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Objectives To determine the color stability and microhardness of three bulk‐fill composites with different polymerization characteristics, after immersion in four different solutions. Materials and Methods Color measurements of three bulk fill (Viscalor (VIS), Tetric PowerFill (TPF), Fill Up! (FUP)) and a microhyrid composite resin (G‐aenial posterior [GCP]) were performed after polymerization. The specimens were immersed in coffee, cola, red wine and distilled water. Discolorations were recorded after 24 h (T1), 10 days (T2) and 30 days (T3) of immersion. ΔE (CIEDE2000) values were calculated. Vickers microhardness (VHN) was measured from top and bottom surfaces at T0 and T3. Data was analyzed with Two‐way ANOVA, One‐way ANOVA and Tukey post hoc tests. Results The highest discoloration was seen in wine and the lowest in distilled water and cola. At T3, there was no difference in distilled water groups, while the statistically highest ΔE00 were obtained in TPF and GCP in coffee, cola and wine. VIS groups had the highest VHN values at T0 and T3 in all solutions. Conclusions Samples immersed in coffee and wine showed discoloration beyond clinically acceptable limits. After 30 days, discoloration occurred in all materials immersed in all solutions. At T3, VIS microhardness generally decreased, while TPF did not. Clinical Significance After 30 days, all bulk‐fill composites immersed in distilled water, coffee and wine showed clinically unacceptable ΔE00.

OBJECTIVE: The aim of this study was to investigate the effect of preheating three bulk-fill and one conventional composite resin on the Vickers microhardness and depth of cure of these composites. METHODS: In this study, three bulk-fill composites-SDR Plus (SDR), Estelite BULK FILL Flow (EST), Admira® Fusion x-tra (AFX), and one conventional composite resin G-ænial POSTERIOR (GP) were used as the control group. The samples were obtained at room temperature (24°C) and at 55°C in T2 mode after being placed in a heating device for 10 minutes. The samples were divided into eight groups (n=10) according to the type of material and heating process that was utilized (preheated and nonheated). All samples were tested with a Vickers microhardness (VHN) tester on the bottom and top surfaces. The first measurements were obtained at baseline; the second set of measurements was performed after the samples were stored in distilled water at 37°C for 24 hours. The depth of cure was calculated using a bottom/top hardness ratio of measurements. Statistical analysis was performed utilizing the SPSS V23 and Shapiro-Wilk tests. Lastly, the Duncan test was used for multiple comparisons (p<0.05). RESULTS: While the VHN increased after the preheating procedure in bulk-fill composites, it decreased in GP. There was no difference between the baseline and the 24-hour VHN values in SDR and GP. After 24 hours, while the VHN of EST increased, the VHN of AFX decreased. There was no difference between the hardness ratios of the AFX and EST samples (p<0.001) and hardness ratios were greater than GP and SDR. CONCLUSION: When comparing the baseline and the 24-hour values, the VHN depended on the type of materials. Sufficient curing depth was obtained in all groups with a thickness of 2mm.

The purpose of this study was to compare the effect of different disinfection protocols of dentin on bond strength of an MDP-containing universal adhesive. Twelve extracted mandibular third molars were separated horizontally at the mid-coronal of crown to get smooth and sound dentin surfaces using low-speed diamond saw. The teeth were randomly fallen into four groups: chlorhexidine (CHX), ozone, Er,Cr:YSGG laser irradiation (LASER) and no treatment (control). After cavity disinfection application, a universal adhesive (G-Premio Bond) was applied to the surface of dentin according to self-etch mode as instructed by the manufacturer. After incremental built-up of composite resin (Charisma Smart), the specimens were immersed in distilled water at 37°C for 24h. Dentin/composite beams with 1 mm² cross sectional area were produced and micro-tensile bond strength (µTBS) was applied on these beams (n=20). Failure mods were determined under a stereomicroscope at ×40. The resin penetration of samples stained with Rhodamine B fluorochrome dye was examined with a confocal laser scanning microscope. Statistical analysis was performed with SPSS-22. Test results were analyzed using One-way Anova and Tukey HSD Post-Hoc tests (p<0.05). The µTBS value of control (35.13±6.20) was the highest statistically among the groups (p<0.05). The lowest µTBS were obtained by LASER (19.25±4.66) and CHX (23.07±7.01). There was no significant difference between CHX and LASER, and between CHX and ozone (p>0.5). All applications of cavity disinfection procedures decreased the µTBS of the resin-dentin interface.

This study aimed to examine the surface characteristics of low shrinkage composites and adhesion of Streptococcus mutans and Streptococcus mitis to these materials.Control material (glass) and three low shrinkage composites (Charisma Diamond, Kalore GC, Beatiful II LS) were used. After polishing procedure was applied to composite specimens, surface roughness (SR), surface free energy (SFE), and contact angle measurements were performed. Surfaces of composite were analyzed using scanning electron microscope and energy-dispersive X-ray spectroscopy. After pellicle formation with artificial saliva, S. mutans and S. mitis biofilms were incubated in 5% CO 2 for 24 h at 37 C and were analyzed using confocal laser scanning microscopy. The lowest SR and highest SFE values were found in the control group. While the contact angle of control was statistically lower than composites, statistically difference was not found between composite groups. S. mutans adhesion of composites was significantly lower than control group, but there was no significant difference between composites. S. mitis adhesion of all groups was statistically similar. SR did not affect the S. mutans and S. mitis adhesion. Less adherence of S. mutans to low shrinkage composites was associated with low SFE and high contact angle values.Even though the highest SR was observed in the Charisma Diamond, no difference was found between the composites in terms of bacterial adhesion.