Resin-based Composite Materials Research Articles

Multiscale modeling and thermal conductivity evaluation of nano-reinforced composite materials with pore defect

The performance of resin-based composite materials often exhibits diversity due to the designability of various components. Thermal conductivity, an important thermal parameter of the composite, plays a significant role in thermal-chemical reactions, thermal stress analysis, temperature conduction, etc. However, it is relatively difficult to experimentally explore the thermal conduction mechanism of hybrid composite materials, mainly due to the relatively difficult control of various components. Therefore, this paper proposes a sequentially coupled cross-scale numerical method to characterize the thermal conductivity of nano-reinforced composite materials with pores by a multiscale periodic Representative Volume Element model generated by an improved Random Sequential Absorption algorithm. Firstly, periodic temperature boundary conditions are described, and the thermal conductivity performances of nano-reinforced matrix and composite with pores are investigated based on the finite element homogenization theory. Then, the proposed modes are validated and grid sensitivity analysis is conducted, indicating that the optimal grid sizes for the RVE models are 1.9 nm for the nano-reinforced matrix and 0.14 μm for the composite with pores based on a comprehensive comparison of four pore characterization methods, respectively. Furthermore, the study explored the effect of multiple parameters including nanoparticle content, pore content, and pore shape on thermal conductivity. Numerical findings reveal that the thermal conductivity of the nanocomposite matrix exhibits a linear increase with higher particle content. Specifically, compared to 0 % particle content, the thermal conductivity rises by 141.92 % at 12 % particle content. While the composite material's transverse thermal conductivity is sensitive to porosity content, it is less influenced by pore shape. The method proposed in this paper provides an effective approach for studying the thermal conduction of nano-reinforced composite materials with pores, and the research findings also offer theoretical guidance for process engineers.

Preparation of three dimensional boron nitride-aluminum oxide dual thermal network resin-based composite materials and their performance study

With the gradual miniaturization and integration of electronic devices, the design and development of new high thermal conductivity polymer-based composite materials are crucial for enhancing the performance of modern electronic devices. In this study, three-dimensional boron nitride (3D-BN) aerogels with vertically aligned structures were prepared using the ice templating method, serving as the primary thermal conductive network. Subsequently, aluminum oxide (Al2O3)/epoxy resin (EP) nanofluids were infiltrated into the aerogel’s air pores using vacuum impregnation. The Al2O3 particles in contact with each other formed the secondary thermal conductive network. Thus, a 3D BN-Al2O3/EP composite material with a dual thermal conductive network structure was successfully fabricated. The composite material exhibited a high thermal conductivity coefficient of 1.077 Wm−1K−1 when loaded with 17.67 wt% BN and 26.23 wt% Al2O3, representing a 496 % increase compared to pure EP and a 211 % increase compared to 3D-BN/EP composite materials. Furthermore, this composite material demonstrated excellent thermal stability and mechanical properties. This work provides a new direction for designing novel polymer-based composite materials with low filler loading and high thermal conductivity performance.

Three-Dimensional Thermo-Chemo-Mechanical Coupled Curing Analysis for the Filament Wound Composite Shell.

Carbon fiber resin-based composite materials are widely employed in the manufacturing of composite shells. During the curing process, the temperature gradients and cure degree gradients make it easy to generate thermal strains in both carbon fibers and resin, with the resin experiencing cure shrinkage strain due to the curing reaction, ultimately leading to residual stresses and strains. In this paper, a three-dimensional thermo-chemo-mechanical coupled curing model of the composite shell was established based on a resin test, and the changes of temperature, curing degree, residual stress, and strain during the solidification of the composite shell were investigated. First, the curing property parameters and elastic modulus of HCM-2184 resin were obtained through a curing dynamic test and a tensile test. Then, considering the heat release and shrinkage reaction of solidification, a coupled thermo-chemo-mechanical curing model was developed with the CHILE (α) elastic model, and the curing process of the composite shell was simulated numerically. The results show that the resin used in the test belongs to the autocatalytic reaction. For thin composite shells, the heat accumulation inside the shell during curing is not obvious. During the curing process, the curing shrinkage behavior of the resin is an important factor for the generation of residual stress and residual strain.

Cutting Efficiency of Diamond Grinders on Composite and Zirconia.

