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Background: The aim of this in-vitro study is to investigate the effect of post-curing time and units on the degree of conversion (DC), microhardness (VHN) and staining susceptibility (∆E00) of two 3D printed permanent resins (Crowntec (SCT), Varseosmile CrownPlus (VSP)). Methods: A total of 180 disc-shaped samples (10*10*2 mm), 60 for each experiment, from the tested materials (30 SCT, 30 VSP) were printed on 3D printer. Half of the samples were post-cured in LC-3DPrint Box and the other half in Phrozen Cure V2 and were divided into 3 subgroups according to post-curing time of 5, 10 and 30 min (n = 5). The DC of the samples was determined using a Fourier transform infrared spectrometer. The VHN values were measured with a Vickers hardness tester. The color of the samples was initially measured using a spectrophotometer and then again after one month of staining in coffee. The ∆E00 was calculated with the CIEDE2000 formula. Data obtained from each parameter examined were analyzed by SPSS software using One-Way ANOVA, post-hoc Tukey, post-hoc Tamhane's T2, Independent-samples T test and Pearson's correlation test (α = 0.05). Results: While DC and VHN ​​of the tested materials increased in parallel with the post-curing time, ∆E00 decreased. The highest DC (74.6 ± 3.8) and VHN (29.1 ± 0.8) and the lowest ∆E00 (1.9 ± 0.1) were obtained in LC-3DPrint Box-30 min post-curing group of VSP. The effect of the type of post-curing units on the DC and ∆E00 of the materials was statistically significant (p < 0.05) except for the SCT-5 min and SCT-30 min groups. The VHN was statistically significantly higher in LC-3DPrint Box at all post-curing times of the tested materials (p < 0.05). A significant positive correlation was found between DC and VHN (r = 0.796, p < 0.001), while a significant negative correlation was observed between DC and ∆E00 (r=-0.763, p < 0.001). Conclusion: The study demonstrated that extending the post-curing time led to improvements in the degree of conversion and microhardness, while simultaneously reducing the stainability of the materials tested. Additionally, the type of post-curing unit used had a significant impact on these results, further highlighting the importance of both curing time and equipment in optimizing material properties. [ABSTRACT FROM AUTHOR]

The article discusses the mechanical, fracture, and thermal characterization of post-cured hybrid epoxy nanocomposites reinforced with Graphene nanoplatelets and h-Boron Nitride. The study explores the impact of dual nanofiller reinforcement and post-curing temperatures on the composites' properties, including tensile, flexural, and impact strength. Experimental data combined with ANSYS simulation provides insights into enhancing material properties for high-performance applications. The study confirms that incorporating GNPs and h-BN in an epoxy matrix improves mechanical properties, offering promise for aerospace and automotive applications. Simulation results closely matched experimental findings, validating the study's outcomes. [Extracted from the article]

Abstract Background The aim of this in-vitro study is to investigate the effect of post-curing time and units on the degree of conversion (DC), microhardness (VHN) and staining susceptibility (∆E00) of two 3D printed permanent resins (Crowntec (SCT), Varseosmile CrownPlus (VSP)). Methods A total of 180 disc-shaped samples (10*10*2 mm), 60 for each experiment, from the tested materials (30 SCT, 30 VSP) were printed on 3D printer. Half of the samples were post-cured in LC-3DPrint Box and the other half in Phrozen Cure V2 and were divided into 3 subgroups according to post-curing time of 5, 10 and 30 min (n = 5). The DC of the samples was determined using a Fourier transform infrared spectrometer. The VHN values were measured with a Vickers hardness tester. The color of the samples was initially measured using a spectrophotometer and then again after one month of staining in coffee. The ∆E00 was calculated with the CIEDE2000 formula. Data obtained from each parameter examined were analyzed by SPSS software using One-Way ANOVA, post-hoc Tukey, post-hoc Tamhane’s T2, Independent-samples T test and Pearson’s correlation test (α = 0.05). Results While DC and VHN ​​of the tested materials increased in parallel with the post-curing time, ∆E00 decreased. The highest DC (74.6 ± 3.8) and VHN (29.1 ± 0.8) and the lowest ∆E00 (1.9 ± 0.1) were obtained in LC-3DPrint Box-30 min post-curing group of VSP. The effect of the type of post-curing units on the DC and ∆E00 of the materials was statistically significant (p

Abstract Background The purpose of the study was to measure the degree of conversion (DC) of direct-printed aligners (DPA) that were post-cured under ambient and nitrogen atmosphere at specific time intervals and investigate the kinetics of polymerization reaction of this material. Methods A total of 48 aligners were produced in 4 printing series by a 3D printer with TC-85DAC resin (Graphy Inc). From each series of printing, 12 aligners were included. The aligners were divided into two groups according to their post-curing conditions. One group was post-cured under ambient air with the presence of oxygen and the other under a nitrogen atmosphere, both using the same UV post-curing unit recommended by the company. The aligners were post-cured at six different time intervals: 1, 2, 3, 5, 10, and 20 min. Each time interval included 8 aligners, with 2 aligners from each series. The DC of the cured aligners was measured by means of attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) through acquisition of the respective spectra for each UV-curing condition. Statistical analysis was performed to compare the results and differences within each atmosphere post-curing protocol, as well as between the different selected atmosphere conditions. Statistical significance level was set at p-value ≤ 0.05. Results Pairwise analysis between post-curing protocols showed statistically significant differences only at the first minute of polymerization. Post-curing with nitrogen did not yield statistically significant results across different time intervals. Post-curing in ambient air showed some significant differences on the 1st and 2nd minute of the post-curing process. Conclusions Almost complete double bond conversion was observed. Significant differences were observed only during the first minute of polymerization under the nitrogen atmosphere.

