Effect of surface sealant on the surface roughness of different composites and evaluation of their microhardness.

PURPOSE: The aim of this study was to evaluate the effect of a surface sealant on the surface roughness of different composites and compare their microhardness values. MATERIALS AND METHODS: Sixty disc-shaped specimens were prepared and assigned to 6 groups (n =10). Groups were prepared as follows; Group 1 (Herculite XRV Ultra), Group 2 (Beautifil Bulk Restorative) and Group 3 (Filtek Bulk Fill Posterior Restorative). Groups 4, 5, and 6 were prepared by applying a surface sealant (BisCover LV) on the specimens in groups 1, 2 and 3. Surface hardness of the discs in group 1, 2, and 3 and surface roughness of the discs in all groups were measured using the Vickers hardness test and a profilometer, respectively. One-way ANOVA was used to test for differences among the groups. RESULTS: No significant differences were observed in the microhardness and roughness between the experimental and control groups for each restorative materials. Group 3 showed the highest surface hardness and group 4 showed the lowest surface roughness values. CONCLUSION: Using the BisCover LV resin after the polishing step has no significant effect on the surface roughness. The highest hardness values were obtained for the Filtek Bulk Fill Posterior Restorative after the polishing step. The smoothest surfaces were obtained for all experimental groups using the BisCover LV resin after the polishing step, Herculite XRV Ultra showed lower average roughness values than the other materials.

Microleakage of high viscosity glass-ionomer and glass-carbomer with and without coating before and after hydrothermal aging / Microinfiltracao de ionomero de vidro de alta viscosidade e carbômero de vidro com e sem revestimento antes e depois de envelhecimento hidroterma

Objective: The objective of this study was to evaluate the microleakage patterns of GIC and GGC with and without their protective surface coatings on enamel and dentin margins before and after aging. Material and Methods: Two rectangular cavities (height: 2 mm; width: 3 mm; depth: 1.5 mm) were prepared on each tooth at the cemento-enamel junction were prepared on human permanent molars (N=56) and the teeth were randomly assigned to be restored with one of the following: a) high viscosity glass-ionomer cement (GIC) (EQUIA Fil, C Corp., Tokyo, Japan) (n=28), b) glasscarbomer cement (GCC) (Glass Carbomer Products, Leiden, The Netherlands) (n=28). Half of the teeth were further divided into two groups where one group received protective surface coating (SC) (G-Coat Plus, GC Corp) (n=14) and the other group did not (n=14). Half of the teeth were stored for 24 hours (n=7), and the other half was thermocycled (5000 cycles, 5-55°C) (n=7). For microleakage analysis, the teeth were immersed in 5% methylene blue dye for 24 hours, sectioned into two equal halves. Microleakage patterns were evaluated using stereomicroscope and scored on a scale of 0-3 (0: No dye penetration, 1: Dye penetration less than half of the axial wall, 2: Dye penetration more than half the axial wall, 3: Dye penetration spreading along the axial wall). Data were analyzed using Kruskal-Wallis tests at the significance level of 0.05. Results: Compared to 24 h storage, after thermocycling, surface coating on GIC decreased microleakage significantly compared to GCC (p=0.046) but not for GCC. In the thermocycled groups, coated GIC showed significantly less leakage at the enamel margin but no significant difference was found with both GIC and GCC in the dentin margins. Conclusion: The application of surface coating significantly reduced the microleakage scores of GIC but not GCC, within the enamel margins only. (AU)

