and the PEEK surfaces treated by sandblasting and abrasive paper grinding showed a statistically higher shear bond strength compared to the control (p < 0.05). For clinical application, the ATR material and subtractive surface treatments are recommended for 3D-printed PEEK abutments.

Post-processing of DLP-printed denture base polymer: Impact of a protective coating on the surface characteristics, flexural properties, cytotoxicity, and microbial adhesion.

OBJECTIVES: To investigate the effect of a protective coating on the surface characteristics, flexural properties, cytotoxicity, and microbial adhesion of vat-photopolymerization additive-manufacturing denture base polymers. METHODS: The specimens were additively manufactured using digital light processing (DLP). Specimen surfaces were coated with the same printed resin, and mechanical polishing was used for comparison. Surface topography, arithmetical mean height (Sa), and water contact angle values were measured. Furthermore, flexural strength (FS)/modulus and fractography were evaluated. Also, cytotoxicity was evaluated by an extract test. Finally, an adhesion test was used to investigate the adhesion of mixed oral bacteria to the specimens. RESULTS: The Sa values in the polished (0.26 ± 0.08 µm) and coated (0.38 ± 0.14 µm) groups were significantly lower than in the untreated (2.21 ± 0.42 µm) and control (2.01 ± 0.37 µm) groups. The coating treatment resulted in a higher FS compared to the untreated surface (p = 0.0002). After the coating treatment, no significant differences were found in relative cell viability between the groups (p > 0.05). The quantitative results showed significantly higher bacterial adhesion in the untreated group than in the polished (p = 0.0047) and coated (p < 0.0001) groups. SIGNIFICANCE: The surface characteristics and flexural properties were optimized by the protective coating. Also, the protective coating did not adversely affect cytocompatibility. Moreover, the coating treatment could effectively decrease oral bacteria adhering to the surfaces. Therefore, the protective coating treatment can be a less time-consuming alternative to mechanical polishing as a post-processing procedure for the digital denture.

Needle Penetration Simulation: Influence of Penetration Angle and Sample Stress on the Mechanical Behaviors of Polymers Applying a Cast Silicone and a 3D-Printed Resin.

For surgical catheterization training applications, realistic and effective materials are desired. In this study, the relevance of a needle puncture angle and a simulated wall stress on different elastic materials were determined in a previously developed experimental setup. Both settings were considered individually in two new setups. In addition, a control setup with neither angle nor prestress was designed. During the process of puncturing the samples of two materials (Replisil 9N and Formlabs Elastic 50A), force−displacement values were collected, and three predefined parameters evaluated. The differences between the angled/stressed groups and the control group were analyzed. The additively processed material required a significantly higher force to puncture than the conventional one (p < 0.001). Moreover, a needle angulation of 45° required more force than puncturing orthogonally. Prestressing the samples did not clearly influence the resulting force. An evaluation of relative parameters showed that the investigated materials behaved differently but not linearly differently under the influence of needle angle and prestress. Therefore, it is essential to evaluate the properties and suitability of materials for surgical training models in appropriate experimental setups considering multiple parameters.

Rinsing postprocessing procedure of a 3D-printed orthodontic appliance material: Impact of alternative post-rinsing solutions on the roughness, flexural strength and cytotoxicity.

OBJECTIVE: The present study evaluated the effect of different rinsing postprocessing solutions on surface characteristics, flexural strength, and cytotoxicity of an additive manufactured polymer for orthodontic appliances. These solutions have been deemed an alternative to the standard isopropanol which is a flammable liquid, known to have toxic effects. METHODS: Tested specimens were manufactured using direct light processing of an orthodontic appliance polymer (FREEPRINT® splint 2.0, Detax) and post-processed with different post-rinsing solutions, including isopropanol (IPA), ethanol (EtOH), EASY 3D Cleaner (EYC), Yellow Magic7 (YM7), and RESINAWAY (RAY), respectively. All groups were post-cured following the manufacturer's instructions. Surface topography and roughness (Ra and Rv) were evaluated. In addition, flexural strength was measured by a three-point bending test. An extract test was performed to evaluate cytotoxicity. The data were analyzed by the Kruskal-Wallis test with Dunn's multiple comparisons test (p < 0.05). RESULTS: Various post-rinsing solutions did not significantly affect the roughness values (Ra and Rv). Specimens post-processed with EtOH (98.1 ± 12.4 MPa) and EYC (101.1 ± 6.3 MPa) exhibited significantly lower flexural strength compared to the groups of IPA (110.7 ± 5.3 MPa), RAY (112.1 ± 5.6 MPa) and YM7 (117.3 ± 5.9 MPa), respectively. Finally, there were no cytotoxic effects of parts cleaned with different post-rinsing solutions. SIGNIFICANCE: Considering the use of 3D-printed orthodontic appliance materials, different rinsing postprocessing procedures did not affect surface characteristics. However, the flexural strength was significantly influenced, which could be attributed to the chemical ingredients of the post-rinsing solutions. Various post-rinsing treatments had no alternation concerning cytocompatibility.

