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PURPOSE: To assess the effect of preheating resin-based materials and ultrasound application on the failure load of a lithium disilicate glass-ceramic. MATERIALS AND METHODS: Ninety ceramic specimens were produced (14×12×1.0 mm) and divided into 9 groups (n = 10) to be bonded to a dentin analog (Nema G10) with light-cured luting agent (LC), flowable resin composite (FL), and supra-nano filled resin composite (SN), as follows: LC/R - LC at room temperature; LC/P - preheated LC; LC/P/U - preheated LC and Ultrasound; FL/R - FL at room temperature; FL/P - preheated FL; FL/P/U - preheated FL and Ultrasound; SN/R - SN at room temperature; SN/P - preheated SN; SN/P/U - preheated SN and Ultrasound. The failure load test was performed in a universal testing machine with the aid of acoustic detection. The data was analyzed with two-way ANOVA (for failure load) and Weibull statistics (Weibull modulus - m and characteristic strength, based on 95% confidence intervals - CI). RESULTS: The analyses of failure load revealed no statistically significant difference among groups considering the type of luting agent (P = 0.075; F = 2,673), the application method (P = 0.772; F = 2,259), and the interaction between them (P = 0.297; F = 1,248). The characteristic strength did not show differences among groups (95% CI). The m, which indicates structural reliability, showed lower values for SN/P/U and SN/P, with a difference from other selected groups (95% CI). CONCLUSION: Preheating of resin-based materials and ultrasound application did not affect the failure load of lithium disilicate glass-ceramic. Lower reliability was observed with supra-nano filled resin composite.

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This study aims to evaluate the fatigue resistance of monolithic zirconia (Yz) and multilayer ceramic structures using the CAD-on technique in different thicknesses. Fifty (N=50) standardized single crowns preparations were made in fiberglass-reinforced epoxy resin (NEMA grade G10), digitalized, and restorations were machined in CAD-CAM, composing 5 groups (n= 10): Control: 1.5 mm (milled zirconia framework + manual layered porcelain); Yz monolithic 1.5 mm; Yz monolithic 1.0 mm; CAD-on 1.5 mm; and CAD-on 1.0 mm (milled zirconia framework 0.5 mm thickness bonded by a low fuse ceramic to a milled lithium disilicate layer of 1.0 mm or 0.5 mm, respectively). The G10 bases were conditioned with 10% hydrofluoric acid; the crowns were air abraded with 110 µm alumina particles; and then luted onto each other with self-adhesive resin cement. A cyclic fatigue test was performed (initial load: 400N for 10,000 cycles, frequency of 20 Hz, step size of 200N) until failure, and the data was submitted to a survival statistical analysis. No failures were observed at Yz monolithic 1.5 mm. High and similar performance was observed for Cad-On groups and Yz monolithic 1.0 mm. The control group depicted the worst behavior. The Weibull modulus of CAD-on 1.5 mm was higher than the control while being similar to the other conditions. Both the monolithic systems and the CAD-on technique showed high and similar fatigue fracture behavior and survival rates, which were also higher than the control bilayer system. Both systems reduced the occurrence of delamination failures, making them suitable for clinical use.

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Abstract This study aims to evaluate the fatigue resistance of monolithic zirconia (Yz) and multilayer ceramic structures using the CAD-on technique in different thicknesses. Fifty (N=50) standardized single crowns preparations were made in fiberglass-reinforced epoxy resin (NEMA grade G10), digitalized, and restorations were machined in CAD-CAM, composing 5 groups (n= 10): Control: 1.5 mm (milled zirconia framework + manual layered porcelain); Yz monolithic 1.5 mm; Yz monolithic 1.0 mm; CAD-on 1.5 mm; and CAD-on 1.0 mm (milled zirconia framework 0.5 mm thickness bonded by a low fuse ceramic to a milled lithium disilicate layer of 1.0 mm or 0.5 mm, respectively). The G10 bases were conditioned with 10% hydrofluoric acid; the crowns were air abraded with 110 μm alumina particles; and then luted onto each other with self-adhesive resin cement. A cyclic fatigue test was performed (initial load: 400N for 10,000 cycles, frequency of 20 Hz, step size of 200N) until failure, and the data was submitted to a survival statistical analysis. No failures were observed at Yz monolithic 1.5 mm. High and similar performance was observed for Cad-On groups and Yz monolithic 1.0 mm. The control group depicted the worst behavior. The Weibull modulus of CAD-on 1.5 mm was higher than the control while being similar to the other conditions. Both the monolithic systems and the CAD-on technique showed high and similar fatigue fracture behavior and survival rates, which were also higher than the control bilayer system. Both systems reduced the occurrence of delamination failures, making them suitable for clinical use.

