Search Results (209)

Background/Objectives: 3D printing of removable dentures and temporary crowns and bridges is currently one of the fastest-developing technologies in prosthetic dentistry. However, little is known about the effect of different beverage solutions on the strength and color of 3D-printed denture resins. The study aimed to determine the effect of coffee, red wine, 40% ethyl alcohol, and water (reference samples) on six 3D-printed denture resins (Denture 3D+ (Nexdent); Vita Vionic (Vita), Lucitone Digital Print 3D (Dentsply), DX Denture Flex (Dentex); Formlab Denture Base (Formlabs, Optiprint Dentona). Materials and Methods: Resin samples measuring 3.3 × 10 × 65 mm (144 total) and disks 1 × 20 mm (108 total) were produced using an Asiga printer. The printed materials were then stored in coffee, red wine and distilled water and vodka for 30 days. After this time, they were subjected to a flexural strength (FS) test and the measurement of color change (CC), and compared to reference samples measured before contact with the solutions. One- and two-way ANOVA were used for statistical analysis to compare samples before and after contact with the solutions. Results: The vodka solution affected the materials’ FS—the strength was reduced from 10% (Lucitone) to 88% (Detax). For the sample with the most significant FS reduction, the elastic modulus could not be determined. The largest CCs were observed for coffee (E = 22.66 ± 1.26), and red wine (E = 21.04 ± 0.70), whereas vodka had the least effect on CC (Lucitone E = 1.04 ± 0.41 and Form Labs E = 1.31 ± 0.85). Conclusions: 3D-printed resins are susceptible to the effects of commonly consumed substances, such as coffee, vodka, and red wine. When designing and manufacturing removable prosthetic restorations, it is necessary to carefully consider the dietary habits of patients and the materials from which the removable prosthetics are printed. Full article

The accuracy of full-arch digital impressions remains a topic of debate despite advancements in intraoral scanning technologies. This in vitro study aimed to evaluate the effect of different intraoral scanner generations (TRIOS 3, TRIOS 5, and TRIOS 6) on full-arch digital impression accuracy by comparing dentate and fully prepared models. A dentate and a fully prepared maxillary model were digitized using a high-accuracy desktop scanner to create reference datasets. The models were fabricated with a 3D printer, and a total of 60 digital impressions were obtained, with 10 repeated scans for each scanner–model combination. Accuracy was assessed by comparing STL datasets with the reference models using root mean square (RMS) deviation values. The results showed that TRIOS 3 and TRIOS 5 demonstrated similar accuracy performance across both model types, whereas TRIOS 6 exhibited higher deviation values, particularly in the fully prepared model. Furthermore, model type had a significant effect on accuracy, and a statistically significant interaction was observed between scanner type and model type. These findings indicate that digital impression accuracy is influenced not only by scanner generation but also by surface morphology and reference characteristics. Full article

The incorporation of antimicrobial additives into 3D-printed denture base resins is a promising strategy for reducing denture stomatitis, but the mechanical consequences and temporal stability of such modifications remain poorly characterized. This in vitro pilot study evaluated the effects of incorporating 4% (w/w) K18—a quaternary ammonium methacryloxy silane dissolved in isobornyl acrylate (IBOA)—into three commercially available photopolymer resins printed across four platforms representing stereolithography, digital light processing, and liquid crystal display technologies. Flexural strength, flexural modulus, and flexure at break were measured at three time points: without K18, immediately after mixing, and one-week post-mixing. K18-IBOA incorporation produced significant reductions in all mechanical parameters across most resin–printer combinations. The magnitude and direction of changes were strongly dependent on printer–resin combination interactions, precluding generalization across systems. At one week, visible clumping consistent with phase separation was observed in all formulations, and one resin–printer combination exhibited catastrophic structural failure upon removal from the build platform. These findings suggest that 4% w/w K18-IBOA additions are unlikely to yield clinically acceptable denture bases without further formulation optimization, underscoring the importance of temporal stability assessment in the development of antimicrobial-modified photopolymer resins. Full article

