Marginal microleakage of class II composite resin restorations due to restorative techniques / Microinfiltração marginal de restaurações classe II de resina composta devido às técnicas restauradoras

Purpose: To evaluate the marginal microleakage of class II composite resin (CR) restorations due to restorative techniques. Methods: Forty human extracted premolars were assigned to 4 groups (n=10). Class II cavities were prepared (4-mm wide, 2-mm axially, with the gingival margin located 1 mm beyond the cementum-enamel-junction), and the restorative adhesive system Prime & Bond 2.1/TPH3 (Dentsply) was used. CR was inserted by the oblique incremental technique (OIT) and cured in continuous exposure. The restoratives techniques were: group 1 (control): OIT; group 2: flowable resin (1 mm) applied in the gingival wall + OIT; group 3: OIT + three pre-cured spheres inserted in the first increment of CR; and, group 4: OIT + strip of fiberglass inserted in the first increment of CR. The specimens were subjected to a thermocycling regimen of 500 cycles (1 min at 5º-37º-55ºC), coated with two layers of nail varnish up to 1 mm from the restoration margins, and immersed in 0.5% basic fuchsine solution for 24 h. The extension of dye penetration at the cervical wall (μm) was evaluated using an optic microscope at x40. Data were analyzed using analysis of variance (ANOVA) (α=0.05). Results: The microleakage values were: G1: 370 μm ± 241; G2: 398 μm ± 354; G3:205 μm ± 119; and G4: 413 μm ± 340. No statistically significant differences were found among the restorative techniques (P=0.081). Conclusion: Marginal microleakage values were not influenced by the different restorative techniques tested.

Objetivo: Avaliar a microinfiltração marginal de restaurações classe II de resina composta (RC) em função de técnicas restauradoras. Metodologia: Quarenta pré-molares humanos extraídos foram divididos em 4 grupos (n=10). Cavidades classe II foram preparadas (4 mm de largura, 2 mm de altura e margem gengival localizada a 1 mm além da junção amelo-cementária, e foi usado o sistema adesivo Prime & Bond 2.1/TPH3 (Dentsply). A RC foi inserida pela técnica incremental oblíqua (OIT) e polimerizada em exposição contínua. As técnicas restauradoras foram: grupo 1 (controle): OIT; grupo 2: resina fluida (1 mm) aplicada na parede gengival + OIT; grupo 3: OIT + três esferas pré-polimerizadas no primeiro incremento de RC; e grupo 4: OIT + tira de fibra de vidro inserida no primeiro incremento de RC. Os espécimes foram submetidos à termociclagem por 500 ciclos (1 min a 5º-37º-55ºC), cobertos com duas camadas de esmalte até 1 mm das margens da restauração e imersos em solução de fucsina básica a 0,5% por 24 h. A extensão da penetração do corante na parede cervical (μm) foi avaliada com microscópio ótico (x40). Os dados foram analisados por ANOVA (α=0,05). Resultados: Os valores de microinfiltração foram: G1: 370 μm ± 241; G2: 398 μm ± 354; G3: 205 μm ± 119 e G4: 413 μm ± 340. Não houve diferença estatisticamente significativa entre as técnicas restauradoras (P=0,081). Conclusão: Os valores de microinfiltração marginal não foram influenciados pelas diferentes técnicas restauradoras neste estudo.

Effect of cavity preparation design on the fracture resistance of directly and indirectly restored premolar

Aim: The aim of this study was to evaluate the fracture resistance of human premolars with extensive cavity preparations of the inlay and onlay types, for performing direct and indirect composite resin restorations. Methods: Eight-four premolars were divided into 7 groups (n=12): G1=intact teeth; G2=inlay/Filtek Z-250 direct; G3=inlay/ Filtek Z-250 light polymerized indirectly; G4=inlay/ Solidex; G5=onlay/ Filtek Z-250 direct; G6=onlay/ Filtek Z-250 light polymerized indirectly; G7=onlay/ Solidex. Indirect Filtek Z- 250 restorations were light activated using the EDG-lux oven. All samples were submitted to axial compression load in a Universal Testing Machine until fracture. The data were submitted to the one-way ANOVA and Tukey’s test (a=0.05). Results: The results (N) were: G6-1938a, G5-1570ab, G7-1285b, G1-1215b, G4-1174b, G3-1146b and G2-1112b. The onlay cavities restored indirectly with Filtek Z-250 presented significantly higher fracture resistance (G6) than the other groups, except for onlay restorations made directly with Filtek Z-250 (G5), which, in turn, did not differ significantly from the other groups. However, the onlay restorations made with Filtek Z-250 led to more catastrophic failure modes. Conclusions: 1. Adhesive inlay restorations, irrespective of the type of composite resin and light-activation technique used, restored the fracture resistance of intact teeth.