Objectives This study was aimed to determine the effects of modeling resins on the surface microhardness of composites. Materials and Methods Six resin-based composites (Charisma Smart, Estellite Asteria, CeramX-One SphereTEC, Admira Fusion, Filtek Ultimate, and Clearfil Majesty Es-2) and three wetting agents (Modeling Liquid, Composite Primer, and Modeling Resin) were investigated. In all, 240 specimens were prepared, and wetting agents were applied prior to light curing in the experimental groups. After 24 hours, specimens were polished and Vickers microhardness (VHN) values were measured. Statistical Analysis Shapiro–Wilk and two-way analysis of variance (ANOVA) were used for analyses (p < 0.05). Results Both modeling resin and composites were determined to be effective factors (p < 0.001). The control group showed the highest VHN (70.37 ± 7.94), followed by Modeling Liquid (64.68 ± 12.07), Composite Primer (59.84 ± 6.33), and Modeling Resin (58 ± 3.52b; p < 0.001). Filtek Ultimate showed the highest VHN (76.62 ± 9.78c), whereas Charisma Smart (58.87 ± 7.95), and Clearfil Majesty (67.27 ± 2.58) showed the lowest (p < 0.001). Clearfil Majesty–Modeling Liquid (46.62 ± 5.33) and Charisma Smart–Composite Primer (50.81 ± 0.39) combinations showed the lowest VHN, whereas Filtek Ultimate–control (87.15 ± 2.12) and Filtek Ultimate–Modeling Liquid (84.24 ± 3.11) showed the highest (p < 0.001). Conclusion All tested modeling resins decreased VHN value, and the amount of reduction varied among composites and wetting agents. It might be safer not to use wetting agents unless they are necessary.

The aim of this study is to determine the cytotoxicity of three different nano composite resins (CRs) on human gingival fibroblast (hGF) and periodontal ligament fibroblast (hPDLF) cell lines. These CRs selected were nanohybrid organic monomer-based Admira Fusion (AF), nanohybrid Bis-(acryloyloxymethyl) tricyclo [5.2.1.0.sup.2,6] decane-based Charisma Topaz (CT), and supra nano filled resin-based Estelite Quick Sigma (EQS). MTT assay was performed to assess the cytotoxicity of CRs at 24 h and one week. AF and EQS applied on hGF cells at 24 h and one week demonstrated similar cytotoxic outcomes. Cytotoxicity of CT on hGF cells at one week was higher than 24 h (p = 0.04). Cytotoxicity of CT on hGF cells was higher at 24 h (p = 0.002) and one week (p = 0.009) compared to control. All composites showed higher cytotoxicity on hPDLF cells at one week than the 24 h (AF; p = 0.02, CT; p = 0.02, EQS; p = 0.04). AF and EQS demonstrated lower cytotoxicity on hPDLF cells than the control group at 24 h (AF; p = 0.01, EQS; p = 0.001). CT was found more cytotoxic on hPDLF cells than the control (p = 0.01) and EQS group (p = 0.008) at one week. The cytotoxicity of CRs on hGF and hPDLF cells vary, according to the type of composites, cell types, and exposure time.

Single-shade universal resin composites (SsURC) are preferred in clinical practice to reduce time for shade selection and obtain good esthetic results. In this study, the static mechanical properties of seven new SsURCs were investigated, their spectral analyzes were performed and scanning electron microscopy (SEM) evaluations were presented. Charisma Diamond One/DO, Admira Fusion x-tra/AFX, Omnichroma/OC, OptiShade/OS, Essentia Universal/EU, Zenchroma/ZC, Vittra APS Unique/VU were used in a three-point bending test to determine flexural strength (FS) and elastic modulus (EM); Vickers micro-hardness (VHN) and hardness-ratio (HR) were performed with a micro-hardness tester from top/bottom after 24-h/15-days of storage in distilled water at 37°C (±1 °C). The degree of conversion (DC) was assessed by using Fourier transform infrared spectroscopy (FTIR). The structure of the resin matrix and filler content were assessed by SEM. Data were analyzed using IBM SPSS V23 and the R program and the significance level was taken as p < 0.05. The main effect of the tested SsURCs was found to be statistically significant on FS, EM, VHN, and DC values (p < 0.001). Bis-GMA free SsURCs (AFX, DO, VU) showed better DC and HR except for OC. All seven tested SsURCs conform to the requirements of ISO standards for dental resin composites for all tested categories.

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Objectives: Lately, computer-aided design (CAD) computeraided manufacturing (CAM) systems with simplified procedures for indirect restoration have gained rapid improvements and commenced to be used in daily practice of dental clinicians. The aim of this pilot in vitro study was to analyze the bonding efficiency and observation of the failure mode of hybrid ceramic CAD/CAM block materials after termo-cycling, with different immediate dentin sealing (IDS) techniques.Materials and Methods: Eighteen freshly extracted human molars were selected, and mounted with acrylic resin, fixed the root up to 2.0 mm under the cementoenamel junction. Standardized, flat, nonretentive, midcoronal dentin surfaces were prepared. Using the stratified random sampling process, all teeth (N=18) were divided into groups of three by approximately similar sizes; afterwards, these teeth were randomly distributed into the groups 1, 2 and 3 (n = 6). The specimens from groups 2 and 3 received IDS, whereas delayed dentin sealing was carried out for specimens of control group (Group 1). For IDS materials, universal adhesive system G-Premio Bond (GC, Tokyo, Japan) and highly filled flowable resin composite G-aenial Universal Flo (GC, Tokyo, Japan) were used. All block material specimens were prepared using the cutting instrument (IsoMet 1000; Buehler, USA) and were fitted with a standardized 3x3-mm 3 cubes cutted out of a CAD/CAM block of hybrid ceramic (Cerasmart, GC; Tokyo, Japan). Dual-polymerized resin cement G-CEM Link Force (GC, Tokyo, Japan) was utilized to lute restoration materials for all groups. To test the shear bond strength (SBS) each of the specimens was placed in a jig with 90 o to the vertical plane and tested a universal testing machine (Shimadzu AG-IS; Shimadzu Corp). One-way ANOVA was used to analyze the data of the SBS. Results were evaluated statistically significant for p<0.05.Results: No statistically significant difference revealed by the statistical analysis between Group 1,2 and 3 (p=0,372). This means there is no significant difference in the sealing methods (p>0,05). Bond failure rates showed similar results in all groups, where the most frequent failure pattern detected was 'adhesive type'.Conclusions: Within the limitation of this in vitro pilot study, the following conclusion was drawn: 2 Different IDS procedures tested does not statistically (p<0.05) effect the SBS of hybrid ceramic CAD/CAM material bonded to dentin with G-CEM Link Force.