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PURPOSE To investigate the discoloration and surface properties of four CAD/CAM composite resins provoked by a variety of food solutions and cigarette smoke. MATERIALS AND METHODS A total of 74 specimens (N = 370) were prepared per material (Brilliant Crios [Coltene], CeraSmart [GC], Lava Ultimate [3M Espe], Shofu Block HC [Shofu], and SonicFill 2 [Kerr]). Discoloration (ΔE) was investigated with a spectrophotometer. Measurements were taken before immersion in the storage media for 2 weeks (carrot juice, curry, cigarette smoke, red wine, energy drink, and distilled water), immediately after immersion, and after manual polishing of the specimens following immersion. The mean surface roughness (Ra) was measured using a profilometer. Qualitative surface observation was performed with scanning electron microscopy (SEM). Data were analyzed using Kolmogorov-Smirnov, Mann-Whitney U, and one-way analysis of variance with Tukey post hoc tests. RESULTS The highest influence on ΔE after immersion was observed by the storage medium (ηP. = 0.878, P < .001), followed by the interaction between storage medium and material (ηP. = 0.770, P < .001) and the material (ηP. = 0.306, P < .001). For ΔE after polishing, the highest influence was indicated by the interaction of material and medium (ηP. = 0.554, P < .001), followed by the medium (ηP. = 0.244, P < .001) and the material (ηP. = 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 provoked the highest Ra values (0.120 to 0.355 μm). SEM pictures indicated a loss of the organic matrix after manual polishing. CONCLUSION The different materials reacted dissimilarly in the various storage media in terms of discoloration. Surface roughness increased after immersion and polishing. Neither discoloration nor surface roughness could be reset to default by manual polishing.

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, 2022.

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.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).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.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.

ZusammenfassungDie Versorgung mit Gesichtsprothesen (Epithesen) ist eine technische wie auch psychologische Herausforderung– für die betroffenen Patienten wie auch die Epithetiker und Behandler. Der technologische Fortschritt bei digitalen Prozessketten von der Erfassung, über die Weiterverarbeitung bis hin zur Fertigung erlaubt es in diesem Teilgebiet erhebliche Verbesserungen zu ermöglichen. So können kontaktlose Abformungen von Defekten die Belastungen für den Patienten reduzieren und das digitale Design die Laufzeit und Reproduzierbarkeit für die Versorger verbessern. Der 3D-Druck stellt in Aussicht, Prototypen bis hin zu fertigen Prothesen verlässlich fertigen zu können, wobei abschließende Individualisierungen auch langfristig noch nötig sein werden. Der vorliegende Artikel beschreibt die Grundzüge der Versorgung, den derzeitigen Entwicklungsstand und zukünftige Möglichkeiten bei der Versorgung von gesichtsversehrten Patienten.

ZusammenfassungFür die Behandlung junger Patienten mit kraniofazialen Anomalien ist die Entwicklung eines digitalen Workflows für das Design von Apparaturen auf Basis von intraoralen Scans die erste Hürde. Um die Sicherheit dieser Patientengruppe zu gewährleisten, werden potenzielle additiv oder subtraktiv gefertigte Materialien getestet und die Genauigkeit in vitro gemessen.

ZusammenfassungDurch die stetige Weiterentwicklung digitaler Fertigungswege stehen zahlreiche Möglichkeiten zur Herstellung kieferorthopädischer Apparaturen zur Verfügung. Digitalisierte Arbeitsprozesse sind heutzutage aus der Zahnmedizin nicht mehr wegzudenken.Unter Umgehung handwerklich-manueller Fehlerquellen offerieren die digitalen Systeme eine Steigerung der Qualität sowie Kosteneffizienz, bei gleichzeitig gesteigertem Patientenkomfort. Dabei ist die intraorale Datenerfassung von größter Wichtigkeit, da bereits hier die Weichen für den gesamten digitalen Workflow gestellt werden.Bei der anschließenden Fertigung kann prinzipiell zwischen additiven und subtraktiven Verfahren unterschieden werden. In diesem Artikel sollen die gängigen CAM-Methoden anhand der Herstellungsmöglichkeiten einer Gaumennahterweiterungsapparatur dargestellt und verglichen werden.Es konnte gezeigt werden, dass sich alle Fertigungsverfahren zur Herstellung einer Gaumennahterweiterungsapparatur eignen.

