Preparation and evaluation of new inorganic matrix composites containing submicron monomodal

In this study dental composites containing a novel monomodal inorganic matrix based on submicron Ba-Al-Si glass particles (NanoFine NF180, Schott) were prepared and evaluated. Composites with particles of similar composition but micron-sized (UltraFine UF1.0, Schott) served as a reference. The study was carried out in two phases: (i) characterization of the inorganic particles, involving x-ray microanalysis and granulometry; (ii) preparation and characterization of micron and submicron composites involving analysis of the morphology of the composites and measurements of radiopacity, degree of C=C conversion, hardness, flexural strength and modulus, work-of-fracture, surface roughness and gloss before and after toothbrushing abrasion and compressive creep. The composites were formulated from the same co-monomer based on Bis-GMA, Bis-EMA8, UDMA and TEGDMA at a 7:7:5:1 (w/w) ratio, with photoinitiators added. A mass of 75% of micron and 78% of submicron particles were incorporated based on pilot studies. Quantitative data restricted to direct comparisons between the composites were analyzed using t-tests. Roughness and gloss data for the comparison between the composites before and after toothbrushing were submitted to Repeated Measures Analysis of Variance and Student-Newman-Keuls test (5%). Both inorganic systems showed narrow grain size range (175±30 and 1000±200nm), with differences restricted to the size and specific area of the particles, which determined differences in the amount of silane used (13% for submicron and 3.2% for micron particles). Particles from both systems were homogeneously dispersed in the resin phase, although the submicron particles occupied larger area of the material s surface. The composites showed statistically similar results for radiopacity, flexural strength, work-of-fracture, and creep. The submicron composite had significantly higher hardness than the micron composite, whereas significantly lower flexural modulus and C=C conversion. No significant differences in roughness between the composites were observed before toothbrushing, while the submicron composite showed significantly higher gloss. The abrasion increased significantly the roughness and reduced the gloss of both materials. Surface roughness was still similar and the gloss of the submicron composite significantly higher after toothbrushing. In conclusion, the monomodal submicron glass filler system tested showed potential for application in the development of restorative dental composites, especially because of the esthetic properties compared with the micron systemNeste estudo, foram preparados e avaliados compósitos odontológicos contendo nova matriz inorgânica monomodal baseada em partículas de vidro de Ba-Al-Si (NanoFine NF180, Schott) de tamanho submicrométrico. Compósitos contendo partículas de composição similar, porém tamanho micrométrico (UltraFine UF1.0, Schott), foram testados como referência. O estudo se desenvolveu em duas fases: (i) caracterização de partículas inorgânicas, envolvendo microanálise de raios-x e granulometria; (ii) obtenção e caracterização de compósitos micro e submicrométricos envolvendo análise da morfologia dos compósitos preparados e determinação da radiopacidade, grau de conversão de C=C, dureza, resistência e módulo de flexão, trabalho de fratura, rugosidade e brilho da superfície antes e após desgaste por abrasão e escoamento compressivo (creep). Os compósitos foram formulados a partir do mesmo co-monômero baseado em Bis-GMA, Bis-EMA8, UDMA e TEGDMA, na razão 7:7:5:1 (m/m), ao qual fotoiniciadores foram adicionados. Foi acrescentada massa de 75% do sistema micrométrico e 78% do submicrométrico, com base em estudos-piloto. Os dados quantitativos restritos à comparação direta entre os compósitos foram analisados utilizando testes-t. Os dados de rugosidade e brilho na comparação dos compósitos antes e após a escovação foram submetidos à Análise de Variância para Medidas Repetidas e teste de Student-Newman-Keuls (5%). Ambos sistemas inorgânicos apresentaram estreita faixa do tamanho de grão (175±30 e 1000±200nm), com diferenças entre as partículas restritas ao tamanho e área específica, o que determinou diferença na quantidade de silano utilizada (13% para submicrométricas e 3,2% para micrométricas). As partículas de ambos sistemas foram dispersas de forma homogênea na matriz resinosa, embora as submicrométricas ocuparam maior área da superfície do material. Os compósitos apresentaram resultados estatisticamente similares para radiopacidade, resistência à flexão, trabalho de fratura e escoamento compressivo. O compósito submicrométrico apresentou dureza significativamente superior ao material micrométrico, enquanto módulo de elasticidade e grau de conversão foram significativamente menores. Não foi observada diferença significativa na rugosidade entre os compósitos antes da escovação, enquanto o compósito submicrométrico mostrou brilho significativamente maior. A abrasão aumentou significativamente a rugosidade e reduziu significativamente o brilho de ambos materiais. A rugosidade continuou estatisticamente similar e o brilho do compósito submicrométrico significativamente maior após a abrasão. Em conclusão, o sistema monomodal submicrométrico de carga de vidro testado apresentou potencial de utilização no desenvolvimento de compósitos restauradores odontológicos, especialmente em função de suas propriedades estéticas comparadas ao sistema micrométric