Objetivo: O objetivo deste estudo foi avaliar os padrões de microinfiltração de GIC e GGC com e sem seus revestimentos protetores superficiais nas margens de esmalte e dentina antes e após o envelhecimento. Material e Métodos: duas cavidades retangulares (altura: 2 mm; largura: 3 mm; profundidade: 1,5 mm) foram preparadas em cada dente na junção cemento-esmalte de molares permanentes humanos (N = 56), sendo aleatoriamente designados para serem restaurados com um dos seguintes: a) cimento de ionômero de vidro (GIC) de alta viscosidade (EQUIA Fil, C Corp., Tóquio, Japão) (n = 28), b) cimento de vidrocarbômero (GCC) Carbomer Products, Leiden, Holanda) (n = 28). Metade dos dentes foram divididos em dois grupos, onde um grupo recebeu revestimento protetor de superfície (SC) (G-Coat Plus, GC Corp) (n = 14) e o outro grupo não (n = 14). Metade dos dentes foram armazenados por 24 horas (n = 7), e a outra metade foi termociclada (5000 ciclos, 5-55 ° C) (n = 7). Para análise de microinfiltração, os dentes foram imersos em corante azul de metileno a 5% por 24 horas, seccionados em duas metades iguais. Os padrões de microinfiltração foram avaliados usando estereomicroscópio e pontuados numa escala de 0-3 (0: Sem penetração de corante; 1: penetração de corante inferior à metade da parede axial; 2: penetração de corante mais do que metade da parede axial; 3: penetração de corante ao longo da parede axial). Os dados foram analisados pelo teste de Kruskal-Wallis ao nível de significância de 0,05. Resultados: em comparação com o armazenamento de 24 h, após a termociclagem, o revestimento de superfície no GIC diminuiu significativamente a microinfiltração em comparação com o GCC (p = 0,046), mas não para o GCC. Nos grupos termociclados, o GIC revestido apresentou significativamente menos infiltração na margem do esmalte, mas não houve diferença significativa para o GIC e o GCC nas margens dentinárias. Conclusão: A aplicação do revestimento de superfície reduziu significativamente os escores de microinfiltração do GIC, mas não do GCC, apenas nas margens do esmalte. (AU)

Mechanical properties of bulk-fill versus nanohybrid composites: effect of layer thickness and application protocols / Propriedades mecânicas de compósitos de resina bulk versus nano-híbrida: efeito da espessura da camada e protocolos de aplicação

Objective: The objective of this study was to evaluate the compressive strength, flexural strength and flexural modulus of high-viscosity, low-viscosity bulk-fill, and conventional nanohybrid resin composite materials alone and when covered with nano-hybrid resin composite at different incremental thicknesses on the bulk-fill composites. Material and Methods: Specimens (N=60) were fabricated from the following materials or their combinations (n=10 per group): a) conventional nano-hybrid composite Z550 (FK), b) high-viscosity bulk-fill composite (Tetric N Ceram-TBF), c) low-viscosity bulk-fill composite SDR (SDR), d) Sonicfill (SF), e) SDR (2 mm)+FK (2 mm), f) SDR (4 mm)+FK (4 mm). After 24 h water storage, compressive strength was measured in a universal testing machine (1 mm/min). Additional specimens (N=40) (25x2x2 mm3) were made from FK, TBF, SDR and SF in order to determine the flexural strength and the flexural modulus, (n=10) and subjected to three-point bending test (0.5 mm/min). Data were analyzed using one-way ANOVA and Tamhane's T2 post-hoc tests (p p<0.05). Results: The mean compressive strength (MPa) of the nano-hybrid composite (FK) was significantly higher (223.8±41.3) than those of the other groups (123±27 - 170±24) (p <0.001). SDR (4 mm)+FK (2 mm) showed significantly higher compressive strength than when covered with 4 mm (143±30) or when used alone (146±11) (p <0.05). The mean flexural strength (159±31) and the flexural modulus of FK (34±7) was significantly higher than that of the high- or low-viscosity bulk-fill composites (p<0.001). The mean flexural strength of SF (132±20) was significantly higher compared to TBF (95±25) (p <0.05). Conclusion: Bulk-fill resin composites demonstrated poorer mechanical properties compared to nano-hybrid composite but similar to that of SF. Increasing the thickness of low-viscosity bulk-fill composite (SDR) from 2 to 4 mm underneath the nano-hybrid composite (FK) can improve the mechanical properties of the bulk-fill composites.(AU)