Fracture toughness of 3Y-TZP ceramic measured by the Chevron-Notch Beam method: A round-robin study.

OBJECTIVE: This interlaboratory round robin test investigated the robustness of the Chevron-Notch Beam (CNB) test method and the effect of the processing and testing variations on the fracture toughness of a dental 3Y-TZP ceramic. METHODS: The round robin test was performed precisely following the procedures recommended in ISO 24370:2005 and applied on a commercial 3Y-TZP ceramic (product information). A total of 335 test specimens with dimensions 3×4 x 45 mm³ was equally distributed among 10 participating laboratories of varying experience in fracture toughness testing. A standard operating procedure was defined with either narrow processing tolerances or alternative (wider) processing tolerances (as proposed in ISO 24370). Fracture toughness data (series 2) was analyzed using one way ANOVA followed by post hoc Tukey HSD test and 95% Confidence Intervals (CI) were computed (p < 0.05). A further, preceding round-robin (series 1) test was conducted with - more possible variations of test conditions regarding CNB notch processing and storage conditions. Those results are summarized in the supplement and discussed with the actual ISO 24370 test. RESULTS: Fracture toughness of the 3Y-TZP ceramic material, summarized over all laboratories was measured to KIc = 4.48 ± 0.11 MPam0.5 for the standard processing tolerance and KIc = 4.55 ± 0.31 MPam0.5 for the alternative tolerance. The results revealed a significant influence of cutting offset and notch geometry on KIc when using CNB method. The test medium also has a significant influence on KIc in terms of reduced fracture toughness under the influence of water. With defined testing conditions the number of valid tests and reduced standard deviation increased. In case of strictly following such standard operation procedures, KIc can be determined with high reliability. There is no difference between the involved laboratories, but significant influence of cutting offset on KIC was observed. SIGNIFICANCE: The CNB method is suitable method for determination of KIc on fine-grained ceramics such as 3Y-TZP ceramic. By using tighter tolerances for processing and testing, i.e. closely following the ISO 24370 procedure, a highly-precise evaluation of fracture toughness with low data variation is achievable. The information of the storage medium should always be reported along with the data. CNB fracture toughness testing is an alternative method compared to Single-edge V-notch beam (SEVNB), especially for fine-grained ceramics.

Tailoring the biologic responses of 3D printed PEEK medical implants by plasma functionalization.

OBJECTIVE: The objective of this study was to determine the effect of two plasma surface treatments on the biologic responses of PEEK medical implants manufactured by fused filament fabrication (FFF) 3D printing technology. METHODS: This study created standard PEEK samples using an FFF 3D printer. After fabrication, half of the samples were polished to simulate a smooth PEEK surface. Then, argon (Ar) or oxygen (O2) plasma was used to modify the bioactivity of FFF 3D printed and polished PEEK samples. Scanning electron microscopy (SEM) and a profilometer were used to determine the microstructure and roughness of the sample surfaces. The wettability of the sample surface was assessed using a drop shape analyzer (DSA) after plasma treatment and at various time points following storage in a closed environment. Cell adhesion, metabolic activity, proliferation, and osteogenic differentiation of SAOS-2 osteoblasts were evaluated to determine the in vitro osteogenic activity. RESULTS: SEM analysis revealed that several spherical nanoscale particles and humps appeared on sample surfaces following plasma treatment. The wettability measurement demonstrated that plasma surface treatment significantly increased the surface hydrophilicity of PEEK samples, with only a slight aging effect found after 21 days. Cell adhesion, spreading, proliferation, and differentiation of SAOS-2 osteoblasts were also up-regulated after plasma treatment. Additionally, PEEK samples treated with O2 plasma demonstrated a higher degree of bioactivation than those treated with Ar. SIGNIFICANCE: Plasma-modified PEEK based on FFF 3D printing technology was a feasible and prospective bone grafting material for bone/dental implants.