The mechanical properties of polymer matrix composites are a function of their curing and post‐curing temperatures. This research has experimentally investigated the effect of post‐curing temperature on the mode I fracture toughness of glass/epoxy composites. For this purpose, double cantilever beam (DCB) specimens are fabricated using the wet lay‐up assisted with vacuum bagging technique and post‐cured under three different curing processes. The mode I fracture tests are carried out in two categories. The post‐curing temperature remains constant for the first group of specimens while tests are conducted at three different elevated temperatures. In the second group of specimens, tests are performed at a constant temperature to evaluate the influence of three post‐curing processes on the outcomes. The test results showed that increasing the post‐curing temperature led to an upward trend in initiation and propagation fracture toughness. Additionally, the results indicated that as the test temperature increased, regardless of the curing process, both initiation and propagation fracture toughness also increased. Room temperature test results show that the post‐curing process at 80°C increased initiation and propagation fracture toughness by 20% and 15%, respectively, while the post‐curing process at 100°C improved these by 40% and 22%. [ABSTRACT FROM AUTHOR]

Background: The purpose of the study was to measure the degree of conversion (DC) of direct-printed aligners (DPA) that were post-cured under ambient and nitrogen atmosphere at specific time intervals and investigate the kinetics of polymerization reaction of this material. Methods: A total of 48 aligners were produced in 4 printing series by a 3D printer with TC-85DAC resin (Graphy Inc). From each series of printing, 12 aligners were included. The aligners were divided into two groups according to their post-curing conditions. One group was post-cured under ambient air with the presence of oxygen and the other under a nitrogen atmosphere, both using the same UV post-curing unit recommended by the company. The aligners were post-cured at six different time intervals: 1, 2, 3, 5, 10, and 20 min. Each time interval included 8 aligners, with 2 aligners from each series. The DC of the cured aligners was measured by means of attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) through acquisition of the respective spectra for each UV-curing condition. Statistical analysis was performed to compare the results and differences within each atmosphere post-curing protocol, as well as between the different selected atmosphere conditions. Statistical significance level was set at p-value ≤ 0.05. Results: Pairwise analysis between post-curing protocols showed statistically significant differences only at the first minute of polymerization. Post-curing with nitrogen did not yield statistically significant results across different time intervals. Post-curing in ambient air showed some significant differences on the 1st and 2nd minute of the post-curing process. Conclusions: Almost complete double bond conversion was observed. Significant differences were observed only during the first minute of polymerization under the nitrogen atmosphere. [ABSTRACT FROM AUTHOR]

In recent years, additive manufacturing (AM) has been recognized as a transformative force in the dental industry, with the ability to address escalating demand, expedite production timelines, and reduce labor-intensive processes. Despite the proliferation of three-dimensional printing technologies in dentistry, the absence of well-established post-processing protocols has posed formidable challenges. This comprehensive review paper underscores the critical importance of precision in post-processing techniques for ensuring the acquisition of vital properties, encompassing mechanical strength, biocompatibility, dimensional accuracy, durability, stability, and aesthetic refinement in 3D-printed dental devices. Given that digital light processing (DLP) is the predominant 3D printing technology in dentistry, the main post-processing techniques and effects discussed in this review primarily apply to DLP printing. The four sequential stages of post-processing support removal, washing, secondary polymerization, and surface treatments are systematically navigated, with each phase requiring meticulous evaluation and parameter determination to attain optimal outcomes. From the careful selection of support removal tools to the consideration of solvent choice, washing methodology, and post-curing parameters, this review provides a comprehensive guide for practitioners and researchers. Additionally, the customization of post-processing approaches to suit the distinct characteristics of different resin materials is highlighted. A comprehensive understanding of post-processing techniques is offered, setting the stage for informed decision-making and guiding future research endeavors in the realm of dental additive manufacturing. [ABSTRACT FROM AUTHOR]

Sandwich composites are engineering materials that can be optimized and replaced with metals, mainly applied in aircraft fields because of their high strength-to-weight ratio. The quality of the composite sandwich structure depends on which fabrication method is applied. The methods used in this study are vacuum bagging, VARI, and VARI + post-curing. In vacuum bagging methods, fiber and resin are laminated manually and then covered with plastic bagging. The plastic is connected to a vacuum pump using a hose to suck the air out. Then, the VARI (Vacuum Assisted Resin Infusion) method utilizes vacuum pressure from a vacuum pump to flow resin to the laminated area of the fibers. Therefore, this study applies various methods to determine possible differences in product yields in terms of complex parts, thickness, and mechanical properties of 3C3 Carbon Sandwich Composite UD12K 0°/DVC. The results of the research concluded that the optimal method to produce high mechanical properties is obtained from the VARI method, as seen from the results of the three-point. The bending test is 26.07 MPa, better than the vacuum bagging test, which is only 17.53 MPa. The post-curing also increased mechanical properties for the flatwise test at 4082.1 MPa, 3204.2 N for the edgewise test, and 38.05 N for the three-point bending test. The VARI method is also supported by showing the surface morphology structure from the three-point. The bending flexural test shows a tight and dense structure so that the bond between the matrix and the fiber is perfectly bonded.

The purpose of this study was to obtain information on the influence of the size factor on the climatic aging of circular fiber plastics produced by pultrusion. The kinetics of moisture transfer was obtained in humidification and drying modes at 60 °C in samples of epoxy basalt fiber reinforcement bars: after 28 months of exposure in the extremely cold climate of Yakutsk and 30 months of exposure in the moderately warm climate of Gelendzhik. It was shown that the 2D Langmuir model adequately describes the kinetics. The diffusion coefficients in the reinforcement direction for bars with diameters of 6, 8, 10, 16 and 20 mm turned out to be significantly higher than in the radial direction. To clarify the aging mechanism of the bars and the tensile, compressive and bending strength, the coefficient of linear thermal expansion and the glass transition temperature of the epoxy matrix of the bars with a diameter of 6, 8 and 10 mm after 51 months of exposure in Yakutsk and 54 months of exposure in Gelendzhik were measured. It was shown that after climatic exposure, the deformability of the bars decreased with increasing diameter of the bar; the glass transition temperature increased more significantly in the bar with a smaller diameter. In 6 mm diameter bars, the compressive and bending strength limits decreased by 10–25 % due to the plasticizing effect of moisture. With the same depth of moisture penetration into the volume of the samples, its effect on the strength of thin bars was significant, and for thick bars, it was insignificant. An increase in the glass transition temperature by 6 °C, associated with the additional curing of the polymer matrix, occurred in the surface layer of the epoxy basalt fiber reinforcement bars and was revealed in bars with a smaller diameter. [ABSTRACT FROM AUTHOR]