In this study, the structural, thermal, and mechanical properties of nanocomposites obtained by adding zinc oxide (ZnO) nanoparticles (NPs), produced by phyto-mediated synthesis using Dianthus chinensis plant extract, to a PMMA-based photopolymer resin at different ratios (0.05%, 0.10%, 0.15%, 0.20%, and 0.25%, by weight) were evaluated. The prepared composite resins were produced in different test geometries using a DLP (digital light processing)-based 3D printer (Asiga Ultra). Following the structural characterization of ZnO nanoparticles, tensile, compressive, and flexural mechanical tests were performed on the resulting composites, as well as FTIR, TGA, DSC, and DMA analyses. The FTIR results showed that ZnO NPs were physically integrated into the matrix. TGA and DSC analyses revealed that the addition of ZnO NPs, particularly at an addition rate of 0.15%, increased thermal stability. DMA analyses showed an increase in storage modulus and glass transition temperature as the addition rate increased. In mechanical tests, the highest modulus of elasticity and maximum strength values were obtained at additive ratios of 0.10–0.15%. The highest tensile strength (55.31 MPa) and compressive strength (388.53 MPa) were obtained at ZnO contents of 0.10–0.15 wt%, while the maximum flexural strength reached 125.94 MPa at 0.15 wt% ZnO. In addition, the storage modulus increased from 1.469 × 10⁹ Pa for the control resin to 1.872 × 10⁹ Pa for the composite containing 0.15 wt% ZnO, indicating improved stiffness and thermomechanical stability. The stress–strain curves show that improvements in ductility and deformation capacity of the material are achieved at these additive ratios. The findings demonstrate that green-synthesized ZnO nanoparticles are an effective and sustainable additive material for improving the mechanical and thermal performance of DLP-based photopolymer dental resins. Full article

Background/Objectives: Resin 3D printing is widely used to fabricate orthodontic diagnostic models, but the practical performance of commercial desktop workflows compared to dental-certified workflows is still debated. This study compared the dimensional accuracy and 7-day stability of maxillary orthodontic models printed from the same master STL file using a dental-certified workflow versus two commercial desktop workflows. Methods: An ISO 20896-1:2019-based reference cast with four 6 mm calibration spheres was used to generate a master STL file. Fifteen models were printed (n = 5 per workflow) using Primeprint™ (dental-certified workflow) and two commercial desktop printers (Anycubic Photon Mono M5s; Phrozen Sonic Mighty 14K REVO). The models were digitized at baseline (T0, ≤48 h) and after 7 days (T7) using a laboratory scanner. Surface superimposition in CloudCompare^® calculated the RMS (root mean square) surface deviation and mean signed deviation, and two calibrated operators performed independent extractions. Results: The mean RMS deviations were <0.10 mm for all workflows at both time points. No between-workflow differences were detected at T0 (H = 2.000; p = 0.368) or T7 (H = 1.520; p = 0.468), no within-workflow T0–T7 changes were significant (all p > 0.05), and the inter-operator agreement was excellent (ICC 0.991–0.999). Conclusions: Under the tested workflows, dental-certified and commercial desktop resin printing produced orthodontic models with a comparable global surface accuracy and short-term dimensional stability. Full article

Background/Objectives: Among vat polymerization technologies, liquid-crystal display (LCD) 3D printing has gained popularity in dentistry because of its affordability and acceptable resolution. However, the factors influencing the dimensional accuracy of LCD-printed surgical splints, particularly build platform position, remain insufficiently investigated. This study aimed to evaluate the influence of build platform position on the trueness and precision of orthognathic surgical splints fabricated using LCD 3D printing technology. Methods: Thirty-six surgical splints were printed from a master digital file using an LCD 3D printer. All surgical splints were printed with a 90-degree layer orientation to the building platform. The layer thickness was set at 100 μm. The surgical splints were divided into three groups according to their printing position on the building platform: middle (M), left (Lt), and right (Rt). Each 3D-printed surgical splint was sprayed with an opaque scanning spray and then rescanned to create digital files for testing. A surface-based superimposition and deviation analysis was performed using specialized 3D software to evaluate accuracy of surgical splints. Root mean square error (RMSE) values were statistically analyzed. Results: There were no statistically significant differences in trueness among the middle, left, and right printing positions on the build platform (p > 0.05). In contrast, printing position significantly affected precision, with surgical splints printed at the center of the build platform demonstrating significantly lower RMSE values compared with those printed at the left and right positions (p < 0.001). In addition, no significant difference in precision was detected between the left and right positions. Conclusions: The printing position on the build platform significantly influences the precision of orthognathic surgical splints fabricated using LCD 3D printing technology. Splints printed at the central region of the build platform exhibited the highest precision, whereas trueness was not significantly affected by printing position. These findings suggest that preferential placement of surgical splints at the center of the build platform may improve fabrication consistency and predictability in digital orthognathic surgery workflows. Full article

