Hydrofluoric acid concentration, time and use of phosphoric acid on the bond strength of feldspathic ceramics

Abstract The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.

Effect of hydrofluoric acid concentration and etching time on resin-bond strength to different glass ceramics

Abstract: The objective of this study was to evaluate the effect of the hydrofluoridric acid (HF) concentration and time of acid conditioning on bond strength of three glass ceramics to a resin cement. Thus, fifty blocks (10 mm x 5 mm x 2 mm) of each ceramic (LDCAD: IPS e.max CAD; LCAD: IPS Empress CAD and LDHP: IPS e.max Press) were made and embedded in acrylic resin. The surfaces were polished with sandpaper (#600, 800, 1000, and 1200 grits) and blocks were randomly divided into 15 groups (n = 10) according to the following factors: Concentration of HF (10% and 5%), conditioning time (20 s and 60 s) and ceramic (LDCAD, LDHP, and L). After conditioning, silane (Prosil / FGM) was applied and after 2 min, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block using a Teflon strip as matrix and light cured for 40 s (1,200 mW/cm2). Then, the samples were thermocycled (10,000 cycles, 5/55°C, 30s) and submitted to the shear bond test (50 KgF, 0.5 mm/min). The data (MPa) were analyzed with 3-way ANOVA and Tukey's test (5%). Failure analysis was performed using a stereomicroscope (20x) and a scanning electron microscope (SEM). ANOVA revealed that the "concentration" factor (p = 0.01) and the interaction "acid concentration X ceramic" (p = 0.009) had a significant effect, however, the "ceramic" (p = 0.897) and "conditioning time" (p = 0.260) factors did not influence the results. The LDHP10%60s (10.98 MPa)aA* group presented significantly higher bond strength than LDHP10%20s (6.57 MPa)bA, LCAD5%20s (6,90 ±3,5)aB and LDHP5%60s (5.66 ± 2,9MPa)aA* groups (Tukey). Failure analysis revealed that 100% of specimens had mixed failure. In conclusion, etching with 5% HF for 20 seconds is recommended for lithium disilicate and leucite-reinforced CAD/CAM ceramics. However, for pressed lithium disilicate ceramic, 10% HF for 60 s showed significantly higher bond strength to resin cement.

Adhesion to a lithium disilicate glass ceramic etched with hydrofluoric acid at distinct concentrations

Abstract This study evaluated the effect of different hydrofluoric acid (HF) concentrations on the bond strength between a lithium disilicate-based glass ceramic and a resin cement. Eighty ceramic-blocks (12×7×2 mm) of IPS e.Max CAD (Ivoclar Vivadent) were produced and randomly assigned to 8 groups, considering 2 study factors: HF concentration in 4 levels, i.e., 1% (HF1), 3% (HF3), 5% (HF5), and 10% (HF10), and storage in 2 levels, i.e., baseline (tests were performed 24 h after cementation), and aged (storage for 150 days + 12,000 thermal-cycles at 5°C and 55°C). Acid etching (20 s) was performed, followed by washing, drying, and silanization. Four resin cement cylinders (ϕ= 0.96 mm) were built-up from starch matrices on each ceramic sample (n= 40). Additional ceramic samples were etched and analyzed for contact angle, micro-morphology, and roughness. In baseline condition (without aging), the HF3, HF5, and HF10 groups showed similar bond strength values (13.9 - 15.9 MPa), and HF1 (11.2 MPa) presented lower values than HF5, being that statistically different (p= 0.012). After aging, all the mean bond strengths statistically decreased, being that HF3, HF5, and HF10 (7.8 - 11 MPa) were similar and higher than HF1 (1.8 MPa) (p= 0.0001). For contact angle, HF3, HF5, and HF10 presented similar values (7.8 - 10.4°), lower than HF1 and CTRL groups. HF5 and HF10 presented rougher surfaces than other conditions. For better bond strength results, the tested ceramic may be etched by HF acid in concentrations of 3%, 5%, and 10%.

Resumo Este estudo avaliou o efeito de diferentes concentrações de ácido fluorídrico (HF) na resistência de união entre uma cerâmica vítrea à base de dissilicato de lítio e um cimento resinoso. Oitenta blocos cerâmicos (12×7×2 mm) de IPS e.Max CAD (Ivoclar Vivadent) foram produzidos e distribuídos aleatoriamente em 8 grupos, considerando 2 fatores de estudo: concentração de HF em 4 níveis, isto é, 1% (HF1), 3% (HF3), 5% (HF5), e 10% (HF10), e armazenamento em 2 níveis, isto é, condição inicial (testes foram realizados 24 h após a cimentação), e envelhecidos (150 dias de armazenamento + 12.000 ciclos térmicos a 5°C e 55°C). Condicionamento ácido (20 s) foi realizado, seguido por lavagem, secagem e silanização. Quatro cilindros de cimento resinoso (ϕ= 0.96 mm) foram construídos a partir de matrizes de amido em cada amostra cerâmica (n= 40). Amostras cerâmicas adicionais foram condicionadas e analisadas quanto ao ângulo de contato, micro-morfologia e rugosidade. Na condição inicial (sem envelhecimento), os grupos HF3, HF5, e HF10 mostraram valores de resistência de união similares (13.9 - 15.9 MPa), e HF1 apresentou valores menores que HF5, sendo estatisticamente diferente (p= 0.012). Após o envelhecimento, todas as médias de resistência de união diminuíram estatisticamente, sendo que HF3, HF5 e HF10 foram similares e maiores que HF1 (p= 0.0001). Para o ângulo de contato, HF3, HF5 e HF10 apresentaram valores similares (7.8 - 10.4°), menores que os grupos HF1 e CTRL. HF5 e HF10 apresentaram superfícies mais rugosas que as outras condições. Para melhores resultados de resistência de união, a cerâmica testada pode ser condicionada com ácido fluorídrico nas concentrações de 3%, 5% e 10%.