The post-curing process of cured composites is essential in enhancing the strength, stiffness, elevating the glass transition temperature, and reducing residual stress in polymer thermoset composites. The curing temperature and time are the key factors that affect these properties. In-situ polymerization method was used to prepare composites with varying weight percentages of graphene nanoplatelets (GNP) and hexagonal boron nitride (h-BN) nanofillers (0.1, 0.2, and 0.3 wt% GNP-based composites; 0.3, 0.4, and 0.5 wt% h-BN-based composites; 0.4, 0.5, and 0.6 wt% h-BN+GNP-based composites). The cured composites were post-cured at temperatures of 80°C, 120°C, and 160°C for 120 minutes in a hot air oven. The presence of GNPs and h-BNs in the composites is confirmed using Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Further mechanical and thermal properties were evaluated by conducting tensile, flexural, impact, fracture and differential scanning thermometry (DSC) tests. The simulation analyses were performed using Ansys software, and the results demonstrated a strong correlation with the experimental data, with discrepancies between the two consistently within a standard margin of 20%.

In the manufacture and repair of equipment parts for processing abrasive mixtures in mining, chemical and other industries, protective coatings for internal and external surfaces of pumps, transport systems, and hydraulic structures, epoxy composite materials are widely used in world practice. To improve the performance properties of wear-resistant epoxy materials, in most cases, they are post-cured, optimization of which modes makes it possible to reduce the negative effects of temperature changes in products of different dimensions and thickness on their performance. An analysis of studies and publications on improving the performance properties of protective wear-resistant epoxy materials has shown that insufficient attention is paid to the issues of the predicted influence of changes in temperature and time on the performance of epoxy products when developing technological regimes for their post-curing. The purpose of the article is determining the optimal post-curing regime for wear-resistant epoxy compositions with possible prediction of changes in their properties with temperature deviations from this regime. Using the method of mathematical planning of the Box-Wilson experiment, the optimal post-curing regime for wear-resistant epoxy compositions was established (80°C × 2.4 hours + 100°C × 2.2 hours), which can be used in the manufacture and repair of parts of various sizes and thicknesses, coatings. The influence of the abrasive attack angle during gas-abrasive wear of epoxy compositions on their wear resistance was clarified and it was revealed that the maximum wear of unfilled compositions occurs at an abrasive attack angle of 45°, which must be taken into account when using the products. A comparative assessment of serial (New Technologies LLC, Dnepr) and developed optimized post-curing modes of thick-walled wear-resistant epoxy products highly filled with multidisperse silicon carbide (sand-nozzles of hydrocyclone) has proven the possibility of reducing the overall process cycle using the optimized mode while improving wear resistance and physical and mechanical properties. [ABSTRACT FROM AUTHOR]

This study aims to investigate the influence of post-polymerization (post-curing) conditions on surface characteristics, flexural properties, water sorption and solubility, and cytotoxicity of additively manufactured denture base materials. The tested specimens were additively manufactured using digital light processing and classified into different post-curing condition groups: submerged in water (WAT), submerged in glycerin (GLY), and air exposure (AIR). An uncured specimen (UNC) was used as a control. The surface topography and roughness were observed. The flexural strength and modulus were determined via a three-point bending test. The water sorption and solubility were subsequently tested. Finally, an extract test was performed to assess cytotoxicity. Different post-curing conditions had no significant effects on the surface topography and roughness (Sa value). Various post-curing conditions also had no significant effects on the flexural strength. Notably, the flexural modulus of the WAT group (2671.80 ± 139.42 MPa) was significantly higher than the AIR group (2197.47 ± 197.93 MPa, p = 0.0103). After different post-curing conditions, the water sorption and solubility of the specimens met the ISO standards. Finally, all post-curing conditions effectively reduced cytotoxic effects. Post-curing with different oxygen levels improved flexural properties, and flexural modulus significantly increased after the specimens were submerged in water. In addition, water sorption and solubility, and cytocompatibility were optimized by post-curing, irrespective of the post-curing conditions. Therefore, the water-submerged conditions optimized the flexural modulus of the 3D-printed denture base materials. • The underwater method of post-curing resulted in the highest flexural modulus. • Flexural strength was not significantly affected by different oxygen content. • Different post-curing conditions did not induce cytotoxicity. • The underwater method is a promising post-processing procedure. [ABSTRACT FROM AUTHOR]

Post-curing is the process of applying extra light to complete the polymerization process of 3D printing. The mechanical properties of light-cured three-dimensional (3D) printed resin can be improved by decreasing the oxygen concentrations during post-curing, and nitrogen-saturated post-curing has been applied for this purpose. This study aimed to evaluate and compare the color stability of 3D-printed resin crowns that were post-cured in both normal air and nitrogen-saturated conditions. Crowns were fabricated with a 3D printer and post-cured in normal air (control group; air) or nitrogen-saturated conditions (experimental group; nitrogen). The specimens in each group were subdivided into four subgroups, each exposed to different discoloration agents: distilled water, coffee, wine, and curry. Post-immersion color changes were measured using a digital spectrophotometer and analyzed using repeated-measures ANOVA. Fourier transform infrared (FT-IR) spectroscopy evaluated the degree of conversion of resin over immersion times for both post-curing conditions. Upon comparing the effects of post-curing conditions, a significant difference between the control and experimental groups in terms of immersion time in the wine and curry subgroups was found. FT-IR analysis showed a significant difference in the degree of conversion between the air and nitrogen groups from 10 to 300 s. These findings suggest that nitrogen-saturated post-curing can potentially enhance the conversion rate of 3D-printed resin crowns, thereby improving their color stability. [ABSTRACT FROM AUTHOR]

Current 3D-printing technology has been widely used for creating dental resin restorations. This study aimed to evaluate the effect of light intensity, time, and energy post-curing on the surface color of 3D-printed resin crowns. However, the influences of post-curing parameters on the restoration after printing still need to be explored. Therefore, this project investigates the effect of post-cure conditions on resin color. Specimens from single-crown (SC) and pontic (PO) specimens underwent post-curing at various light intensities (105, 210, 420, 630, and 860 mW/cm2) for 5, 10, and 15 min. Specimens were observed at three predetermined points and measured using a commercial spectrophotometer that utilizes the CIE Lab∗ color space. Subsequently, samples were analyzed for color differences (ΔE). ΔE color differences in evaluated samples were influenced by the light intensity, time, and energy post-curing. SC samples showed a significant color difference (P < 0.05), with the lowest value at 5 min of 16 (860 mW/cm2), while 10 and 15 min had a difference of 4 (210 mW/cm2). PO samples exhibited a significant decrease in the color difference (P < 0.05) at 5 and 10 min of 16 (860 mW/cm2), and at 15 min of 12 (630 mW/cm2). The results of this study indicate that exposing a resin crown to a high light intensity results in color stability and allows shorter post-curing times. [ABSTRACT FROM AUTHOR]