This research investigated the feasibility of 3D-printed external fixator (EF) rings made from carbon fiber reinforced polyamide 6 (PA6-CF) as an alternative to the conventional metallic counterpart. The study integrated tensile testing with digital image correlation (DIC) in as-printed and cold plasma-sterilized conditions, finite-element analysis (FEA) under wire loading, topology optimization for material and energy reduction, and evaluation of printability limits for large PA6-CF rings. The average Young’s modulus was 4.76 GPa and the maximum tensile strength was 60.5 MPa for as-printed samples, decreasing by 6.4% and 10.4% after sterilization, respectively. Using these properties as model inputs, FEA predicted safety factors larger than 1.42 for all configurations under 1000 N wire pretension, while topology optimization targeted up to 50% mass reduction without compromising ring stiffness. The study also revealed challenges in the printability of PA6-CF for large and thin components, including dimensional contraction, significant warping and moisture-induced defects, requiring an experienced 3D printer operator. Full article

The increasing adoption of digital light processing (DLP) three-dimensional (3D) printing in prosthodontics has enabled the rapid fabrication of denture bases with improved dimensional accuracy and reproducibility. However, the mechanical performance and surface characteristics of 3D-printed denture base resins remain inferior to those of conventional heat-polymerized polymethyl methacrylate (PMMA), limiting their long-term clinical reliability. This study aimed to investigate the effect of incorporating zinc oxide (ZnO) and samarium oxide (Sm₂O₃) nanoparticles, individually and as hybrid nanofiller systems, on the mechanical and wettability properties of a DLP 3D-printed denture base resin. ZnO and Sm₂O₃ nanoparticles were incorporated into a photopolymerizable denture base resin at concentrations of 1 and 2 wt.%, producing seven experimental formulations, including a control group. A total of 280 specimens were fabricated using a DLP 3D printer and subjected to standardized post-processing. Nanoparticle dispersion and morphology were examined using field-emission scanning electron microscopy (FE-SEM), while Fourier-transform infrared spectroscopy (FTIR) was employed to assess possible chemical interactions between the nanofillers and the polymer matrix. Mechanical performance was evaluated through impact strength, transverse strength, and flexural strength tests, and surface wettability was assessed using static water contact angle measurements. Statistical analysis was conducted using one-way ANOVA followed by Tukey’s post hoc test (α = 0.05). The results demonstrated that all nanoparticle-reinforced groups exhibited significantly enhanced mechanical properties compared with the unmodified control resin. The incorporation of 1 wt.% nanofillers yielded the most pronounced improvements, with the 1 wt.% ZnO group achieving the highest transverse strength and the 1 wt.% ZnO–Sm₂O₃ hybrid group exhibiting the maximum flexural strength. Increasing the nanofiller concentration to 2 wt.% resulted in partial reductions in impact and flexural strength, which were attributed to nanoparticle agglomeration and increased light scattering during photopolymerization. FTIR analysis revealed no evidence of chemical bonding between the resin matrix and the nanofillers, indicating that the observed enhancements were primarily governed by physical reinforcement mechanisms. Wettability analysis showed that Sm₂O₃-containing formulations significantly reduced the water contact angle, indicating increased surface hydrophilicity, whereas ZnO incorporation produced more hydrophobic surfaces. Within the limitations of this in vitro study, the findings suggest that low-concentration incorporation of ZnO and Sm₂O₃ nanoparticles represents an effective strategy to enhance the mechanical integrity and tailor the surface properties of DLP 3D-printed denture base resins. These results suggest potential clinical relevance of nanoparticle-reinforced printed denture bases, emphasizing the importance of optimized filler loading to avoid agglomeration-induced performance degradation. Full article