Shock Absorption Behavior of Elastic Polymers for Sports Mouthguards: An In Vitro Comparison of Thermoplastic Forming and Additive Manufacturing.

BACKGROUND: There are several in vitro testing options to investigate the efficacy of sports mouthguards. None of these represent everyday situations, but the effects of simple laws of physics can be observed. This enables the comparison of conventional materials for mouthguards towards fabrications from additive manufacturing. METHODS: A ball-drop experiment measured the maximum force and temporospatial distribution of a vertical impact on six material groups and a reference group (No-MG). Three conventional materials (ethylenvinylacetate) with 1, 2, and 3 layers were compared with additively manufactured (AM) specimens of comparable layering with a respective thickness of 4 mm, 5 mm, and 6.8 mm. RESULTS: A maximum force of 8982.35 N ± 305.18 (No-MG) was maximum damped to 2470.60 N ± 87.00 (conventional 6.8 mm) compared with 5585.09 N ± 203.99 (AM 6.8 mm) Thereby, the ratio between shock absorption per millimeter was best for 4 mm thickness with means of 1722 N (conventional) and 624 N (AM). CONCLUSIONS: Polymer layers demonstrated a force reduction up to 71.68%. For now, additively processed resins of comparable hardness and layering are inferior to conventional fabrications.

Development of Personalized Non-Invasive Ventilation Interfaces for Neonatal and Pediatric Application Using Additive Manufacturing.

The objective of this study was to present a methodology and manufacturing workflow for non-invasive ventilation interfaces (NIV) for neonates and small infants. It aimed to procure a fast and feasible solution for personalized NIV produced in-house with the aim of improving fit and comfort for the patient. Three-dimensional scans were obtained by means of an intraoral (Trios 3) and a facial scanner (3dMd Flex System). Fusion 360 3D-modelling software was employed to automatize the design of the masks and their respective casting molds. These molds were additively manufactured by stereolithography (SLA) and fused filament fabrication (FFF) technologies. Silicone was poured into the molds to produce the medical device. In this way, patient individualized oronasal and nasal masks were produced. An automated design workflow and use of additive manufacturing enabled a fast and feasible procedure. Despite the cost for individualization likely being higher than for standard masks, a user-friendly workflow for in-house manufacturing of these medical appliances proved to have potential for improving NIV in neonates and infants, as well as increasing comfort.

The impact of 3D printed models on spatial orientation in echocardiography teaching.

PURPOSE: During our transthoracic echocardiography (TTE) courses, medical students showed difficulty in spatial orientation. We implemented the use of 3D printed cardiac models of standard TTE views PLAX, PSAX, and A4C and assessed their efficacy in TTE-teaching. METHODS: One hundred fifty-three participants were split into two groups. A pre-test-retest of anatomy, 2D -, and 3D orientation was conducted. The intervention group (n = 77) was taught using 3D models; the control group (n = 76) without. Both were comparable with respect to baseline parameters. Besides test-scores, a Likert scale recorded experiences, difficulties, and evaluation of teaching instruments. RESULTS: From the 153 students evaluated, 123 improved, 20 did worse, and ten achieved the same result after the course. The median overall pre-test score was 29 of 41 points, and the retest score was 35 (p < 0.001). However, the intervention group taught with the 3D models, scored significantly better overall (p = 0.016), and in 2D-thinking (p = 0.002) and visual thinking (p = 0.006) subtests. A backward multivariate linear regression model revealed that the 3D models are a strong individual predictor of an excellent visual thinking score. In addition, our study showed that students with difficulty in visual thinking benefited considerably from the 3D models. CONCLUSION: Students taught using the 3D models significantly improved when compared with conventional teaching. Students regarded the provided models as most helpful in their learning process. We advocate the implementation of 3D-printed heart models featuring the standard views for teaching echocardiography. These findings may be transferable to other evidence based medical and surgical teaching interventions.

Rapid additive manufacturing of an obturator prosthesis with the use of an intraoral scanner: A dental technique.

A protocol for a completely digital manufacturing process for an obturator prosthesis is described. An intraoral scanner was used to capture the mandible and maxilla together with the sinus defect. The obturator base and the artificial teeth were created with a computer-aided design software program and manufactured by 3-dimensional printing. Stainless steel clasps provided the retention for the prosthesis.