Dentin bond optimization using the dimethyl sulfoxide-wet bonding strategy : A 2-year in vitro study

Objective. This study evaluated a new approach, named dimethyl sulfoxide (DMSO)-wet bonding, to produce more desirable long-term prospects for the ultrafine interactions between synthetic polymeric biomaterials and the inherently hydrated dentin substrate. Methods. Sound third molars were randomly restored with/without DMSO pretreatment using a total-etch (Scocthbond Multipurpose: SBMP) and a self-etch (Clearfil SE Bond: CF) adhesive systems. Restored teeth (n = 10)/group were sectioned into sticks and submitted to different analyses: micro-Raman determined the degree of conversion inside the hybrid layer (DC); resin dentin microtensile bond strength and fracture pattern analysis at 24 h, 1 year and 2 years of aging; and nanoleakage evaluation at 24h and 2 years. Results. DMSO-wet bonding produced significantly higher 24 h bond strengths for SBMP that were sustained over the two-year period, with significantly less adhesive failures. Similarly, DMSO-treated CF samples presented significantly higher bond strength than untreated samples at two years. Both adhesives had significant less adhesive failures at 2 years with DMSO. DMSO had no effect on DC of SBMP, but significantly increased the DC of CE DMSO-treated SBMP samples presented reduced silver uptake compared to untreated samples after aging. Significance. Biomodification of the dentin substrate by the proposed strategy using DMSO is a suitable approach to produce more durable hybrid layers with superior ability to withstand hydrolytic degradation over time. Although the active role of DMSO on dentin bond improvement may vary according to monomer composition, its use seems to be effective on both self-etch and etch-and-rinse bonding mechanisms. (C) 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Influence of silicon dioxide or acrylated polisiloxane on resin-based materials physical properties

Orientador: Luis Roberto Marcondes MartinsDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: A utilização de resinas compostas restauradoras cresceu consideravelmente nos últimos anos, porém, a alteração de cor associado à degradação da resina composta ainda é um importante fator para sua substituição. Portanto, o objetivo dos estudos foram de avaliar in vitro as propriedades físicas de diferentes selantes experimentais e os seus efeitos sobre a superfície de resinas compostas. No primeiro capítulo foram abordados os efeitos da utilização de cobertura de nanopartículas de dióxido de silício (SiO2) sobre diferentes resinas compostas. Os grupos experimentais foram divididos de acordo com os fatores resina composta (Filtek Z250XT, Filtek Z350XT e IPS Empress Direct) e a aplicação ou não de cobertura de SiO2 (n=8). Foram avaliados rugosidade superficial (Ra), energia livre de superfície (mJ/cm2), ângulo de contato formado pela água (?o) e alteração de cor (?E) após 24h de armazenamento em água destilada e após 15, 90 e 180 dias de armazenamento em vinho tinto. Os dados obtidos foram analisados por meio de Análise de Variância de Medidas Repetidas e teste de Tukey (?=0.05). O tempo de exposição ao vinho tinto influenciou negativamente em todas as variáveis, a aplicação da cobertura de SiO2 reduziu a energia livre de superfície, tornando as resinas mais hidrófobas. O aumento na rugosidade superficial foi observada a partir de 90 dias para todas as resinas compostas, independente do tratamento. Quanto a alteração de cor, a Filtek Z250XT e a IPS Empress Direct apresentaram menores valores de ?E quando comparadas à Filtek Z350XT. No segundo capítulo, os grupos estudados foram: PER - selante resinoso comercial (PermaSeal); STD - resina padrão manipulada (matriz monomérica Bis-EMA+TEGDMA carregada com 10% de partículas inorgânicas); SIL-resina padrão modificada por nanopartículas de SiO2 e; APS-resina padrão modificada por polissiloxano acrilado (n=10). Foram avaliados grau de conversão (%), sorção de água e solubilidade (µg/mm3) e módulo de elasticidade (GPa) em corpos de prova maciços confeccionados a partir dos selantes resinosos. Para os ensaios de ângulo de contato com a água (?o) e alteração de cor (?E), os selantes resinosos foram aplicados sobre a superfície de discos de resina composta (Filtek Z250XT) para então realizar a avaliação das amostras, um grupocontrole sem tratamento foi incluído nestes ensaios. O ?E foi calculado a partir de medidas obtidas antes e depois de 15 dias de imersão das amostras em vinho tinto. Os resultados foram analisados por meio de Análise de Variância de 1 critério e posterior teste de Tukey (?=0.05). A adição de nanopartículas de SiO2 promoveu menor solubilidade, adequado módulo de elasticidade e menor grau de alteração de cor e; a incorporação de polissiloxano acrilado promoveu melhor grau de conversão, menor sorção de água, apresentou maior hidrofobicidade e causou menor grau de alteração de cor quando comparadas aos controles. Portanto, a incorporação de aditivos hidrófobos não interferiu negativamente nas propriedades físicas dos selantes experimentais e foram efetivos para tornar resinas compostas mais hidrófobas e reduzir a sua alteração de corAbstract: The use of restorative composites has been increased in dental practice, however, the color change associated to composite surface degradation is still important issue for composite restorations replacement. Therefore, the aim of these studies were to in vitro evaluate physical properties of different experimental surface sealants and its effects on composite resins surfaces. In the first chapter, it has been evaluated the effects of the silicon dioxide nanoparticles (SiO2) coating on different composites. The experimental groups were divided according to the resin composite type (Filtek Z250XT, Filtek Z350XT and IPS Empress Direct) and application or not of SiO2 coating (n=8). Surface roughness (Ra), surface free energy (mJ/cm2), water contact angle (?o) and color change (?E) were evaluated after 24h deionized water storage and after 15, 90 and 180 days of red wine storage. Data were analyzed using Repeated Measures ANOVA and Tukey test (? = 0.05). The red wine storage time negatively influenced all variables, irrespective of treatment or resin composite. The SiO2 coating application decreased the surface free energy, making the composite more hydrophobic. The increase in surface roughness was observed from 90 days for all composites, regardless of treatment. Significant less color change was observed in the Filtek Z250XT and the IPS Empress Direct compared to Filtek Z350XT. In the second chapter, the groups were: PER-commercial resin-based coating (PermaSeal); STD-standard manipulated resin (Bis-EMA+TEGDMA-based monomer matrix loaded with 10% of inorganic filler); SIL-standard resin modified by SiO2 nanoparticles adding; APS-standard resin modified by acrylated polysiloxane adding (n = 10). The degree of resin conversion (%) Water sorption and solubility (mg/mm3) and elasticity modulus (GPa) were evaluated in massive specimens prepared from the resin-based coatings. These resin-based coatings were applied on the composite resin discs surfaces (Filtek Z250XT) to water contact angle (?o) and color change (?E) tests. A control group without surface treatment was included in these trials. The ?E was calculated from measurements taken before and after 15 days of red wine storage. The results were analyzed using one - way ANOVA and Tukey test (? = 0.05). The addition of SiO2 promoted lower solubility, appropriate elasticity modulus and lower degree of color change, and; the incorporation of acrylated polysiloxane provided better degree of conversion, reduced water sorption, the highest hydrophobicity and cause less color change compared to that of controls. Therefore, the incorporation of hydrophobic additives did not negatively affect the physical properties of the resin-based coatings and were effective to make the composite more hydrophobic and less stain susceptibleMestradoDentísticaMestra em Clínica Odontológic