The effect of hydrofluoric acid and resin cement formulation on the bond strength to lithium disilicate ceramic

Abstract To investigate how the hydrofluoric acid (HF) concentrations applied to a lithium disilicate glass-ceramic (EMX) affects the surface morphology and microtensile bond strength (μTBS) of ceramics to dentin, using light-cured resin cements with or without UDMA. Sixty-three EMX square ceramic blocks were etched for 20 seconds using different HF concentrations (1%, 5% and 10%) and luted to dentin using two types of resin cement combinations: BisGMA/TEGDMA and BisGMA/TEGDMA/UDMA (n = 10). Each bonded EMX-dentin block was sectioned to obtain 1 mm2 sticks for μTBS evaluation. Half of the sticks were tested after 24 hours and the other half was assessed after 6 months of water storage. Data were statistically assessed using split-plot three-way ANOVA and multiple comparisons were performed using the Tukey's post hoc test (α = 0.05). One EMX sample from each HF concentration was analyzed using field-emission scanning electron microscope (FE-SEM) to characterize the etching pattern. According to the FE-SEM images, increasing the concentration of HF from 1 to 5 and then to 10% led to increased removal of glassy matrix and greater exposure of lithium disilicate crystals. The 10% HF concentration yielded higher μTBS when compared to 1% for BisGMA/TEGDMA formulation (p < 0.05); whereas HF 1% and 5% showed similar μTBS values when compared to 10% HF for BisGMA/TEGDMA/UDMA resin matrix (p > 0.05) at both storage times. Water aging decreased the μTBS values (p < 0.05), except when 10% HF was associated with BisGMA/TEGDMA resin cement. Resin cement formulation and hydrofluoric acid concentrations can interfere with the immediate and long-term glass-ceramic bond strength to dentin.

The Effect of Hydrofluoric Acid Concentration and Heat on the Bonding to Lithium Disilicate Glass Ceramic

Abstract The aim of this study was to evaluate the effects of hydrofluoric acid (HF) concentration and previous heat treatment (PHT) on the surface morphology and micro-shear bond strength (mSBS) of a lithium disilicate glass ceramic (EMX) to resin cement. One hundred four EMX specimens were randomly assigned to two groups (n=52) according to the HF concentration: 5% and 10%. A new random distribution was made according to the PHTs (n=13): control (no PHT); previously heated HF (70 °C); previously heated EMX surface (85 °C); the combination of heated HF + heated EMX surface. The etching time was set at 20 s. All EMX blocks were silanated and received a thin layer of an unfilled resin. Five resin cement cylinders were made on each EMX surface using Tygon tubes as matrices, and then stored for 24 h at 37 °C. One random etched EMX sample from each group was analyzed using field-emission scanning electron microscopy (FE-SEM). The data were subjected to two-way ANOVA and multiple comparisons were performed using the Tukey post hoc test (a=0.05). For the control groups, 5% HF showed statistically lower mSBS values when compared to 10% HF (p<0.05). PHT increased the mSBS values for 5% HF, yielding statistically similar results to non-PHT 10% HF (p<0.05). FE-SEM images showed increased glassy matrix removal when PHT was applied to HF 5%, but not to the same degree as for 10% HF. PHT has the potential to improve the bond strength of 5% HF concentration on lithium disilicate glass ceramic.

Resumo O objetivo deste estudo foi avaliar os efeitos das concentrações de ácido fluorídrico (AF) e do prévio tratamento térmico (PTT) na morfologia da superfície e resistência de união ao microcisalhamento (mRUM) de uma cerâmica vítrea de dissilicato de lítio (EMX) ao cimento resinoso. Cento e quatro espécimes de EMX foram aleatoriamente distribuídos em dois grupos (n=52) de acordo com a concentração do AF: 5% e 10%. Os espécimes foram novamente distribuídos de forma aleatória de acordo com o PTT (n=13): controle (sem PTT); AF previamente aquecido (70 °C); superfície do EMX previamente aquecida (85 °C); combinação entre AF e EMX aquecidos. O tempo de condicionamento foi fixado em 20 s. Todos os espécimes de EMX foram silanizados e receberam a aplicação de uma fina camada de um adesivo sem carga. Cinco cilindros de cimento resinoso foram confeccionados usando tubos Tygon como matrizes e então armazenados por 24 h a 37 °C. Uma amostra condicionada de cada grupo foi aleatoriamente selecionada e analisada em um microscópio eletrônico de varredura em emissão de campo (MEVEC). Os dados foram submetidos ao teste ANOVA de dois fatores e múltiplas comparações foram feitas pelo teste de Tukey (a=0.05). Para os grupos controle, AF 5% mostrou valor de mRUM estatisticamente menor do que AF 10% (p<0.05). PTT aumentou os valores de mRUM para o AF 5%, proporcionando resultados estatisticamente similares ao grupo AF 10% controle (p<0.05). MEVEC mostrou um aumento na remoção da matriz vítrea quando o PTT foi aplicado ao grupo AF 5%, no entanto esse efeito não foi visto no grupo AF 10%. O PTT tem o potencial de melhorar a resistência de união do AF 5% na cerâmica vítrea reforçada por disilicato de lítio.

Micromorfología superficial de 2 cerámicas grabables tratadas con diferentes ácidos / Superficial micromorphology of 2 etchable ceramics treated with different acids

Para lograr una unión fuerte entre las restauraciones de cerámica sin metal y las resinas de cementación se indican acondicionamientos de superficie previos a la cementación. Nuestro objetivo es describir y comparar al MEB las superficies de cerámicas feldespáticas y reforzadas con disilicato de litio antes y después de ser tratadas con 2 procedimientos ácidos. Se utilizaron 8 bloques de cerámica feldespática (A) y 8 de cerámica reforzada con disilicato de litio (B). Se subdividieron en 2 grupos de 4 bloques (A1 y A2) y (B1 y B2). Los grupos A1 y B1 fueron tratados con ácido fluorhídrico 9% (HF) y los grupos A2 y B2 con ácido fluorhídrico, seguido de ácido fosfórico al 35%. Posteriormente, se observaron al MEB (1.000 ×) y se procesaron las imágenes con el programa Matlab R2012a, que mide el contraste. Los estadísticos utilizados fueron el test ANOVA y el test «t¼ no pareado Resultados El ácido fluorhídrico 9% crea irregularidades en ambos tipos de cerámicas. Al aplicar HF, seguido de ácido fosfórico sobre la cerámica feldespática no se aprecian diferencias en el contraste, con respecto a utilizar solo HF. Al usar ambos ácidos, en la cerámica reforzada con disilicato de litio se aprecian menos irregularidades respecto a las tratadas con un solo ácido. Conclusiones El ácido fluorhídrico 9% crea microrretenciones en ambas cerámicas. El HF al 9%, seguido del ácido fosfórico 35% parece modificar los valores de contraste de la cerámica colada, en cambio en las feldespáticas no hay diferencias significativas con ambos tratamientos.