This in vitro study was carried out to compare the cutting efficiency of diamond grinders on zirconia and resin-based composite materials. Grinders were employed with a special holder for the handpiece to apply a constant load (160 g) for resin-based composite (8 cuts, 40 s each) and zirconia materials (4 cuts, 5 min each; n = 10 for each material and grinder). To assess the efficiency of the grinders, weight measurements of the material were taken before and after the grinding process. Scanning electron micrographs were captured for instrument surfaces before and after testing and for the resulting surface of the materials. In the resin-based composite group, there were significant differences in weight removal between the burs for both the baseline (first cut; p = 0.009) and removal after the eighth cut (p = 0.049). Statistically significant decreases in weight removal compared to the baseline values were noted for the third, fourth, sixth, and seventh steps (p ≤ 0.046). For the zirconia group, significant differences existed in weight removal between the burs for the baseline (first cut; p < 0.001) and removal after the fourth cut (p < 0.001). A significant positive correlation was observed between removal and the number of cuts (Pearson: 0.673; p < 0.001). A statistically significant decrease in removal compared to the respective baseline value was found for the fourth step (p = 0.006). The initial wear removal and durability significantly differed between the grinders used on resin-based composite and zirconia. Achieving comparable weight removal took five times longer when grinding zirconia compared to the resin-based composite.

Effect of polymerisation protocols on water sorption, solubility and hygroscopic expansion of fast-cure bulk-fill composite

ObjectiveThis study examines the effect of two light-curing protocols from a LED polywave light curing unit (LCU) on water sorption, solubility, and hygroscopic expansion of fast and conventional bulk-fill resin-based composites (RBCs) aged in distilled water for 120 d. MethodsThree bulk-fill RBCs materials were studied: Tetric PowerFill® (fast photo-polymerised composite) (TPF), Tetric EvoCeram bulk-fill (EVO), and GrandioSo x-tra bulk-fill (GSO) (conventional photo-polymerised composites). Specimens were prepared within a 3D-printed resin mold (8-mm diameter x 4-mm height) and light-cured from one side only with 2 modes of polywave LCU (Bluephase® PowerCure): 3 s mode and for 20 s in “Standard” mode. Water sorption and solubility were measured at fixed time intervals for 120 d of distilled water storage, then reconditioned to dry to measure desorption for 75 d, all at 37 ± 1 °C. Hygroscopic (volumetric) expansion was recorded at the same time intervals up to 120 d. Data were analysed through SPSS using Two-way ANOVA, One-way ANOVA, independent t-tests, and Tukey’s post-hoc correction tests (p < 0.05). ResultsTPF, when irradiated for 3 s demonstrated minimal water sorption (0.83%), solubility (1.01 μg/mm3), and least volumetric expansion (1.64%) compared to EVO and GSO. While EVO showed the highest water sorption (1.03%) and solubility (1.95 μg/mm3) at 3 s. GSO had the lowest sorption (0.67%) and (0.56%) in 3 s and 20 s protocols, respectively. Nevertheless, all the sorption and solubility data were within the ISO 4049 limits. SignificanceFor TPF, fast (3 s) polymerisation did not increase either water sorption or solubility, compared with 20 s irradiation. However, with the two comparative bulk-fill composites, fast cure increased water sorption by 15–25% and more than doubled solubility. These findings were consistent with the lesser volumetric expansions observed for Tetric PowerFill at both the fast and standard protocols, indicating its relative stability across polymerisation protocols.

Effect of Various Toothpaste Tablets on Gloss and Surface Roughness of Resin-based Composite Materials.

To evaluate the effect of various toothpaste tablets on gloss and surface roughness of resin-based composite. Sixty-four resin-based composite specimens were divided into four groups of 16 specimens each. Gloss and roughness were measured before and after simulated brushing with three types of toothpaste tablets and one conventional toothpaste: CT: Chewtab Toothpaste Tablets; AT: Anticavity Toothpaste Tablets; HC: Charcoal Toothpaste Tablets; CP: Cavity Protection toothpaste. The Kruskal-- Wallis procedure was performed to compare the differences by groups. Post-hoc comparisons were conducted with Bonferroni corrections (α=0.05). There was a significant drop in gloss for all groups. CT and AT maintained the highest gloss with means of 81.6 GU and 74.1 GU, respectively. The lowest gloss of 24.5 GU was observed for HC. There was a significant increase in roughness for all groups except for CT. CT had the lowest roughness with a mean of 0.034 μm, while HC had the highest roughness with a mean of 0.074 μm. There was a significant correlation between post-brushing gloss and post-brushing roughness (p<0.001, r=-0.884). Chewtab Toothpaste Tablets had the least effect on gloss and roughness, while Charcoal Toothpaste Tablets had the most negative effect on the surface properties of resin-based composites.

