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Background. Recently, dentists can utilize three-dimensional printing technology in fabricating dental restoration. However, to date, there is a lack of evidence regarding the effect of printing layer thicknesses and postprinting on the mechanical properties of the 3D-printed temporary restorations with the additive manufacturing technique. So, this study evaluated the mechanical properties of a 3D-printed dental resin material with different printing layer thicknesses and postprinting methods. Methods. 210 specimens of a temporary crown material (A2 EVERES TEMPORARY, SISMA, Italy) were 3D-printed with different printing layer thicknesses (25, 50, and 100 μm). Then, specimens were 3D-printed using DLP technology (EVERES ZERO, DLP 3D printer, SISMA, Italy) which received seven different treatment conditions after printing: water storage for 24 h or 1 month, light curing or heat curing for 5 or 15 minutes, and control. Flexural properties were evaluated using a three-point bending test on a universal testing machine (ISO standard 4049). The Vickers hardness test was used to evaluate the microhardness of the material system. The degree of conversion was measured using an FT-IR ATR spectrophotometer. Statistical analysis was performed using two-way analysis of variance (ANOVA) and Tukey’s honestly significant difference (HSD) test (p≤0.05). Results. The 100 μm printing layer thickness had the highest flexural strength among the other thickness groups. As a combined effect printing thickness and postprinting conditions, the 100 μm with the dry storage group has the highest flexural strength among the tested groups (94.60 MPa). Thus, the group with 100 μm thickness that was heat cured for 5 minutes (HC 5 min 100 μm) has the highest VHN value (VHN=17.95). Also, the highest mean DC% was reported by 50 μm layer thickness (42.84%).Conclusions. The thickness of the 100 μm printing layer had the highest flexural strength compared to the 25 μm and 50 μm groups. Also, the postprinting treatment conditions influenced the flexural strength and hardness of the 3D-printed resin material.

Background Three-dimensional (3D) printing technology has revolutionized dentistry, particularly in fabricating provisional restorations. This systematic review and meta-analysis aimed to thoroughly evaluate the flexural strength of provisional restorations produced using 3D printing while considering the impact of different resin materials. Methods A systematic search was conducted across major databases (ScienceDirect, PubMed, Web of Sciences, Google Scholar, and Scopus) to identify relevant studies published to date. The inclusion criteria included studies evaluating the flexural strength of 3D-printed provisional restorations using different resins. Data extraction and quality assessment were performed using the CONSORT scale, and a meta-analysis was conducted using RevMan 5.4 to pool results. Results Of the 1914 initially identified research articles, only 13, published between January 2016 and November 2023, were included after screening. Notably, Digital Light Processing (DLP) has emerged as the predominant 3D printing technique, while stereolithography (SLA), Fused Deposition Modeling (FDM), and mono-liquid crystal displays (LCD) have also been recognized. Various printed resins have been utilized in different techniques, including acrylic, composite resins, and methacrylate oligomer-based materials. Regarding flexural strength, polymerization played a pivotal role for resins used in 3D or conventional/milled resins, revealing significant variations in the study. For instance, SLA-3D and DLP Acrylate photopolymers displayed distinct strengths, along with DLP bisacrylic, milled PMMA, and conventional PMMA. The subsequent meta-analysis indicated a significant difference in flexure strength, with a pooled Mean Difference (MD) of − 1.25 (95% CI − 16.98 - 14.47; P  < 0.00001) and a high I 2 value of 99%, highlighting substantial heterogeneity among the studies. Conclusions This study provides a comprehensive overview of the flexural strength of 3D-printed provisional restorations fabricated using different resins. However, further research is recommended to explore additional factors influencing flexural strength and refine the recommendations for enhancing the performance of 3D-printed provisional restorations in clinical applications.