Resumo Este estudo teve como objetivo avaliar o comportamento à fadiga de estruturas cerâmicas monolíticas de zircônia (Yz) e multicamadas utilizando a técnica CAD-on em diferentes espessuras. Cinquenta (N=50) preparos unitários padronizados foram confeccionados em resina epóxi reforçada com fibra de vidro (NEMA grau G10), digitalizados e as restaurações usinadas em CAD-CAM, compondo 5 grupos (n= 10): Controle: 1,5 mm (estrutura de zircônia fresada + porcelana estratificada manualmente); Yz monolítica 1,5 mm; Yz monolítica 1,0 mm; CAD-on em 1,5 mm; e CAD-on 1,0 mm (estrutura de zircônia fresada com 0,5 mm de espessura ligada por uma cerâmica de baixa fusão a uma camada de dissilicato de lítio fresado de 1,0 mm ou 0,5 mm, respectivamente). As bases do G10 foram condicionadas com ácido fluorídrico a 10%; as coroas foram jateadas com partículas de alumina de 110 μm; e então cimentadas uma sobre a outra com cimento resinoso autoadesivo. Foi realizado um teste de fadiga cíclica (carga inicial: 400N para 10.000 ciclos, frequência de 20 Hz, step de 200N) até a falha, e os dados foram submetidos a uma análise estatística de sobrevivência. Nenhuma falha foi observada para Yz monolítica de 1,5 mm. Desempenho alto e semelhante foi observado para os grupos Cad-On e Yz monolítica 1,0 mm. O grupo controle apresentou o pior comportamento. O módulo de Weibull do CAD-on 1,5 mm foi maior que o grupo controle, sendo semelhante às outras condições. Tanto os sistemas monolíticos quanto a técnica CAD-on apresentaram alto e semelhante desempenho mecânico e taxas de sobrevivência, que também foram superiores ao sistema bicamada de controle. Ambos os sistemas reduziram a ocorrência de falhas de delaminação, tornando-os adequados para uso clínico.

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STATEMENT OF PROBLEM: Preheated composite resin and adhesive coating have been recommended as luting agents for ceramic veneers; however, information about the mechanical behavior of feldspathic porcelain veneers after using these methods is still limited. PURPOSE: The purpose of this in vitro study was to evaluate the influence of the use of preheated composite resin or an adhesive resin layer on the strengthening of a feldspathic porcelain. MATERIAL AND METHODS: Feldspathic porcelain disks were fabricated (N=210), etched (10% hydrofluoric acid for 90 seconds), and bonded according to resin-based luting agents (30 per group) for the biaxial flexural strength tests: photopolymerized resin cement, flowable composite resin, preheated composite resin, with or without previous adhesive coating. Characteristic strength and Weibull modulus were calculated. The viscosity of the luting agents was measured by using isothermal analyses. Finite element analysis simulated the flexural test. Fractographic and bonded interfaces were observed. RESULTS: The use of preheated composite resin led to the lowest stress levels in the feldspathic porcelain veneers. However, it did not increase the ceramic strengthening compared with other luting agents, as higher values were observed with flowable composite resin (P<.05). The use of an adhesive resin layer had no significant effect on ceramic strengthening when associated with preheated composite resin or resin cement (P>.05). Preheated composite resin presented the highest viscosity and led to incomplete filling of the porcelain surface irregularities. Failures originated on the ceramic surface subjected to tensile stress and were typically associated with pores at the ceramic-luting agent interface. CONCLUSIONS: The use of preheated composite resin or an adhesive resin layer did not have a positive effect on strengthening feldspathic porcelain.