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.

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.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 (SThe SThe 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.

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 (

Objective Since the post-rinsing time is inconsistently recommended, this study aims to investigate the effect of post-rinsing time on the flexural strength and cytotoxicity of an stereolithographically (SLA) printed orthodontic splint material. Methods SLA-printed specimens were ultrasonically rinsed with isopropanol (IPA) for 5 min, 12 min, 20 min, 30 min, 1 h, and 12 h, respectively. Surface characterization was conducted by scanning electron microscopy and roughness measurements. Flexural strength was evaluated using a three-point bending test. Cytotoxicity was determined by direct contact test and extract test. For both tests, cell viability (live/dead staining) and cell metabolic activity (CCK-8 assay) were evaluated. Additionally, water sorption and water solubility were tested to analyze the mass loss from immersion. Results No apparent surface alterations could be detected on the samples post-rinsed for less than 1 h. In contrast, when the post-rinsing time was prolonged to 12 h, surface fissures could be observed. Flexural strength linearly decreased with increasing post-rinsing time. All post-processed specimens did not show an obvious cytotoxic effect. Significance The removal of cytotoxic methacrylate monomers by post-rinsing with IPA could be achieved in 5 min. Extending post-rinsing time could not improve the cytocompatibility of the SLA-printed orthodontic splint material, and may result in a decrease in flexural strength.

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.

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 present study aimed to evaluate the bonding between three 3D printed custom tray materials and three elastomeric impression/adhesive systems using the peel test.Test blocks were 3D printed by three different technologies using Dental LT, FREEPRINT tray, and polylactide (PLA) tray materials. The reference test blocks were conventionally fabricated with Zeta Tray LC, a light-curing resin. The surface topographies of the four tray materials were investigated by scanning electron microscopy (SEM) analyses and roughness measurements. The peel bond strength between the four tray materials and three impression/adhesive systems, vinylsiloxanether (VSXE), vinyl polysiloxane (VPS), and polyether (PE), was measured (n=12 per group). The peeling failure modes and rupture sites were identified microscopically.The four tray materials featured different surface topographies. The peel bond strength was not significantly different with VSXE and PE, but PLA and the reference showed higher peel bond strength with VPS than the Dental LT and FREEPRINT tray (p0.05). The rupture site of adhesive failure in all groups was partly at the adhesive-impression material interface and partly within the adhesive but never at the adhesive-tray material interface.The 3D printed tray materials can achieve satisfactory chemical compatibility with the adhesives of VSXE, VPS, and PE. Surface topographies generated by the 3D printing technologies may affect bonding. Generally, 3D printed tray materials can provide clinically adequate bond strength with the elastomeric impression/adhesive systems. PLA is recommended for bonding with VPS when severe impression removal resistance is detected.

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.

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.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.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).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.

A combination of facial and intraoral scans produces a fully digitalized virtual patient. This concept allows for a 3D smile design and individualized virtual articulator application, which makes the rehabilitation outcome more predictable in terms of esthetics and function.In the present clinical case, the patient was 'digitalized' with the use of facial and intraoral scans. The full-mouth rehabilitation by means of implant- and tooth-supported single ceramic restorations was performed through both digital and analog workflows. The 3D printing of the restoration patterns was achieved through the rapid prototyping (RP) approach, and the ceramic milling through the rapid manufacturing approach. The clinical and technical performance of both additive and subtractive manufacturing methods were assessed for this type of rehabilitation.Both additive and subtractive manufacturing of ceramic restorations yielded a clinically acceptable marginal fit, which was inspected on the conventionally fabricated stone cast. As the milling of small ceramic restorations has met with failure in the past, the 3D printing of restoration patterns in the context of an RP approach may be regarded as a viable technical option.