Surface treatments for repair of resin composite restorations

The aim of this study was to evaluate in vitro the performance of surface treatments of composite resins used to improve the repair ability of restorations. The study was developed in three stages: (1) systematic review of the literature on laboratory studies that compared different types of surface treatments used to enhance the repair bond strengths; (2) evaluation of the effect of diamond burs granulometry of used for abrasion of composites before the repair; (3) preparation and evaluation of experimental primers containing various concentrations of acidic monomer, silane, polyacrylic acid or methacrylic acid to enhance the repair potential of composite restorations. In stage 1, the search was conducted in three international databases, and included articles that assessed the repair bond strength of composite submitted to different surface treatments (control: untreated composite). In total 15 articles were included, the bond strength data extracted and subjected to meta-analysis using random effects model. Data showed that the application of chemical or physical + chemical surface treatments improve the repair bond strengths. In stage 2, fresh or aged composites were treated with medium, fina (F) or extra-fine (FF) diamond burs. The best repair ability was observed when the fine diamond bur was used, while aging did not affect significantly the composite repair ability, particularly due to the rougher aspect of aged composite. In stage 3, divided into two articles, the composites were treated using experimental primers and the repair bond strengths were characterized. Application of primers improved the bond strengths compared to the control groups (no composite treatment), being the best combination of formulation observed for the presence of up to 10 wt% acidic monomer, silane, polyacrylic and methacrylic acids. Analyzing the three stages of this study, it can be concluded that application of physical surface treatments (such as fine-grit diamond bur), chemical surface treatments (such as resin-based primers) and combination of physical + chemical treatments might positively influence the bond strength of dental methacrylate-based composite restoratives. The use of surface treatments prior to composite repair should, thus, be encouraged in clinical practice.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESO objetivo deste estudo foi avaliar in vitro o desempenho de tratamentos de superfície de resinas compostas visando melhoria da capacidade de reparo das restaurações. O estudo se desenvolveu em três etapas: (1) revisão sistemática da literatura acerca de estudos laboratoriais que comparassem diferentes tipos de tratamentos superficiais utilizados para aprimorar a resistência de união de reparos; (2) avaliação do efeito da granulometria de pontas diamantadas utilizadas na asperização de resinas compostas antes do reparo; (3) preparo e avaliação de primers experimentais contendo variadas concentrações de monômero ácido, silano, ácido poliacrílico ou ácido metacrílico para potencializar o reparo de restaurações de compósito. Na etapa 1, a busca foi realizada em três bases de dados internacionais, sendo incluídos artigos que tivessem avaliado a resistência de união de reparos de resina composta submetida a diferentes tratamentos (controle: compósito não tratado). Ao todo 15 artigos foram incluídos, os dados de resistência de união extraídos e submetidos a meta-análise utilizando modelo de efeitos aleatórios. Os dados mostraram que a aplicação de tratamentos de superfície químicos ou físicos + químicos melhoram a resistência de união dos reparos. Na etapa 2, compósitos “novos” ou envelhecidos foram tratados com pontas diamantadas de granulação média, fina (F) ou extrafina (FF). Melhor capacidade de reparo foi observada quando a ponta diamantada fina foi utilizada, enquanto o envelhecimento do compósito não afetou significativamente a capacidade de reparo, especialmente pelo compósito envelhecido estar mais rugoso. Na etapa 3, dividida em dois artigos, os compósitos foram tratados utilizando primers experimentais e a resistência de união dos reparos foi caracterizada. Observou-se que os primers aprimoram a resistência de união dos reparos comparados aos grupos controle (sem tratamento do compósito), sendo a melhor combinação de composição observada para a presença de até 10% em massa de monômero ácido, silano, ácido poliacrílico e ácido metacrílico. Ao promover análise das três fases deste estudo, conclui-se que os tratamentos superficiais físicos (como pontas diamantadas de granulação fina), químicos (como primers resinosos) e a combinação de tratamentos físicos + químicos podem influenciar positivamente a resistência de união do procedimento reparador de compósitos odontológicos à base de metacrilatos. Dessa forma, a utilização de tratamentos de superfície previamente ao reparo deve ser encorajada na prática clínica

