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The aim of this study was to compare color changes, surface roughness and gloss of a microhybrid and nanohybrid composite whitened in a simulated in-office or at-home procedure using 40% hydrogen peroxide or 16% carbamide peroxide, respectively. CIELab coordinates were measured before, during and after treatment using VITA EasyShade V (VITA) and ΔE00 calculated. Surface roughness was measured using a surface roughness tester (SJ210; Mitutoyo). Gloss was measured using a gloss checker (IG-331; Horiba). At-home whitening resulted in ΔE00 of 1.23±0.49 (microhybrid) and 1.01±0.76 (nanohybrid). In-office exposure resulted in ΔE00 of 0.69±0.38 (microhybrid) and 0.72±0.50 (nanohybrid). There were no significant differences in ΔE00, surface roughness and gloss between whitening protocols (p>0.05). Color changes of a microhybrid and nanohybrid composite following simulated in-office or at-home whitening reached CIEDE2000 50:50% perceptibility but not acceptability threshold. Surface roughness and gloss of the microhybrid and nanohybrid composite were not affected by whitening. [ABSTRACT FROM AUTHOR]

Objective: To analyze the effects of factors 'composite,' 'medium,' and 'time' on color, translucency, and sorption/solubility of sculptable universal composites for enamel layering upon immersion in colored beverages. Materials and methods: Disk‐shaped specimens, 10 mm in diameter and 2 mm thick (n = 5/group), of ultrafine, hybrid composite Essentia (GC), microhybrid Gaenial Anterior (GC), nanofilled Filtek Ultimate Enamel and Body (3M ESPE) were immersed in red wine, coffee, or distilled water for 15 days. CIELab color coordinates were measured and CIEDE2000 (∆E00) and Translucency Parameter differences (∆TP00) were calculated. Sorption and solubility were determined according to ISO 4049:2009. Data were analyzed using the analyses of variance and Tukey's post‐hoc test (α = 0.05). Results: Essentia and Gaenial exhibited the lowest and the highest staining‐dependent color differences, with mean ∆E00 range of 1.7–6.1 and 5.1–11.3, respectively (p < 0.05). ∆TP00 was more pronounced in wine than in coffee (p < 0.05). Sorption and solubility varied between 9.8 and 15.3 μg/mm3 and −1.6 and −5.4 μg/mm3, respectively, with positive correlation between ∆TP00 and sorption (p = 0.005). Conclusions: Total color and translucency differences of sculptable composites for enamel layering were material‐, time‐ and medium‐dependent. Translucency differences positively correlated with sorption. Overall, the ultrafine, hybrid composite exhibited the best results in terms of color stability, sorption and solubility. Clinical significance: Clinicians should be aware of differences in color stability of sculptable composites for enamel layering as these are directly exposed to discoloration in the oral environment and are directly related to patients' long‐term satisfaction and restoration longevity. Ultrafine, hybrid composite may be preferred due to better color stability, lower sorption and solubility compared to nanofilled and microhybrid composites evaluated in this study. [ABSTRACT FROM AUTHOR]