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.

A multilayer mouth guard is known to have the best protective performance. However, its manufacturing in a digital workflow may be challenging with regards to virtual design and materialization. The present case demonstrates a pathway to fabricate a multilayer individualized mouth guard in a fully digital workflow, which starts with intraoral scanning. A free-form CAD software was used for the virtual design. Two various CAM techniques were used, including Polyjet 3D printing of rubber-like soft material and silicone printing using Drop-on-Demand technique. For both methods the outer layer was manufactured from more rigid materials to facilitate its protective function; the inner layer was printed from a softer material to aid a better adaptation to mucosa and teeth. Both 3D printed multilayer mouth guards showed a clinically acceptable fit and were met with patient appraisal. Their protective capacities must be evaluated in further clinical studies.

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.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 (OSEM 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 OPlasma-modified PEEK based on FFF 3D printing technology was a feasible and prospective bone grafting material for bone/dental implants.

PURPOSE To assess the bonding between conventional and additively manufactured silicone elastomers and cylindrical retention titanium magnets for anchorage of facial prostheses. METHODS The customized titanium retention magnets were embedded in conventional and additively produced silicone blocks without primer application (n = 20) and with two commercially available primers G611 (n = 20) and A304 (n = 20) applied onto the magnet surface. The pull out test was performed in the universal testing machine using 45° and 90° angulation and the pull out strength was measured for each group. Additionally the SEM images of the pulled out magnets' surface were obtained and the amount of residual silicone onto the magnet surface was quantified. RESULTS Significantly higher pull out strength values (p < 0.05) were revealed for 90° specimens (0.11 - 0.17 ± 0.01 N/mm2) compared to the 45° group (0.03 ± 0.02 N/mm2). The pull out test with primer revealed no significant differences between the G 611 and A 304 primers in the additive group. However, significantly (p < 0,05) higher values were observed for conventional specimens in the A304 group (1.10 ± 0.21 N/mm2) compared to the G611 group (0.59 ± 0.27 N/mm2). CONCLUSION The application of both used primers may be an acceptable technical option for the anchorage of retention titanium magnets in silicone facial prostheses, produced additively in a fully digital workflow.

Different approaches for digital workflows have already been presented for their use in palatal plates for newborns and infants. However, there is no evidence on the accuracy of CAD/CAM manufactured orthodontic appliances for this kind of application. This study evaluates trueness and precision provided by different CAM technologies and materials for these appliances. Samples of a standard palatal stimulation plate were manufactured using stereolithography (SLA), direct light processing (DLP) and subtractive manufacturing (SM). The effect of material (for SM) and layer thickness (for DLP) were also investigated. Specimens were digitized with a laboratory scanner (D2000, 3Shape) and analyzed with a 3D inspection software (Geomagic Control X, 3D systems). For quantitative analysis, differences between 3D datasets were measured using root mean square (RMS) error values for trueness and precision. For qualitative analysis, color maps were generated to detect locations of deviations within each sample. SM showed higher trueness and precision than AM technologies. Reducing layer thickness in DLP did not significantly increase accuracy, but prolonged manufacturing time. All materials and technologies met the clinically acceptable range and are appropriate for their use. DLP with 100 µm layer thickness showed the highest efficiency, obtaining high trueness and precision within the lowest manufacturing time.

Different approaches for digital workflows have already been presented for their use in palatal plates for newborns and infants. However, there is no evidence on the accuracy of CAD/CAM manufactured orthodontic appliances for this kind of application. This study evaluates trueness and precision provided by different CAM technologies and materials for these appliances. Samples of a standard palatal stimulation plate were manufactured using stereolithography (SLA), direct light processing (DLP) and subtractive manufacturing (SM). The effect of material (for SM) and layer thickness (for DLP) were also investigated. Specimens were digitized with a laboratory scanner (D2000, 3Shape) and analyzed with a 3D inspection software (Geomagic Control X, 3D systems). For quantitative analysis, differences between 3D datasets were measured using root mean square (RMS) error values for trueness and precision. For qualitative analysis, color maps were generated to detect locations of deviations within each sample. SM showed higher trueness and precision than AM technologies. Reducing layer thickness in DLP did not significantly increase accuracy, but prolonged manufacturing time. All materials and technologies met the clinically acceptable range and are appropriate for their use. DLP with 100µm layer thickness showed the highest efficiency, obtaining high trueness and precision within the lowest manufacturing time.