Conservative dentistry: non-beveled esthetic restorations in anterior teeth

The pursuit of esthetic excellence in dentistry today requires dental practitioners to enhance their knowledge and technique in restorations of the anterior teeth. Due to the high incidence and prevalence of fractures in this dental area, mimicking the optical properties and characteristics of the dental structure in young patients (aged 6 to 15 years) is a major challenge. This case report describes the minimally invasive, non-beveled restoration of two fractured anterior teeth (class IV). After diagnosing fractures of teeth 11 and 21 in a 10-year-old patient, a composite mock-up was performed, followed by a diagnostic wax-up. With the aid of a silicon guide, the restorations were prepared without beveling the enamel surface. We performed color stratification by using different types of composite resins. Finally, finishing and polishing procedures were carried out

New material perspective for endocrown restorations: effects on mechanical performance and fracture behavior

Abstract The aim of this study was to investigate the mechanical performance and the fracture behavior of endocrown restorations prepared using distinct restorative materials. A total of 42 sound molars with similar crown size and shape were cut at 2 mm above the cementoenamel junction and endodontically treated. They were categorized according to the restorative material used to fabricate endocrown restorations (n=7), namely, conventional composite (Filtek™ Z350 XT), bulk fill composite (Filtek™ Bulk Fill), conventional composite modeled using resin adhesives (SBMP: Scotchbond™ Multipurpose Adhesive; or SBU: Scotchbond™ Universal Adhesive), and IPS e.max lithium disilicate (Ivoclar Vivadent; positive control). Unprepared sound teeth were used as negative control. All endocrowns were bonded using a self-adhesive cement (Rely-X™ U200). The teeth were submitted to fatigue (Byocycle) and fracture (EMIC DL500) testing. Load-to-fracture (in N) and work-of-fracture (Wf, in J/m2) values were analyzed by ANOVA (p 0.05). The endocrowns fabricated by combining Z350 and SBMP had the least harsh fractures, in contrast to endocrowns prepared using Z350 only, which exhibited an equilibrium between repairable and irrepairable fractures. The e.max endocrowns exhibited more aggressive failures (root fracture) than other groups, resulting in higher rates of irrepairable fractures. In conclusion, dental practitioners may satisfactorily restore severely damaged nonvital teeth using the endocrown technique. Composite endocrowns prepared using resin adhesive as modeler liquid or using bulk fill material may result in less aggressive failures, thus providing a new material perspective for endocrown restorations

Influence of surface moisture condition on the bond strength to dentin of etch and rinse adhesive systems

evaluate the immediate microtensile bond strength (&#956;TBS) of three two-step etch-andrinse adhesive systems applied under different dentin surface moisture conditions. Methods: Class V cavities were prepared in seventy-two bovine incisors. Each tooth was randomly allocated into three groups, according to the adhesive system used: Single Bond 2 (SB), Prime & Bond 2.1 (PB) and XP Bond (XPB). Each group was divided in three subgroups, according to the dentin moisture condition: over-wet, moist and dry (n=8). For the moist subgroups the adhesive was applied as to the manufacturers instructions; for the over-wet ones, without drying the cavity after the rinsing procedure; and for the dry subgroups, drying the surface for 20 s. The teeth were restored with Filtek Z-250 and stored in distilled water (24 h); next, each restoration was sectioned in beam-shaped specimens which were stored for 24 h at 37 °C. Each specimen was submitted to &#956;TBS test (EMIC), and data were analyzed using two-way ANOVA and Tukey test (p<0.05). Results: There was a statistically significant interaction between the adhesive system type and the dentin surface moisture condition (p=0.003). SB and XPB presented higher bond strength in the moist dentin condition, and PB showed high &#956;TBS values in the dry substrate. Conclusions: The moisture condition influenced the bond strength between the adhesives and dentin. SB performed better in the moist condition, whereas PB and XPB showed satisfactory bond strength in the moist and in the dry substrates. The over-wet dentin condition only impaired bond strength to SB and XPB