With the developments in digital dentistry in recent years, subtractive and additive manufacturing and materials have emerged for the production of dental restoration. Novel permanent composite-based restorative materials are also among these materials. Because of their variety and increased use by clinicians, it is also important to know the properties, such as surface roughness and color stability, that are necessary for the longevity of these new materials. This study aimed to investigate the color stability, stainability, and surface roughness (R_a) of additively and subtractively manufactured permanent composite-based restorative materials and compare them with a feldspathic glass ceramic. Two different subtractively manufactured composite-based blocks (Cerasmart 270, Vita Enamic), two different additively manufactured permanent composite-based resins (Crowntec and Permanent Crown Resin), and one feldspathic glass ceramic (Vita Mark II) as a control were compared. A total of 150 specimens were prepared (10 per material for surface roughness and 20 per material for color stability and stainability). The R_a values and the color parameters were measured before and after thermocycling. The specimens of the staining test were then divided into two subgroups and stored for 7 days in distilled water (control) or coffee. The color parameters were remeasured after the storage period. The color differences (∆E₀₀) were evaluated for each measuring range, and these values are interpreted in terms of clinical perceptibility (ΔE₀₀ ≤ 1.30) and clinical acceptability (ΔE₀₀ ≤ 2.25) thresholds. All data were statistically analyzed (α = 0.05). While Vita Enamic exhibited the highest mean R_a, Crowntec showed the lowest mean R_a after thermocycling. Crowntec had the highest mean ΔE₀₀ both after thermocycling and storage in solutions. While Vita Mark II displayed the lowest mean ΔE₀₀ after thermocycling. Cerasmart 270 showed the lowest stainability in coffee. All tested materials showed acceptable surface roughness after thermocycling that was equal to or below the plaque accumulation threshold of 0.2 µm. However, the mean ΔE₀₀ of tested materials were lower than clinical acceptability thresholds, except for Crowntec in all measuring ranges and Vita Enamic immersed in coffee.

Background: The aim of the study was to determine and compare the biaxial flexural strength (BFS) and Vickers hardness (VHN) of additive and subtractive manufactured permanent composite-based restorative materials, before and after thermal aging. Methods: A total of 200 specimens were prepared; 100 disc-shaped specimens (diameter 13 × 1.2 mm) for the BFS test and 100 square specimens (14 × 14 × 2 mm) for the VHN test. The specimens were made from various materials: two subtractive composite-based blocks (Cerasmart 270 [CS], Vita Enamic [VE]), two additive composite-based resins used for two different vat polymerization methods (digital light processing [DLP]; Saremco Print Crowntec [SC] and stereolithography [SLA]; Formlabs Permanent Crown Resin [FP]), and one feldspathic glass-matrix ceramic block (Vita Mark II [VM]) as the control group. Specimens of each material were divided into two subgroups: thermal cycled or non-thermal cycled (n = 10). BFS and VHN tests were performed on all groups. Data were analyzed with two-way ANOVA and post hoc Tukey test (α = 0.05). Results: The type of restorative material used for the specimen had a statistically significant influence on both BFS and VHN values. However, thermal cycling did not affect the BFS and VHN values. After thermal cycling, the results of the BFS test were ranked from best to worst as follows: CS, FP, SC, VE, then VM. For the VHN values, the order from best to worst was as follows: VM, VE, CS, FP, then SC. Conclusions: 3D printed and milled composite groups showed higher BFS than feldspathic ceramics. When the VHN results were examined, it was seen that the 3D resin groups had the lowest VHN values. Furthermore, it was observed that the thermal cycle had no effect on BFS or VHN.

Background: This study compared the impact of thermal cycling on the flexural strength of denture-base materials produced through conventional and digital methods, using both subtractive and additive approaches. Methods: In total, 60 rectangular specimens were fabricated with specific dimensions for flexural strength tests. The dimensions were set according to the International Organization for Standardization (ISO) guideline 20795-1:2013 as 64 × 10 × 3.3 ± 0.2 mm. Specimens from each material group were divided into two subgroups (thermal cycled or nonthermal cycled, n = 10/group). We used distinct methods to produce three different denture-base materials: Ivobase (IB), which is a computer-aided-design/computer-aided-manufacturing-type milled pre-polymerized polymethyl methacrylate resin disc; Formlabs (FL), a 3D-printed denture-base resin; and Meliodent (MD), a conventional heat-polymerized acrylic. Flexural strength tests were performed on half of the samples without a thermal-cycle procedure, and the other half were tested after a thermal cycle. The data were analyzed using a two-way analysis of variance and a post hoc Tukey test (α = 0.05). Results: Based on the results of flexural-strength testing, the ranking was as follows: FL > IB > MD. The effect of thermal aging was statistically significant for the FL and IB bases, but not for the MD base. Conclusions: Digitally produced denture bases exhibited superior flexural strength compared with conventionally manufactured bases. Although thermal cycling reduced flexural strength in all groups, the decrease was not statistically significant in the heat-polymerized acrylic group.

In resins produced with a 3D printer, the printing parameters affect the properties of the restoration produced. This study examined the effect of the printing angle and post-curing time on the optical properties of temporary restorations. A total of 135 disk-shaped Formlabs temporary resins (10 × 2 mm) were produced at three different printing angles (0, 45, and 90 degrees) and post-cured for three different times (20, 40, and 60 min) (n = 15). Color and translucency measurements were taken for each group with a spectrophotometer (VITA Easyshade V). The ΔE values between printing angles and curing times influence each other. The highest color change was observed in the groups produced with a 90° printing angle. Considering the post-curing times, the highest color change was observed in the groups cured for 40 min. Increasing the curing time from 20 to 40 min decreases the translucency, whereas further increasing the curing time does not significantly affect the translucency. In terms of the impact on the translucency caused by the printing angles, 0° exhibited a lower translucency compared to other printing angles. During the 3D printing of temporary prostheses, both printing angles and post-curing times can affect their optical properties.

Introduction Temporary restorations produced with a 3D printer have become very popular recently. There are limited studies in the literature comparing 3D printing and traditionally produced temporary materials. Objectives The aim of this study is to examine the color and roughness changes...