Thermal, Physical, and Electrical Characterization of Millettia Pinnata Leaf Powder, Alumina, Glass Sheet, Boron Nitride Reinforced Epoxybased Hybrid Composites: An Experimental Scrutiny

Aims and objectives:: The aim of this study was to fabricate epoxy resin-based hybrid composites reinforced with biodegradable Millettia pinnata leaf powder in conjunction with glass sheets, boron nitride, and alumina for the production of printed circuit boards. Method:: For this application, various thermal, physical, and electrical tests were conducted by the authors. The thermal test results showed that the alumina-based epoxy hybrid composite has more thermal stability than the neat epoxy. Moreover, upon adding BN/Alumina, the flame retarding properties of the epoxy hybrid composites improved. We also observed that with the increase in the content of BN and alumina, the thermal conductivity of the hybrid composite was enhanced. From the water absorption tests, the hybrid composite with 6g BN showed the least amount of water consumption. Particularly, adding BN and leaf powder from 2 to 6 g gave better results for the decrease in water absorption, as compared to adding alumina in the epoxy-based hybrid composite. Result:: Lastly, from the electric tests, we observed that with the increase in frequencies, the dielectric constant of the hybrid composite decreases. At a lower frequency range, the hybrid composite having 2g of BN and millettia pinnata leaf powder shows the lowest dielectric constant, whereas, at a higher frequency range, 2g of alumina and millettia pinnata leaf powder shows the lowest dielectric constant. Conclusion:: We predict that the results reported in this investigation will aid in accelerating the engineering applications of epoxy resin-based hybrid composite materials and help patent the material compositions for specific purposes.

Progressive Tooth Wear Against Resin-Based Restorative Composites.

The composition and properties of resin-based composite materials could affect tooth wear and lead to clinical problems. Therefore, the study objective was to characterize human tooth wear behavior against a bulk-fill restorative (BF) compared to a conventional resin composite (RC) and a CAD/CAM resin nano ceramic (RN). Square-shaped specimens of each material were prepared and sub-divided according to the number of testing cycles (n=8): 100,000, 250,000, and 500,000 cycles. An occlusal wear test was performed using a chewing machine with 49 N, 2 Hz, in 37°C distilled water. Human premolar cusps were used as antagonists. Micro-CT and laser scanner were used to scan antagonists and specimens, respectively. Wear volume was assessed using a software and the wear pattern was examined with SEM. Softening in solvent analysis was performed by measuring the materials' Knoop microhardness (KHN) before and after immersion in ethanol. Wear volume data were analyzed with two-way ANOVA and Student-Neuman-Keuls test (α=0.05). For tooth and specimen wear volume, there was statistical significance for material and number of cycles, but not for the interaction between factors. BF resulted in less tooth (p=0.008) and specimen (p=0.030) wear than RN and RC, which were similar (p⟩0.05). Volume loss increased from 100,000 to 500,000 cycles. BF showed the lowest microhardness (KHN1); and %ΔKHN similar to RC, but greater than RN. BF induced less volume loss to the tooth than RC and RN, while presenting greater wear resistance. The tooth wear pattern and damage progression were mild for all materials. Resin composites show favorable wear behavior, leading to low volume loss and mild structural damage of the tooth. Regular bulk-fill resin composite stands out for its efficient restorative technique, low wear susceptibility and reduced capacity to wear down the tooth.

Evaluation of Monomer Releasing from Dentin Replacement Materials

The aim of this study is to determine and quantify the monomer elution from four different resin-based composite dentin replacement materials for 3 months using HPLC. Four different composite dentin replacement materials were used in the present study: EverX (EVX), X-tra base (XTB), SDR (SDR), and GrandioSO Heavy Flow (GHF). Fifteen samples from each material were prepared (5×5×4 mm). After preparation, each specimen was immersed in a 10 ml 75% ethanol/distilled water solution for three different periods: 1 h, 24 h, and 3 months (n=5). After the immersion period, 0.5 ml of solutions were taken from each bottle and analyzed using HPLC. At the end of the 3-month immersion period, the elution of monomers was determined mostly from SDR, GHF, EVX, and XTB, respectively. TEGDMA, the most released monomer of all groups, was released from all samples after 1 h, 24 h, and 3 months. The amount of monomer released in all composite groups at the end of the 3-month immersion period was significantly higher than the monomer amounts released after the 1-hour immersion period. The monomers were eluted from the composite dentin replacement materials during all immersion periods, and the amount of eluted monomers was increased with time.