Objective: To determine color changes in bulk‐fill composite and universal composite restorations with dissimilar dentin replacement materials in extracted teeth after staining in red wine. Materials and Methods: Cylindrical, 4 mm deep, class I cavities were prepared in 140 human molars. Bottom 2 mm was restored with Biodentine (Septodont), everX posterior (GC) or experimental HAP inserts. Each dentin replacement material was covered with a 2‐mm layer of a universal composite Filtek Z250 or Z550 (3M ESPE) or Gradia Posterior (GC). Groups combining top composite layer and the underlying dentin replacement were designated as "composite_dentin replacement." Filtek Bulk Fill (3M ESPE) and Tetric EvoCeram Bulk Fill (Ivoclar Vivadent) were placed as a single 4‐mm layer. Color measurements were performed using Vita Easyshade 4.0 (Vita Zahnfabrik) initially and after 48‐hours storage in red wine at 37°C. Results: Color differences (ΔEoo) ranged between 2.1 ± 0.7 (Z250_HAP) and 7.8 ± 1.1 (Z550_everX). EverX resulted in higher ΔEoo of the overlying composite than HAP (P < .001) and Biodentine (P = .006). Generally, ΔEoo was affected more by decreasing lightness (ΔL′) than changes in chroma (ΔC′). Conclusions: EverX resulted in higher ΔEoo of the restoration than Biodentine and experimental HAP after staining in red wine. No significant differences in ΔEoo may be expected in different composites with the same underlying dentin replacement material. The same was generally true for bulk‐fill and universal composites. Clinical Significance: Similar extent of color changes may be expected in bulk‐fill and universal composites. Highly translucent everX might exhibit greater color differences irrespective of the capping composite than non‐translucent materials. Clinicians have a wider choice of composite materials to cover a particular dentin replacement material, for example, everX or Biodentine, as similar color differences may be expected in various overlying composite brands. [ABSTRACT FROM AUTHOR]

This study correlated the refractive indices (RIs) of unfilled resin mixtures and resin-based composites (RBCs) with color and translucency of conventional and low-shrinkage RBCs. Unfilled resin mixtures based on different ratios of conventional monomers Bisphenol A-glycidyl-methacrylate (BisGMA)/triethyleneglycol-dimethacrylate (TEGDMA) and urethane-dimethacrylate (UDMA)/TEGDMA and a low-shrinkage monomer FIT-852 (FIT, Esstech Inc.)/TEGDMA were used to prepare model RBCs, containing 30 wt % of the organic matrix and 70 wt % of silanated barium-glass fillers ( n = 1.553, Esstech Inc.). The RIs of resins were measured on an ABBE refractometer, those of cured RBCs using the Becke-line method in immersion oils. Color and translucency were determined using an AvaSpec-2048 (Avantes BV) spectrometer. The RIs of unfilled resin mixtures decreased with increasing amounts of TEGDMA. Cured RBCs had higher RIs than their respective resin mixtures. BisGMA-based composites were more translucent with significantly lower L* values than FIT- and UDMA-based RBCs. The RIs of unfilled resins positively correlated with cured RBCs ( p = 0.001), as did the RIs with translucency ( p = 0.001) and color ( p = 0.008). Resin mixtures and corresponding RBCs based on UDMA and its modified low-shrinkage version, FIT, showed similar optical properties. The RIs of unfilled resins appeared to be good predictors of the RIs of cured RBCs. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 7-13, 2017. [ABSTRACT FROM AUTHOR]

Elution of potentially toxic substances, including monomers, from resin-based dental composites may affect the biocompatibility of these materials in clinical conditions. In addition to the amounts of eluted monomers, mathematical modeling of elution kinetics reveals composite restorations as potential chronic sources of leachable monomers. The aim of this work was to experimentally quantify elution of main cross-linking monomers from four commercial composites and offer a mathematical model of elution kinetics. Composite samples ( n = 7 per group) of Filtek Supreme XT (3M ESPE), Tetric EvoCeram (Ivoclar Vivadent), Admira (Voco), and Filtek Z250 (3M ESPE) were prepared in 2-mm thick Teflon moulds and cured with halogen or light-emitting diode light. Monomer elution in ethanol and water was analyzed using high-performance liquid chromatography up to 28 days postimmersion. The mathematical model was expressed as a sum of two exponential regression functions representing the first-order kinetics law. Elution kinetics in all cases followed the same mathematical model though differences in rate constants as well as the extent of monomer elution were material-, LCU-, medium-dependent. The proposed mechanisms of elution indicate fast elution from surface and subsurface layers and up to 100 times slower monomer extraction from the bulk polymer. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 101B: 61-67, 2013. [ABSTRACT FROM AUTHOR]

