3D-printed Resin Research Articles

Influence of the post-processing protocol on a biocompatible 3D-printed resin.

This study aimed to evaluate the cytotoxicity of a biocompatible 3D-printed resin material for occlusal devices after post-processing with two different high-intensity UV-polymerization devices and two rinsing solvents, in the presence of human gingival fibroblasts (HGFs). Sample discs from the 3D-printed resin material were printed (2 mm in height and 6mm in diameter [N = 40]) and divided into 4 groups (n = 10) based on post-processing methods: a high-intensity UV polymerization device with isopropyl alcohol, a high-intensity UV polymerization device with a modified glycol solvent, a UV cleaning and curing unit with isopropyl alcohol, a UV cleaning and curing unit with a modified glycol solvent, and a control group cultured in DMEM medium. Different tests were performed to evaluate their cytocompatibility on HGFs: MTT assay, cell migration assay, cell cytoskeleton staining, scanning electron microscopy (SEM), and cell apoptosis and generation of intracellular reactive oxygen species (ROS). Statistical analyses were performed using one-way ANOVA and the Tukey post hoc test (α = 0.05). Cytocompatibility, MTT assay, cell migration assay, cell cytoskeleton staining, and SEM images were similar, regardless of the post-processing protocol, compared with the control group. No differences were found in the cytotoxicity of the 3D-printed resin material for occlusal devices after the following post-processing methods: two different UV-polymerization devices and two rinsing solvents (isopropyl alcohol and a modified glycol solvent).

Evaluation of the Mechanical Properties of Provisional 3DPrinted Resin After Repair with Different Materials: An In-Vitro Study.

To evaluate the mechanical properties of the 3D printed provisional restoration material that was repaired using different materials. The bar specimens have been manufactured using three-dimensional printing technology in accordance with the ISO 10477:2020 standards and divided into 5 groups randomly. For repair material application and replacement on the standardized silicone mold, the test specimens were ground at the center by 1x2x2 mm. No grinding was done on the control group specimens. Flowable composite, bis-acrylic composite resin, polymethyl methacrylate resin, and temporary 3D printing resin are utilized as repair materials (n=16). The specimens underwent a three-point-bending (3PB) test, with a cross-head speed of 1mm/min, in order to assess their flexural strength (FS) and flexural modulus (FM). The data received statistical analysis with one-way ANOVA and Tukey test. A Weibull analysis was performed, and the Weibull modulus of specimens was calculated. Control group specimens were showed the highest FS (142±12.6 MPa) and FM (4497±1205 MPa) values. Among the test groups, the utilization of temporary 3D printing resin as a repair material exhibited the greatest FS (67±33.3 MPa) values and showed statistical significance when compared to all other groups. Repairing 3D-printed provisional resin material weakens its mechanical properties. However, utilizing the own resin made of 3D-printed provisional resin material can be an effective choice for implementing minor modifications and additions.

3D-Printed Permanent Resin Crowns on Pre-Molar and Molar Teeth; Two-Year Results of a Prospective Clinical Study.

The aim of this prospective clinical study was to evaluate the 12 and 24-month clinical results of overlay and one-piece endodontic crown restorations applied with additively manufactured 3D printed permanent ceramic-filled resin (PCR) according to the Modified US Public Health Service (USPHS) criteria. A total of 33 indirect restorations (16 overlay, 17 endocrown) (4 premolar, 29 molar) produced using PCR (Formlabs) were applied to 30 patients by a single dentist. The restorations were evaluated according to the modified USPHS criteria at baseline (7 days), 12 and 24 months times by two independent evaluators. The study registration number is NCT05168852. In the comparisons of the dependent criteria scores, the Related Samples Cochran Q test was used, and in post-hoc paired comparisons, the Bonferroni test. The Fisher-Freeman-Halton test was applied in the comparisons of categorical variables according to the restoration type groups (α = 0.05). No statistically significant difference was determined between the evaluation criteria scores at baseline, 12 months, and 24 months for the marginal adaptation (P=0.05), retention (P=1), interproximal contact (P=0.368), color match (P=1), surface texture (P=1), and patient satisfaction (P=1). The only score criteria that showed a statistically significant difference between baseline and 24 months (P=0.001) among all other criteria was marginal discoloration. This criteria's score change was from 100% A score to 69.7% A score. In the 2-year follow-up of indirect single-tooth restorations produced with 3D-printed PCR, all restorations showed acceptable clinical performance. (≥99.5%A+B score at 2 years).