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Objetivo: O objetivo do estudo foi avaliar o uso de diferentes marcas de silano na resistência de união entre a cerâmica de dissilicato de lítio e o cimento resinoso. A hipótese nula avaliada foi que as diferentes marcas de silanos apresentariam similar resistência de união. Métodos: Foram confeccionados 80 discos de dissilicato de lítio (IPS E.max CAD) com (12 mm x 1 mm). Após a cristalização, foram incluídos em tubos de PVC com resina acrílica e polidos com lixas de carbeto de silício, sob irrigação com água. Após aplicação de ácido hidrofluorídrico 10%, foram lavados e secos e divididos aleatoriamente em 4 grupos para aplicação do silano (n=20). S-Y: Yller; S-M: Monobond N; S-U: Ultradent; S-DS: Dentsply Sirona. Uma matriz de silicone com 4 orifícios foi confecionada e preenchida posteriormente com o cimento resinoso (Multilink N) para realização do teste de microcilhamento (EMIC) e os dados foram avaliados pelo teste one-way ANOVA. Resultados: Análise de variância mostrou que não houveram diferenças estatísticas nos valores médios entre os grupos de tratamento (p=0,404). A média e desvio padrão (DP) da resistência de união (MPa) nos grupos foram: S-Y: 26,9 (6,3); S-M: 28,3 (5,8); S-U: 29,0 (8,0); S-DS: 31,8 (11,0). Conclusões: As diferentes marcas de silano avaliadas apresentaram resistência de união similar entre si. Porém, a aplicação de silano é fundamental para obter melhorias na resistência de união(AU)

Objective: To evaluate the use of different brands of silane in the bond strength between lithium disilicate and resin cement. The null hypothesis evaluated was that the different brands of silanes would present similar bond strength. Methods: 80 lithium disilicate discs (IPS E.max CAD) were made with 12 mm in diameter x 1 mm in thickness. After crystallization, they were included in PVC tubes with acrylic resin and polished with silicon carbide sandpaper, under irrigation with water, creating a smooth and flat surface and randomly divided into 4 groups (n = 20). G1: Yller; G2: Monobond N; G3: Ultradent; G4: Dentsply Sirona. The samples were stored for 24h in distilled water for subsequent microcutting testing. One-way analysis of variance was used to obtain the results. Results: Analysis of variance showed that there were no statistical differences in the mean values between the treatment groups (p = 0.404). The mean and standard deviation (SD) of the bond strength (MPa) in the groups were: G1: 26.9 (6.3); G2: 28.3 (5.8); G3: 29.0 (8.0); G4: 31.8 (11.0). Conclusions: The different brands of silane evaluated showed similar bond strength. However, application of silane is essential to obtain improvements in bond strength(AU)

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OBJECTIVE: This study sought to describe the clinical and laboratory procedures and to discuss aspects involved in obtaining satisfactory esthetics on substrates presenting different colors. CLINICAL CONSIDERATIONS: This case report describes the clinical and laboratory procedures for obtaining an optimal esthetic result using different ceramic framework materials veneered with feldspathic ceramic over substrates of different colors. Zirconia frameworks were used for darkened substrates and were reinforced with lithium disilicate for substrates with minimal discoloration. The same feldspathic veneering ceramic was applied to provide similar translucency and color for favorable esthetics. CONCLUSIONS: The materials explored in the present case report presented favorable aesthetic results in masking darkened substrates. CLINICAL SIGNIFICANCE: Clinicians should consider the condition and color of the substrate when selecting the restorative material for masking such a condition.

