Methods: Twelve extracted human, intact third molars were used. A flat dentine surface was exposed by sectioning the tooth in the coronal one third of the crown perpendicular to the long axis. A smear layer was produced using 600- and 1000-grit silicone carbide discs under water. Teeth were allocated to four groups: I Filtek Silorane adhesive system, II AdheSE One (1-step self-etch), III AdheSE (2-step self-etch), IV Excite (etch-and-rinse). Adhesives were applied according to manufacturers' instructions and cured for 10 s with an LED unit. From each tooth, four 1 mm thick sections were cut, polished, subjected to acid-base pre-treatment, critically point dried, gold sputtered and examined at x3000-x10000 magnification using SEM. Statistical analysis was done using one-way analysis of variance (ANOVA).
Results: Filtek Silorane and Excite adhesive systems showed similar dense, thick, cone-shaped resin tags with numerous lateral branches. AdheSE showed numerous longer and thinner resin tags with a few thin lateral branches. AdheSE One showed resin tags with similar morphological characteristics to AdheSE though less numerous. Significant differences in the HL thickness are indicated with the same superscripts: Filtek SiloraneA,B 1.9±0.7 μm, AdheSE OneA,B 0.9±0.3 μm, AdheSEA 3.7±1.0 μm, ExciteB 5.1±1.3 μm (p<0.05, one-way ANOVA).
Conclusions: Filtek Silorane adhesive system showed morphological characteristics of the adhesive-dentine interface similar to the etch-and-rinse system.