Preparation of UV curable acrylamide modified epoxy resin and performance in 3D printing

A novel UV-curable 3D printing resin was synthesized by combining diglycidyl ether of bisphenol A (DGEBA) and acrylamide (AAM) to create a UV-curable acrylamide-modified epoxy resin prepolymer. This prepolymer was then uniformly mixed with the photoinitiator TPO and the reactive diluent hydroxyethyl methacrylate (HEMA). By adjusting the prepolymer content, UV-curable 3D printing resins were formulated with prepolymer concentrations of 30 wt%, 40 wt%, and 50 wt%, respectively. Infrared spectroscopy and nuclear magnetic resonance studies indicated that the amino groups in acrylamide reacted with the epoxy groups. When the prepolymer was added at concentrations of 30 wt% and 40 wt%, the viscosity met the requirements for UV-curable 3D printing. Upon completion of curing, these three distinct resins exhibited high mechanical strength, with tensile strength reaching up to 59.42 MPa and flexural strength peaking at 72.25 MPa. The elongation at break ranged from 2.60 % to 4.91 %. Scanning electron microscopy was used to examine the UV-cured 3D printed samples, and comparison with the design files revealed that the printed samples exhibited excellent dimensional stability. The study results indicated that this novel UV-curable epoxy vinyl resin formulation possessed excellent mechanical properties, suitable curing characteristics, and high resolution, making it a highly promising prepolymer for UV-curable 3D printing.

Characterization of 3D printed composite for final dental restorations.

This study evaluated the mechanical, optical, microstructural, surface, and adhesive behavior of a 3D printing resin comparing it with a machinable resin composite. Specimens of different sizes and shapes were either printed (Vitality, Smart Dent) or machinable (Grandio Blocs, Voco GmbH) resin composites with similar composition were prepared. Surface and mechanical characterization were performed with Knoop hardness, flexural strength (three-point-bending), and elastic modulus tests. The wear of the tested materials was evaluated against steatite antagonists. The optical properties stability (color change, ΔE00, and translucency, TP00) were observed after staining in red wine. In addition, the bond strength of the resin composites to two resin cement protocols were investigated with microshear bond strength tests at baseline and after thermocycling. Scanning electron microscope (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS) was used for microstructural and chemical characterization. Statistical analyses were performed with t- and ANOVA tests. Hardness values (132.76 (16.32) KH- Machinable and 35.87 (2.78) KH - Printed), flexural strength (172.17 (26.99) MPa - Machinable and 88.69 (8.39) MPa - Printed), color and translucency change (1.86 (0.31)/0.06 - Machinable and 3.73 (0.36)/9,16- Printed), and wear depth (24.97mm (3.60)- Machinable and 7.16mm (2.84) - Printed) were statistically different. Average Regarding bond strength, mean values (MPa) for non-aged and aged groups were respectively 21.76 (6.64) / 31.9 (12.66) for Bifix cement (Voco GmbH, Cuxhaven, Germany) and 26.75 (5.14) / 24.36 (6.85) for Variolink cement (Ivoclar Vivadent, Schaan, Liechtenstein) in Printed and 17.79 (3.89) / 9.01 (3.36) ) for Bifix cement and 22.09 (6.55) / 11.01 (3.77) for Variolink cement in Machinable materials. The material and aging factors did affect bond strength but the cement factor did not (p = 0.202). No statistical differences were observed for mean roughness (Ra) between materials. The better dispersion and larger size of the inorganic particles in the Machinable resin were contrasted with the clustered smaller particles of printed resin, under SEM. The mechanical properties and color stability of the machinable resin were superior to those of the printed resin, probably due to the greater amount and dispersion of inorganic particles in the Mach resin, but bond strength after aging was stronger and more stable in the printed resin. 3D-printed resin composites with similar compositions to machinable resin composites do not necessarily exhibit the same properties, which can impact clinical performance. Understanding these differences can assist manufacturers in improving their materials and help clinicians distinguish between materials appropriate for provisional and final restorations.