An In Vitro Investigation of the Role of Implant Abutment Materials on the Fracture Resistance and Failure Mode of Implant-Supported Restorations.

Implant-supported restorations have gained popularity in modern dentistry, and the choice of abutment material is crucial for their long-term success. This in vitro study aimed to evaluate the fracture resistance and failure mode of implant-supported restorations using different abutment materials. Ninety standardized implant-supported restorations were included in the study. Abutments made of titanium, zirconia, and a hybrid material (titanium base with a zirconia veneer) were evaluated. Standardized abutments were fabricated, and screw-retained restorations were fabricated using a resin-based composite material. Cyclic loading was applied using a universal testing machine to simulate masticatory forces. Fracture resistance was measured in terms of the number of cycles to failure (NCF), and failure modes were analyzed. The findings indicate that zirconia abutments exhibited higher fracture resistance compared to titanium and hybrid abutments. Longer implants demonstrated higher fracture resistance, suggesting improved stability and resistance to mechanical forces. Increased loading angles resulted in decreased fracture resistance of implant-supported restorations, emphasizing the need for proper occlusal adjustment. Central loading showed higher fracture resistance than lateral and posterior loading locations. The distribution of failure modes varied among the abutment materials, with bulk prosthesis fracture being the most common in the titanium group, while abutment fracture was predominant in the zirconia and hybrid groups. This in vitro study demonstrated that the choice of abutment material significantly influenced the fracture resistance and failure mode of implant-supported restorations. Zirconia abutments exhibited the highest fracture resistance, followed by hybrid and titanium abutments. The failure mode analysis revealed different patterns of failure for each abutment material.

Comparison of the stress distribution in base materials and thicknesses in composite resin restorations

Resin-based composite materials are commonly used for restorations, but their dimensional changes during the polymerization could cause various clinical problems. This study evaluated the influence of a base of different materials and thicknesses on the stress magnitude and distribution in a second maxillary premolar with an MOD resin composite restoration using three-dimensional finite element analysis. A sound tooth without cavity was considered as the control group (ST), and another group was restored with composite resin without applying a base material in a MOD cavity (CR). The other three groups were restored with composite resin along with the following base materials: glass ionomer cement, low-viscosity resin, and tricalcium silicate, respectively (CR-GIC, CR-LR, and CR-TS). These three groups were further divided into two subgroups according to the thickness of the base layer: thin (0.5 mm) and thick (1.0 mm). The stress distribution was compared using the maximum principal stress after polymerization shrinkage and vertical loading with 600 N on the occlusal surface. Group ST showed the lowest stress value, and its stress propagation was confined to outer enamel surfaces only. Group CR demonstrated the highest stress distribution in the tooth-restoration interface with increased failure risk on marginal areas. The thin and thick subgroups of the three groups with a base layer had lower stress levels than Group CR. The base materials reduced the marginal stress caused by polymerization shrinkage of composite resin in MOD cavities. Different base materials and thicknesses did not affect the stress distribution.

The Influence of Variable Stiffness of the Shape Memory Alloys Carbon Composite Structure on Mechanical Vibration.

The purpose of this study is to investigate the dynamic properties of new structures formed by combining carbon fiber and epoxy resin-based composite materials with SMA (shape memory alloy) "smart materials" in the form of NiTiNol wire. Such a combination will have an impact on the dynamics of the structure, especially in terms of stiffness controllability. Key mechanical parameters such as natural frequency and stiffness, as well as the effect of temperature, were determined through experimental studies.

