The impact of different surface treatments on the shear bond strength of orthodontic metal brackets applied to different CAD/CAM composites

To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different CAD/CAM composites treated with different surface treatments. Specimens of two CAD/CAM composites were obtained of Lava Ultimate (LU; n=60) and Brilliant Cri

Effect of low shrinkage monomers on physicochemical properties of dental resin composites

The aim of this study was to evaluate the effect of low shrinkage monomers on physicochemical properties of dental resin composites. Two low shrinkage resin composites: one with a crosslink branching monomer (Kalore, GC Corp) and a novel monomer (Venus Diamond, Heraeus Kulzer) were compared to a conventional resin composite formulation (Filtek Z250, 3M/ESPE). The volumetric shrinkage was evaluated by µCT analysis (n=5) and the physicochemical properties by degree of C=C conversion (DC), flexural strength (FS) and Young's modulus (YM) (n=10). All samples were light cured by a LED device (Radii, SDI) with 16 J/cm2. The results were analysed by one-way ANOVA and Tukey test for multiple comparisons (α=0.05). No statistical difference was found between µCT shrinkage values to Kalore (1.8%) and Venus Diamond (1.7%) (p≥0.05); Z250 presented statistical highest shrinkage value (2.0%). Kalore presented higher statistical DC (60.8%) than Venus Diamond (49.5%) and Z250 (49.6%). No statistical difference was found between FS or YM properties to Venus Diamond and Z250; Kalore presented statistical lowest FS and YM properties (p≥0.05). Using novel monomers seem to reduce polymerization shrinkage without affecting the physicochemical properties evaluated of resin composites rather than using crosslink branching monomers.The aim of this study was to evaluate the effect of low shrinkage monomers on physicochemical properties of dental resin composites. Two low shrinkage resin composites: one with a crosslink branching monomer (Kalore, GC Corp) and a novel monomer (Venus Di263272276sem informaçãosem informaçãoO objetivo deste trabalho foi avaliar o efeito de monômeros de baixa contração de polimerização nas propriedades físico-químicas de resinas compostas. Duas resinas de baixa contração de polimerização com monômeros do tipo crosslink (Kalore GC Corp) ou d

Efeito da aplicação prolongada do sistema adesivo convencional de 2 passos na qualidade de restaurações de resina composta em lesões cervicais não cariosas: Ensaio clínico controlado, randomizado, duplo cego / Effect of the extended time of application of the conventional two-step adhesive system on the longevity of composite resin restorations in non-carious cervical lesions: a double-blind randomized clinical trial

Objetivo: Este ensaio clínico randomizado duplo-cego avalia a influência do aumento do tempo de aplicação em dois sistemas adesivos de duas etapas de etch-and-rinse (Peak® Universal Bond (P); Ultradent Products Ind e Single Link (SL); Angelus Dental Products Industry) aplicados em lesões cervicais não cariocas (NCCLs). Métodos: Um total de 119 restaurações foram colocadas aleatoriamente em 35 pacientes, de acordo com os seguintes grupos: P1 - aplicado de acordo com o fabricante; P2X - aplicado pelo tempo duplo; SL1 e SL2X (o mesmo modo de aplicação). O composto de resina Amelogen (Ultradent) foi colocado de forma incremental. As restaurações foram avaliadas imediatamente (linha de base) e 6 meses, usando os critérios FDI e USPHS. As análises estatísticas foram realizadas utilizando testes apropriados (=0,05). Resultados: Vinte e quatro restaurações foram perdidas aos 6 meses (4 para P1, 2 para P2X, 9 para SL1 e 9 para SL2X) (p < 0,05 entre grupos). A sensibilidade pós-operatória não foi observada em nenhum dos períodos de recall. Foram consideradas cinco restaurações com pequenas discrepâncias na adaptação marginal no recall de 6 meses usando os critérios de IDE (8 para P1, 7 para P2X, 12 para SL1 e 8 para SL2X; p > 0,05 entre os grupos). Dez restaurações foram consideradas como tendo pequenas discrepâncias na descoloração marginal no recall de 6 meses (2 para P1, 1 para P2X, 3 para SL1 e 2 para SL2X; p > 0,05 entre os grupos). Conclusão: O aumento do tempo de aplicação do sistema adesivo em duas etapas não melhorou o comportamento clínico das restaurações compostas colocadas nos NCCLs. Entretanto, o comportamento clínico pode ser influenciado pela composição dos sistemas adesivos

Effect of Different Crosslinkers on Denatured Dentin Collagen’s Biostability, MMP Inhibition and Mechanical Properties