АДГЕЗИВНАЯ АКТИВНОСТЬ МИКРООРГАНИЗМОВ К СТОМАТОЛОГИЧЕСКИМ МАТЕРИАЛАМ ДЛЯ 3D ПЕЧАТИ И ВАКУУМНОЙ ФОРМОВКИ

Relevance: The adhesive activity of the oral microbiome to new generation materials is the subject of study by the global medical community, and the issue of choosing structural materials is still being discussed in the scientific community and is of a controversial nature. Objective: To study the adhesion of representatives of the oral microbiome to samples of modern dental materials under experimental conditions (in vitro). Materials and methods: Samples of photopolymer resins for 3D printing: Dental Crown LCD, Dental Sand A1-A2, Dental Clear Pro, (n=30), (1-3 groups), thermoforming plates for vacuum forming: EV Gasket Bleaching 080, Bioplast multicolor 3.0*123 mm, Bioplast color 3.0*125 mm (n=30), (groups 4-6); clinical isolates of the microbiome as test strains: Staphylococcus aureus, Streptococcus oralis, Neisseria subflava, Actinomyces oris, Candida albicans (n=5). Research methods: experimental, microbiological, cultural, analytical and statistical. Results: The degree of adhesion of representatives of the oral microbiome to the studied structural materials is in the range from 0 to 4.91 (Ia) and depends on both the species composition of the microbiome and the physico-chemical properties of the materials. The high adhesion index for all microbiota groups was noted for vacuum forming materials (4.91), and the lowest was Dental Crown LCD (0), which makes it possible to recommend it for practical use. Conclusions: The choice of structural material should be made, including taking into account the adhesive activity of the oral microbiome in order to reduce the risk of complications. It is recommended to give preference to materials with a low adhesive activity index.

Comparative Micro-CT Analysis of Minimally Invasive Endodontic Systems Using 3D-Printed Replicas and Natural Teeth

(1) Background: This study aimed to compare the shaping abilities of modern minimally invasive endodontic systems using natural teeth and 3D-printed resin replicas. These replicas offer a standardized approach for studying root canal preparation while eliminating the variability and scarcity of natural teeth. (2) Methods: Eleven mandibular molars with Vertucci class IV anatomy and their 3D-printed replicas (n = 132 canals) were scanned using micro-CT before and after preparation with six rotary systems. Shaping abilities were assessed by comparing volume, surface area, and unprepared areas between natural teeth and their 3D replicas, focusing on the apical third. Statistical analysis included the Shapiro–Wilk test to assess data normality and ANOVA and t-tests to compare different endodontic systems. (3) Results: Both qualitative and quantitative analyses revealed high similarity between natural teeth and 3D replicas. No significant differences in volume or surface area were found except in the apical third, where 3D replicas showed slightly larger increases in volume. (4) Conclusions: 3D resin replicas closely mimic natural teeth and provide a practical tool for assessing the shaping abilities of endodontic systems. This study demonstrates that 3D-printed models are suitable for endodontic research, offering a standardized and accessible alternative to natural teeth.

In situ Cyclization of Aromatic Thioethers in Emissive Materials to Generate Phosphorescent Dibenzothiophenes

AbstractIn this contribution, we explored the photocyclization of thioethers to highly substituted dibenzothiophenes (DBT) using solely UV‐light without any need for additives. This cost‐effective, robust and environmentally friendly approach yielded phosphorescent compounds, which were characterized by X‐ray crystallography and state‐of‐the‐art photophysical methods. The resulting DBTs feature ultralong photoluminescence lifetimes and quantum yields close to unity in frozen glassy matrices. The reaction mechanism was elucidated in detail through a combination of quantum chemical calculations and experimental results, providing evidence that triplet states are involved in the cyclization process. Additionally, the photoreaction can also be induced within materials. For this purpose, the precursors were integrated into polymer films or polymer resins suitable for 3D printing. Irradiation of these polymeric objects allows motifs with ultralong phosphorescence to be irreversibly inscribed through the proceeding photocyclization. The in situ photogeneration of DBTs from aromatic thioethers overcomes the observed incompatibilities regarding solubility in polymer resins for 3D printing.