OBJECTIVES To investigate the influence of additive manufacturing method and build angle on surface characteristics and Candida albicans (C. albicans) adhesion to 3D printed denture base polymers. METHODS Specimens of 3D printing denture base polymers were prepared by two printers, namely, stereolithography (SLA, Form 3B) and digital light processing technology (DLP, Solflex 350 plus). Three build angles were used: 0°, 45°, and 90°. Surface topography was examined by scanning electron microscopy. Also, arithmetical mean height (Sa) values were calculated. An adhesion test was performed to observe initial C. albicans adhesion to the specimens. The data were statistically analyzed using the two-way analysis of variance and Tukey's multiple comparison test. RESULTS The data of Sa values had statistically significant differences, which were mainly determined by the main factor of build angle (p

This in-vitro study investigates the bonding interfaces reached by the conditioning of a splint material additively manufactured by digital light processing (AM base) as well as the shear bond strength (SBS) of resins bonded to these surfaces (repair material). Therefore, the AM base was either stored in dry for 12 h or wet environment for 14 days to simulate ageing by intraoral wear. The dry and wet group was bonded after physical and/or chemical conditioning to cylinders made from polymethylmethacrylate or four novel polymers allowing splint modifications. Blasted and methylmethacrylate (MMA)-conditioned Polymethylmethacrylate (PMMA) bonded to PMMA acted as the gold standard. The surface profiles revealed highest differences of Ra towards the gold standard in AM base conditioned with other than MMA after sandblasting. The adhesively bonded repair materials of the wet AM base were further aged in wet environment for 14 days. The SBS of the gold standard (25.2 MPa and 25.6 MPa) was only reached by PMMA bonded to blasted and MMA-conditioned AM base after dry (22.7 MPa) and non-conditioned after wet storage (23 MPa). Four repair materials failed to reach the threshold of 5 MPa after dry storage and three after wet storage, respectively. Non-conditioned AM base revealed the highest risk for adhesive fractures when using other resins than PMMA.

Different approaches for digital workflows have already been presented for their use in palatal plates for newborns and infants. However, there is no evidence on the accuracy of CAD/CAM manufactured orthodontic appliances for this kind of application. This study evaluates trueness and precision provided by different CAM technologies and materials for these appliances. Samples of a standard palatal stimulation plate were manufactured using stereolithography (SLA), direct light processing (DLP) and subtractive manufacturing (SM). The effect of material (for SM) and layer thickness (for DLP) were also investigated. Specimens were digitized with a laboratory scanner (D2000, 3Shape) and analyzed with a 3D inspection software (Geomagic Control X, 3D systems). For quantitative analysis, differences between 3D datasets were measured using root mean square (RMS) error values for trueness and precision. For qualitative analysis, color maps were generated to detect locations of deviations within each sample. SM showed higher trueness and precision than AM technologies. Reducing layer thickness in DLP did not significantly increase accuracy, but prolonged manufacturing time. All materials and technologies met the clinically acceptable range and are appropriate for their use. DLP with 100 µm layer thickness showed the highest efficiency, obtaining high trueness and precision within the lowest manufacturing time.