Background Dental resin-based composites are widely recognized for their aesthetic appeal and adhesive properties, which make them integral to modern restorative dentistry. Despite their advantages, adhesion and biomechanical performance challenges persist, necessitating innovative strategies for improvement. This study addressed the challenges associated with adhesion and biomechanical properties in dental resin-based composites by employing molecular docking and dynamics simulation. Methods Molecular docking assesses the binding energies and provides valuable insights into the interactions between monomers, fillers, and coupling agents. This investigation prioritizes SiO 2 and TRIS, considering their consistent influence. Molecular dynamics simulations, executed with the Forcite module and COMPASS II force field, extend the analysis to the mechanical properties of dental composite complexes. The simulations encompassed energy minimization, controlled NVT and NPT ensemble simulations, and equilibration stages. Notably, the molecular dynamics simulations spanned a duration of 50 ns. Results SiO 2 and TRIS consistently emerged as influential components, showcasing their versatility in promoting solid interactions. A correlation matrix underscores the significant roles of van der Waals and desolvation energies in determining the overall binding energy. Molecular dynamics simulations provide in-depth insights into the mechanical properties of dental composite complexes. HEMA-SiO 2 -TRIS excelled in stiffness, BisGMA-SiO 2 -TRIS prevailed in terms of flexural strength, and EBPADMA-SiO 2 -TRIS offered a balanced combination of mechanical properties. Conclusion These findings provide valuable insights into optimizing dental composites tailored to diverse clinical requirements. While EBPADMA-SiO 2 -TRIS demonstrates distinct strengths, this study emphasizes the need for further research. Future investigations should validate the computational findings experimentally and assess the material's response to dynamic environmental factors.

As cementation represents the last stage of the work involved in making various indirect restorations (metal ceramic crowns and bridges, full ceramic crowns and bridges, inlays, onlays, and fiber posts), its quality significantly contributes to the clinical success of the therapy performed. In the last two decades, the demand for ceramic indirect restorations in everyday dental practice has considerably increased primarily due to the growing significance of esthetics among patients, but also as a result of hypersensitivity reactions to dental alloys in some individuals. In this context, it is essential to ensure a permanent and reliable adhesive bond between the indirect restoration and the tooth structure, as this is the key to the success of aesthetic restorations. Resin-based luting materials benefit from excellent optical (aesthetic) and mechanical properties, as well as from providing a strong and durable adhesive bond between the restoration and the tooth. For this reason, resin cements are a reliable choice of material for cementing polycrystalline ceramic restorations. The current dental material market offers a wide range of resin cement with diverse and continually advancing properties. In response, we wish to note that the interest in the properties of resin-based cements among clinicians has existed for many years. Yet, despite extensive research on the subject and the resulting continued improvements in the quality of these materials, there is still no ideal resin-based cement on the market. The manuscript authors were guided by this fact when writing the article content, as the aim was to provide a concise overview of the composition, properties, and current trends, as well as some future guidelines for research in this field that would be beneficial for dental practitioners as well as the scientific community. It is extremely important to provide reliable and succinct information and guidelines for resin luting materials for dental dental practitioners.

Aim. The objective of this in vitro study was to evaluate the bond strength of universal adhesive systems in self-etch and etch-and-rinse modes at the repair interface between aged and new composite resins. Materials and Methods. Composite resin (Filtek Z250) was thermocycled to represent aged composite resin to be repaired. New composite resin was placed over the aged substrate after surface conditioning: NC (negative control, no surface treatment), A (adhesive only), SBM (Scotchbond Multi-Purpose in etch-and-rinse mode), CSE (Clearfil SE Bond in self-etch mode), SBU (Single Bond Universal), ABU (All Bond Universal), and TBU (Tetric N-Bond Universal). Universal adhesives (SBU, ABU, and TBU) were applied both in etch-and-rinse and self-etch modes. 1 mm×1 mm×8 mm beams were sectioned, and microtensile bond strength was measured after 24 hours of water storage and 10,000 thermocycling processes (n=20/group). The fracture surfaces were observed with a scanning electron microscope to evaluate the failure pattern. Results. The repair bond strength between the old and new composite resins was material-dependent. Universal adhesives significantly improved the repair bond strength (p<0.05), while no significant difference was observed between the etch modes (self-etch or etch-and-rinse) for each universal adhesive (p>0.05). Thermocycling significantly reduced the bond strength in all groups (p<0.05). Conclusion. Universal adhesives in both etch-and-rinse and self-etch modes outperformed the conventional 3-step etch-and-rinse and 2-step self-etch adhesive systems in terms of resin repair bond strength.