Sustainable and Recyclable Acrylate Resins for Liquid-Crystal Display 3D Printing Based on Lipoic Acid.

The development of renewable vinyl-based photopolymer resins offers a promising solution to reducing the environmental impact associated with 3D printed materials. This study introduces a bifunctional lipoate cross-linker containing a dynamic disulfide bond, which is combined with acrylic monomers (n-butyl acrylate) and conventional photoinitiators to develop photopolymer resins that are compatible with commercial stereolithography 3D printing. The incorporation of disulfide bonds within the polymer network's backbone imparts the 3D printed objects with self-healing capabilities and complete degradability. Remarkably, the degraded resin can be fully recycled and reused for high-resolution reprinting of complex structures while preserving mechanical properties that are comparable to the original material. This proof-of-concept study not only presents a sustainable strategy for advancing acrylate-based 3D printing materials, but also introduces a novel approach for fabricating fully recyclable 3D-printed structures. This method paves the way for reducing the environmental impact while enhancing material reusability, offering significant potential for the development of eco-friendly additive manufacturing.

Energy Harvesting Using Optimized ZnO Polymer Nanocomposite-Based 3D-Printed Lattice Structure

A 3D-printable polymer can provide an effective solution for developing piezoelectric structures. However, their nanocomposite formulation and 3D printing processability must be optimized for fabricating complex geometries with high printability. In the present study, we optimized the 3D-printable piezoelectric composite formulation for developing complex geometries by an additive manufacturing approach. The zinc oxide (ZnO) nanomaterial was synthesized by the hydrothermal method. The ZnO loading in the 3D-printed flexible resin was optimized to exhibit good interfacial adhesion and enable 3D printing. The lattice structure was fabricated to improve the piezoelectric response compared with the solid structure. The lattice structure block printed with 10 wt% ZnO showed a good piezoelectric response, with a linear increase in the generated output voltage for an increase in force. The maximum power density of 0.065 μW/cm2 was obtained under 12 N force at 1 Hz. The fabricated structure generated a peak–peak voltage of ~3 V with a foot heel strike.

Influence of Material, Sterilization, and Disinfection on the Accuracy of Three-Dimensional Printed Surgical Templates: An InVitro Study.

To evaluate the influence of the three-dimensional (3D) printing technology, material, sterilization, and disinfection on the accuracy of guided surgical templates. Fifty printed resin surgical templates were designed and fabricated using a digital light processing 3D printer with a photopolymerizing resin, and 50 printed metal surgical templates were designed and fabricated using a selective laser melting 3D printer with a titanium alloy. Templates from both groups were randomly divided into five subgroups involving different sterilization and disinfection procedures. The group without any sterilization or disinfection procedure served as the control group, whereas the other groups were used as the study groups (hydrogen peroxide gas plasma sterilization, 5% povidone-iodine disinfection, 75% ethyl alcohol disinfection, and steam autoclave sterilization). Implant simulations were performed on the 3D-printed resin models, and postoperative impressions were acquired with scan bodies attached to the implants. All surgical templates were digitally scanned. The root mean square was used to determine and quantify fabrication accuracy and reproducibility, and the definitive and planned implant positions were compared. The printed resin templates exhibited lower fabrication accuracy and reproducibility, as well as higher 3D deviations, after steam autoclave sterilization (p < 0.001); however, the printed metal templates were not affected by the different sterilization or disinfection procedures (p > 0.05). Printed metal surgical templates are viable alternatives for guided implant surgery. Preoperative steam or gas plasma sterilization is recommended, especially for metal templates, as resin templates show deformation and decreased accuracy after steam sterilization. chictr.org.cn number: ChiCTR2400081334.