PURPOSE To investigate the tensile bond strength between zirconia abutments and titanium bases, luted with two different resin composite cements, after different cleaning procedures. MATERIALS AND METHODS Zirconia abutments and titanium bases were luted with either a DMA/HEMA-based cement (n = 80; Multilink Hybrid Abutment, Ivoclar Vivadent) or a Bis-GMA/TEGDMA-based cement (n = 80; Panavia V5, Kuraray Noritake). The adhesive gap of half of the specimens was polished (n = 40 per resin composite cement). Four separate specimens underwent roughness measurements and scanning electron microscopy. The specimens were divided into four groups (n = 10 per subgroup): (1) not cleaned, (2) cleaning in an ultrasonic bath, (3) cleaning in an autoclave, and (4) treatment with low-pressure plasma. The specimens were thermocycled (20,000×, 5°C/55°C), tensile bond strength was tested, and fracture types were analyzed. Data were examined using the Kolmogorov-Smirnov test, univariate ANOVA with additional partial eta-squared (ηp2), and the Mann-Whitney U test. The defined level of significance was adjusted by Bonferroni correction (P < .003). RESULTS The tensile bond strength of specimens luted with the DMA/HEMA-based cement was higher than that of specimens luted with the Bis-GMA/TEGDMA-based cement. The polishing step and the cleaning procedures showed no impact on tensile bond strength results. Specimens luted with the DMA/HEMA-based cement presented more cohesive fractures, whereas specimens luted with the Bis-GMA/TEGDMA-based cement presented themselves with more fractures of the interface between the resin composite cement and zirconia abutment. Ra values showed a decline in roughness after polishing for both resin composite cements. CONCLUSION As the DMA/HEMA-based cement showed higher tensile bond strength values, the usage of this resin composite cement for luting implant abutments to titanium bases can be recommended. Neither polishing nor the use of different cleaning procedures had an impact on tensile bond strength.

Purpose To set up the digital database (DDB) of various anatomical parts, skin details and retention elements in order to simplify the digital workflow of facial prostheses manufacturing; and to quantify the reproduction of skin wrinkles on the prostheses prototypes with stereolithography (SLA) and direct light processing (DLP) methods. Methods Two structured light scanners were used to obtain the nasal and auricle forms of 50 probands. Furthermore, the ala nasi and scapha areas were captured with the digital single lens reflex camera and saved in jpeg format. The four magnetic retention elements were remodeled in computer aided design (CAD) software. The 14 test blocks with embossed wrinkles of 0.05–0.8 mm were printed with SLA and DLP methods and afterwards analyzed by means of profilometry and confocal microscopy. Results The introduced DDB allows for production of customized facial prosthesis and makes it possible to consider the integration of concrete retention elements on the CAD stage, which makes the prosthesis modelling more predictable and efficient. The obtained skin structures can be applied onto the prosthesis surface for customization. The reproduction of wrinkles from 0.1 to 0.8 mm in depth may be associated with the loss of 4.5%–11% of its profile with SLA or DLP respectively. Besides, the reproduction of 0.05 mm wrinkles may be met with up to 40% profile increasement. Conclusions The utilization of DDB may simplify the digital workflow of facial prostheses manufacturing. The transfer of digitally applied skin wrinkles till the prostheses’ prototypes may be associated with deviations from 11 to 40%.

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.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.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.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.

Biodegradable zinc (Zn) and Zn-based alloys have been recognized as promising biomaterials for biomedical implants. Sterilization is an essential step in handling Zn-based implants before their use in clinical practice and there are various sterilization methods are available. However, how these treatments influence the Zn-based biomaterials remains unknown and is of critical relevance. In this study, three commonly-applied standard sterilization methods, namely gamma irradiation, hydrogen peroxide gas plasma and steam autoclave, were used on pure Zn and Zn3Cu (wt%) alloy. The treated Zn and ZnCu alloy were investigated to compare the different influences of sterilizations on surface characteristics, transient and long-term degradation behavior and cytotoxicity of Zn and Zn alloy. Our results indicate that autoclaving brought about apparently a formation of inhomogeneous zinc oxide film whereas the other two methods produced no apparent alterations on the material surfaces. Consequently, the samples after autoclaving showed significantly faster degradation rates and more severe localized corrosion, especially for the ZnCu alloy, owing to the incomplete covering and unstable zinc oxide layer. Moreover, the autoclave-treated Zn and ZnCu alloy exhibited apparent cytotoxic effects towards fibroblasts, which may be due to the excessive Zn ion releasing and its local concentration exceeds the cellular tolerance capacity. In contrast, gamma irradiation and hydrogen peroxide gas plasma had no apparent adverse effects on the biodegradability and cytocompatibility of Zn and ZnCu alloy. Our findings may have significant implications regarding the selection of suitable sterilization methods for Zn-based implant materials among others.