Volumetric shrinkage (VS) of conventional, bulk-fill, and core build-up resin-based composites (RBCs) of various thickness (1-5 mm) was measured using the modified bonded-disk method with confocal laser scanning microscopy. Additionally, the bottom-totop ratio of Vickers hardness (%VH) was measured. Conventional RBCs exhibited significantly higher VS than bulk-fill and core build-up RBCs (p<0.05). As specimen thickness increased, VS relative to volume (%VS) and difference in VS at each depth (VSdepth) decreased. For conventional RBCs, there was a significant drop in VSdepth between 1 mm and 2 mm (p<0.05), and another drop was observed between 3 mm and 4 mm (p<0.05) where %VH decreased below 90%. For bulk-fill and core build-up RBCs, VSdepth decreased significantly between 2 mm and 3 mm (p<0.05), but %VH exceeded 90% even in 5 mm deep cavities. These results indicated that post-curing contributed to lower shrinkage in deeper layers, and that conventional RBCs were not adequately polymerized at the depth of over 3 mm. [ABSTRACT FROM AUTHOR]

Post-curing is the process of applying extra light to complete the polymerization process of 3D printing. The mechanical properties of light-cured three-dimensional (3D) printed resin can be improved by decreasing the oxygen concentrations during post-curing, and nitrogen-saturated post-curing has been applied for this purpose. This study aimed to evaluate and compare the color stability of 3D-printed resin crowns that were post-cured in both normal air and nitrogen-saturated conditions. Crowns were fabricated with a 3D printer and post-cured in normal air (control group; air) or nitrogen-saturated conditions (experimental group; nitrogen). The specimens in each group were subdivided into four subgroups, each exposed to different discoloration agents: distilled water, coffee, wine, and curry. Post-immersion color changes were measured using a digital spectrophotometer and analyzed using repeated-measures ANOVA. Fourier transform infrared (FT-IR) spectroscopy evaluated the degree of conversion of resin over immersion times for both post-curing conditions. Upon comparing the effects of post-curing conditions, a significant difference between the control and experimental groups in terms of immersion time in the wine and curry subgroups was found. FT-IR analysis showed a significant difference in the degree of conversion between the air and nitrogen groups from 10 to 300 s. These findings suggest that nitrogen-saturated post-curing can potentially enhance the conversion rate of 3D-printed resin crowns, thereby improving their color stability.

The aim of this study was to evaluate the effect of surface polishing as well as the post-curing atmospheres (air and nitrogen gas) on the physical properties of an occlusal splint material for additive manufacturing. Flexural strength, flexural modulus, Vickers hardness number (VHN), degree of carbon double bond conversion (DC), water sorption (WSP), and water solubility (WSL) were evaluated. Surface polishing significantly affected the evaluated properties. Regardless of the post-curing atmosphere, flexural strength, flexural modulus, VHN, and DC showed significantly higher values for the polished specimens when compared with the unpolished ones, while WSP and WSL were significantly lower for the polished specimens. Unpolished specimens post-cured at nitrogen gas showed significantly higher VHN and DC values. However, the effect of the post-curing at a nitrogen gas atmosphere was non-significant in polished specimens. The current results suggested that surface polishing plays a role in the physical properties of the evaluated occlusal splint material and can enhance all the evaluated properties regardless of the post-curing atmosphere. Meanwhile, the post-curing at a nitrogen gas atmosphere can enhance the VHN and DC but its effect is confined only to the surface layers, which can be removed during surface polishing. [ABSTRACT FROM AUTHOR]

Eggshells are a potentially polluting industrial waste that are disposed of as landfill which has proven to be hazardous to the environment. The usage of chicken eggshells as a biofiller for polymer matrix composites instead of its disposal as landfill has proven advantageous in various studies. On the other hand, using eggshells as a filler material to replace inorganic calcium carbonate usage would be another environment friendly act. The present study is focused on studying the effects of eggshell filler addition and post-curing on polymer composites which could be utilised for domestic applications. Herein, uncarbonised and carbonised eggshell filler material were processed from waste eggshells. Hybridisation of the carbonised and uncarbonised eggshell filler was carried out. All three variants of eggshell fillers (10 wt.%) were used in the fabrication of composites. A hand lay-up technique was employed in the fabrication of unfilled composites along with three variants of filled composites, namely, uncarbonised, carbonised, and hybrid eggshell filled composites. The fabricated and cured composites were further subjected to post-curing at a temperature of 60 °C for a period of 2 h. All four variants of post-cured composites were then subjected to mechanical testing according to American Society for Testing and Materials (ASTM) standards. The tests revealed that all three variants of filled composites possess better mechanical properties in comparison with unfilled composites. Further, in comparison with unfilled composites, the carbonised eggshell filled composites showcased 42% and 49% improvement in flexural and tensile properties, respectively. The modes of failure of the specimens were observed and tabulated. SEM imaging revealed that the eggshell filler contributed to the strengths of the composites by means of arresting and deviating cracks. It was also observed that the post-cured specimens displayed improved properties when compared with our previous studies on non-post-cured specimens. In summary, the study showcased the benefits of eggshell filler addition and the post-curing of polymer composites. [ABSTRACT FROM AUTHOR]