Surface conditioning prior to cementing is indicated to achieve a strong bond between metal-free ceramic restorations and resin cements. The aim of this study is to describe and compare the scanning electron microscopy (SEM) images of the surfaces of Feldspathic ceramic and Lithium disilicate glass ceramic before and after being treated with two acid procedures. For this, 8 blocks of Feldspathic ceramic (A) and 8 of Ceramic lithium disilicate (B) were used. They were subdivided into two groups of 4 blocks (A1 and A2) and (B1 and B2). Groups A1 and B1 were treated with 9% Hydrofluoric Acid (HF) and the A2 and B2 groups, with 9% Hydrofluoric Acid followed by 35% Phosphoric Acid. Subsequently, they were observed using SEM (1,000 ×) and the images processed with the program Matlab R2012a, which measures the contrast. The statistics used were ANOVA test and the unpaired t test. Results 9% Hydrofluoric Acid creates irregularities in both types of ceramics. When applying HF followed by Phosphoric Acid on Feldspathic ceramics, no differences in contrast were found, compared to using only HF. With ceramic lithium disilicate using both acids, there are fewer irregularities with respect to those treated with a single acid. Conclusion 9% Hydrofluoric Acid creates micro-retentions in both ceramics. 9% HF followed by 35% Phosphoric Acid appears to significantly modify the Lithium disilicate glass ceramic contrast values. On the other hand, the Feldspathic ceramic showed no significant differences with both treatments.

Influência do tempo de condicionamento ácido na alteração superficial, resistência de união e compressão da cerâmica de dissilicato de lítio / Influence of etching time on the superficial alterations, bond strength and compression resistence of lithium disilicate ceramic

Este estudo in vitro propôs analisar os padrões de condicionamento da superfície da cerâmica a base de dissilicato de lítio após três tempos de condicionamento com ácido fluorídrico a 10%, a influência desses tempos na resistência ao cisalhamento de cilindros cerâmicos e à compressão de placas cerâmicas cimentadas em esmalte de dentes bovinos. Para análise de superfície foram utilizadas 36 placas de cerâmica (IPS e.max Press), sem tratamento e condicionadas por 10s, 20s e 60s (E0,E10,E20,E60; n=3), observadas em MEV, energia dispersiva espectroscópica (EDS) e perfilômetro. Para o teste de resistência de união, 180 cilindros cerâmicos (2mm diâmetro x 2mm comprimento; n=20) foram condicionados e cimentados (80 m de espessura) com RelyX ARC em esmalte variando os sistemas adesivos {Silano+Single Bond (S); RelyX Ceramic Primer Silano +Single Bond (R); Single Bond Universal (U)}, obtendo-se os grupos: E10S, E20S, E60S, E10R, E20R, E60R, E10U, E20U e E60U. Após 24h realizou-se o teste de cisalhamento (EMIC, 0,5mm/min, 50Kgf). O teste de compressão ao esmalte (Kratos, 0,5mm/min 50Kgf) foi realizado após 24h da cimentação de 60 placas cerâmicas quadradas (5x5mm com 1mm de espessura; n=10), condicionadas e cimentadas (RelyX ARC, 80m) variando os sistemas adesivos R e U (10R, 20R, 60R, 10U, 20U e 60U). Os resultados da análise em MEV mostraram que foi mantido o mesmo padrão de condicionamento, porém, mais evidenciado com o aumento do tempo de tratamento. A quantidade de sílicio observada em EDS foi: E0:24,73% < E10:61,10% < E20:67,50% = E60:67,54% e a rugosidade: E0: 6,25 m < E10: 10,6m < E20: 12,0m < E60: 18,0m. Para os resultados dos ensaios de cisalhamento foi usado um modelo linear generalizado, com distribuição normal para a variável resposta e função de ligação do tipo raiz quadrada. Para compressão, usamos um modelo linear normal. Em ambos os casos, a hipótese de normalidade dos desvios foi verificada a partir do Q-Q Plot e do Teste de Kolmogorov-Smirnov. Para os testes de cisalhamento (MPa), independente do tempo de condicionamento, o grupo S apresentou os menores valores, enquanto os grupos R e U apresentaram valores semelhantes (E10S:84,2±7,2A/a, E10R:124,4±7,9A/b, E10U:117,2±7,8A/b, E20S:102,3±7,6B/a, E20R:146,2±8,2B/b, E20U:138,4±7,9B/b, E60S:107,2±7,8B/a, E60R:152,1±8,1B/b, E60U:144,1±8,1B/b). Para o teste de compressão (N), os valores Médios foram: 10R:869,8±122a, 10U:879,3±159a, 20R:795,0±219ab, 20U:852,3±227ab, 60R:772,7±162b, 60U:704,0±235b. O aumento do tempo de condicionamento da superfície da cerâmica a base de dissilicato de lítio aumentou a rugosidade superficial, não demonstrou diferença significativa da resistência de união de 20s par 60s, e apresentou leve diminuição para resistência de compressão.(AU)

The present in vitro study aimed to analyze the etching patterns of lithium disilicate based ceramic after three etching times with 10% hydrofluoric acid, and the influence of these times on the shear bond strength of ceramic cylinders and compression resistance of ceramic plates cemented to bovine enamel teeth. For the surface analysis, 36 ceramic plates (IPS e.max Press) were used untreated and etched for 10s, 20s and 60s (E0, E10, E20, E60; n = 3), as observed in SEM, energy dispersive spectroscopy (EDS) and profilometry. For the bond strength test, 180 ceramic cylinders (2x2mm; n = 20) were etched and cemented with RelyX ARC (80 m thick) on the enamel varying adhesive systems {Silane + Single Bond (S); RelyX Ceramic Primer Silane + Single Bond (R); Single Bond Universal (U)}, yielding the groups: E10S, E20S, E60S, E10R, E20R, E60R, E10U, E20U and E60U. After 24h, the shear bond strength test was performed (EMIC, 0.5 mm/min, 50Kgf). The ceramic compression test (Kratos, 0.5 mm/min, 50Kgf) was performed 24h after etching and cementing (RelyX ARC, 80m) 60 square ceramic plates (5x5mm, 1mm thick; n = 10), varying R and U adhesive systems (10R, 20R, 60R, 10U, 20U and 60U). The same pattern of damage was maintained as seen in the SEM analysis, however, it worsened with increasing the etching time. The amounts of silicium seen on EDS were: E0: 24.73%

Four chemical methods of porcelain conditioning and their influence over bond strength and surface integrity

OBJECTIVE: To assess four different chemical surface conditioning methods for ceramic material before bracket bonding, and their impact on shear bond strength and surface integrity at debonding.METHODS: Four experimental groups (n = 13) were set up according to the ceramic conditioning method: G1 = 37% phosphoric acid etching followed by silane application; G2 = 37% liquid phosphoric acid etching, no rinsing, followed by silane application; G3 = 10% hydrofluoric acid etching alone; and G4 = 10% hydrofluoric acid etching followed by silane application. After surface conditioning, metal brackets were bonded to porcelain by means of the Transbond XP system (3M Unitek). Samples were submitted to shear bond strength tests in a universal testing machine and the surfaces were later assessed with a microscope under 8 X magnification. ANOVA/Tukey tests were performed to establish the difference between groups (α= 5%).RESULTS: The highest shear bond strength values were found in groups G3 and G4 (22.01 ± 2.15 MPa and 22.83 ± 3.32 Mpa, respectively), followed by G1 (16.42 ± 3.61 MPa) and G2 (9.29 ± 1.95 MPa). As regards surface evaluation after bracket debonding, the use of liquid phosphoric acid followed by silane application (G2) produced the least damage to porcelain. When hydrofluoric acid and silane were applied, the risk of ceramic fracture increased.CONCLUSIONS: Acceptable levels of bond strength for clinical use were reached by all methods tested; however, liquid phosphoric acid etching followed by silane application (G2) resulted in the least damage to the ceramic surface.