To investigate the discoloration and surface properties of four CAD/CAM composite resins provoked by a variety of food solutions and cigarette smoke.A total of 74 specimens (N = 370) were prepared per material (Brilliant Crios [Coltene], CeraSmart [GC], Lava Ultimate [3M Espe], Shofu Block HC [Shofu], and SonicFill 2 [Kerr]). Discoloration (ΔE) was investigated with a spectrophotometer. Measurements were taken before immersion in the storage media for 2 weeks (carrot juice, curry, cigarette smoke, red wine, energy drink, and distilled water), immediately after immersion, and after manual polishing of the specimens following immersion. The mean surface roughness (Ra) was measured using a profilometer. Qualitative surface observation was performed with scanning electron microscopy (SEM). Data were analyzed using Kolmogorov-Smirnov, Mann-Whitney U, and one-way analysis of variance with Tukey post hoc tests.The highest influence on ΔE after immersion was observed by the storage medium (ηThe different materials reacted dissimilarly in the various storage media in terms of discoloration. Surface roughness increased after immersion and polishing. Neither discoloration nor surface roughness could be reset to default by manual polishing.

Objective The aim of this interlaboratory round robin test was to prove the robustness of the DIN EN ISO 6872:2019 and to identify the influence of processing and testing variations. Methods Each of the 12 laboratories participated (A–L) received 60 (n = 720) assigned zirconia specimens. All participants seperated the specimens from the blanks, sintered them, polished half of all specimens and performed the biaxial flexural test (DIN EN ISO 6872:2019). The surface roughness was determined by using tactile measuring device. Fractographic examination was performed under scanning-electron-microscopy (SEM). Data was analysed using Kolmogorov–Smirnov-, Kruskal–Wallis-, Mann–Whitney-U-test and two-parametric Weibull statistic (p Results The results for both preparation methods (as-fired and polished) showed significant differences for some participants. The values for as-fired groups ranged between 513 (I) and 659 (E) MPa. H showed higher Weibull modulus than C, E and I. Within polished groups flexural strengths values from 465 (L) to 1212 (E) MPa were observed, with a tendency to clustered groups A, I, J, L (465–689 MPa) and remaining groups (877–1212 MPa). E presented the highest and H the lowest Weibull modulus. Within A and J, no impact of the preparation method on flexural strength values was observed. Within L, as-fired specimens showed higher flexural strength than polished ones. The flexural strength increase did only associate to a certain extent with measured surface roughness. Fractography showed defect populations depending on polishing techniques, associated to the strength level, especially for polished groups. Reduced strength is related to machining defects, regardless of the surface state. Significance DIN EN ISO 6872:2019 can be seen as guidance to biaxial flexural strength testing but additional effort is necessary to ensure interlaboratory comparability. Calibrated furnaces and reliable sintering conditions are mandatory requirements together with detailed specifications on finishing or polishing procedures. Biaxial flexural testing is really a matter of understanding specimen preparation, alignment and mechanical testing by itself. DIN EN ISO 6872:2019 should further recommend reporting of mean surface roughness along with any biaxial flexural strength data. Fractography is a mandatory tool in interpretation and understanding of strength data.