Background: Digital intraoral scanning has become an essential component of modern restorative dentistry, offering enhanced accuracy, workflow efficiency, and patient comfort compared to conventional impression techniques. Despite these advantages, the accuracy of intraoral scanners (IOS) can be affected by multiple parameters, among which scanning strategy and device design are particularly influential. Purpose: This study aimed to investigate the effect of different scanning strategies on scan accuracy and precision, focusing on two widely used intraoral scanners (Medit i700 and Trios 5) in a controlled in vitro environment. Materials and Methods: A standardized digital test object was created according to ISO 20896-1 specifications to ensure uniformity and comparability. The object was printed using a high-precision 3D printer and scanned multiple times with both IOS systems, employing distinct scanning strategies under identical environmental conditions. Data analysis was performed using descriptive and comparative statistics, including Mean, Median, Mean Absolute Deviation (MAD), Root Mean Square Error (RMSE), Standard Deviation (SD), and Variance, to evaluate trueness and precision. Results: The Medit i700 consistently exhibited lower deviation values and greater precision compared with the Trios 5, reflecting higher trueness and precision. Scanning strategy influenced scan outcomes; structured, systematic scanning paths produced more stable and accurate datasets. The Trios 5 demonstrated higher variability, suggesting increased sensitivity to operator motion and scanning trajectory. Conclusions: Both the scanner type and scanning strategy substantially affect intraoral scan accuracy. The superior performance of the Medit i700 indicates greater robustness and operator-independent stability. Clinically, these results underscore the importance of standardized scanning protocols, as operator consistency may be a key determinant of digital impression accuracy and, consequently, of clinical outcomes. Full article

Background/Objectives: The purpose of this in vitro study is to evaluate the effect varying palatal vault depths have on the accuracy of complete maxillary denture bases fabricated using additive manufacturing technology. Methods: One hundred complete maxillary denture bases were manufactured on two different digital light processing (DLP) dental 3D printers at five different palatal depths. After manufacturing, the denture bases were post-cured, scanned, and then analyzed in metrology software. Statistically significant differences were determined using two-way ANOVA tests for normally distributed data and the Kruskal–Wallis test for non-normally distributed data. Color deviation maps were used to give clinical relevance to the results. Results: Significant differences were found for both printers among some groups for the different palatal depths. In relation to the negative mean deviation, the data revealed that the NextDent printers were the least accurate (0.047 ± 0.004) in the group with the deepest palate. The positive mean deviation revealed the most deviation (0.077 ± 0.009) in the group with the deepest palate, which was also mirrored in the Asiga printer (0.050 ± 0.002). The color deviation maps revealed areas of positive and negative average deviation in all groups. The effect of the printer model (p = 0.007) and palatal depth (p = 0.04) on negative average deviation was significant. The effect of the interaction of printer and palatal depth was also significant (p = 0.001). Conclusion: Deeper palatal vaults are associated with higher deviation in DLP 3D-printed complete maxillary denture bases manufactured through additive manufacturing. Full article