The temperature coefficient of resistance (TCR) determines the electrical performance of materials in electronics. For a carbon nanotube (CNT) nanocomposite, change of resistivity with temperature depends on changes in CNT intrinsic conductivity, tunnelling thresholds and distances, matrix' coefficient of thermal expansion, and other factors. In our study, we add one more influencing factor–the degree of cure. Complexities of the curing process cause difficulties to predict, or even measure, the curing state of the polymer matrix while uncertainty in the degree of cure influences TCR measurements leading to biased values. Here we study the influence of the cure state on the TCR of a single-walled CNT/epoxy polymer nanocomposite. For the given degree of cure, TCR measurements are conducted in the temperature range 25–100 °C, followed by the next 24 h of post-curing and a new cycle of measurements, 8 cycles in total. We find that contrary to industry practice to expect a high degree of cure after 3 h at 130 °C, the curing process is far from reaching the steady state of the material and continues at least for the next 72 h at 120 °C, as we observe by changes in the material electrical resistivity. If TCR measurements are conducted in this period, we find them significantly influenced by the post-curing process continuing in parallel, leading in particular to non-monotonic temperature dependence and the appearance of negative values. The unbiased TCR values we observe only when the material reaches the steady state are no longer influenced by the heat input. The dependence becomes steady, monotonically increasing from near zero value at room temperature to 0.001 1/°C at 100 °C. [ABSTRACT FROM AUTHOR]

The present study details the composite fabrication, characterization, and full recyclability of the biobased polymer resins with flax fiber as the reinforcement. Two different biobased resins are selected by varying the resin hardener combination and curing parameters for the comparison. The optimum parameters for the composite preparation are finalized by evaluating the neat resin's mechanical and glass transition temperature (Tg) values. According to the results obtained, a biobased epoxy resin cured by a cleavable hardener displayed the highest Tg (i.e., 93.5°C) upon a two‐step cure cycle, guaranteeing full recyclability. Subsequently, eco‐composite flat panels are manufactured using the selected formulation reinforced with commercial flax‐based fabric. These panel's flexural strength, modulus, and interlaminar shear strength are measured after each curing step. The recyclability yield of the composite is tested, through a specific chemical process, demonstrating the possibility of separating and recovering both the constituent fibers and resin from the composite panels. [ABSTRACT FROM AUTHOR]

Despite the fact that three-dimensional (3D) printing is frequently used in the manufacturing of occlusal splints, the effects of the 3D printer type and post-curing methods are still unclear. The aim of this study was to investigate the effect of the printer type (digital light processing: DLP; and liquid crystal display: LCD) as well as the post-curing method with two different atmospheric conditions (air and nitrogen gas (N2)) on the mechanical and surface properties of 3D-printed soft-type occlusal splint material. The evaluated properties were flexural strength, flexural modulus, Vickers hardness (VHN), fracture toughness, degree of double bond conversion (DC%), water sorption, water solubility, and 3D microlayer structure. The printer type significantly affected all the evaluated properties. Flexural strength, flexural modulus, and fracture toughness were significantly higher when specimens were printed by a DLP printer, while VHN and DC% were significantly higher, and a smoother surface was noticeably obtained when printed by an LCD printer. The post-curing at an N2 atmosphere significantly enhanced all of the evaluated properties except water sorption, 3D microlayer structure, and fracture toughness. The current results suggested that the printer type and the post-curing methods would have an impact on the mechanical and surface properties of the evaluated material. [ABSTRACT FROM AUTHOR]

Although three-dimensional (3D) printing is clinically convenient to fabricate occlusal splints, it is still unclear how the post-curing method and the printer type can affect 3D-printed splints. This study aimed to evaluate the effect of stroboscopic post-curing at a nitrogen gas (N2) atmosphere versus post-curing in an air atmosphere, as well as the printer type (liquid crystal display (LCD) and digital light processing (DLP)) on the mechanical properties of a 3D-printed hard-type occlusal splint material. Flexural strength, flexural modulus, Vickers hardness number (VHN), fracture toughness, degree of double bond conversion (DC), 3D microlayer structure, water sorption, and water solubility were evaluated. The post-curing method significantly affected all evaluated properties except fracture toughness and 3D microlayer structure, while the printer type significantly affected all evaluated properties except flexural strength and flexural modulus. VHN and DC were significantly higher, and the smoother surface was noticeably obtained when printed by LCD printer and post-cured at an N2 atmosphere. The current results suggested that the post-curing method and the printer type would play a role in the mechanical properties of the evaluated material and that the combination of post-curing at an N2 atmosphere and LCD printer could enhance its mechanical properties and surface smoothness. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of the light intensity of curing and the post-curing duration on the mechanical properties and accuracy of the interim dental material. After designing the specimen, 3D printing was performed, and the light intensity was divided into groups G20, G60, G80, and G120 (corresponding to 1.4–1.6, 2.2–3.0, 3.8–4.4, and 6.4–7.0 mW/cm2, respectively), with no post-curing or 5, 10, or 20 min of post-curing being performed. The flexural properties, Vickers microhardness, degree of conversion (DC), and 3D accuracy were then evaluated. The flexural properties and Vickers microhardness showed a sharp increase at the beginning of the post-curing and then tended to increase gradually as the light intensity and post-curing time increased (p < 0.001). On the other hand, there was no significant difference between groups in the accuracy analysis of a 3D-printed three-unit bridge. These results indicate that the light intensity of the post-curing equipment influences the final mechanical properties of 3D-printed resin and that post-curing can be made more efficient by optimizing the light intensity and post-curing time. [ABSTRACT FROM AUTHOR]

