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Abstract This study investigated the in vitro performance of the commercial bis-acryl composite resins Systemp C&B II (SYS, Ivoclar Vivadent), Protemp 4 (PT4, 3M ESPE), Structur 2C (ST2, Voco) and ProviPlast (PVP, Biodinamica). Characterization involved optical (color stability, translucency parameter, fluorescence), surface (roughness, morphology and elemental composition), physical-chemical (viscosity, polymerization kinetics) and mechanical analyses (Poisson ratio, biaxial flexural strength, flexural modulus). Most tests were carried out after 24 h, but optical and mechanical analyses were carried out after storage in water at 37 °C for 1, 15, and 30 days. Data were statistically analyzed (a=0.05). Most results were material dependent. SYS and PT4 showed stability in color and translucency over time. All materials had similar or higher fluorescence than human enamel. SC2 and PVP showed rougher surfaces than the other bis-acryl composites. Smaller filler particles were observed on the surface of PT4 and PVP compared with the coarser particles from ST2 and SYS. Viscosity readings indicated a thixotropic behavior for all tested materials. SYS had the lowest and PT4 the highest degree of C=C conversion after 10 min. In the polymerization kinetics, PT4 had the highest maximum polymerization rate and reached earlier the transition between polymerization autoacceleration and autodeceleration. PT4 and SYS had significantly higher flexural strength and modulus than ST2 and PVP for most storage times. Results for Poisson ratio varied between materials. Longer storage periods were generally associated with higher frequency of catastrophic failures in the flexural tests. In conclusion, the performance of bis-acryl composite resins varied largely among materials.

Resumo Este estudo investigou o desempenho in vitro de quatro resinas compostas bisacrílicas comerciais: Systemp C&B II (SYS, Ivoclar Vivadent), Protemp 4 (PT4, 3M ESPE), Structur 2C (ST2, Voco) e ProviPlast (PVP, Biodinamica). A caracterização envolveu análises ópticas (estabilidade de cor, parâmetro de translucidez, fluorescência), de superfície (rugosidade, morfologia e composição elementar), físico-químicas (viscosidade, cinética de polimerização) e mecânicas (razão de Poisson, resistência à flexão biaxial, módulo de elasticidade). A maioria dos testes foram realizados após 24 h, enquanto análises ópticas e mecânicas foram realizadas após armazenamento em água a 37 °C por 1, 15 e 30 dias. Os dados foram analisados estatisticamente (a=0,05). Grande parte dos resultados foi dependente do material. SYS e PT4 mostraram estabilidade de cor e translucidez ao longo do tempo. Todos os materiais apresentaram fluorescência similar ou maior que o esmalte humano. SC2 e PVP apresentaram superfícies mais rugosas que os outros materiais. Menores partículas de carga foram observadas na superfície de PT4 e PVP comparadas às partículas mais irregulares de ST2 e SYS. As leituras de viscosidade indicaram comportamento tixotrópico para todos os materiais testados. SYS teve a menor e PT4 o maior grau de conversão de C=C após 10 min. Na cinética de polimerização, PT4 teve a maior taxa máxima de polimerização e atingiu mais cedo a transição entre autoaceleração e autodesaceleração da polimerização. PT4 e SYS apresentaram resistência à flexão e módulo de elasticidade significativamente maiores que ST2 e PVP na maioria dos períodos de armazenamento. Resultados da razão de Poisson variaram entre os materiais. Períodos mais longos de armazenamento foram em geral associados a maior frequência de falhas catastróficas nos testes de flexão. Em conclusão, o desempenho das resinas compostas bisacrílicas variou amplamente entre os materiais.