Influence of 3D printing system, postpolymerization and aging protocols on resin flexural strength and dimensional stability for printing occlusal splints, models and temporary restorations.

Investigate the effect of different postpolymerization protocols, aging, and 3D printing systems on the flexural strength (σ), dimensional stability, and roughness of resins used to fabricate occlusal splints, dental models, and temporary restorations. 180 bars (25 × 2 x 2mm-ISO 4049) of each type of resin (T-Temporary/Cosmos Temp, Yller; OS-Occlusal splint/Cosmos Splint, Yller; MO - Models/ Cosmos Model, Yller) were printed and divided into 12 groups (n = 15) according to the factors: "Postpolymerization" (Ctr - Control; UV - Ultraviolet oven and MW - Microwave); "Printer" (SLA- stereolithography (Forms 2/Formslab); LCD- liquid crystal display (FlashForge Foto 6.0/FlashForge)) and "Aging" (TC - 10,000 thermocycling cycles and Without). Each bar was measured with a digital caliper at 11 points before and after postpolymerization to evaluate dimensional stability. The samples were subjected to the σ test (100Kgf;1mm/min). Data was evaluated using Three- and Two-way ANOVA, and Tukey's test (5%). Weibull analysis, Scanning Electron Microscopic and optical profilometry was performed. LCD printing system and UV oven postpolymerization exhibited the highest σ (P < .05). The groups printed in SLA and post-polymerized in microwave ovens showed the greatest variations in their dimensions, for the occlusal splint resin, the OS-SLA-MW group (-4.29 ± 3.15)A showed a shrinkage of 40.2%. The resins for models (3.31 ± 0.66)A and temporary (-2.06 ± 1.52)A showed a shrinkage of 33% and 20.6%, respectively. LCD printing with UV light postpolymerization was the most effective method for resins used in occlusal splints, dental models, and temporary restorations. SLA printing with UV postpolymerization showed the most significant dimensional changes, leading to shrinkage in occlusal splint resins, while model resins and temporary restorations expanded. Resins for 3D printing should ideally be post-polymerized with UV light and printed using LCD technology, as this approach results in better mechanical properties and less dimensional change compared to microwave oven post-polymerization.

Evaluation of Wear on Primary Tooth Enamel and Fracture Resistance of Esthetic Pediatric Crowns Manufactured from Different Materials

Background and Objectives: Advances in dental materials and CAD-CAM technology have expanded crown options in primary teeth due to their improved appearance and mechanical properties. Thus, this study aimed to assess the enamel wear and fracture resistance of prefabricated, milled, and 3D-printed esthetic pediatric crowns. Materials and Methods: The study involved 60 extracted maxillary second primary molars and 60 3D-printed resin dies, divided into six groups based on different crown materials (n = 10): prefabricated zirconia, prefabricated composite, milled composite, milled resin matrix ceramic, milled PEEK, and 3D-printed resin. Prefabricated crowns were selected after the preparation of the typodont mandibular second primary molar tooth, while milled and 3D-printed crowns were custom produced. The specimens underwent mechanical loading of 50 N at 1.6 Hz for 250,000 cycles with simultaneous thermal cycling. The 3D and 2D wear amounts were evaluated by scanning the specimens before and after aging. Then, the fracture resistance and failure types of the restorations were recorded. Results: The results showed that the milled PEEK group had superior fracture resistance compared to the other groups, while prefabricated zirconia crown group had the lowest value. Milled resin matrix ceramic crown group displayed the lowest 3D wear volume, while 3D-printed crown group showed the highest 2D wear. Conclusions: The restorative material type did not have a significant effect on the wear of primary tooth enamel. The fracture resistance of the tested materials differed according to the material type. Although the milled PEEK group showed the highest fracture resistance, all tested materials can withstand chewing forces in children.