The aim of this study was to optimize the concentration of 2,4,6-trimethylbenzoylthphenylphosphine oxide (Lucirin® TPO) in unfilled and filled composite resins in relation to the degree of conversion (DC). Increasing concentrations of Lucirin®TpO between 0.05-- 4.97 wt% were added to equimolar mbtaires of Bis-GMA/TEGDMA. Filled resins contained 75 wt% fillers. Standardized samples were cured using a polywave LED light-curing unit (bluephase® G2, Ivoclar Vivadent). Increased initiator concentrations increased logarithmically the DC of unfilled and flllsd resins The DC of unfilled resins was in the range of 73--91% at the top and 63--81% at the bottom surfaces and that of filled resins was in the range of 53--81% at the top and 47--70% at the bottom surfaces. The DC in unfilled and filled resins reached a plateau at 1 03 wt% and 1.50 wt% Lucirin® TPO, respectively. Fillers significantly reduced conversion but had no effect on the logarithmic relationship between initiator concentration and the DC. [ABSTRACT FROM AUTHOR]

Objectives To evaluate optical properties (color and translucency) of ‘sandwich’ restorations of resin-based composites and esthetically unfavorable dentin restoratives. Methods Cylindrical ‘dentin’ specimens (8 mm in diameter and 2 mm thick, N = 5/group) were prepared using EverX Posterior (GC), Biodentine (Septodont), experimental hydroxyapatite (HAP) or conventional composites (Gradia Direct Posterior, GC; Filtek Z250 and Filtek Z500, 3M ESPE). Capping ‘enamel’ layers were prepared using composites (Gradia Direct Posterior, Filtek Z250 or Z550) of A1 or A3 shade and the following thickness: 0.6, 1 or 2 mm. Color (ΔE) and translucency parameter (TP) were determined using a spectrophotometer (VITA Easyshade Advance 4.0, VITA Zahnfabrik). Data were statistically analyzed using analysis of variance with Tukey’s post-hoc tests ( α = 0.05). Results TP was greatly affected by layer thickness, whilst ΔE depended on shade and layer thickness of the capping composite. HAP and Biodentine showed significantly lower TP and higher ΔE (deviation from ‘ideal white’) than composites (p < 0.05). Greater TP was seen in EverX_composite groups than in corresponding control groups of the same shade and thickness. TP of composites combined with Biodentine or HAP was below 2, lower than the corresponding control groups (p < 0.05). Within-group differences of ΔE were greatest in HAP_composite groups. EverX_Gradia and EverX_FiltekZ250 combinations showed the most comparable ΔE with the control groups. Significance A 2 mm thick layer of composite covering dentin restoratives with unfavorable esthetics is recommended for a final ‘sandwich’ restoration that is esthetically comparable to a conventional, mono-composite control restoration. [ABSTRACT FROM AUTHOR]

Objective To study the effect of a low-shrinkage methacrylate monomer and monoacylphosphine oxide photoinitiator on color, translucency, and color stability of model resin-based composites (RBCs). Methods Four micro-hybrid RBCs were prepared containing barium-glass fillers in bisphenol A-glycidyl-methacrylate (BisGMA) and triethyleneglycol-dimethacrylate (TEGDMA) or urethane-based low-shrinkage monomer FIT-852 (FIT; Esstech Inc.) and TEGDMA matrix. Camphorquinone (CQ)/amine or Lucirin TPO were used as photoinitiators. Commercial low-shrinkage RBCs (Charisma Diamond, Heraeus Kulzer and N’Durance, Septodont) and conventional RBCs (Tetric EvoCeram, Ivoclar Vivadent and Filtek Z250, 3M ESPE) were used as controls. Color and translucency were measured using Thermo Scientific Evolution (Thermo Fisher Scientific) and SpectroShade™ Micro (MHT Optic Research) spectrophotometers. Color stability was evaluated after immersion in black tea (pure, with milk or lemon) and distilled water. Data were analyzed using analyses of variance with Tukey's post-test ( α = 0.05). Results Photoinitiators had no significant effect on baseline color. Initially whiter FIT-based RBCs showed greater staining in all staining solutions than BisGMA-based RBCs. TPO-containing RBCs showed better color stability than CQ-containing RBCs irrespective of the base monomer. Tea and tea with lemon induced greatest color changes. Adding milk to tea significantly reduced material staining. Significance Urethane-based low-shrinkage monomer FIT and conventional BisGMA affected color, translucency and color stability of their respective RBCs. Despite being used in posterior teeth, low-shrinkage RBCs are expected to have favorable optical and esthetic properties. Manufacturers are urged to provide information on optical properties of monomers and monomer mixtures in their low-shrinkage RBCs to allow understanding of interaction with fillers and photoinitiators. [ABSTRACT FROM AUTHOR]