The effect of printing parameters on the surface characteristics of three-dimensional (3D)-printed denture base resins (DBRs) is neglected. Therefore, this study investigated the effect of printing orientation and post-curing time on the surface roughness and hardness. One conventional heat-polymerized (HP) resin and two 3D-printing resins (NextDent (ND) and ASIGA (AS)) were used to fabricate a total of 250-disc (10 × 2.5 mm) specimens. ND and AS specimens were printed with different orientations (0-, 45-, and 90-degree) and each orientation group was subjected to four post-curing times (30, 60, 90, 120 min). Printed specimens were thermo-cycled (10,000 cycles) followed by the measuring of surface roughness (Profilometer (Ra)) and hardness (a Vickers hardness (VH)). ANOVA and post hoc tests were used for data analysis (α = 0.05) at significant levels. AS and ND showed no significant changes in Ra when compared with HP (p ˃ 0.05), except the 45-degree orientation (AS/90 min and AS/120 min) significantly increased surface roughness (p ˂ 0.001). There was no significant difference in Ra with different orientations and post-curing time for both materials AS and ND (p ˃ 0.05). Compared with HP, 3D-printed DBRs showed low VH values (p ˂ 0.001). For AS, 90-degree orientation showed a significant decrease in VH at 60, 90, and 120 min when compared with 0- and 45-degree orientation (p ˂ 0.001), while ND showed no significant difference in VH with different printing orientations (p ˃ 0.05). The VH of AS and ND improved when increasing post-curing time to 120 min (p ˂ 0.001), and the printing orientations and post-curing time did not affect the Ra of 3D-printed DBRs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of four oxime esters is studied here as Type I photoinitiators for high performance systems. • Some of these oxime esters can outperformed benchmark photoinitiators. • The oxime esters were tested in 3D-inkjet printing applications, displaying highly promising results. • These oxime esters exhibit a dual-curing behavior, especially interesting for thermal post-curing treatment. Material jetting technology is emerging as a prominent technique within the additive manufacturing domain for printing multi-material objects. Despite its various advantages, including high printing resolution, oxygen inhibition remains the main issue for UV-curable materials. Oxime esters are interesting photoinitiators for this application due to their ability to undergo a photocleavage reaction followed by decarboxylation, limiting the diffusion of oxygen. A series of four commercially available oxime esters were studied as Type I photoinitiators, with the photoinitiating ability and photochemical properties of two of them never having been investigated before. Initially, their UV–visible absorption properties were studied, revealing significant absorption up to 420 nm. Photopolymerization kinetic studies indicate that the oxime esters can outperformed benchmark photoinitiators such as phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) by reaching around 80 % of double bond conversion in 12 µm layer under air (for O-16) against 60 % for BAPO under the same conditions. Finally, the oxime esters were tested in 3D-inkjet printing applications, displaying highly promising results with tack-free surfaces. [ABSTRACT FROM AUTHOR]

Background. Post-cured composite resins exhibit improvements in physical and mechanical properties due to additional polymerization conversion. However, the post-curing techniques might influence the color stability of composite resin materials. Thus, this study evaluated the color stability of a nanofilled composite resin (Filtek Z350 XT - 3M ESPE) subjected to different post-curing techniques. Methods. Sixty samples (color A2) were randomly allocated to six experimental groups (n=10): G1: photoactivation (P) (control); G2: P + microwave oven with distilled water; G3: P + microwave oven without distilled water; G4: P + conventional oven; G5: P + dry-heat sterilizer; G6: P + steam autoclave. All the groups were stored in distilled water for 60 days and immersed daily in 5 mL of a coffee solution for 3 minutes. The color readings (CIEL*a*b* system) were performed at two different time intervals, initially and after 60 days, in a reflectance spectrophotometer (UV-2600; Shimadzu). The colorimetric readings were performed using the Color Analysis software (CIEL*a*b* system). Results. Group G6 exhibited significantly low values of total color change (ΔE=13.16). The control (ΔE=15.32) and G5 (ΔE=15.49) groups exhibited intermediate values, with no difference between them. In turn, the groups in which the resin was heated in a microwave (G2 ΔE=18.55 and G3 ΔE=19.45) exhibited the most significant color changes (one-way ANOVA and Tukey test, P≤0.05). Conclusion. Steam autoclave post-polymerization increased the color stability of the nanofilled resin subjected to artificial aging and coffee immersion.

Projection stereolithography (SLA) is a layer-by-layer 3D printing technique used to create complex structures and intricate geometries with high accuracy and surface finish. The final mechanical properties of any SLA printed parts are highly dependent on the process parameters and post-cure process. Proper post-curing helps cross-linking the unreacted double bond remaining after the printing and thereby enhance the mechanical strength. In this study, the impact of process parameters such as infill density, exposure time, and layer height on the tensile strength of Phrozen Beige low-irritation resin was investigated first. Maximum tensile strength of 25.792 MPa was attained at 100% infill volume of a layer thickness of 30 μm for an exposure time of 8 s. The effect of post-curing time and temperature on the ultimate tensile strength was evaluated. Phrozen Beige resin demonstrated an increase of 33.56% after 1 hour of post-curing at 25°C. Phrozen Aqua-Gray 4K resin exhibited an improvement of 44.57% after 2 h of post-curing at 25°C. Maximum tensile strength and faster achievement of completely cured state occurred at a higher post-curing temperature at the heat deflection temperature due to the acceleration of cross-linking of uncured photopolymers. [ABSTRACT FROM AUTHOR]

This endeavour also entails developing novel materials for composites that are superior to existing composites. Lapox L-12 resin, E glass fibre material, and cerium oxide, which are the rare earth material family member in the periodic table. The combination of these materials was utilised to investigate the wear loss, and surface roughness in a dry sliding wear in two conditions: with and without post-curing (at 100oC for 60 minutes) with process parameters such as percentage of filler material, normal load and sliding speed. The experiments were planned according to L16 orthogonal array based on Taguchi design. Results reveal that wear loss and surface roughness is minimum in post-cured glass fiber reinforced polymer (GFRP) composites compoared to without post-cured specimens. The optimum process parameters level for minimum wear loss of post-cured GFRP composites, optimum process parameters are percentage of filler material is 20%, load is 15N and sliding speed is 0.25 m/s. [ABSTRACT FROM AUTHOR]

The design and fabrication of engineering structures require an excellent understanding of loads experienced by these members, the different weather conditions under which they operate, and their effect on operational life and fuel efficiency. Engineers are continuously challenged to find ways of enhancing these structures' operation life and reduce the weight; this demand led to the development of composite materials. This paper's objective was to develop a composite with a high temperature-to-weight ratio and testing their mechanical strength and transition temperature. Therefore, in this paper, glass fiber reinforced composite was developed using 4, 4 bismaleimidodiphenylmethane (BMPM), O, odiallyl bisphenol A (DABA) as resin, and dimethyl formamide (DMF) as a solvent to evaluate their applicability at the higher temperature. Glass-BMPM /DABA-PMC Laminates were fabricated in this regard. The composites were evaluated at variable curing temperatures ranging from 180 to 220 °C. The glass transition temperature of the developed composite was determined to assess its workability at the higher temperature. The mechanical properties like tensile, flexural, and fatigue strength of the developed composite were determined to evaluate its compatibility at the higher temperature. The glass transition temperature increased from 217 to 243 °C after curing the composite between 180 and 220 °C. The ultimate tensile stress was observed at 340 ± 30 MPa after curing. The flexural stress of Glass BMPM was 276 MPa, before curing and 325 MPa after curing. The increased transition temperature and improved mechanical properties of the composite with curing temperatures confirmed its workability at higher temperatures. [ABSTRACT FROM AUTHOR]