CAD/CAM technologies and materials have the potential to improve the treatment of Robin Sequence with orthodontic appliances (Tübingen palatal plate, TPP). However, studies on the provided suitability and safety are lacking. The present study evaluates CAD/CAM technologies and materials for implementation into the workflow for producing these orthodontic appliances (TPPs), manufactured by different techniques and materials: additive manufacturing (AM) and subtractive manufacturing (SM) technologies vs. conventional manufacturing. The fracture load was obtained in a universal testing machine, and the breaking behavior of each bunch, as well as the necessity of adding a safety wire, was evaluated. The minimum fracture load was used to calculate the safety factor (SF) provided by each material. Secondary factors included manufacturing time, material cost and reproducibility. Dental LT clear showed the highest fracture load and best breaking behavior among AM materials. The highest fracture load and safety factor were obtained with Smile polyether ether ketone (PEEK). For the prototyping stage, the use of a Freeprint tray (SF = 114.145) is recommended. For final manufacturing, either the cost-effective approach, Dental LT clear (SF = 232.13%), or the safest but most expensive approach, Smile PEEK (SF = 491.48%), can be recommended.

How much skin surface details of facial prostheses can be transferred throughout the digital production chain has not been quantified.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.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. RFor 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.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.

This study tested and compared properties of six modern indirect veneering resin composites (VRC), namely Ceramage (Shofu), dialog Vario (Schutz Dental), Gradia Plus (GC Europe), in:joy (Dentsply), Signum composite (Heraeus Kulzer), and SR Nexco (Ivoclar Vivadent). Specimens were fabricated from dentin and enamel pastes and following properties were analyzed: (1) two-body wear (TB), (2) surface roughness (SR), (3) Martens hardness parameters (HM and EIT), and (4) translucency (T). The highest impact on HM and EIT was exerted by VRC brand (HM: ηP2=0.960/ EIT: ηP2=0.968; p

Aim Patients with cardiogenic shock or ARDS, for example, in COVID-19/SARS-CoV-2, may require extracorporeal membrane oxygenation (ECMO). An ECLS/ECMO model simulating challenging vascular anatomy is desirable for cannula insertion training purposes. We assessed the ability of various 3D-printable materials to mimic the penetration properties of human tissue by using porcine aortae. Methods: A test bench for needle penetration and piercing in sampled porcine aorta and preselected 3D-printable polymers was assembled. The 3D-printable materials had Shore A hardness of 10, 20, and 50. 17G Vygon 1.0 × 1.4 mm × 70 mm needles were used for penetration tests. Results: For the porcine tissue and Shore A 10, Shore A 20, and Shore A 50 polymers, penetration forces of 0.9036 N, 0.9725 N, 1.0386 N, and 1.254 N were needed, respectively. For piercing through the porcine tissue and Shore A 10, Shore A 20, and Shore A 50 polymers, forces of 0.8399 N, 1.244 N, 1.475 N, and 1.482 N were needed, respectively. ANOVA showed different variances among the groups, and pairwise two-tailed t-tests showed significantly different needle penetration and piercing forces, except for penetration of Shore A 10 and 20 polymers (p = 0.234 and p = 0.0857). Significantly higher forces were required for all other materials. Conclusion: Shore A 10 and 20 polymers have similar needle penetration properties compared to the porcine tissue. Significantly more force is needed to pierce through the material fully. The most similar tested material to porcine aorta for needle penetration and piercing in ECMO-implantation is the silicon Shore A 10 polymer. This silicon could be a 3D-printable material in surgical training for ECMO-implantation.

This study determinates the persistence of retention force in Akers-clasps for removable partial dentures made from Co-Cr alloy. Therefore, standardized computer-aided designed (CAD) clasp #1 specimens were made by direct metal laser melting (DMLM, n = 10) and by lost-wax dental casting (DC) of computer-aided manufactured (CAM) replicas (n = 10, DC) from two comparable Co-Cr alloys. The retention force was tested after manufacturing for 9000 cycles of setting and removal from a molar tooth crown analog made from zirconia; simulating in-vitro a duration of six years in service. The first and last 360 cycles (T0 and T1, 3 months each) of all specimens were selected for comparison of retention forces between the materials. A constant decrease of 6% from the initial retention force (T0 = 4.86 N, SD = 0.077; T1 = 4.57 N, SD = 0.037) was detected at the DC specimens, and an increase of 4% in DMLM specimens (T0 = 5.69 N, SD = 0.078; T1 = 5.92 N, SD = 0.077); all differences were statistically significant (p < 0.0001). Even if these deviations are not of clinical relevance, further studies and applications should investigate the fatigue behavior of laser melted Co-Cr-alloys for dental application.