Development and mechanical properties of nano SiO2 modified photosensitive resin for high-strength and high-brittleness 3D printing in rock reconstruction

3D printing technology, as a rapid prototyping method, can accurately reconstruct the internal structural characteristics of samples, making it highly promising for rock engineering applications. However, current 3D printing materials used to reconstruct rocks suffer from low strength and high ductility, which is inconsistent with the high strength and brittleness of natural rocks. This paper explores the use of silane coupling agents KH550 (γ-aminopropyl triethoxysilane) and KH570 (γ-methacryloxypropyl trimethoxysilane) to modify nano SiO2 powder. Through sample preparation and uniaxial compression tests, the mechanical properties and failure characteristics of the modified nano SiO2 powder were analyzed. The results indicate that, using the preparation method with a mass ratio of E-44 epoxy resin, KH550 modified nano SiO2 powder, and 593 curing agent at 80:40:26, the samples achieved an uniaxial compressive strength of up to 30.55 MPa without enhanced brittle post-processing. The failure characteristics exhibited significant axial tensile damage. Additionally, combining CT scanning technology demonstrated that the structural and mechanical properties of the samples can be effectively reproduced. Therefore, the 3D printing materials discussed in this paper provide a viable reference for accurately reconstructing high-strength and high-brittleness rock masses.

Investigating the acoustic performance of metamaterials with internal simple expansion chamber structure

The tunable acoustic properties are possessed by acoustic metamaterials (AMMs) with internal configurable structures. Nine samples(B1-B9) were designed in SOLIDWORKS and then fabricated using 3D-printed photopolymer resin featuring an internal Simple Expansion Chamber (SEC) structure. SEC length varied from 2 to 18 mm, maintaining a constant area expansion ratio (m) of 16. Sound Absorption Coefficient (SAC) and Sound Transmission Loss (STL) were measured through the Impedance Tube Apparatus (ITA). The sample with a 4 mm SEC length exhibited a maximum SAC of 0.99 at 4.8 kHz. As SEC length increased peak SAC and peak absorption frequency linearly decreased. Across all samples, STL ranged from 1- 41 dB (0.5-2.4 kHz) and 20-36 dB (2.4-6 kHz) revealing a periodic pattern in the tested frequency range. With SEC increasing from 2 to 18 mm Peak STL decreased from 41.2 to 38.8 dB. This research contributes valuable insights into the design of acoustic materials for effective noise attenuation showcasing the potential for achieving at least a 20 dB reduction in the 2.4-6 kHz range.

Effects of glazing on flexural-strength of 3D-printed permanent resins

Effects of glazing on flexural-strength of 3D-printed permanent resins

Mechanical properties of 3D-printed resin with various printing orientation

Mechanical properties of 3D-printed resin with various printing orientation

Crashworthiness Investigations for 3D-Printed Multi-Layer Multi-Topology Engineering Resin Lattice Materials.

In comparison to monolithic materials, cellular solids have superior energy absorption capabilities. Of particular interest within this category are the periodic lattice materials, which offer repeatable and highly customizable behavior, particularly in combination with advances in additive manufacturing technologies. In this paper, the crashworthiness of engineering multi-layer, multi-topology (MLMT) resin lattices is experimentally examined. First, the response of a single- and three-layer single topology cubic and octet lattices, at a relative density of 30%, is investigated. Then, the response of MLMT lattices is characterized and compared to those single-topology lattices. Crashworthiness data were collected for all topology arrangements, finding that while the three-layer cubic and octet lattices were capable of absorbing 9.8 J and 7.8 J, respectively, up to their respective densification points, the unique MLMT lattices were capable of absorbing more: 19.0 J (octet-cube-octet) and 22.4 J (cube-octet-cube). These values are between 94% and 187% greater than the single-topology clusters of the same mass.