Objective: This in vitro study aimed to evaluate and compare the trueness and precision of four extraoral 3D facial scanning systems using a standardized 3D-printed human head model. Methods: A 3D-printed head model with 16 anatomical landmarks and 17 inter-landmark linear distances was fabricated using a high-resolution 3D printer. Caliper measurements were used as reference standards. The model was scanned 15 times by four systems: a handheld scanner (MetiSmile, Shining 3D, Hangzhou, China), a desktop scanner (RAYFace v2.0, Ray Co., Seongnam, Gyeonggi-do, Republic of Korea), and two mobile applications (Heges and Polycam, iPhone 15, Apple Inc., Cupertino, CA, USA). All digital distances were measured in Blender software. To assess intra-observer reliability, all measurements were repeated twice by the same examiner with a 3-week interval between sessions, and intra-class correlation coefficients were calculated using a two-way mixed-effects, single-measurement, absolute-agreement model (ICC 3,1). Trueness, defined as the absolute deviation from the reference caliper values, was compared across scanners using the Kruskal–Wallis test due to its non-normal distribution. Precision, regional trueness and precision values across the four scanners defined as the standard deviation of repeated scans, was analyzed using One-way ANOVA with Tukey post-hoc comparisons for normally distributed datasets (α = 0.05). Distances were measured digitally in Blender software, and trueness (absolute deviation from reference) and precision (standard deviation of repeated scans) were analyzed using the Kruskal–Wallis test and One-way ANOVA with Tukey post hoc comparisons (α = 0.05). Results: The Polycam application demonstrated the highest trueness (0.49 ± 0.32 mm), followed by MetiSmile (0.51 ± 0.36 mm), RAYFace (0.58 ± 0.39 mm), and Heges (0.73 ± 0.42 mm). The MetiSmile scanner showed the highest precision (0.12 ± 0.07 mm), while RAYFace and Polycam exhibited moderate precision (0.28 ± 0.19 mm and 0.15 ± 0.06 mm, respectively). Vertical measurements tended to be more accurate than horizontal ones, and the lower facial region showed smaller deviations; however, these differences were not statistically significant (p > 0.05). Conclusions: MetiSmile achieved the highest precision and Polycam the highest trueness. Although all systems showed mean deviations < 1 mm, only three demonstrated <0.6 mm accuracy (except for Heges scanner). These results suggest that professional and mobile-based scanners can provide clinically acceptable facial data for educational and preliminary digital workflow applications, though further validation under clinical conditions is required. This study provides quantitative evidence on the accuracy and repeatability of commonly available extraoral 3D facial scanning systems under controlled laboratory conditions. The results indicate that both professional-grade and mobile-based scanners can reproduce facial morphology with clinically acceptable deviations, particularly in flat and stable regions such as the forehead and chin. Although only three systems achieved mean trueness below 0.6 mm, all demonstrated errors within 1 mm, sufficient for diagnostic visualization, digital smile design, and preliminary virtual patient modeling. These findings support the safe and cost-effective adoption of extraoral facial scanning in dental education and treatment planning, while emphasizing the need for further validation in real clinical environments where motion, lighting, and soft-tissue variability may affect accuracy. Full article

Background/Objectives: Fully digital workflows used in implant dentistry have been evolving to improve rehabilitation times and patient satisfaction. More studies are necessary for full scientific validation. The aim of this study was to evaluate the 6-month outcome of implant-supported fixed prostheses for full edentulism rehabilitation using OnX Tough 2 resin (SprintRay) and the Pro 2 (SprintRay) 3D printer following the All-on-4 concept. Methods: This study included 16 patients (10 female, 6 male) with 20 implant-supported fixed full-arch prostheses following the All-on-4 concept (10 rehabilitations for each stackable guide and photogrammetry protocols). Primary The primary outcome measure was implant and prosthetic survival. The secondary outcome measures included manufacturing issues, prosthetic passive fit, marginal bone loss (MBL), mechanical and biological complications, modified plaque and bleeding indexes, pocket depths, patient subjective evaluation, and the Oral Health Impact Profile. Results: No patients were lost to follow-up. Two prostheses failed and 2 two implants were lost, resulting in a cumulative survival rate of 90% and 97.5% at 6 months for prostheses and implants, respectively. The mean MBL was 0.31 mm ± 0.52 mm at 4 months. The mechanical complications rate was 50% at patient level. One patient (6.3%) experienced one biological complication. The grades regarding “comfort of prostheses in the mouth” and “overall chewing feeling” were 9.35 ± 1.29 and 8.79 ± 1.67 out of 10, respectively. The mean total sum of the OHIP-14 was 1.61 out of 56. Conclusions: Implant-supported full-arch rehabilitations with fixed prostheses following the All-on-4 concept, through a fully digital workflow protocol, are a viable option in the short term. Full article