The present study aimed to evaluate the repairability of a 3D printed denture base material. The effects of surface treatments and artificial aging on the shear bond strength (SBS) were investigated.A total of 224 specimens were printed by digital light processing technology (Rapid Shape D30II) using a 3D printing denture base material (FREEPRINT denture). To evaluate the repairability, the SBS and failure modes were measured after surface treatment and artificial aging. Specifically, half of the specimens were further performed with thermocycling (5-55 °C, 5000 cycles) for artificial aging. The aged and non-aged specimens were further divided into four subgroups (n = 28) to simulate a denture base repair with one of the following treatments: control (without surface treatment), monomer (applying methylmethacrylate for 120 s), P600 (grinding with P600 silicon carbide paper) and sandblasting (blasted with 125 μm aluminum oxide with 2 bar), respectively. Surface roughness was measured (n = 6) and surface topography was observed by scanning electron microscopy (n = 2). A test rod was built on the sample surface using the same 3D printing material. Afterward, all specimens further underwent thermocycling (5-55 °C, 10,000 cycles).For non-aged groups, no significant differences in SBS could be found (p 0.05), and bondings failed cohesively in the denture base material. Regarding the aged control and monomer group, adhesive failures at the interface were primarily observed, and SBS values were statistically lower than those of the other groups (p 0.05).The 3D printed denture base material exhibited favorable repairability. For the realignment surface, the SBS at the bonding interface is satisfying and additional surface treatments could be not necessary. In contrast, the aged surface could significantly decrease the SBS; hence subtractive surface treatments are highly recommended.

A new application of a polyetheretherketone (PEEK) post-core restoration combined with polyvinylsiloxane (PVS) attachments was proposed and substantiated. This study aimed to evaluate retentive characteristics of the PEEK post-core restoration with PVS attachment systems. Specimens with PVS attachments were fabricated to evaluate retention force during 10,000 cyclic dislodgements. Additionally, the retention forces of PVS attachments with three different values of Shore hardness were further measured before and after aging treatments. The results of cyclic dislodgement test indicated a strong negative linear relationship between the cyclic times and retention force (p < 0.0001, r = −0.957). Furthermore, the retention forces of the PVS were significantly improved with Shore hardness increased, which was also affected by the aging treatment (F (2, 138) = 10.95, p < 0.0001). Therefore, the PEEK post-core restoration with PVS attachments exhibited the favorable retention force, which could be a promising alternative for dental prostheses.

(1) Background: To date, no information on the polishability of milled and 3D-printed complete denture bases has been provided, which is relevant in terms of plaque accumulation. (2) Methods: three groups (n = 30) were manufactured using the cold-polymerization polymethilmethacrilate, milling (SM) and 3D printing (AM). 10 specimens of each group were left untreated (reference). 10 more specimens were pre-polished (intermediate polishing) and 10 final specimens were highgloss polished. An additional 20 specimens were 3D printed and coated with the liquid resin (coated), 10 of which were additionally polished (coated + polished). For each group Ra and Rz values, gloss value and REM images were obtained. (3). The “highgloss-polished” specimens showed statistically lower Ra and Rz values in the SM, followed by AM and conventional groups. In the AM group statistically lower surfaces roughness was revealed for highgloss-polished, “coated + polished”, and “coated” specimens, respectively. (4) Conclusions: The milled specimens demonstrated superiors surface characteristics than 3D printed and conventionally produced after polishing. The polished specimens demonstrated superior surface characteristics over coated specimens. However, the surface roughness by both polished and coated specimens was within the clinically relevant threshold of 0.2 µm.