Abstract The aim was to evaluate the effect of 2% grape seed extract (GSE) containing phosphoric acid (PhA) on the bond strength to enamel and dentin. The control group was 37% PhA. The following three PhA formulations with 2% GSE and 20% ethanol were obtained: GSE5 = 5% PhA; GSE10 = 10% PhA; and GSE20 = 20% PhA. The enamel and dentin surfaces of molars were etched with the acid solutions, followed by Scotchbond Multi-Purpose adhesive and composite resin application. The tensile bond strength (TBS) test evaluated the bond to enamel after 24 h, and the microtensile bond strength (μTBS) test evaluated the bond to dentin after 24 h and 12-month water storage. Etched enamel and dentin were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The TBS data were submitted to one-way ANOVA, while µTBS data were submitted to two-way ANOVA and Tukey’s test (α = 0.05). The TBS (MPa) to enamel did not significantly differ among the control (48.1 ± 15.7), GSE5 (46.1 ± 9.6), GSE10 (49.8 ± 13.6) and GSE20 (44.1 ± 11.9) groups (p = 0.537). The µTBS (MPa) to dentin of the control (28.4 ± 14.4) and GSE20 (24.1 ± 8.1) groups were significantly higher than those of the GSE5 (16.8 ± 7.4) and GSE10 (17.5 ± 6.6) groups at 24 h (p < 0.006). After 12-month storage, only GSE5 (21.0 ± 7.8) and GSE10 (17.6 ± 8.0) did not show significantly decreased μTBS (p > 0.145). SEM micrographs showed a shallower enamel etching pattern for GSE5. AFM images showed the formation of collagenous globular structures for GSE5 and GSE10. The different acid solutions did not influence the TBS to enamel, and the µTBS to dentin was stable over time when dentin was etched with GSE5 and GSE10.

AbstractResin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used.

O objetivo deste estudo foi avaliar a resistência ao cisalhamento de quatro sistemas adesivos de frasco único com solvente acetona e um sistema com solvente etanol em esmalte e à dentina. Cinqüenta molares humanos foram seccionados ao meio no sentido mesiodistal e incluídos com resina acrílica em tubos de PVC. As superfícies vestibulares foram desgastadas até atingir dentina plana, enquanto as superfícies linguais foram desgastadas até atingir esmalte plano. Os espécimes foram polidos até lixa d'água de granulação 600 e divididos aleatoriamente entre os 5 grupos (n=20; 10 espécimes de dentina e 10 espécimes de esmalte), de acordo com o sistema adesivo utilizado: One-Step (Bisco); Gluma One Bond (Heraeus Kulzer), Solobond M (Voco), TenureQuik w/F (Den-Mat) and OptiBond Solo Plus (Kerr) (controle). Os adesivos foram aplicados conforme as instruções dos fabricantes. Uma cápsula cilíndrica gelatinosa (d=4,5mm), preenchida com compósito híbrido de cada fabricante foi posicionada sobre a superfície dental e fotopolimerizada durante 40 s. Após 24 h, os corpos-de-prova foram submetidos a ensaios de cisalhamento em uma máquina de ensaios Instron com velocidade de 5 mm/min. Os dados foram analisados estatisticamente pela ANOVA a um critério e teste de Duncan post hoc (p£0.05). As médias de resistência ao cisalhamento resistência em esmalte e dentina (MPa) (±SD) foram: Esmalte: One-Step=11,3(±4,9); Gluma One Bond=16,3(±10,1); Solobond M=18,9(±4,5); TenureQuik w/F=18,7(±4,5) e OptiBond Solo Plus=16,4(±3,9); Dentina: One-Step=6,4(±2,8); Gluma One Bond=3,0(±3,4); Solobond M=10,6(±4,9); TenureQuik w/F=7,8(±3,9) e OptiBond Solo Plus=15,1(±8,9). Em esmalte, todos os agentes adesivos tiveram resultados estatisticamente semelhantes entre si (p>0.05). Entretanto, em dentina, o sistema adesivo a base de etanol apresentou maior resistência de união que todos os sistemas a base de acetona (p£0.0001). O tipo de solvente presente nos sistemas adesivos de frasco único não exerceu influência na sua capacidade de união ao esmalte, mas se mostrou um componente importante na adesão dentinária, o que deve ser levado em conta quando da escolha de um sistema adesivo.

The aim of this study was to assess the shear bond strength of four acetone-based one-bottle adhesive systems to enamel and dentin, and compare to that of an ethanol-based system used as control. Fifty human molars were bisected mesiodistally and the buccal and lingual surfaces were embedded in acrylic resin using PVC cylinders. The buccal surfaces were ground to obtain flat dentin surfaces, while the lingual surfaces were ground to obtain flat enamel surfaces. All specimens were polished up to 600-grit sandpapers and randomly assigned to 5 groups (n=20; 10 dentin specimens and 10 enamel specimens), according to the adhesive system used: One-Step (Bisco); Gluma One Bond (Heraeus Kulzer); Solobond M (Voco); TenureQuik w/F (Den-Mat) and OptiBond Solo Plus (Kerr) (control). Each adhesive system was applied according to the manufacturers' instructions. The respective proprietary hybrid composite was applied in a gelatin capsule (d=4.3mm) and light-cured for 40 s. The specimens were tested in shear strength with an Instron machine at a crosshead speed of 5 mm/min. Bond strengths means were analyzed statistically by one-way ANOVA and Duncan's post-hoc (p£0.05). Shear bond strength means (MPa) (±SD) to enamel and dentin were: Enamel: One-Step=11.3(±4.9); Gluma One Bond=16.3(±10.1); Solobond M=18.9(±4.5); TenureQuik w/F=18.7(±4.5) and OptiBond Solo Plus=16.4(±3.9); Dentin: One-Step=6.4(±2.8); Gluma One Bond=3.0(±3.4); Solobond M=10.6(±4.9); TenureQuik w/F=7.8(±3.9) and OptiBond Solo Plus=15.1(±8.9). In enamel, the adhesive systems had statistically similar bond strengths to each other (p>0.05). However, the ethanol-based system (OptiBond Solo Plus) showed significantly higher bond strength to dentin than the acetone-based systems (p£0.0001). In conclusion, the solvent type (acetone or ethanol) had no influence on enamel bond strength, but had great influence on dentin bonding, which should be taken into account when choosing the adhesive system.