Three-dimensional printing is growing rapidly in applied dentistry. To print faster, increase workflow, and minimise resin consumption, it is important to use the right printer and correct printing orientation. This report aims to analyse whether different printing orientations and types of printing materials could affect the flexural strength of a series of photopolymerisable resin samples. Seven different dental light-curing resins (Keyguide, C&B, Ivory, Vertysguide, Bite, Tera, and Nextdent Cast) and a single modern digital light processing (DLP) 3D printer (Moon Night) were used for this purpose. Different printing orientations (0°, 45°, and 90°) were evaluated. The resin specimens were designed using 3D Builder 20.0.4.0, MeshMixer 3.5.0 and Chitubox software 2.0.8. A total of 15 specimens (five for each orientation evaluated) in the shape of a rectangular parallelepiped with dimensions of 2 mm × 2 mm × 25 mm were produced for each of the seven selected resin materials with the Moon Night printer. After printing and post-processing (MoonWash 2 and MoonLight 2), each resin specimen was subjected to a mechanical test with a universal testing machine. After breaking the specimen, the flexural strength values were recorded using Bluehill computer software (Instron Corporation, Canton, MA, USA). According to the obtained results, the build angle does not affect the flexural strength of the printed products, whereas the difference occurs due to the different printing materials used. Full article

Additive manufacturing via stereolithography (SLA) enables the fabrication of highly customized lattice structures, yet the interplay between geometry and graded density in defining mechanical behavior remains underexplored. This research investigates the mechanical behavior and failure mechanisms of cylindrical lattice structures considering uniform, linear, and quadratic density variations. Various configurations, including IsoTruss, face-centered cubic (FCC)-type cells, Kelvin structures, and Tet oct vertex centroid, were examined under a complete factorial design that allowed a thorough exploration of the interactions between lattice geometry and density variation. A 3D printer working with SLA was used to fabricate the models. For the analysis, a universal testing machine, following ASTM D638-22 Type I and ASTM D1621-16 standards, was used for tension and compression tests. For microstructural analysis and surface inspection, a scanning electron microscope and a digital microscope were used, respectively. Results indicate that the IsoTruss configuration with linear density excelled remarkably, achieving an impressive energy absorption of approximately 15 MJ/m³ before a 44% strain, in addition to presenting the most outstanding mechanical properties, with a modulus of elasticity of 613.97 MPa, a yield stress of 22.646 MPa, and a maximum stress of 49.193 MPa. On the other hand, the FCC configuration exhibited the lowest properties, indicating lower stiffness and mechanical strength in compression, with an average modulus of elasticity of 156.42 MPa, a yield stress of 5.991 MPa, and the lowest maximum stress of 14.476 MPa. The failure modes, which vary significantly among configurations, demonstrate the substantial influence of the lattice structure and density distribution on structural integrity, ranging from localized bending in IsoTruss to spalling in FCC and shear patterns in Kelvin. This study emphasizes the importance of selecting fabrication parameters and structural design accurately. This not only optimizes the mechanical properties of additively manufactured parts but also provides essential insights for the development of new advanced materials. Overall, the study demonstrates that both lattice geometry and density distribution play a crucial role in determining the structural integrity of additively manufactured materials. Full article

Background: Three-dimensional (3D) printing technologies such as Stereolithography (SLA) and Digital Light Processing (DLP) are widely used in dental implantology for the fabrication of surgical guides. While both methods offer clinical viability, their comparative accuracy, efficiency, and material consumption remain subjects of debate. Objectives: To compare the dimensional accuracy, printing time, and material consumption of dental surgical guides fabricated using an SLA printer (Formlabs Form 3B) and a DLP printer (NextDent 5100) at various printing orientations. Methods: A standardized surgical guide was designed and printed on both printers across seven orientations (0–90°). Five guides per angle were fabricated per technology (n = 35 per printer), scanned, and compared with the CAD reference to evaluate dimensional accuracy. Printing time and resin consumption were recorded. Statistical analyses included the Shapiro–Wilk test and Mann–Whitney U test (α = 0.05). Results: Within the evaluated printers and resins, SLA-printed guides demonstrated slightly lower Root Mean Square (RMS) values in most regions, especially in occlusal and drill hole surfaces, while DLP guides tended to undersize Optimal accuracy was observed at 45° for SLA and 60° for DLP. Material consumption was lower for the SLA printer compared with the DLP printer, but SLA required longer printing time (90–200 min vs. 25–75 min for DLP). Conclusions: Both technologies produced clinically acceptable guides under the tested conditions. The tested SLA printer tended to offer slightly higher accuracy and material efficiency, whereas the DLP printer achieved shorter printing times, supporting its use in high-throughput workflows. Printing orientation significantly influenced accuracy and resource use. Full article