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OBJECTIVE: To evaluate the cyclic contact fatigue resistance and failure mode of ceramics for monolithic and multilayer restorations. METHODS: Ceramic structures (10 mm × 1.8 mm) were fabricated as follows (n = 28): (1) CAD-on- trilayer structure composed of Y-TZP (yttria stabilized tetragonal zirconia polycrystal- IPS e.max ZirCAD) infrastructure, fusion glass-ceramic (IPS e.max CAD Crystall/Connect) and lithium disilicate-based glass-ceramic (IPS e.max CAD); (2) ZFC- bilayer structure composed of Y-TZP infrastructure veneered by a fluorapatite glass-ceramic (IPS e.max Ceram); (3) LDC- monolithic lithium-disilicate glass-ceramic (IPS e.max CAD); and (4) YZW- monolithic Y-TZP (Zenostar Zr Translucent). All ceramics structures were bonded to a dentin analog substrate (G10). Specimens were submitted to cyclic contact fatigue test in a pneumatic cycling machine with 80 N load and 2 Hz frequency in distilled water at 37 °C. Test was interrupted after 104, 105, 5 × 105 and 106 cycles and the presence or absence of failure was recorded. Fatigue data were analyzed using Kaplan-Meier (log rank) and Holm-Sidak tests (α = 0.05). The relationship between the type of crack leading to failure and the experimental group was analyzed using chi-square test (α = 0.05). RESULTS: There was no statistical difference between CAD-on and YZW groups (p = 0.516), which presented the highest survival rates after cyclic loading, followed by ZFC and LDC groups (p < 0.01). There was a significant relationship between type of crack and experimental group (p < 0.001). LDC specimens showed the greatest frequency of radial cracks, while cone cracks were more prevalent for ZFC and CAD-on specimens. SIGNIFICANCE: Monolithic Y-TZP (YZW) showed similar fatigue resistance to CAD-on multilayer specimens, but different failure mode. Monolithic lithium disilicate glass-ceramic (LDC) and Y-TZP conventionally veneered by glass-ceramic (ZFC) showed lower survival time under fatigue.

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This study evaluated the fracture load (Lf) and the failure mode of CAD-on (Ivoclar Vivadent) ceramic structures, testing the hypotheses that Lf of multilayer structures is governed by the veneering ceramic strength and that chipping is more frequent in multilayer than monolithic structures. Disc-shaped specimens were fabricated as follows: CAD-on- trilayer structure composed of Y-TZP (yttria stabilized tetragonal zirconia polycrystal- IPS e.max ZirCAD) infrastructure, fusion glass-ceramic (IPS e.max CAD Crystall/Connect) and lithium disilicate-based glass-ceramic (IPS e.max CAD); YLD- bilayer structure composed of Y-TZP infrastructure and fluorapatite layering ceramic (IPS e.max Ceram); LDC- monolithic lithium-disilicate glass-ceramic (IPS e.max CAD); and YZW- monolithic Y-TZP (Zenostar Zr Translucent). The specimens were loaded in compression until failure and fracture surfaces were evaluated using fractographic principles. Lf values were statistically analyzed using the Weibull statistics, Kruskal-Wallis and Dunn tests (a= 0.05). YZW (1329 N) and CAD-on (1085 N) showed the greatest Lf median values, followed by YLD (832 N) and LDC (421 N). All monolithic structures (LDC and YZW) fractured catastrophically and all YLD structures failed by chipping. The CAD-on technique seems to be a very promising fabrication process because it showed high Lf, similar to monolithic zirconia, and small chipping rate.

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Objetivos: Avaliar a resistência adesiva de diferentes sistemas adesivos universais em esmalte e dentina erodidos. Métodos: As unidades experimentais foram compostas por 30 fragmentos de esmalte bovino e 30 fragmentos de dentina bovina divididos aleatoriamente em três grupos experimentais de acordo com os sistemas adesivos universais utilizados (n = 10): Single Bond Universal (3M ESPE), Peak Universal (Ultradent) e Ambar Universal (FGM). Previamente as restaurações, os fragmentos de esmalte e dentina foram submetidos à desafio erosivo em ácido cítrico a 0,3% (pH = 2,6) durante cinco minutos, quatro vezes por dia por cinco dias. Um cilindro de resina composta (Forma, Ultradent) com 2mm de diâmetro foi construído em cima de cada fragmento. A resistência ao cisalhamento foi avaliada em máquina de ensaio universal (1mm/min). Os valores obtidos de resistência da união (MPa) foram analisados por ANOVA dois fatores e teste de Bonferroni (α=0,05). Resultados: Não houve diferença significativa entre os sistemas adesivos testados no mesmo substrato. O esmalte apresentou maiores valores de resistência da união que a dentina. Houve predomínio da falha coesiva em resina no esmalte e falha adesiva na dentina. Conclusão: Os sistemas adesivos universais testados apresentaram resistência adesiva semelhantes entre si dentro do mesmo substrato erodido(AU)