Objetivo: O objetivo deste estudo foi avaliar a resistência à compressão, resistência à flexão e módulo de flexão de materiais compósitos de alta viscosidade, baixa viscosidade e compósitos nanohíbridos convencionais e quando cobertos com resina composta nano-híbrida em diferentes espessuras incrementais sobre os compósitos de resina tipo bulkfilll. Material e Métodos: Os espécimes (N = 60) foram fabricados a partir dos seguintes materiais ou suas combinações (n = 10 por grupo): a) compósito nano-híbrido convencional Z550 (FK), b) compósito de bulk-fill de alta viscosidade (Tetric N CeramTBF), c) compósito SDR (SDR) de bulk-fill de baixa viscosidade, d) Sonicfill (SF), e) SDR (2 mm) + FK (2 mm), f) SDR (4 mm) + FK (4 mm). Após 24 h de armazenamento em água, a resistência à compressão foi medida em uma máquina universal de ensaios (1 mm / min). Espécimes adicionais (N = 40) (25x2x2 mm3) foram confeccionados com FK, TBF, SDR e SF para determinação da resistência à flexão e do módulo de flexão, (n = 10) e submetidos ao teste de flexão de três pontos (0,5 mm / min). Os dados foram analisados utilizando one-way ANOVA e testes post-hoc T2 de Tamhane (p <0,05). Resultados: A resistência média à compressão (MPa) do compósito nano-híbrido (FK) foi significativamente maior (223,8 ± 41,3) que os demais grupos (123 ± 27 - 170 ± 24) (p <0,001). SDR (4 mm) + FK (2 mm) apresentou resistência à compressão significativamente maior do que quando coberta com 4 mm (143 ± 30) ou quando usada sozinha (146 ± 11) (p <0,05). A resistência à flexão média (159 ± 31) e o módulo de flexão de FK (34 ± 7) foram significativamente maiores do que os compósitos do tipo bulk-fill de alta ou baixa viscosidade (p <0,001). A resistência à flexão média do FS (132 ± 20) foi significativamente maior em comparação ao TBF (95 ± 25) (p <0,05). Conclusão: Os compósitos de resina do tipo bulk-fill demonstraram propriedades mecânicas mais insatisfatórias em comparação com o compósito nano-híbrido, mas semelhantes aos do SF. O aumento da espessura do composto de bulkfilll de baixa viscosidade (SDR) de 2 a 4 mm sob o compósito nano-híbrido (FK) pode melhorar as propriedades mecânicas dos compósitos de bulk-fill.(AU)

Effect of Different Antioxidants on the Microtensile Bond Strength of an Adhesive System to Sodium Hypochlorite-treated Dentin.

PURPOSE: To evaluate the effects of different antioxidant treatments on the microtensile bond strength of an adhesive system to sodium hypochlorite (NaOCl)-treated dentin. MATERIALS AND METHODS: Thirty extracted third molars were sectioned 3 mm below the occlusal surface and divided into six groups according to the antioxidant treatment received: control group: distilled water; NaOCl group: 5.25% NaOCl and distilled water; proanthocyanidin (PA) group: 5.25% NaOCl, 5% PA and distilled water; 1-week storage group: 5.25% NaOCl and storage for 1 week in distilled water; Accel group: 5.25% NaOCl, Accel, and distilled water; noni group: 5.25% NaOCl, noni fruit juice, and distilled water. NaOCl, PA, Accel, noni, and distilled water were administered for 30 s, 10 min, 30 s, 10 min, and 30 s, respectively. A self-etching adhesive system (Single Bond Universal Adhesive) was applied to each specimen and a resin composite (Filtek Z550) was built up to a height of 5 mm on the dentin surface. Each specimen was serially sectioned to obtain sticks with a cross-sectional area of 1 mm2, and their microtensile bond strength was determined. Statistical differences between groups were analyzed using one-way ANOVA and Tamhane's T2 test. RESULTS: Microtensile bond strength in the NaOCl group was significantly lower than in all other groups. However, there were no significant differences in the bond strength between the groups treated with different antioxidants. CONCLUSIONS: NaOCl significantly reduced the microtensile bond strength of the adhesive system. The application of PA, Accel, and noni fruit juice to NaOCl-treated dentin significantly improved the microtensile bond strength.