To compare the translucency and masking of zirconia-reinforced lithium silicate with lithium disilicate glass-ceramic and hybrid composite. One hundred and twenty disc-shaped specimens were fabricated using Enamic, Celtra Duo, IPS E.max CAD, and Suprinity. Twelve groups were prepared according to material type and thickness (0.5, 1.0, and 1.5 mm). The specimens were tested over five substrates: composite resin-A3.5 shade (A3.5 control group), zirconia-A1 shade (ZR), nickel–chromium alloy (NC), black (B), and white (W). A spectrophotometer operating at wavelengths from 360 to 750 nm and a view-area size of 9.53 mm was used for color measurement. Mean color difference values (ΔΕ) were found to be lowest in Suprinity and highest in IPS E.max. CAD. Color difference values were significantly related to substrate shade. The A3.5 substrate revealed the significantly lowest ΔΕ values of all the substrates (P = 0.05). Regarding the translucency parameters for ceramics of different thicknesses, a significant difference was observed among all groups except in Suprinity. Different ceramic types with different thicknesses and substrate strongly affect translucency and masking. Fabricating durable aesthetic restorations that also meets patients’ expectations is among the most significant challenges in dentistry. With high demand for more natural restorations, ceramics based on computer-aided design (CAD) and computer-aided manufacture (CAM) became popular and exhibited excellent results. However, various factors such as abutment shade, luting cement color, and ceramic type, thickness, and translucency may affect the prosthesis shade. The objective of this study was to evaluate the effects of these factors on the final shades of CAD/CAM-based ceramic restorations.

The objectives of this study were to evaluate the shear bond strength (SBS) of a resin composite (RC) and a resin-modified glass ionomer (RMGI) to four different bioceramic materials and to compare the effects of the immediate vs. delayed placement of restoration on the SBS. A total of 160 Teflon blocks and 40 blocks/material, were randomly filled with one of the bioceramic materials (NeoPUTTY^®, NeoMTA2^®, TotalFill^® BC RRM™ Fast Set Putty, and ProRoot^® MTA). The restoration was performed immediately or in a delayed time frame (after 7 days) using a Filtek™ Z350 XT Flowable composite (bonded to the bioceramic materials using Single bond universal 3M) or GC Fuji II LC^® RMGI. The SBS test was performed at a crosshead speed of 1 mm/min, and the failure mode was evaluated under a digital microscope by one blinded examiner. One-way analysis of variance (ANOVA) with the Games–Howell post hoc test was used to compare the mean SBS between the groups. The mean SBS of the bioceramic materials to RC was significantly higher than to RMGI except for ProRoot MTA (p-value 0.65). The SBS values to RC were as follows: ProRoot MTA (7.64 MPa); NeoMTA2 (8.57 MPa) which was significantly higher than both NeoPUTTY (4.04 MPa) and TotalFill^® BC RRM™ Fast Set Putty (4.38 MPa). For RMGI groups, ProRoot MTA showed the highest SBS (7.18 MPa), followed by NeoMTA2 (4.15 MPa), NeoPUTTY (1.62 MPa), and TotalFill^® BC RRM™ Fast Set Putty (1.54 MPa). The delayed timing restoration showed a significantly higher SBS than the immediate, except for the immediate RMGI restoration with MTA. To conclude, the SBS of RC to the bioceramic materials was significantly higher than RMGI, except for ProRoot MTA. Both restorative materials had a significantly higher SBS to the MTA groups in comparison to premixed bioceramics. Delayed RC restoration had a higher SBS than immediate restoration. Similarly, delayed RMGI restoration had a higher SBS than immediate restoration with premixed bioceramic but not with MTA.

Background: The adoption of 3D printing in restorative dentistry is increasing, with the post-curing duration of a material being identified as a key determinant of its performance. This study evaluated the effect of the post-polymerization time on the flexural strength (FS) and Vickers microhardness (VHN) of a 3D-printed composite. Methods: Specimens of Formlabs Permanent Crown Resin were 3D printed and divided into four groups according to their post-curing time: no post-curing time and 20, 40, and 60 min post-curing time. Flexural strength testing was carried out using a three-point test of 40 bar-shaped specimens (n = 10/group), followed by fractography observations under a scanning electron microscope (SEM). Vicker microhardness testing was also conducted with 40 disk-shaped specimens (n = 10/group). The inorganic filler content was measured using the ash method, and the filler morphology was characterized under an SEM. Statistical analyses were performed using adjusted ANOVA and regression tests. Results: The highest median FS values were observed at 40 min post-curing (133.07 MPa), with significant differences across all groups (p < 0.0001). The highest median VHN values were found at 40 min post-curing (32.09 VHN), with significant differences between groups (p < 0.0001). A significant positive correlation (rho = 0.7488; p < 0.0001) was found between the flexural strength and Vickers hardness with changing post-curing durations. The 3D resin composite had an average filler content of 66.82% based on weight. Conclusions: With the limitation of the current in vitro setup, a post-polymerization time of 40 min was shown to lead to the best material performance. The post-printing polymerization time significantly affects the Vickers hardness and FS of 3D Formlabs Permanent Crown Resin. Further research should explore the effects of different resin compositions, clinical conditions, and curing protocols to enhance the general applicability of these findings. Clinical implications: Extending the post-printing polymerization time does not inherently result in improved material properties. A considered adjustment of the post-curing time can significantly impact the mechanical properties of a 3D-printed composite.