Aim The purpose of this study was to evaluate the performance of polyethylene fiber reinforced resin composite fillings compared to bulk fill resin composite fillings in endodontically treated teeth over a two-year monitoring period. Method A total of 240 individuals with endodontically treated lower molars and a moderate amount of tooth structure were divided into two equal groups of 120 each. One group received polyethylene fiber reinforced bulk fill resin composite restorations while the other group received only bulk fill resin composite restorations, both applied as per manufacturer guidelines. Two proficient experienced blinded assessors assessed the restorations using modified USPHS criteria at baseline, 6, 12, and 24 months. Statistical analysis used Data analysis involved the utilization of Mann-Whitney U, Friedman's test, and Nemenyi post hoc test, with age data being displayed as mean and standard deviation. The significance level was established as p < 0.05, and R software was utilized for statistical analysis. Results There were no notable distinctions in any parameters or scores between the intervention and comparator groups at various time points. Alpha scores were present for retention, gross fracture, and secondary caries at all follow up intervals. Conclusion Both direct resin composite restorations reinforced with polyethylene fibers and direct bulk fill resin composite restorations placed in endodontically treated molars with moderate remaining tooth structure demonstrated satisfactory clinical outcomes during a 24-month follow-up period. Clinical relevance Bulk fill resin composites directly placed in endodontically treated molars with moderate remaining tooth structure showed promise as a treatment option over a two-year period. Clinical trial registration (06-01-2022) on Keywords: Fiber reinforced composite, Teeth that have undergone endodontic treatment, Ribbond, Clinical trial that is controlled and randomized, Polyethylene fibers, Class II cavities, Bulk fill composite

Background It was aimed to investigate the effect of sandblasting and laser surface treatment on shear bond strength in composite restoration repair in vitro. Methods A micro-hybrid composite (Filtek Z250, 3 M-ESPE, USA) was used to prepare 120 samples. The samples were subjected to a thermal cycle test 5,000 times between 5 and 55 0 C, and they were randomly divided into 12 groups ( n  = 10). No surface treatment was performed in Groups 1 to 4, which were designed as control groups. The surfaces of the samples in Groups 5 to 8 were sandblasted with a Cojet device, and the surfaces of the samples in Groups 9 to 12 were applied Er, Cr: YSGG laser. After the sample surfaces were divided into groups with and without acid etching, universal adhesive was applied, and the repair process was performed using Filtek Z250 or nano-filled resin composite (Filtek Ultimate, 3 M-ESPE, USA). The thermal cycle test was repeated 5,000 times between 5 and 55 0 C on all repaired samples. The repair shear bond strength of the samples was measured using a universal testing device (Shimadzu IG-IS, Kyoto, Japan). The fracture types were evaluated by optical microscopy and scanning electron microscopy (SEM). Statistical analyses of the findings were evaluated by the Kruskal Wallis test and Mann Whitney U test at 0.05 significance degree. Results The highest mean shear bond strength values were obtained from the samples sandblasted with CoJet, followed by Er, Cr: YSGG laser, and the control group. It was determined that there was a significant difference between the mean shear bond strength values obtained from the control group and the other surface treatment groups ( p  < 0.05). In general, significantly higher mean shear bond strength values were obtained when the universal adhesive was applied in total-etch mode compared to the application in self-etch mode ( p  < 0.05). Additionally, it was determined that higher shear bond strength values were obtained with Filtek Ultimate compared to Filtek Z250 ( p  < 0.05). Conclusion Within the limitations of this study, it can be concluded that the use of universal adhesive in total-etch mode, in addition to surface treatments on the resin composite surface in the repair protocol and the use of nano-filled resin composite as repair material can increase the mean shear bond values in repair.