An experimental study of the penetration resistance of UHMWPE laminates with limited thickness

Ultra-high molecular weight polyethylene (UHMWPE) laminates represent the most weight-efficient industrial fiber-reinforced resin-based composite material for ballistic protection. To comprehensively understand the anti-penetration mechanism and quantify the anti-penetration performance of UHMWPE laminates, theoretical, experimental, and equation-fitting methods are employed to study and test the ballistic response characteristics of UHMWPE laminates. The results reveal that UHMWPE fibers possess a theoretically determined longitudinal wave velocity that exceeds 10 km/s and exhibit an extremely strong stress diffusion capacity. The anti-penetration mechanism and performance of UHMWPE laminates are significantly influenced by the laminate thicknesses, projectile velocities, and temperatures. As the laminate thickness increases, the ballistic limits of UHMWPE laminates increase almost linearly. Large area delamination and back face deformation play a crucial role in the energy dissipation of UHMWPE laminates. With the increase of projectile velocities, there exists an energy limit representing the maximum energy absorption capacity of the UHMWPE laminates that is worthy of reasonable utilization in spacing ballistic-proof armors. Additionally, the ballistic performance of UHMWPE laminates generally decreases with increasing temperatures, and this trend becomes more pronounced after 80 ℃. Based on data-driven analysis, this paper proposes an equation for calculating the ballistic limit of UHMWPE laminates that takes into account the temperatures and projectile shapes, with a prediction error basically within 5 %. The research results can offer valuable guidance for the ballistic-proof design of UHMWPE laminates.

Testing mechanical properties and degree of conversion of resin-based composite material containing contact killing antibacterial agent in comparison with fluoride composite resin

BackgroundA major drawback of resin composites is their tendency to accumulate microbial biofilms that can lead to secondary caries. The objective of this study was to compare the mechanical properties and the degree of conversion of commercial resin-based composite materials containing a contact-killing antibacterial agent, dimethylaminohexadecyl methacrylate (DMAHDM), at different concentrations, with a fluoride-releasing composite material. Materials and methodsFour groups were tested: Tetric N Ceram composite material (G1), Tetric Evo Ceram (G2), and Tetric N Ceram with the addition of contact-killing antibacterial agent DMAHDM at concentrations of 3% (G3) and 5% (G4). The mechanical properties, including flexural strength, elastic modulus, and Vickers microhardness and the degree of conversion were investigated. ResultsAdding 3 % and 5 % DMAHDM resulted in flexural strength values that were comparable to Tetric Evo Ceram. Tetric N Ceram was comparable to the group containing 3 % DMAHDM (p > 0.05). However, it was significantly greater when compared to Tetric Evo Ceram (93.3 ± 9.4) and 5 % DMAHDM (p < 0.05). Both the elastic modulus and Vickers microhardness values of Tetric N Ceram were significantly higher than those of the other groups (p < 0.05). Furthermore, the elastic modulus of Tetric Evo Ceram showed similar results to groups with 3 % and 5 % DMAHDM. Nevertheless, the Vickers microhardness value is significantly higher when compared to 5 % DMAHDM (0.394 ± 0.021) (p < 0.05) while it was comparable to that of 3 % DMAHDM (0.484 ± 0.016) (p > 0.05). There was no statistically significant difference in the degree of conversion between the groups (p > 0.05). ConclusionAdding 3% DMAHDM to Tetric N Ceram resulted in flexural strength values that were similar to those of Tetric N Ceram and Tetric Evo Ceram. DMAHDM did not affect the degree of conversion of Tetric N Ceram composite.

Comparison between Different Bulk-Fill and Incremental Composite Materials Used for Class II Restorations in Primary and Permanent Teeth: In Vitro Assessments.

Several advantages, including improved aesthetics and conservative cavity preparation, made resin-based composite (RBC) a popular restorative material. However, several limitations come with RBC restorations such as the necessity for proper isolation of the tooth and an incremental layering for the material due to the limitations of the depth of cure. Despite these advantages and limitations, the usage of these restorative materials is increasingly being expanded due to the advancement made since their introduction. To overcome some of the limitations, several types of RBC restorations were developed. Four different RBC materials used for class II restorations in primary and permanent teeth were compared: Z350 XT Filtek™ Universal Restorative (ZXT), Filtek™ Bulk Fill Flowable Restorative (FBF), Beautifil-Bulk Flowable (BBF) and Tetric™ N-Flow (TNF). Flexure strength, elastic modulus, surface roughness, microhardness and microleakage were assessed using standard methods or previously published protocols. The data and differences between the groups were analyzed using One-way analysis of variance (ANOVA), Tukey's multiple comparisons, Kruskal-Wallis and Wilcoxon rank-sum (Mann-Whitney) tests. The study found that BBF (86.24 ± 7.41 MPa) and ZXT (64.45 ± 11.52 MPa) had higher flexural strength than FBF (50.89 ± 8.44 MPa) and TNF (50.67 ± 9.40 MPa), while both exhibited the highest values of surface roughness. Elastic modulus was the highest with BBF, which was not statistically significant from FBF or ZXT (p > 0.05). ZXT (109.7 ± 7.83 VH) exhibited the highest value of microhardness, which was statistically significant from the other three materials (p < 0.0001). Microleakage was assessed after thermocycling for 20,000 cycles to simulate two years in the mouth. FBF (70%) exhibited the most resistance to microleakage. Different types of RBC restorations exhibit different characteristics. The clinician needs to choose the most appropriate restorative material based on different clinical scenarios.