Purpose. This study aims to compare the volumetric change, degree of conversion (DOC), and cytotoxicity of 3D-printed restorations post-cured under three different conditions. Materials and Methods. 3D-printed interim restorations were post-cured under three different conditions and systems: 5 min, 30 min, and 24 h. Three-unit and six-unit fixed dental prostheses (n = 30 for each case) were printed; ten specimens from each group were post-cured and then scanned to compare their volumetric changes. Root-mean-squared (RMS) values of the data were acquired by superimposing the scanned files with original files. Thirty disk-shaped specimens were printed to evaluate the DOC ratio. Fourier transform infrared spectroscopy was used to compare the DOCs of 10 specimens from each group. Human gingival fibroblasts were used to measure the cell viability of every specimen (n = 7). The data from this experiment were employed for one-way analysis of variance and Tukey's post-hoc comparisons. Results. Differences between the three-unit restorations were statistically insignificant, regardless of the post-curing conditions. However, for the six-unit restorations, a high RMS value was acquired when the post-curing duration was 30 min. The average DOC was approximately 56 - 62%; the difference between each group was statistically insignificant. All the groups exhibited cell viability greater than 70%, rendering them clinically acceptable. Conclusion. The post-curing conditions influenced the volume when the length of the restoration was increased. However, this deviation was found to be clinically acceptable. Additionally, postcuring did not significantly influence the DOC and cytotoxicity of the restorations. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of different post-curing light intensities on the trueness, compressive strength, and resin polymerization of 3D-printed 3-unit fixed dental prostheses (FPD)., Materials and Methods: A total of 60 specimens were prepared to support a 3-unit FDP with a deep chamfer marginal design, utilizing computer-aided design and computer-aided manufacturing (CAD-CAM) technology. Light-polymerizing FDP resin with varying light intensities (105, 210, 420, and 840 mW/cm 2 ) was employed for 10 min. Subsequently, trueness assessment, fracture load testing, scanning electron microscopy (SEM) surface examination, and Fourier-Transform Infrared (FTIR) analysis were conducted. A one-way analysis of variance (ANOVA) was performed to ascertain the differences between the experimental groups (p < 0.05)., Results: The group exposed to 210 mW/cm 2 showed the highest trueness (57.6 ± 2.1 µm), while the 840 mW/cm 2 group had the highest deviation (79.3 ± 2.7 µm) (p < 0.001). Significant differences in fracture resistance were found between groups (p < 0.001), with mean fracture strengths of 1149.77 ± 67.81 N, 1264.92 ± 39.06 N, 1331.34 ± 53.62 N, and 1439.93 ± 34.58 N for light intensities of 105, 210, 420, and 840 mW/cm 2 , respectively (p < 0.001). The resin polymerization analysis shows a peak intensity surge at 3579 cm -1 for O-H and C-H stretching vibrations, except in samples exposed to 105 mw/cm 2 light, with the lowest peak at 2890 cm -1 . The performance of resin polymerization is most significant under the condition of 840 mW/cm 2 ., Conclusion: The light intensity of 210 mW/cm 2 exhibited the highest trueness, while the 840 mW/cm 2 group showed the highest deviation. However, the light intensity of 840 mW/cm 2 demonstrated the highest compressive strength. Furthermore, polymerization occurred at all post-treatment light intensities except 105 mW/cm 2 . These findings indicate that while low-intensity usage offers greater trueness, high-intensity usage provides better compressive strength and polymerization. Therefore, 210 mW/cm 2 could be the recommended solution for post-curing., (© 2024 by the American College of Prosthodontists.)