Incorporating an artificially synthesized fluoride complex into urethane-acrylate-based 3D printing resin: Effects on mechanical properties, cytotoxicity, antimicrobial actions, and its long-term fluoride-releasing properties

ObjectivesTo synthesize a 3D printing resin with antibacterial and long-term fluoride-releasing properties. Methods(4,4-Bis-4-[2‑hydroxy-3-(2-methacryloyloxy)propoxy]-phenyl-pentanol-amine)-N,N-diacetic acid zirconium (IV) fluoride complex was synthesized from 4,4-bis-(4-hydroxyphenyl)-pentanoic acid and monitored using proton nuclear magnetic resonance spectroscopy. The synthesized complex was incorporated into a urethane-acrylate-based (UA) resin at 5 wt% and 10 wt% (5F-UA and 10F-UA groups, respectively). The UA resin without the synthesized complex was considered as the control group. All groups were 3D printed using a DLP printer, followed by 10 min of washing and 20 min of curing. Surface characteristics were observed using scanning electron microscopy. The mechanical properties were assessed by measuring its flexural strength and Vickers hardness. The antibacterial property was investigated with direct and indirect contact tests and a WST-8 metabolic activity assay. The suspension was fully mixed and diluted for counting the number of colony-forming units. The cell viability test was performed using a cell proliferation assay. The amount of fluoride released was measured daily for 28 days using ion chromatography. One-way analysis of variance was performed for statistical analyses using SPSS software. ResultsThe amount of fluoride released increased with the concentration of fluoride complex in the resin. The fluoride ions were constantly released at a low concentration from the 3D printed specimens (5F-UA: around 0.13 ppm daily; 10F-UA: around 0.22 ppm daily). The antibacterial efficacy was acceptable in both the 5F-UA and 10F-UA groups, and higher in the latter. No cytotoxicity of the resin was detected. The mechanical properties were significantly influenced by the addition of the fluoride-releasing complex. ConclusionsThe present 3D printing UA resin incorporating a fluoride complex effectively inhibited the growth of S. mutans and demonstrated the ability to slowly release fluoride over an extended period of time. Clinical significanceThis study provided informative composition of a fluoride-releasing UA-based 3D printing resin, ideal for dental applications such as crowns, bridges, removable partial dentures, and orthodontic appliances, which can benefit from sustained fluoride release and antimicrobial properties. Further modifications to the resin composition can be easily achieved to enhance the resin qualities.

Effect of aging on dimensional accuracy and color stability of CAD-CAM milled and 3D-printed denture base resins: a comparative in-vitro study

BackgroundThere is a lack of studies comparing the dimensional accuracy and color stability of denture base resins made using computer-aided design and computer-aided manufacturing (CAD-CAM) milling, 3-dimensional (3D) printing, and conventional denture processing techniques. This makes it challenging to determine the best method to fabricate complete dentures. The objective of this in vitro investigation was to assess and contrast the color stability and dimensional accuracy of denture base resins that were 3D printed and CAD-CAM milled, both before and after aging by thermocycling using digital surface matching technology and a benchtop laser scanner without using a spray, to optimize adaptation of the denture base and cast to minimize any imperfections and to evaluate the impact of the denture cleansing solution on the stability of color.MethodsEvaluation of the dimensional accuracy (n = 27) was completed on a sectional maxillary stone cast using a digital 3D-surface matching software before and after 5000 thermocycles. A spectrophotometer was used to measure the color change (△E00) of all disc specimens (N = 54) before and after 500 thermocycles and immersion in denture cleansing solution for 30 cycles (3 min each) daily for 6 days. The Kruskal Wallis test, Dunn’s post hoc test, Tukey’s test with Bonferroni adjustment, one sample t test and independent t test were used to statistically analyze the data (α < 0.05).ResultsThermocycling decreased the dimensional accuracy of the heat polymerized group at all 5 locations and the 3D-printed group at locations 1, 3 and 5 (P > .05), while it had no significant difference on the CAD-CAM milled group at all locations (P < .05). The color change (△E00) was lowest in the CAD-CAM milled group, moderate in the heat-polymerized group and highest in the 3D-printed group. After immersion in denture cleanser, the color change (△E00) was significantly higher in the 3 groups compared with after thermocycling (P > .001).ConclusionsCAD-CAM milled resins had the highest dimensional accuracy and the best color stability, conventional heat polymerized acrylic resins showed moderate change in dimensional accuracy and color stability, while the 3D- printed resin had the lowest dimensional accuracy and color stability after aging by thermocycling.