Dentin bond optimization using the dimethyl sulfoxide-wet bonding strategy: A 2-year in vitro study

Objective. This study evaluated a new approach, named dimethyl sulfoxide (DMSO)-wet bonding, to produce more desirable long-term prospects for the ultrafine interactions between synthetic polymeric biomaterials and the inherently hydrated dentin substrate. Methods. Sound third molars were randomly restored with/without DMSO pretreatment using a total-etch (Scocthbond Multipurpose: SBMP) and a self-etch (Clearfil SE Bond: CF) adhesive systems. Restored teeth (n = 10)/group were sectioned into sticks and submitted to different analyses: micro-Raman determined the degree of conversion inside the hybrid layer (DC); resin dentin microtensile bond strength and fracture pattern analysis at 24 h, 1 year and 2 years of aging; and nanoleakage evaluation at 24h and 2 years. Results. DMSO-wet bonding produced significantly higher 24 h bond strengths for SBMP that were sustained over the two-year period, with significantly less adhesive failures. Similarly, DMSO-treated CF samples presented significantly higher bond strength than untreated samples at two years. Both adhesives had significant less adhesive failures at 2 years with DMSO. DMSO had no effect on DC of SBMP, but significantly increased the DC of CE DMSO-treated SBMP samples presented reduced silver uptake compared to untreated samples after aging. Significance. Biomodification of the dentin substrate by the proposed strategy using DMSO is a suitable approach to produce more durable hybrid layers with superior ability to withstand hydrolytic degradation over time. Although the active role of DMSO on dentin bond improvement may vary according to monomer composition, its use seems to be effective on both self-etch and etch-and-rinse bonding mechanisms321214721481CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESsem informaçã

Biomechanical behaviour of bulk-fill resin composites in class II restorations

The aim of this study was to evaluate the biomechanical properties expressed by shrinkage stress, cuspal strain, fracture strength and failure mode in molars with large class II mesio-occlusal-distal restorations. Sixty-four human caries-free third molars were selected and distributed randomly into four groups: Z100 restorative material (Z100), Tetric N-Ceram Bulk-Fill (TNC), Filtek Bulk-Fill (FBF) and Aura Ultra Universal (ABF). The bulk-fill materials were inserted in one singular bulk increment and the conventional composite resin in three ones. Polymerisation shrinkage stress was evaluated by optical Fibre Bragg Gratings (FBG) sensors (n = 6). The cuspal deformation was measured using an extensometer during three moments: restorative procedure, axial compressive loading and at fracture (n = 10). The fracture strength was evaluated on a universal machine. The failure mode was analysed by Scanning Electron Microscopy (SEM). Data were analysed using one-way ANOVA tests with Tukey's posthoc test (α = 5%). Data of the failure mode were submitted to a likelihood ratio chi-square test. Z100 presented the highest mean value for the shrinkage stress (p  0.05). Bulk-fill composites promoted less polymerisation shrinkage stress than conventional microhybrid composite during and after the light curing process in class II posterior resin composite restorations98255261This study was supported by the Institute of Physics Gleb Wataghin (University of Campinas) and Dental Research Center Biomechanics, Biomaterials and Cell Biology (Dental School of Federal University of Uberlândia