This study investigated the degree of conversion, depth of cure, Vickers hardness, flexural strength, flexural modulus and volumetric shrinkage of experimental composite containing a low shrinkage monomer FIT-852 (FIT; Esstech Inc.) and photoinitiator 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO; Sigma Aldrich) compared to conventional composite containing Bisphenol A-glycidyl methacrylate (BisGMA) and camphorquinone–amine photoinitiator system. The degree of conversion was generally higher in FIT-based composites (45–64% range) than in BisGMA-based composites (34–58% range). Vickers hardness, flexural strength and modulus were higher in BisGMA-based composites. A polywave light-curing unit was generally more efficient in terms of conversion and hardness of experimental composites than a monowave unit. FIT-based composite containing TPO showed the depth of cure below 2 mm irrespective of the curing light. The depth of cure of FIT-based composite containing CQ and BisGMA-based composites with either photoinitiator was in the range of 2.8–3.0 mm. Volumetric shrinkage of FIT-based composite (0.9–5.7% range) was lower than that of BisGMA-based composite (2.2–12% range). FIT may be used as a shrinkage reducing monomer compatible with the conventional CQ–amine system as well as the alternative TPO photoinitiator. However, the depth of cure of FIT_TPO composite requires boosting to achieve clinically recommended thickness of 2 mm. [ABSTRACT FROM AUTHOR]

Objective To determine the shear bond strength (SBS) between synthetic controlled porous hydroxyapatite (HAP) inserts and restorative materials and dimensional changes of insert-containing restorations during curing. Methods Cylinder-shaped HAP inserts (4 mm in diameter, 1.6 mm thick) were cemented in dentin discs (5 mm × 1.6 mm), cut mid-coronally from human third molars, using one of the following materials: universal microhybrid composite Filtek Z250, flowable composite Filtek Ultimate or glass-ionomer Vitrebond (all 3M ESPE). SBS of the same materials to HAP inserts was tested in a universal testing machine. Three-dimensional digital image correlation system Aramis (GOM) was used to measure strains and displacements. Data were statistically analyzed using one-way ANOVA with Tukey's post-test ( α = 0.05). Results SBS of restorative materials to HAP inserts ranged between 12.2 ± 2.1 MPa (Filtek Z250) and 0.7 ± 0.4 MPa (Filtek Z250 without an adhesive). The ‘total-etch’ approach of adhesive application significantly increased SBS of both Filtek Z250 (12.2 ± 2.1 MPa) and Filtek Ultimate flowable (9.5 ± 2.5 MPa) compared to the ‘self-etch’ approach (8.2 ± 1.6 MPa and 4.4 ± 0.9 MPa, respectively) ( p < 0.05). HAP inserts reduced polymerization shrinkage to below 0.5% as well as displacements in the central region of the restorations. Peripheral shrinkage of restorative materials was similar with and without HAP inserts as were displacements of Filtek Z250 and Vitrebond. Significance Replacing major part of dentin clinically, especially in large cavities, HAP inserts may shorten clinical working time, improve dimensional stability of the restoration by reducing central shrinkage and displacements and provide adhesive bonding to universal composites following a ‘total-etch’ approach. [ABSTRACT FROM AUTHOR]