This study aimed to evaluate the effect of various preheating methods applied to bulk-fill composite resins on temperature changes within the pulp chamber. Ten sound human molars were used. Each tooth was sectioned 2 mm apical to the cementoenamel junction, and the occlusal surface was flattened to leave a 2 mm dentin thickness. Four bulk-fill composite resins were applied at five temperatures (24 °C, 37 °C, 54 °C, 65 °C, and 68 °C) and polymerized using an LED curing unit. Intrapulpal temperature changes were measured with a K-type thermocouple connected to a data logger in a setup simulating pulpal microcirculation. In total, twenty measurements were taken per tooth under each condition. Data were analyzed using one-way ANOVA and post-hoc LSD tests (p < 0.05). The highest intrapulpal temperature increase was observed at 65 °C in all groups using the VisCalor dispenser. The critical temperature threshold was not exceeded in any sample. Significant differences were found between certain temperatures within individual resin groups (p < 0.05), particularly at 65 °C compared to lower temperatures. However, no statistically significant differences were found between different resin types at the same temperatures (p > 0.05). Preheating of bulk-fill composite resins led to an increase in intrapulpal temperature; however, this rise remained below the threshold that could cause irreversible pulpal damage. Preheating bulk-fill composites enhances handling and adaptation but may increase intrapulpal temperature. In this study, the temperature rise remained below the critical threshold, suggesting that the procedure is clinically safe.

Background Bonding between silicone elastomers and rigid substructures is critical to clinical success of extraoral maxillofacial prostheses. This study aimed to investigate the bond strength of silicone elastomers to conventional and alternative 3-dimensional printing resin materials and the effect of artificial aging. Methods The bond strength of seven resin substructure materials to a maxillofacial silicone was tested using the 180° peel test without artificial aging and after artificial aging in 14 groups. Test specimens composed of a silicone elastomer bonded to a substructure which were prepared according to ASTM D903-98 standard. A total of 70 specimens were prepared with a maxillofacial silicone bonded with a primer to substructures made of chemically polymerized clear acrylic, heat-polymerized clear acrylic and heat-polymerized pink acrylic, 3-dimensional surgical guide, 3-dimensional denture base, 3-dimensional polyetherketoneketone, and 3-dimensional polyetheretherketone resins ( n  = 10). Half of the specimens ( n  = 5 per group) were aged in an environmental chamber (Ci4400 Weather-Ometer, Atlas, Inc., USA) to assess the impact of 360 h of accelerated artificial aging. Peel bond strength values were analyzed using two-way ANOVA and post-hoc comparisons with Bonferroni correction (α = 0.05). Bond failures were classified using confocal microscopy. Results Substructure material, artificial aging, and their interaction significantly affected peel bond strength ( p  < 0.001). Polyetherketoneketone and polyetheretherketone exhibited significantly lower mean bond strength in non-aged groups ( p  < 0.05). Within the aged groups, surgical guide and denture base resins demonstrated significantly higher bond strength ( p  < 0.05). The most common failure type was mixed (71.4%), followed by adhesive (20%), cohesive (9%). Conclusions Three-dimensional printed surgical guide resin and denture base resin specimens showed higher mean bond strength after artificial aging compared to commonly used conventional resin substructures and three- dimensional printed polyetherketoneketone and polyetheretherketone.

The long-term color stability and gloss retention of resin composites are among the crucial factors that affect the clinical longevity of esthetic restorations, especially in anterior teeth. This study evaluated the effect of artificial aging by immersion in different storage media and thermocycling on color and gloss of dental single-shade resin composite (Omnichroma) versus multi-shade one (Filtek Z350XT). One hundred resin-composite disc-shaped specimens were used, 50 from each group, Omnichroma and Filtek Z350XT. Ten specimens from each material acted as control group (incubated in saliva). For each material, 40 specimens were divided according to the artificial-aging protocol (immersion at 37 °C for 12 days or thermocycling for 10,000 cycles) and storage media (tea, red wine). Color and gloss were measured before and after artificial aging. Color difference (∆E 00 ) was compared with perceptibility threshold and acceptability threshold. Data were statistically analyzed; independent t test was used to compare results between two tested materials, while two-way ANOVA was used to compare results among the different immersion media within the same material. Artificial aging (immersion or thermocycling) in tea and red wine led to significant color changes and gloss reduction in both materials ( P  < 0.05), in contrast to control group. Red wine produced highest color differences. Both dental resin-composites; the single-shade (Omnichroma) and multi-shade (Filtek Z350XT) displayed unacceptable discoloration and gloss reduction after artificial-aging in tea and red-wine by immersion or thermocycling simulating one-year clinical-service.