Objective: Sound, natural dentin collagen can be stabilized against enzymatic degradation through exogenous crosslinking treatment for durable bonding; however, the effect on denatured dentin (DD) collagen is unknown. Hence, the ability of different crosslinkers to enhance/restore the properties of DD collagen was assessed. Methods: Demineralized natural and DD collagen films (7 mm × 7 mm × 7 µm) and beams (0.8 mm × 0.8 mm × 7 mm) were prepared. DD collagen was experimentally produced by heat or acid exposure, which was then assessed by various techniques. All specimens were then treated with 1 wt% of chemical crosslinker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/n-hydroxysuccinimide (EDC/NHS) and two structurally different flavonoids—theaflavins (TF) from black tea and type-A proanthocyanidins from cranberry juice (CR) for either 30 s or 1 h. The controls were untreated. Dentin films were assessed for chemical interaction and cross-linking effect by FTIR, biostability against exogenous collagenase by weight loss (WL) and hydroxyproline release (HYP), and endogenous matrix metalloproteinases (MMPs) activity by confocal laser microscopy. Dentin beams were evaluated for tensile properties. Data were analyzed using ANOVA and Tukey’s test (α = 0.05). Results: Compared with natural collagen, DD collagen showed pronounced structural changes, altered biostability and decreased mechanical properties, which were then improved to various degrees that were dependent on the crosslinkers used, with EDC/NHS being the least effective. Surprisingly, the well-known MMP inhibitor EDC/NHS showed negligible effect on or even increased MMP activity in DD collagen. As compared with control, cross-linking induced by TF and CR significantly increased collagen biostability (reduced WL and HYP release, p p p < 0.05), regardless of denaturation. Conclusions: DD collagen cannot or can only minimally be stabilized via EDC/NHS crosslinking; however, the challenging substrate of DD collagen can be enhanced or restored using the promising flavonoids TF and CR

Cranberry Juice Extract Rapidly Protects Demineralized Dentin against Digestion and Inhibits Its Gelatinolytic Activity

Improving the longevity of composite restorations has proven to be difficult when they are bonded to dentin. Dentin demineralization leaves collagen fibrils susceptible to enzymatic digestion, which causes breakdown of the resin–dentin interface. Therefore, measures for counteracting the enzymatic environment by enhancing dentin collagen’s resistance to degradation have the potential to improve the durability of dental composite restorations. This study aimed to evaluate the effects of polyphenol-rich extracts and a chemical cross-linker on the cross-linking interaction, resistance to digestion, and endogenous matrix metalloproteinase (MMP) activities of dentin collagen under clinically relevant conditions. Ten-µm-thick films were cut from dentin slabs of non-carious extracted human third molars. Following demineralization, polyphenol-rich extracts—including grape seed (GSE), green tea (GTE), and cranberry juice (CJE)—or chemical cross-linker carbodiimide with n-hydroxysuccinimide (EDC/NHS) were applied to the demineralized dentin surfaces for 30 s. The collagen cross-linking, bio-stabilization, and gelatinolytic activities of MMPs 2 and 9 were studied by using Fourier-transform infrared spectroscopy, weight loss, hydroxyproline release, scanning/transmission electron microscopy, and in situ zymography. All treatments significantly increased resistance to collagenase degradation and reduced the gelatinolytic MMP activity of dentin collagen compared to the untreated control. The CJE- and GSE-treated groups were more resistant to digestion than the GTE- or EDC/NHS-treated ones (p < 0.05), which was consistent with the cross-linking interaction found with FTIR and the in situ performance on the acid-etched dentin surface found with SEM/TEM. The collagen films treated with CJE showed the lowest MMP activity, followed by GSE, GTE, and, finally, EDC/NHS. The CJE-treated dentin collagen rapidly increased its resistance to digestion and MMP inhibition. An application of CJE as short as 30 s may be a clinically feasible approach to improving the longevity of dentin bonding in composite restorations

Collagen Cross-linkers On Dentin Bonding: Stability Of The Adhesive Interfaces, Degree Of Conversion Of The Adhesive, Cytotoxicity And In Situ Mmp Inhibition

To investigate the effect of collagen cross-links on the stability of adhesive properties, the degree of conversion within the hybrid layer, cytotoxicity and the inhibition potential of the MMPs' activity. Methods. The dentin surfaces of human molars were acid-etched and treated with primers containing: 6.5 wt% proanthocyanidin, UVA-activated 0.1 wt% riboflavin, 5 wt% glutaraldehyde and distilled water for 60s. Following, dentin was bonded with Adper Single Bond Plus and Tetric N-Bond; and restored with resin composite. The samples were sectioned into resin-dentin "sticks" and tested for microtensile bond strength (mu TBS) after immediate (IM) and 18-month (18 M) periods. Bonded sticks at each period were used to evaluate nanoleakage and the degree of conversion (DC) under micro-Raman spectroscopy. The enzimatic activity (P1L10 cross-linkers, P1L22 MMPs' activities) in the hybrid layer was evaluated under confocal microscopy. The culture cell (NIH 3T3 fibroblast cell line) and MTT assay were performed to transdentinal cytotoxicity evaluation. Data from all tests were submitted to appropriate statistical analysis (alpha = 0.05). Results. All cross-linking primers reduced the degradation of mu TBS compared with the control group after 18 M (p > 0.05). The DC was not affected (p > 0.213). The NL increased after 18 M for all experimental groups, except for proanthocyanidin with Single Bond Plus (p > 0.05). All of the cross-link agents reduced the MMPs' activity, although this inhibition was more pronounced by PA. The cytotoxicity assay revealed reduced cell viability only for glutaraldehyde (p < 0.001). Significance. Cross-linking primers used in clinically relevant minimized the time degradation of the mu TBS without jeopardizing the adhesive polymerization, as well as reduced the collagenolytic activity of MMPs. Glutaraldeyde reduced cell viability significantly and should be avoided for clinical use. (C) 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.32673274