Background. Post-cured composite resins exhibit improvements in physical and mechanical properties due to additional polymerization conversion. However, the post-curing techniques might influence the color stability of composite resin materials. Thus, this study evaluated the color stability of a nanofilled composite resin (Filtek Z350 XT - 3M ESPE) subjected to different post-curing techniques. Methods. Sixty samples (color A2) were randomly allocated to six experimental groups (n=10): G1: photoactivation (P) (control); G2: P + microwave oven with distilled water; G3: P + microwave oven without distilled water; G4: P + conventional oven; G5: P + dry-heat sterilizer; G6: P + steam autoclave. All the groups were stored in distilled water for 60 days and immersed daily in 5 mL of a coffee solution for 3 minutes. The color readings (CIEL*a*b* system) were performed at two different time intervals, initially and after 60 days, in a reflectance spectrophotometer (UV-2600; Shimadzu). The colorimetric readings were performed using the Color Analysis software (CIEL*a*b* system). Results. Group G6 exhibited significantly low values of total color change (ΔE=13.16). The control (ΔE=15.32) and G5 (ΔE=15.49) groups exhibited intermediate values, with no difference between them. In turn, the groups in which the resin was heated in a microwave (G2 ΔE=18.55 and G3 ΔE=19.45) exhibited the most significant color changes (one-way ANOVA and Tukey test, P≤0.05). Conclusion. Steam autoclave post-polymerization increased the color stability of the nanofilled resin subjected to artificial aging and coffee immersion. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To investigate the impact of 3D print material, build direction, post-curing, and artificial aging on fracture load of fixed dental prostheses (FDPs). Materials and methods: Three-unit FDPs were 3D-printed using experimental resin (EXP), NextDent C&B (CB), Freeprint temp (FT), and 3Delta temp (DT). In the first part, the impacts of build direction and artificial aging were tested. FDPs were manufactured with their long-axis positioned either occlusal, buccal, or distal to the printer's platform. Fracture load was measured after artificial aging (H2O: 21 days, 37 °C). In the second part, the impact of post-curing was tested. FDPs were post-cured using Labolight DUO, Otoflash G171, and LC-3DPrint Box. While the positive control group was milled from TelioCAD (TC), the negative control group was fabricated from a conventional interim material Luxatemp (LT). The measured initial fracture loads were compared with those after artificial aging. Each subgroup contained 15 specimens. Data were analyzed using Kolmogorov-Smirnov test, one-way ANOVA followed by Scheffé post hoc test, t test, Kruskal-Wallis test, and Mann-Whitney U test (p < 0.05). The univariate ANOVA with partial eta squared (ηP2) was used to analyze the impact of test parameters on fracture load. Results: Specimens manufactured with their long-axis positioned distal to the printer's platform showed higher fracture load than occlusal ones (p = 0.049). The highest values were observed for CB, followed by DT (p < 0.001). EXP showed the lowest values, followed by FT (p < 0.001). After artificial aging, a decrease of fracture load for EXP (p < 0.001) and DT (p < 0.001) was observed. The highest impact on values was exerted by interactions between 3D print material and post-curing unit (ηP2 = 0.233, p < 0.001), followed by the 3D print material (ηP2 = 0.219, p < 0.001) and curing device (ηP2 = 0.108, p < 0.001). Conclusions: Build direction, post-curing, artificial aging, and material have an impact on the mechanical stability of printed FDPs. Clinical relevance: The correct post-curing strategy is mandatory to ensure mechanical stability of 3D-printed FDPs. Additively manufactured FDPs are more prone to artificial aging than conventionally fabricated ones. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Computerized Dentistry is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High performance gelatin-based biocompatible hybrid hydrogels are developed using functionalized polyethylene glycol as a cross-linker in presence of chitosan or hydroxyethyl cellulose. Tensile test shows robust and tunable mechanical properties and reveals non-linear and J-shaped stress-strain curves similar to those found for native extracellular matrix. Degradation study demonstrates that the mass loss and change in mechanical properties are dependent on hydrogel composition and cross-linking density. Structural features of the hydrogels are confirmed by infrared spectroscopy. A preliminary biological evaluation is carried out using rat myoblasts and human fibroblasts cell lines. The results show that all hydrogels allow cell adhesion and proliferation during four days culture, hence, they might have a great potential for use in the biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a hard epoxy material based on a mature curing system was prepared. The addition of 2 mol% transesterification catalyst showed the best strengthening effect, as well as satisfactory thermal welding and repairing property. With rheological experiment, a double stress relaxation theory was proposed and a multi-element model was established. Among the two relaxation processes, one was caused by small units in response to external force, the other was caused by chain segments sped up by the transesterification, and the whole relaxation was the superposition of these two parts. A further post-curing process caused by catalyst was found by the DSC analysis. It was the further post-curing process that resulted in the formation of inactive crosslinks without relaxation ability. Therefore, this repairable hard epoxy material still had a service life and couldn't be repaired infinitely. However, it provides a new way to prepare repairable hard materials. Graphical abstract Image 1 Highlights • The system is a hard material unlike normal vitrimer. • An interesting further post curing effect caused by catalyst is found and explained. • A double relaxation theory is proposed and the corresponding model is also establish. [ABSTRACT FROM AUTHOR]

Objective It is known that after light-initiated free radical polymerization of a dimethacrylate monomer system, the curing continues for some period of time after the curing light emission has stopped (so-called delayed post-curing stage, DPCS). It is also known that during free radical polymerization, the presence of oxygen effectively inhibits polymerization of monomers. However, less is known of the influence of oxygen inhibition of light initiated polymerization during the DPCS. The aim of this study was to determine some polymerization related properties of a resin system during the DPCS. Methods Monomer systems of BisGMA-TEGDMA (60/40%) with light sensitive initiator-activator (camphorquinone-amine) system were polymerized by light-initiation (wavelength average 430–480 nm) with a radiation intensity of 1200 mW/mm 2 for 20 s on the ATR sensor of the fourier transform infrared (FTIR) spectrometer. After light curing, the samples were divided into two groups: the DPCS stage was allowed to continue in air (O 2 -exposed group) or the samples were protected from the direct effect of air (O 2 -protected group). The degree of monomer conversion (DC%) was monitored from the sample surface up to 360 min from both groups of samples (n = 6). Sample surfaces were additionally analyzed for surface microhardness (VHN) at four time-points corresponding to time-points of the DC% measurement (n = 6). Results After ending the light-curing of 20 s, i.e. during the DPCS, the DC% still increased from 50% to 65% in the O 2 -protected group, whereas no increase was seen in the O 2 -exposed group. Surface microhardness increased from 2.99 to 9.10 VHN of the O 2 -protected samples and to 4.80 of the O 2 -exposed samples during a 6-h period. Surface microhardness differed significantly between the groups (p < 0.005). There was significant correlation between the microhardness and DPCS (O 2 -protected r = 0.950; O 2 -exposed r = 0.940, p < 0.001). A correlation was also found between degree of conversion values and DPCS time (O 2 -protected r = 0.941; for O 2 -exposed r = 0.780, p < 0.001). Significance The results of this study suggested that O 2 -inhibition of free radical polymerization of dimethacrylate resin occurred after ending the curing light emission. This correlated with a lower surface microhardness of the polymer when the DPCS continued under air-exposure. [ABSTRACT FROM AUTHOR]

Objective: This study evaluated the variation of conversion degree (DC) in the 12 hours following initial photoactivation of a low-shrinkage composite resin (Venus Diamond). Material and Methods: The conversion degree was monitored for 12 hours using Attenuated Total Reflection (ATR) F-TIR Spectroscopy. The composite was placed in 1 or 2 mm rings and cured for 10 or 20 seconds with a LED lamp. ATR spectra were acquired from the bottom surface of each sample immediately after the initial photoactivation (P=0), 30 minutes (P=0.5) and 12 hours after photoactivation (P=12) in order to obtain the DC progression during the post-curing period. Interactions between thickness (T), irradiation time (I) and post-curing (P) on the DC were calculated through ANOVA testing. Results: All the first order interactions were statistically significant, with the exception of the T-P interaction. Furthermore, the shift from P=0 to P=0.5 had a statistically higher influence than the shift from P=0.5 to P=12. The post-curing period played a fundamental role in reaching higher DC values with the low-shrinkage composite resin tested in this study. Moreover, both the irradiation time and the composite thickness strongly influenced the DC. Conclusions: Increased irradiation time may be useful in obtaining a high conversion degree (DC) with a low-shrinkage nano-hybrid composite resin, particularly with 2 mm composite layers.