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This study investigated the in vitro performance of the commercial bis-acryl composite resins Systemp C&B II (SYS, Ivoclar Vivadent), Protemp 4 (PT4, 3M ESPE), Structur 2C (ST2, Voco) and ProviPlast (PVP, Biodinamica). Characterization involved optical (color stability, translucency parameter, fluorescence), surface (roughness, morphology and elemental composition), physical-chemical (viscosity, polymerization kinetics) and mechanical analyses (Poisson ratio, biaxial flexural strength, flexural modulus). Most tests were carried out after 24 h, but optical and mechanical analyses were carried out after storage in water at 37 °C for 1, 15, and 30 days. Data were statistically analyzed (a=0.05). Most results were material dependent. SYS and PT4 showed stability in color and translucency over time. All materials had similar or higher fluorescence than human enamel. SC2 and PVP showed rougher surfaces than the other bis-acryl composites. Smaller filler particles were observed on the surface of PT4 and PVP compared with the coarser particles from ST2 and SYS. Viscosity readings indicated a thixotropic behavior for all tested materials. SYS had the lowest and PT4 the highest degree of C=C conversion after 10 min. In the polymerization kinetics, PT4 had the highest maximum polymerization rate and reached earlier the transition between polymerization autoacceleration and autodeceleration. PT4 and SYS had significantly higher flexural strength and modulus than ST2 and PVP for most storage times. Results for Poisson ratio varied between materials. Longer storage periods were generally associated with higher frequency of catastrophic failures in the flexural tests. In conclusion, the performance of bis-acryl composite resins varied largely among materials.

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OBJECTIVE: This study introduces an innovative method to enhance adhesion of methacrylate-based cements to yttria-stabilized zirconia (Y-TZP) by means of a silica-nanoparticle deposition process. METHODS: Two alkoxide organic precursors, tetraethyl-orthosilicate (TEOS) and zirconium tert-butoxide (ZTB) were diluted in hexane at different concentrations in order to obtain several experimental materials to enhance deposition of a SiO(x) reactive layer to Y-TZP. This deposition was attained via sintering alkoxide precursors directly on pre-sintered zirconia (infiltration method­INF) or application on the surface of fully sintered zirconia (coating method­COA). Untreated specimens and a commercial tribochemical silica coating were also tested as controls and all the treated Y-TZP specimens were analyzed using SEM-EDX. Specimens were bonded using silane, adhesive and dual-cure luting cement and submitted to shear bond strength test after different water storage periods (24 h, 3-, 6- and 12-months). RESULTS: SEM-EDX revealed Y-TZP surface covered by silica nanoclusters. The morphology of silica-covered Y-TZP surfaces was influenced by sintering method, employed to deposit nanoclusters. High bond strength (MPa) was observed when using COA method; highest TEOS percentage achieved the greatest bond strengths to Y-TZP surface (36.7±6.3 at 24 h). However, bonds stability was dependent on ZTB presence (32.9±9.7 at 3 months; 32.3±7.1 at 6 months). Regarding INF method, the highest and more stable resin-zirconia bond strength was attained when using experimental solutions containing TEOS and no ZTB. Both sintering methods tested in this study were able to achieve a bonding performance similar to that of classic tribochemical strategies. SIGNIFICANCE: This study demonstrates that it is possible to achieve a reliable and long-lasting bonding between yttria-stabilized zirconia ceramic and methacrylate-based cements when using this novel, simple, and cost-effective bonding approach.

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OBJECTIVES: Despite nanofill and submicron composites' aim to provide high initial polishing combined with superior smoothness and gloss retention, the question still remains whether clinicians should consider using these new materials over traditional microhybrids. The aim of this paper was to systematically review the literature on how nanofills and submicrons react to polishing procedures and surface challenges in vitro compared with microhybrids. The paper has also given an overview of the compositional characteristics of all resin composites and polishing systems whose performance was presented herein. DATA: The database search for the effect of filler size on surface smoothness and gloss of commercial composites retrieved 702 eligible studies. After deduplication, 438 records were examined by the titles and abstracts; 400 studies were excluded and 38 articles were assessed for full-text reading. An additional 11 papers were selected by hand-searching. In total, 28 articles met inclusion criteria and were included in the study. SOURCES: The databases analyzed were MEDLINE/PubMed, ISI Web of Science, and SciVerse Scopus. STUDY SELECTION: Papers were selected if they presented a comparison between nanofill or submicron and microhybrid composites with quantitative analysis of smoothness and/or gloss on baseline and/or after any aging protocol to assess smoothness and gloss retention. Only in vitro studies written in English were included. CONCLUSIONS: There is no in vitro evidence to support the choice for nanofill or submicron composites over traditional microhybrids based on better surface smoothness and/or gloss, or based upon maintenance of those superficial characteristics after surface challenges.

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