OBJETIVO: avaliar quatro métodos de condicionamento químico da superfície cerâmica, previamente à colagem de braquetes, e seu impacto sobre a resistência ao cisalhamento e a integridade da superfície ao descolamento.MÉTODOS: quatro grupos experimentais (n = 13) foram delineados de acordo com o método de condicionamento da superfície cerâmica empregado: G1 = ácido fosfórico a 37%, seguido da aplicação de silano; G2 = ácido fosfórico líquido a 37%, seguido da aplicação de silano sem lavagem prévia do ácido; G3 = ácido fluorídrico a 10%; e G4 = ácido fluorídrico a 10%, seguido da aplicação de silano. Após o condicionamento da superfície, braquetes metálicos foram colados à porcelana utilizando-se o sistema Transbond XP (3M Unitek). As amostras foram submetidas a ensaios de resistência ao cisalhamento, em máquina de ensaio universal, e as superfícies cerâmicas foram posteriormente avaliadas em microscópio, com magnitude de 8X. Testes ANOVA/Tukey foram realizados para verificar-se a diferença entre os grupos (α = 5%).RESULTADOS: os maiores valores de resistência ao cisalhamento foram encontrados nos grupos G3 e G4 (22,01 ± 2,15MPa e 22,83 ± 3,32Mpa, respectivamente), seguidos por G1 (16,42 ± 3,61MPa) e G2 (9,29 ± 1,95MPa). Quanto à avaliação da superfície após a descolagem do braquete, a utilização de ácido fosfórico líquido seguido da aplicação de silano, sem lavagem do ácido (G2), produziu menores danos à porcelana. Quando ácido fluorídrico e silano foram aplicados, o risco de fraturar a cerâmica aumentou.CONCLUSÕES: níveis aceitáveis de resistência de união para uso clínico foram alcançados por todos os métodos testados. No entanto, o condicionamento com ácido fosfórico líquido, seguido da aplicação de silano (G2), resultou em menor dano à superfície cerâmica.

Heat Treatment of Pre-hydrolyzed Silane Increases Adhesion of Phosphate Monomer-based Resin Cement to Glass Ceramic

This study evaluated the influence of different forms of heat treatment on a pre-hydrolyzed silane to improve the adhesion of phosphate monomer-based (MDP) resin cement to glass ceramic. Resin and feldspathic ceramic blocks (n=48, n=6 for bond test, n=2 for microscopy) were randomly divided into 6 groups and subject to surface treatments: G1: Hydrofluoric acid (HF) 9.6% for 20 s + Silane + MDP resin cement (Panavia F); G2: HF 9.6% for 20 s + Silane + Heat Treatment (oven) + Panavia F; G3: Silane + Heat Treatment (oven) + Panavia F; G4: HF 9.6% for 20 s + Silane + Heat Treatment (hot air) + Panavia F; G5: Silane + Heat Treatment (hot air) + Panavia F; G6: Silane + Panavia F. Microtensile bond strength (MTBS) test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using stereomicroscope and scanning electron microscope (SEM) to categorize the failure types. Data were analyzed statistically using two-way test ANOVA and Tukey's test (=0.05). Heat treatment of the silane containing MDP, with prior etching with HF (G2: 13.15±0.89a; G4: 12.58±1.03a) presented significantly higher bond strength values than the control group (G1: 9.16±0.64b). The groups without prior etching (G3: 10.47±0.70b; G5: 9.47±0.32b) showed statistically similar bond strength values between them and the control group (G1). The silane application without prior etching and heat treatment resulted in the lowest mean bond strength (G6: 8.05±0.37c). SEM analysis showed predominantly adhesive failures and EDS analysis showed common elements of spectra (Si, Na, Al, K, O, C) characterizing the microstructure of the glass-ceramic studied. Heat treatment of the pre-hydrolyzed silane containing MDP in an oven at 100 °C for 2 min or with hot air application at 50±5 ºC for 1 min, was effective in increasing the bond strength values between the ceramic and resin cement containing MDP.

Este estudo avaliou o efeito de diferentes formas de tratamento térmico de um silano pré-hidrolisado na adesão de um cimento resinoso à base de monómeros fosfatados (MDP) à uma cerâmica vítrea. Blocos em resina e cerâmica feldspática (n=48, n=6 para teste de união, n=2 para microscopia) foram divididos aleatoriamente em 4 grupos e submetidos a tratamentos de superfície: G1-ácido fluorídrico (HF) 9,6% por 20 s + Silano + cimento resinoso com MDP (Panavia F) ; G2-HF 9,6% por 20 s + Silano + Tratamento Térmico (forno) + Panavia F; G3-Silano + Tratamento Térmico (forno) + Panavia F; G4-HF 9,6% por 20 s + Silano + Tratamento Térmico (ar quente) + Panavia F; G5-Silano + Tratamento Térmico (ar quente) + Panavia F; G6-Silano + Panavia F. Teste de microtração (MTBS) foi realizado utilizando máquina de ensaios universal (1 mm/min). Após o descolamento, substrato e superfícies aderentes foram analisadas utilizando estereoscópico e microscópio eletrônica de varredura (MEV) para classificação dos tipos de falha. Os dados foram analisados estatisticamente utilizando o teste ANOVA dois fatores e o teste de Tukey (=0,05). O tratamento térmico do silano contendo MDP, com condicionamento prévio com HF (G2:13,15±0,89a e G4:12,58±1,03a) resultou em valores de resistência de união significativamente superiores aos do grupo controle (G1:9,16±0,64b). Os grupos sem condicionamento prévio (G3:10,47±0,70b e G5:9,47±0,32b), apresentaram valores de resistência de união estatisticamente semelhantes entre eles e ao controle (G1). O silano utilizado sem condicionamento prévio e tratamento térmico apresentou os menores valores de resistência de união (G6:8,05±0,37c). As análises em MEV mostraram predominância de falhas adesivas e as análises em EDS demonstraram espectros com elementos semelhantes (Si, Na, Al, K, O, C) caracterizando a microsestrutura da vitro-cerâmica estudada. O tratamento térmico do silano pré-hidrolisado contendo MDP, realizado em forno a 100 °C durante 2 min ou com ar quente a 50±5 °C durante 1 min, foi eficaz no aumento dos valores de união entre cimento resinoso contendo MDP e cerâmica.