Effect of MDP-containing silane and adhesive used alone or in combination on the long-term bond strength and chemical interaction with Lithium Disilicate Ceramics

Purpose: To evaluate the effect of a silane and an adhesive containing MDP, used alone or combined in the same solution, on the microshear bond strength (mu SBS) to lithium disilicate ceramics immediately and after 1-year water storage, and compare the bond strength results with the Raman spectra of the treated lithium disilicate surfaces. Materials and Methods: A total of 30 CAD/CAM blocks of lithium disilicate (LD; IPS e.max CAD) were cut into four square sections (6 x 6 x 6 mm; n = 60 per group) and processed as recommended by the manufacturer. The LD specimens were divided into 12 groups according to the following independent variables: silane coupling agent (no silane; silane without 10-MDP [MBS, Monobond S]; silane with 10-MDP [MB+, Monobond Plus]) and adhesive + luting composite (no adhesive + Enforce; no adhesive + RelyX Ultimate; Prime & Bond Elect [PBE], a silane- and MDP-free universal adhesive + Enforce; Scotchbond Universal Adhesive [SBU], a silane- and MDP-containing universal adhesive + RelyX Ultimate). After each treatment, cylindrical, transparent matrices were filled with a luting composite and light cured. Specimens were stored in water (37 degrees C for 24 h or 1 year) and submitted to the microshear bond strength (mu SBS) test. The failure pattern and mu SBS were statistically evaluated (alpha = 0.05). In addition, specimens were examined for chemical interaction using Raman spectroscopy. Results: The use of the adhesive PBE alone showed higher mean mu SBS compared with both groups with silane (MSB or MB+) without PBE (p < 0.001) at 24 h. The use of the SBU adhesive or MBS silane alone, as well as MB+ associated with SBU, showed higher mean mu SBS (p < 0.001) at 24 h. After 1-year water storage, all groups showed a significant decrease in mean mu SBS. However, the application of PBE or SBU associated with MB+ silane showed higher 1-year mean mu SBS (p < 0.001). In terms of chemical interaction, when silane (MSB or MB+) was applied, only a slight decrease of Si-O peaks occurred. Otherwise, when PBE or SBU adhesives were applied, methacrylate peaks were only observed in the SBU groups. Conclusion: The best results in terms of bond strength after water storage were obtained when an MDP-containing silane was associated with a universal adhesive. The use of a simplified bonding protocol that includes either a silane or a universal adhesive is not recommended.3M ESP

The role of copper nanoparticles in an etch-and-rinse adhesive on antimicrobial activity, mechanical properties and the durability of resindentine interfaces

Objectives: To evaluate the effect of addition of copper nanoparticles at different concentrations into an etchand-rinse adhesive (ER) on antimicrobial activity, Knoop microhardness (KHN), in vitro and in situ degree of conversion (DC), as well as the immediate (IM) and 2-year (2Y) resin-dentine bond strength (μTBS) and nanoleakage (NL). Methods: Seven experimental ER adhesives were formulated according to the amount of copper nanoparticles incorporated into the adhesives (0 [control], 0.0075 to 1 wt.%). We tested the antimicrobial activity of adhesives against Streptococcus mutans using agar diffusion assay after IM and 2Y. The Knoop microhardness and in vitro DC were tested after IM and 2Y. The adhesives were applied to flat occlusal dentine surfaces after acid etching. After resin build-ups, specimens were longitudinally sectioned to obtain beam-like resin-dentine specimens (0.8 mm2 ), which were used for evaluation of μTBS and nanoleakage at the IM and 2Y periods. In situ DC was evaluated at the IM period in these beam-like specimens. Data were submitted to appropriate statistical analyses (α = 0.05). Results: The addition of copper nanoparticles provided antimicrobial activity to the adhesives only in the IM evaluation and slightly reduced the KHN, the in vitro and in situ DC (copper concentrations of 1 wt.%). However, KHN increase for all concentrations after 2Y. After 2Y, no significant reductions of μTBS (0.06 to 1% wt.%) and increases of nanoleakage were observed for copper containing adhesives compared to the control group. Conclusion: Copper nanoparticles addition up to 0.5 wt.% may provide antimicrobial properties to ER adhesives and prevent theConselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) 304104/2013-9 305588/2014-