This study evaluated the effects of the sintering temperature on Vickers microhardness and three-point flexural strength values of two multi-layered zirconia materials. Multi-layered zirconia systems with four distinct layers were selected: DD cube ONE ML (4Y-TZP) and DD cubeX² ML (5Y-TZP). In total, 96 plate-shaped A2-shade specimens were obtained using individual layers of these two zirconia materials. The individual layers were then divided equally into batches with three different sintering temperatures (1300, 1450, and 1600 °C), and the Vickers microhardness was assessed. Another group of 72 bar-shaped specimens was prepared from the same materials. These were similarly divided into three different sintering temperatures, and the flexural strength was assessed. SEM was used to conduct fractographic analyses. The data were analyzed using SPSS 24.0 software with a p-value < 0.05. The microhardness and flexural strength of 4Y-TZP were higher than those of the 5Y-TZP at all the sintering temperatures. A significant difference was found in the microhardness and flexural strength values between groups sintered at different sintering temperatures (p < 0.05). The highest microhardness and flexural strength values were found at 1450 °C (p < 0.05). The microhardness values of different layers were not significantly different (p > 0.05). The sintering temperature and type of ceramic material significantly affected the microhardness and flexural strength. However, the layers did not significantly affect the microhardness.

This study evaluated the effect of post-printing polymerization time on residual monomer elution and water sorption in a 3D-printed resin composite. Eighty samples were fabricated and assigned to four groups based on post-curing duration: 0, 20, 40, and 60 min. Each group was subdivided according to two storage conditions (distilled water and 75% ethanol–water solution), and evaluated at 1 and 7 days. High-performance liquid chromatography (HPLC) quantified eluted monomers. Additionally, 40 specimens underwent a 4-month sorption/desorption cycle for water sorption and solubility assessment. Data were statistically analyzed using kernel regression (monomer data) and Welch ANOVA (water sorption and solubility) at a significance level of p < 0.05. BisEMA was the only monomer detected, with significantly higher elution recorded in ethanol-based storage. Increasing post-curing time notably reduced both monomer release and water sorption/solubility (p < 0.001); however, the optimal results were observed at 40 min post-curing. These findings suggest that extending post-curing beyond an optimal threshold does not further improve composite properties, underscoring the importance of identifying precise curing parameters in order to enhance durability and material performance.

Objective: To measure the flexural strength (FS) of bulk-fill resin composites and assess their long-term water absorption and solubility properties with and without the inclusion of short glass fibres. Methods: One resin composite, everX Flow with fibres, and four commercially available bulk-fill composites without fibres, namely, PALFIQUE, Activa, SDR Plus, and Filtek Bulk Fill One, were tested. Six specimens (2 × 2 × 25 mm) were fabricated for each material and stored in water for 1 day and 30 days to measure the flexural strength using a three-point bending test. To evaluate water absorption and solubility, circular disks measuring 15 × 2 mm (n = 5) were immersed in water for 60 days, and their weights were recorded periodically. After 60 days, the specimens were dried for an additional 21 days to determine solubility. Results: Flexural strength values ranged from 101.7 to 149.1 MPa. Significant distinctions were observed among the resin composites at the onset of the study (p < 0.05). The highest FS value was identified in everX Flow, while ACT exhibited the lowest (p < 0.05). However, the flexural strength values exhibited a significant decrease with increased storage time (p < 0.05), except for ACT, which demonstrated a noteworthy increase. Concerning water absorption and solubility, ACT displayed the highest absorption, while the range of solubility varied from −0.88 to 5.8 μg/mm³. ACT also had the highest solubility, whereas everX Flow exhibited negative solubility. Significance: The addition of short fibres, along with potential differences in matrix composition, enhanced the flexural strength of everX Flow. However, the substantial reduction in flexural strength observed in everX Flow and SDR following exposure to water corroborates the manufacturers’ recommendation to apply a conventional resin composite cap on these materials.