O ácido fluorídrico na resistência ao cisalhamento entre cerâmica feldspática e resina composta / The hydrofluoric acid in the shear strength between feldspathic ceramic and composite resin

Dentre os materiais restauradores, a porcelana se destaca pelo seu alto potencial em reproduzir o aspecto dental. Desta maneira, a sua utilização vem crescendo cada vez mais, e com ela a possibilidade de fraturas. Entretanto, nem sempre uma falha exige a troca da restauração, pois existe a possibilidade de um reparo utilizando resina composta. Este estudo avaliou a resistência ao cisalhamento entre resina composta e cerâmica feldspática submetida ao condicionamento com ácido fluorídrico (HF) em diferentes concentrações. Foram confeccionadas 36 pastilhas de porcelana feldspática e incluídas em resina acrílica, aplainadas com lixas d’água, asperizadas com pontas diamantadas e divididas em três grupos (n=12) de acordo com os tratamentos de superfície: G1) sem condicionamento (controle); G2) condicionamento com HF a 10% por 120 segundos; G3) condicionamento com HF a 5% por 120 segundos. Em seguida, silano e adesivo foram aplicados sobre a superfície da porcelana, seguido da inserção da resina composta com o auxílio de uma matriz metálica bipartida. Após sete dias de armazenamento em estufa, os corpos de prova foram submetidos ao teste de cisalhamento em uma máquina de ensaios universal (EMIC). As médias de resistência foram: G1 105,3N; G2 182,5N e G3 154,51N. Na análise dos dados quantitativos (T student) houve diferença estatística significante entre todos os grupos (p<0,05). A microscopia óptica revelou aproximadamente 58% de falhas coesivas para o G1, 75% para o G3 e 83% para o G2. Concluiu-se que a adesão com o uso do HF a 10% foi superior a adesão obtida quando utilizado o HF a 5%.

Among the restorative materials the porcelain is distinguished by its high potential in reproducing the dental aspect. In this way, their use has been growing increasingly, and, with it the possibility of fracture. However, not every failure demands the exchange the restoration because the possibility of a repair exists with compounded resin. This study evaluated the shear bond strength between composite resin and feldspathic ceramic subjected to etching surface with hydrofluoric acid (HF) at different concentrations. Thirty-six porcelain specimens were mounted into acrylic resin, polished and divided into 3 groups (n=12), according to the following surface treatments: G1) without treatment (control); G2) etched with 10% HF for 120 seconds; G3) etched with 5% HF for 120 seconds. Then the treatment, silane coupling agent and adhesive were applied to the treated specimens, after being bonded with of composite resin with the aid of a bipartite metal matrix. After a 7 days of storage at 37° C, the specimens were subjected to a shearing force in a universal testing machine at a crosshead speed of 0.5 mm/min. The average shear strength were: G1 105.3 N; G2 182.5 N and G3 154.51 N. In the analysis of quantitative data (T student) was difference statistically significant between all groups (p <0.05). Optical microscopy revealed approximately 58% of cohesive failures in the control group, 75% to G3 and 83% for G2. It was concluded that adherence with HF was 10% greater adhesion with the 5% HF.

Micro-shear bond strength and surface micromorphology of a feldspathic ceramic treated with different cleaning methods after hydrofluoric acid etching

Objective: The aim of this study was to evaluate the effect of feldspathic ceramic surface cleaning on micro-shear bond strength and ceramic surface morphology. Material and Methods: Forty discs of feldspathic ceramic were prepared and etched with 10% hydrofluoric acid for 2 minutes. The discs were randomly distributed into five groups (n=8): C: no treatment, S: water spray + air drying for 1 minute, US: immersion in ultrasonic bath for 5 minutes, F: etching with 37% phosphoric acid for 1 minute, followed by 1-minute rinse, F+US: etching with 37% phosphoric acid for 1 minute, 1-minute rinse and ultrasonic bath for 5 minutes. Composite cylinders were bonded to the discs following application of silane and hydrophobic adhesive for micro-shear bond strength testing in a universal testing machine at 0.5 mm/min crosshead speed until failure. Stereomicroscopy was used to classify failure type. Surface micromorphology of each treatment type was evaluated by scanning electron microscopy at 500 and 2,500 times magnification. Results: One-way ANOVA test showed no significant difference between treatments (p=0.3197) and the most common failure types were cohesive resin cohesion followed by adhesive failure. Micro-shear bond strength of the feldspathic ceramic substrate to the adhesive system was not influenced by the different surface cleaning techniques. Absence of or less residue was observed after etching with hydrofluoric acid for the groups US and F+US. Conclusions: Combining ceramic cleaning techniques with hydrofluoric acid etching did not affect ceramic bond strength, whereas, when cleaning was associated with ultrasound, less residue was observed. .

Influencia del tiempo de tratamiento de superficie con ácido fluorhídrico de la porcelana VITA VM 13 en la resistencia de unión a cemento de resina frente a fuerzas de tracción: estudio in vitro / Influence of surface treatment time with hydrofluoric acid of VITA VM13 porcelain on tensile bond strength to a luting resin cement. In vitro study

Introducción: Los procedimientos restauradores indirectos son comunes en la clínica diaria actual. Se debe tener cuidado especial en la cementación, pues la gran mayoría de los fracasos ocurren en la interfase diente/restauración. Por esto es indispensable un adecuado tratamiento de superficie de la restauración para lograr una adhesión óptima a la superficie dentaria. Materiales y Métodos: Treinta cilindros de porcelana VITA VM 13 con dimensiones de 5 mm de altura y 7 mm de diámetro fueron separadas aleatoriamente en 3 grupos (n=10) de acuerdo con los tratamientos recibidos. Grupo I (control) - sin acondicionamiento superficial; Grupo II - grabado con ácido fluorhídrico al 9.6 por ciento por 1 minuto; Grupo III - grabado con ácido fluorhídrico al 9.6 por ciento por 2 minutos. Estas fueron probadas en cuanto a su resistencia de unión a la tracción en una máquina universal para pruebas (INSTRON modelo 4411, 3M). Los valores, expresados en MPa, fueron analizados estadísticamente a un nivel de significación del 5 por ciento, usando el Análisis de la Varianza (ANOVA) de un factor. Resultados: En relación con la prueba de resistencia de unión a la tracción, se encontraron los siguientes valores medios para cada grupo: Grupo I (control) - x=3.35 MPa; Grupo II - x=4.64 MPa; Grupo III - x=3.80 MPa. Conclusiones: Según los resultados obtenidos, se puede concluir que el tratamiento de superficie con ácido fluorhídrico durante 1 minuto, promueve microrretenciones que aumentan significativamente los valores de resistencia a la tracción, que puede traducirse en un beneficio clínico mayor.