Research and Application Progress of Resin-Based Composite Materials in the Electrical Insulation Field.

The research and application progress of resin-based composite materials in the field of electrical insulation has attracted considerable attention and emerged as a current research hotspot. This review comprehensively summarized the research and application progress of resin-based composite materials in the field of electrical insulation, providing detailed insights into their concept, properties, and preparation methods. In addition, a comprehensive evaluation of the electrical insulation performance, mechanical properties, and thermal properties of resin-based composite materials was presented, along with an in-depth analysis of their current application status. Despite the immense potential and development opportunities of resin-based composite materials, they also face several challenges. This review serves as a valuable reference and resource for researchers in related fields and aimed to promote further research and application development of resin-based composite materials in the field of electrical insulation.

PHYSICAL&amp;MECHANICAL PROPERTIES OF COMPOSITES WITH NANO-SIZED CARBON FILLERS FOR FIXING CRACKS

Annually the length of piping networks grows across the Russian Federation, which leads to a larger scope of repair. It is impossible to timely perform repairs, unless innovative technologies are applied. These technologies should prevent the need to cut out defective metal areas or interrupt the pumping process. Over the last years the repair technology is found sufficient, when there is a range of composite materials used to fix crack-like defects. Computational modeling of the crack filling with a composite reveals that reinforcement of the crack edges reduces stress in its peak. Consequently, it allows to prevent an area of their singularity values from occurring. To comply with the requirements to the fixed crack’s parameters, the composite material should be fluid enough and have a high steel adhesionto securely brace the crack edges. In addition, the material should have enough plasticity to compensate local deformation shifts occurring under static or regular loads applied to the structure. The study researches how nanosized carbon fillers — fullerenes, carbon nanotubes and graphene — impact the physical &amp; mechanical properties of the epoxy resin-based composite materials. It is demonstrated that the composite with fullerenes has an enhanced plasticity and a high fluidity. Therefore, this composite can be recommended for fixing narrower cracks in steel structures under regular loads. It is found that the composite with nanotubes maintains the required fluidity for half an hour and can be used, if the crack-like defect cannot be fixed within a tight timeframe. The composite material with graphene is extra strong. Consequently, it can be used to fix cracks in structures under static loads.

Shear Bond Strength of Repaired CAD/CAM Resin-Based Composite Materials Submitted to Er:YAG Laser Treatments at Different Powers

This study aimed to investigate the effects of different powers of Er:YAG laser irradiation on the shear bond strength (SBS) of repaired CAD/CAM resin-based composite materials. A total of 180 CAD/CAM resin-based composite specimens (5 × 5 × 2 mm) were obtained (Shofu Block HC—SB; Grandio Blocs—GB). They were allocated into six groups according to surface pretreatment methods: no surface pretreatment (control), hydrofluoric acid (HF), diamond bur and 3 W, 5 W, and 7 W Er:YAG lasers (20 Hz) (n = 15). Silane and universal adhesive were applied. The repair procedure was completed with nano-ceramic composite resin (Ceram-X Sphere TEC-One). The samples were thermocycled for 10,000 cycles (5–55 °C). The SBS was evaluated with a universal test machine (1 mm/min). A 3D optic profilometer was used to assess the surface topography. Statistical analysis was performed with a two-way ANOVA and Bonferroni tests (p &lt; 0.05). For SB samples, HF and diamond bur caused significantly higher SBSs than 3 W and 7 W lasers, while for GB samples, they led to a significantly higher SBS than all laser treatments. For SB samples, the 5 W laser led to the highest SBS, while for GB samples, the 7 W laser caused the highest SBS (p &lt; 0.05). For both blocks, adhesive failure was more common for the 3 W laser, and a decrease in adhesive failures and an increase in mixed failures were observed with increasing laser irradiation. The 3D optic profilometer revealed that smoother surfaces were obtained with the 3 W laser than other laser irradiation at different powers. Pretreatment with increasing Er:YAG laser powers led to similar bond strengths to hydrofluoric-acid- and diamond-bur-treated CAD/CAM resin-based composite materials. A more powerful laser treatment is required to provide a higher bond strength for restorative materials containing a higher inorganic ceramic content.