Objectives: To evaluate the strength of different universal adhesive systems in enamel and eroded dentine. Materials and Methods: The experimental units were composed of 30 bovine enamel fragments and 30 bovine dentin fragments randomly divided into three experimental groups of enamel and three groups of dentin. The enamel and dentin samples were submitted to erosive challenge and procedures adhesion with adhesive systems divided into three levels according with universal adhesive systems used (n = 10): Single Bond Universal (3M ESPE), Peak Universal (Ultradent) and Ambar Universal (FGM). Previous the restorations, the enamel and dentin fragments were submitted to erosive challenge in 0.3% citric acid (pH = 2.6) for five minutes, four times per day in five days. A composite resin (Forma, Ultradent) cylinder with 2mm diameter was build-up in each fragment. The shear strength was evaluated in a universal test machine (1mm / min). The obtained values of bond strength (MPa) were analyzed by two-way ANOVA and Bonferroni test (α = 0.05). Results: There was no significant difference between adhesive systems tested on the same substrate. The enamel presented higher values of bond strength than dentin. There was a predominance of cohesive failure in resin in enamel and adhesive failure in dentin. Conclusions: The universal adhesive systems tested showed similar adhesive strength in the same eroded substrate(AU)

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Objetivos: O presente estudo buscou avaliar a resistência de união ao cisalhamento de dois sistemas adesivos aplicados em diferentes quantidades de camadas em amostras de esmalte e dentina bovina. Métodos: Os fatores estudados foram os sistemas adesivos em dois níveis: Single Bond Universal e Single Bond 2. As amostras experimentais foram compostas por 30 fragmentos de esmalte bovino (n=5) e 30 fragmentos de dentina bovina (n=5) divididos aleatoriamente em 2 grupos experimentais de esmalte e dois grupos de dentina, sendo esses subdivididos em 3 modos de aplicação do sistema adesivo em 1, 2 ou 3 camadas. Resultados: Os adesivos Single Bond 2 e Single Bond Universal, quando aplicados em 1 ou 3 camadas em dentina ou esmalte apresentaram similaridade estatística (p= 0,8726). Já quando comparamos o sistema adesivo Single Bond 2 e Single Bond Universal em substrato dentinário a aplicação de 2 camadas do sistema adesivo implicam em aumento da resistência adesiva estatisticamente significante (p=0,000) para o grupo Single Bond Universal aplicado em dentina. Conclusão: O adesivo Single Bond Universal apresentou melhor resistência adesiva que o adesivo Single Bond 2 quando aplicados em duas camadas em substrato dentina. Para o substrato esmalte, ambos os sistemas adesivos são efetivos independente do número de camadas aplicadas(AU)

Objectives: The present study aimed to evaluate the shear bond strength of two adhesive systems applied in different amounts of enamel and bovine dentin layers. Methods: The factors studied were adhesive systems at two levels: Single Bond Universal and Single Bond 2. The experimental samples were composed of 30 bovine enamel fragments (n = 5) and 30 bovine dentin fragments (n = 5) randomly divided into two experimental groups of enamel and two groups of dentin, subdivided into 3 different application modes adhesive system in 1, 2 or 3 layers. Results: The Single Bond 2 and Universal Bond adhesives, when applied in one or three layers in to the dentin or enamel, presented statistical similarity (p=0.8726). When comparing the Single Bond 2 and Single Bond Universal adhesive system in the dentin substrate, the application of two layers of the adhesive system implies an increase in the statistically significant adhesive resistance (p=0,000) for the Universal Single Bond group applied to dentin. Conclusion: The Single Bond Universal adhesive presented a higher adhesive strength than Single Bond 2 adhesive when applied in two layers on dentin substrate. For the enamel substrate, both adhesive systems are effective regardless of the number of layers applied

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