Aim: Indirect restorative procedures are common in the current daily practice. Special care must be taken in the cement, as the vast majority of failures occurs at the interface tooth /restoration. Therefore a proper surface treatment of the restoration is essential to achieve optimum adhesion to the tooth surface. Materials and Methods: Thirty porcelain cylinders VITA VM 13 with dimensions of 5 mm in height and 7 mm in diameter were randomly divided into 3 groups (n=10) according to the treatments received. Group I (control) - no surface conditioning; Group II- recorded with 9.6 percent hydrofluoric acid for 1 minute; Group III - recorded with 9.6 percent hydrofluoric acid for 2 minutes. Their tensile bond strength was tested in a universal testing machine (Instron Model 4411, 3M). The values, expressed in MPa, were statistically analyzed at a level of significance of 5 percent, using Analysis of Variance (ANOVA) of a factor. Results: In relation to the bond strength test, tensile strength, revealed the following values for each group: Group I (control) - x=3.35 MPa, Group II - x=4.64 MPa, Group III - x=3.80 MPa. Conclusions: According to the results, it can be concluded that the surface treatment with hydrofluoric acid for 1 minute promotes microretentions, which significantly increase the values of bond strength, tensile strength. This can result in a higher clinical benefit.

Effect of bonding material, etching time and silane on the bond strength of metallic orthodontic brackets to ceramic

The purpose of this study was to evaluate the bond strength of metallic orthodontic brackets to feldspathic ceramic with different etching times, bonding materials and with or without silane application. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. For each etching time, half of the cylinders received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek) or Fuji Ortho LC (GC). Light-activation was carried out with total exposure time of 40 s using UltraLume 5. Shear bond strength testing was performed after 24 h storage. Data were submitted to three-way ANOVA and Tukey's test (α=0.05). The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Specimens etched for 60 s had significantly higher bond strength compared with 20 s. The application of silane was efficient in increasing the shear bond strength between ceramic and both fixed materials. Transbond XT showed significantly higher (p<0.05) bond strength than Fuji Orth LC. There wasa predominance of ARI score 0 (clean ceramic failure surface) for all groups, with an increase in scores 1, 2 and 3 (adhesive material increasingly present on ceramic failure aspect) for the 60-s etching time. In conclusion, 60-s etching time, silane and Transbond XT improved significantly the shear bond strength of brackets to ceramic.

O objetivo neste estudo foi avaliar a resistência de união de bráquetes a cerâmica feldspática com diferentes tempos de condicionamento ácido, materiais de união, com ou sem aplicação do silano. Cilindros de cerâmica feldspática foram condicionados com ácido fluorídrico 10% por 20 ou 60 s. Para cada tempo de condicionamento, metade dos cilindros recebeu duas camadas de silano. Bráquetes metálicos foram fixados aos cilindros utilizando Transbond XT (3M Unitek) ou Fuji Ortho LC (GC). A fotoativação foi realizada com tempo de exposição total de 40 s utilizando LED UltraLume 5. O ensaio de resistência ao cisalhamento foi realizado após 24 h de armazenagem. Os dados foram submetidos à Análise de Variância a três fatores e teste de Tukey (α=0,05). O Índice de Remanescente Adesivo (IRA) foi utilizado para avaliar a quantidade de adesivo remanescente na superfície cerâmica com magnificação de 8×. Os espécimes condicionados por 60 s apresentaram maior resistência de união comparado com 20 s. A aplicação do silano foi efetiva no aumento da resistência de união ao cisalhamento de bráquetes com a cerâmica para ambos os materiais. O Transbond XT mostrou resistência de união significativamente maior que Fuji Orth LC. O IRA mostrou predominância de escore 0 (ausência de resina na superfície cerâmica) para todos os grupos, com aumento de escores 1, 2 e 3 (aumento da presença de resina na superfície cerâmica) para o tempo de condicionamento de 60 s. Em conclusão, o tempo de condicionamento de 60 s, aplicação de silano e resina Transbond XT melhoraram significativamente a resistência de união ao cisalhamento de bráquetes a cerâmica feldspática.

Health Care Plan for Hydrogen Fluoride Spill, Gumi, Korea

No abstract available.

Comparison of fracture resistance of teeth restored with ceramic inlay and resin composite: An in vitro study.

Aim: The aim of this study was to evaluate the in vitro fracture resistance of teeth restored with bonded ceramic inlay and direct composite resin restoration in comparison to the normal tooth. Materials and Methods: This study evaluated the fracture strength of the teeth restored with bonded ceramic inlay and direct composite resin restoration in comparison to the normal teeth. Thirty intact human maxillary first premolars were assigned to three groups: Group 1 - comprising sound/unprepared teeth (control). Group 2 - comprising of Class-II direct composite resin restored teeth and Group 3 - comprising Class-II ceramic inlay restored teeth. Cavities were prepared with occlusal width of 1/3 intercuspal distance and 2 mm deep pulpally. Group 2 teeth were restored with hybrid composite resin (Z350 3M ESPE, USA) and group 3 teeth were restored with Vitadur Alpha alumina (Ivoclare Vivadent, Liechtenstein, Europe). Ceramic inlay was bonded with adhesive cement (rely X resin cement of 3MESPE, USA). The specimens were subjected to a compressive load until they fractured. Data were analyzed statistically by unpaired Student's t test. Results: The fracture resistant strength, expressed as kilonewton (KN), was group 1 - 1.51 KN, group 2 - 1.25 KN, and group 3 - 1.58 KN. Statistically, group III had highest fracture resistance followed by group I, while group II had the lowest average fracture resistance. Conclusion: The fracture resistant strength of teeth restored with ceramic inlay was comparable to that of the normal intact teeth or slightly higher, while teeth restored with direct composite resin restoration showed less fracture resistant strength than that of the normal teeth.