Effect of Various Beverages on Adhesion of Repaired CAD/CAM Restorative Materials.

(1) Background: The purpose of this study was to determine the effect of commonly consumed beverages on the bond strength of three different computer-aided design-computer-aided manufacturing (CAD/CAM) resin-ceramic hybrid materials repaired with resin-based composite (RBC) materials. (2) Materials and Methods: Rectangular prism specimens (N = 138) measuring 6 mm × 5 mm × 2 mm were obtained from GC Cerasmart (GC), Lava Ultimate (LU), and Vita Enamic (VE) blocks. These blocks were polished and then subjected to thermal cycling (10,000 cycles, 5 °C to 55 °C). After the surface treatment was applied, the average surface roughness value was measured. All the surfaces were repaired with RBC. Thermal cycling was performed for the second time. Each group was then distributed into three subgroups according to the beverage used: tea (t), cola (c), and distilled water (0) (n = 15). The specimens were stored in these solutions for 28 days and then subjected to the shear bond strength (SBS) test. Statistical analysis was performed using a two-way ANOVA test with Bonferroni adjustment. (3) Results: The surface roughness of the materials presented no significant difference after different surface treatments (p > 0.05). No significant difference was observed among the materials (p > 0.05). Tea and cola presented similar SBS values (p > 0.05). Both were significantly lower than distilled water (p < 0.001, p < 0.001, respectively). (4) Conclusions: Consumption of beverages reduces the bond strength in surfaces repaired with RBC to CAD/CAM resin-ceramic hybrid materials. (5) Clinical Significance: Repairing damaged resin matrix dental restorations with RBC is advantageous in terms of time and cost by achieving adequate bond strengths. Frequently consumed beverages reduce the bond strength of repaired CAD/CAM resin-ceramic hybrid materials.

In vitro evaluation of CAD/CAM composite materials

ObjectivesThe purpose of this in vitro study was to evaluate the microstructural, elemental and mechanical properties of contemporary computer-aided-design/computer-aided manufacturing (CAD/CAM) resin based composite (RBC) materials. MethodsSix CAD/CAM RBC materials [Brilliant CRIOS (Coltene Whaledent AG), Cerasmart (GC), Lava Ultimate (3M ESPE), Tetric CAD (Ivoclar Vivadent), Shofu Block HC (Shofu), Grandio Blocs (VOCO GmbH)] were tested. Ten rectangular blocks (14 Χ 12 Χ 18 mm) for each material, after metallographic grinding and polishing, were subjected to Instrumented Indentation Testing (ΙIT). Martens Hardness (HM), Indentation Elastic Modulus (EIT), Elastic (ηIT) and Creep indices (CIT) were determined according to formulas provided by ISO 14577. The diagonal length of each indentation was measured and HV was determined. The results of HM, EIT, ηΙΤ, HV, and CIT were statistically analyzed by one-way ANOVA and Tukey post hoc test employing the material as a discriminating variable (a = 0.05), while the possible correlations were determined by Spearman's correlation test. One specimen from each group was examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). ResultsBackscattered Electron images and EDX analysis demonstrated differences in size, shape and type of fillers along with elemental composition among materials tested. Statistical significant differences were identified for all mechanical properties tested. Grandio Blocs had the significantly higher HM (953±7 N/mm2), HV (136±1) and EIT (23±1 GPa) followed by Lava Ultimate (ΗM=674±25 N/mm2, HV=105±2, EIT=15±1 GPa). Elastic index ranged from 41% to 52%, with Shofu Block demonstrating the significantly highest ηIT (52 ± 1%) values. Cerasmart had significantly higher CIT value (8.4 ± 0.1%) than all other materials tested, while Grandio Blocs and Lava Ultimate had the lowest ones. Spearman's correlation revealed that all mechanical properties tested exhibited correlations with each other, apart from ηΙΤ. ConclusionsThe results showed that the CAD/CAM materials tested have differences in their microstructure, elemental composition and mechanical properties. Clinical significanceThe RBCs tested showed significant differences in mechanical properties and thus differences in clinical performance are anticipated. RBCs with increased filler loading had the most favorable combination of hardness, elastic modulus and creep index indicating that these materials may have better clinical performance under intraoral loading conditions.