Effect of etching time and light source on the bond strength of metallic brackets to ceramic

This study evaluated the bond strength of brackets to ceramic testing different etching times and light sources for photo-activation of the bonding agent. Cylinders of feldspathic ceramic were etched with 10 percent hydrofluoric acid for 20 or 60 s. After application of silane on the ceramic surface, metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek). The specimens for each etching time were assigned to 4 groups (n=15), according to the light source: XL2500 halogen light, UltraLume 5 LED, AccuCure 3000 argon laser, and Apollo 95E plasma arc. Light-activation was carried out with total exposure times of 40, 40, 20 and 12 s, respectively. Shear strength testing was carried out after 24 h. The adhesive remnant index (ARI) was evaluated under magnification. Data were subjected to two-way ANOVA and Tukey's test (α=0.05). Specimens etched for 20 s presented significantly lower bond strength (p<0.05) compared with those etched for 60 s. No significant differences (p>0.05) were detected among the light sources. The ARI showed a predominance of scores 0 in all groups, with an increase in scores 1, 2 and 3 for the 60 s time. In conclusion, only the etching time had significant influence on the bond strength of brackets to ceramic.

Este estudo avaliou a resistência de união de bráquetes à cerâmica testando diferentes tempos de condicionamento e fontes de luz para fotoativação do agente de união. Cilindros de cerâmica feldspática foram condicionados com ácido fluorídrico 10 por cento por 20 ou 60 s. Após aplicação de silano na superfície da cerâmica, bráquetes metálicos foram colados aos cilindros utilizando Transbond XT (3M Unitek). Os espécimes de cada tempo de condicionamento foram divididos em 4 grupos (n=15): fonte halógena XL2500, LED UltraLume 5, laser de argônio AccuCure 3000 e arco de plasma Apollo 95E. A fotoativação foi realizada com tempo total de 40, 40, 20 e 12 s, respectivamente. O teste de cisalhamento foi realizado após 24 h. O índice de adesivo remanescente (IAR) foi avaliado sob aumento. Os dados foram submetidos a ANOVA de duas vias e teste de Tukey (p<0,05). Espécimes condicionados por 20 s apresentaram resistência de união significativamente menor que espécimes condicionados por 60 s. Não foram detectadas diferenças significativas entre as fontes de luz. O IAR mostrou predominância de escores 0 para todos os grupos, com aumento nos escores 1, 2 e 3 para o tempo 60 s. Em conclusão, apenas o tempo de condicionamento teve influência significativa na resistência de união de bráquetes à cerâmica.

Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic

The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9 percent hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

O objetivo deste estudo foi avaliar o efeito de diferentes tempos de condicionamento ácido na rugosidade de superfície e resistência flexural de uma cerâmica à base de disilicato de lítio. Espécimes cerâmicos em forma de barra (16 mm x 2 mm x 2 mm) foram produzidos a partir de blocos cerâmicos. Todos os espécimes foram polidos e limpos em banho de ultrasom em água destilada. Os espécimes foram aleatoriamente divididos em 5 grupos (n=15). Grupo A (controle) sem tratamento. Grupos B-E condicionamento com ácido fluorídrico 4,9 por cento (HF) por 4 diferentes períodos de condicionamento: 20 s, 60 s, 90 s e 180 s, respectivamente. As superfícies condicionadas foram observadas sob microscopia eletrônica de varredura. Perfilometria de superfície foi utilizada para examinar a rugosidade das superfícies condicionadas, e os espécimes foram carregados até a falha pelo teste de flexão três pontos. Os valores foram analisados usando ANOVA um fator e teste de Tukey (?=0,05). Todos os períodos de condicionamento produziram superfícies significantemente mais rugosas do que o grupo controle (p<0,05). Os valores de rugosidade aumentaram com o tempo de condicionamento. Os valores médios de resistência à flexão foram (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; e E=314 ± 62. O condicionamento com HF reduziu significativamente os valores médios de resistência à flexão conforme o tempo de condicionamento aumentou (p=0,003). Os achados deste estudo mostraram que o aumento do tempo de condicionamento ácido influenciou a rugosidade de superfície e resistência flexural de uma cerâmica à base de disilicato de lítio confirmando a hipótese do mesmo.

Microtensile bond strength of a repair composite to leucite-reinforced feldspathic ceramic

The purpose of this study was to evaluate the microtensile bond strength of a repair composite resin to a leucite-reinforced feldspathic ceramic (Omega 900, VITA) submitted to two surface conditionings methods: 1) etching with hydrofluoric acid + silane application or 2) tribochemical silica coating. The null hypothesis is that both surface treatments can generate similar bond strengths. Ten ceramic blocks (6x6x6 mm) were fabricated and randomly assigned to 2 groups (n=5), according to the conditioning method: G1- 10 percent hydrofluoric acid application for 2 min plus rinsing and drying, followed by silane application for 30 s; G2- airborne particle abrasion with 30 µm silica oxide particles (CoJet-Sand) for 20 s using a chairside air-abrasion device (CoJet System), followed by silane application for 5 min. Single Bond adhesive system was applied to the surfaces and light cured (40 s). Z-250 composite resin was placed incrementally on the treated ceramic surface to build a 6x6x6 mm block. Bar specimens with an adhesive area of approximately 1 ± 0.1 mm² were obtained from the composite-ceramic blocks (6 per block and 30 per group) for microtensile testing. No statistically significant difference was observed between G1 (10.19 ± 3.1 MPa) and G2 (10.17 ± 3.1 MPa) (p=0.982) (Student's t test; á = 0.05). The null hypothesis was, therefore, accepted. In conclusion, both surface conditioning methods provided similar microtensile bond strengths between the repair composite resin and the ceramic. Further studies using long-term aging procedures should be conducted.

A proposta desse estudo foi avaliar a resistência à microtração entre uma resina composta e uma cerâmica feldspática submetida a diferentes tratamentos de superfície. A hipótese foi que os tratamentos de superfície (deposição de sílica + silanização e o ácido fluorídrico + silanização) promovessem resistências adesivas semelhantes. Dez blocos cerâmicos (Omega 900) de 6x6x6mm foram confeccionados e divididos em dois grupos: G1 - ácido fluorídrico 10 por cento/2 min + silanização; G2 Sistema CoJet: jateamento com partículas de sílica de 30 µm (CoJet-Sand) + ESPE-Sil. Em seguida, o adesivo Single Bond foi aplicado na superfície e fotopolimerizado (40 s); a resina composta Z-250 foi condensada, obtendo-se um bloco de 6 mm. Depois da armazenagem (água destilada/37ºC/7 dias), espécimes retangulares foram seccionados com disco diamantado (6 corpos-de-prova por bloco e 30 corpos-de-prova por grupo), com 1 ± 0,1 mm² de área adesiva. Cada corpo-de-prova foi fixado a um dispositivo adaptado com cianoacrilato e o teste de tração foi realizado. Os dados foram submetidos ao Teste t de Student (p>0,05). A hipótese nula foi aceita (p=0.982): G1 (10,19 ± 3,1 MPa) e G2 (10,17 ± 3,1 MPa) foram similares estatisticamente. Concluiu-se que os métodos de condicionamento da superfície cerâmica geram resistência adesiva similar à da cerâmica. Estudos posteriores empregando envelhecimento a longo prazo devem ser realizados.

Influencia del tratamiento superficial en la resistencia de unión de una cerámica prensada a un cemento con base de resina / The influence of surface treatment on bond strenght between a pressed ceramics and a resin-based cement

Este estudio evaluó la influencia de diferentes métodos de tratamiento superficial de la cerámica Cergogold® (Degussa, Richmond, BC, Canadá) en la resistencia a la tracción a un cemento con base de resina. Cuarenta discos de cerámica prensada fueron confeccionados e incluidos en resina acrílica autopolimerizable. Cuatro diferentes grupos (n=10) fueron clasificados de acuerdo con el tratamiento: Grupo I: control (silano/sin acondicionamiento), Grupo II: microabrasión con óxido de aluminio (50 m), Grupo III: ácido fluorhídrico al 10 por ciento y Grupo IV: combinación de ácido fluorhídrico y microabrasión. Los resultados presentaron diferencias significativas entre los grupos: Grupo I (control) - x=3,89 MPa; Grupo II -x=7,8 MPa; Grupo III - x=5,6 MPa y Grupo IV - x=7,67 MPa, para lo cual se utilizó la prueba de ANOVA/Tukey (p<0,05). El grupo control presentó la media menor, seguido del grupo tratado con ácido fluorhídrico y, con mayor resistencia de unión, los grupos microabrasión y combinación de ambos. Se concluye que todos los tratamientos superficiales efectuados sobre la cerámica Cergogold® incrementaron la resistencia de unión a la tracción a un cemento con base de resina, lo que puede tener implicaciones clínicas de beneficio.

The number of children's cases that you suffer domestic violence is increasing now. The purpose of this study was to analyze the degree of knowledge of the Community Leaders on violence tames, the all is prepared to identify her; the knowledge on which they are the competent organs for the notification; and if, notifying the aggression, they are capable of being acting on behalf of the attacked child. They took place an interview structured with Community Leaders of the Child's Pastoral in the area west of the city of Londrina-PR. The results demonstrate: 56% of the interviewees are capable to identify the domestic violence, where the violence for them only corresponds to "beat in the child", and still 30% of them know that the organ is Guardian Council don't do him for fear of some type. It is ended that the need exists of being if making groups for explanations on the approached theme, trainings with the Leaders and meetings with the families.

Effect of surface treatment on the shear bond strength of a resin-based cement to porcelain

The purpose of this in vitro study was to evaluate the effect of different surface treatments on the shear bond strength of a resin-based cement to porcelain. Sixty pairs of 50 percent aluminous porcelain discs were fabricated. In each pair, one disc measured 6 mm in diameter X 3 mm thickness (A) and the other measured 3 mm in diameter X 3mm thickness (B). The specimens were randomly assigned to 6 groups (n=10 pairs of discs), according to the surface treatment: etching with 10 percent hydrofluoric acid for 2 or 4min (G1 and G2); 50-æm particle aluminum oxide sandblasting for 5 s (G3); sandblasting followed by etching for 2 or 4min (G4 and G5) and control - no treatment (G6). A silane agent was applied to the treated surface of both discs of each pair. Bistite II DC dual-cure resin cement was applied and the B discs were bonded to their respective A discs. Specimens were stored in distilled water at 37°C for 24 h and were tested in shear strength at a crosshead speed of 2 mm/min. Means in MPa were: G1: 14.21 ± 4.68; G2: 8.92 ± 3.02; G3: 10.04 ± 2.37; G4: 12.74 ± 5.15; G5: 10.99 ± 3.35; G6: 6.09 ± 1.84. Data were compared by one-way ANOVA and Tukey's test at 5 percent significance level. Bond strength recorded after 2-min acid etching was significantly higher than 4-min etching (p<0.05) and control (p<0.05), but did not differ significantlyfrom sandblasting alone (p>0.05) or followed by etching for 2 or 4 min (p>0.05). Within the limitations of an in vitro study, it may be concluded that 2-min hydrofluoric acid etching produced a favorable micromechanical retention that enhanced resin cement bond strength to porcelain.

O objetivo deste estudo in vitro foi avaliar o efeito de diferentes tratamentos de superfície na resistência ao cisalhamento da união entre porcelana e cimento resinoso. Foram confeccionados sessenta pares de discos de porcelana aluminizada a 50 por cento, de 6 mm de diâmetro por 3 mm de espessura (A) e 3 mm de diâmetro por 3 mm de espessura (B). Os espécimes foram divididos aleatoriamente em 6 grupos (n=10 pares), de acordo com os tratamentos de superfície: condicionamento com ácido fluorídrico por 2 e 4 min (G1 e G2), jateamento com óxido de alumínio (50 æm) por 5 s (G3), jateamento seguido de ácido fluorídrico por 2 e 4 min (G4 e G5) e controle (G6). Em seguida, foi aplicado silano na superfície tratada de ambos os discos, e os discos B foram cimentados sobre os respectivos discos A, utilizando o cimento resinoso dual Bistite II DC. Os espécimes foram armazenados em água destilada a 37°C por 24 h, para posterior teste de cisalhamento em máquina de ensaio universal. As médias em MPa foram: G1: 14,21 ± 4,68; G2: 8,92 ± 3,02; G3: 10,04 ± 2.37; G4: 12,74 ± 5,15; G5: 10,99 ± 3,35; G6: 6,09 ± 1,84. Os dados foram submetidos à análise de variância a um critério e teste de Tukey (p<0,05). O condicionamento ácido por 2 min apresentou resultados significantemente superiores ao condicionamento por 4 min (p<0,05) e ao grupo controle (p<0,05), porém não diferiu estatisticamente do jateamento, associado ou não ao ácido fluorídrico por 2 ou 4 min (p>0,05). Dentro das limitações de um estudo in vitro, conclui-se que o condicionamento com ácido fluorídrico por 2 min produziu uma retenção micromecânica favorável, que aumentou a resistência de união entre o cimento resinoso e a porcelana.