Re-expansion of dried demineralized dentin is required to optimize resin adhesion. This study tested the hypothesis that bond strengths to dentin depend upon the ability of experimental HEMA(2-hydroxy-ethyl-methacrylate)/solvent primers to re-expand the matrix. Dentin surfaces were acid-etched with 37% phosphoric acid for 20 sec, air-dried for 30 sec, primed with either 35/65% (v/v) HEMA/water, HEMA/methanol, HEMA/ethanol, or HEMA/propanol for 60 sec, and bonded with 4-META-TBBO(4-methacryloyloxyethyl trimellitate anhydride-tri-n-butyl borane) adhesive. After storage in water for 1 day at 37 degrees C, the samples were prepared for microtensile bond strength testing. We used transmission electron microscopy to measure the width of interfibrillar spaces in the hybrid layers. The HEMA/ethanol primer and the HEMA/propanol primer produced the highest and the lowest bond strengths, respectively (p < 0.05). Bond strengths were directly correlated with the width of the interfibrillar spaces (p < 0.05). Bond strengths are related to the ability of the primer to maintain the re-expansion of collapsed demineralized dentin matrix.

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Objective. This study evaluated the effect of immediate or delayed finishing/polishing using different systems on the surface roughness, hardness, and microleakage of a silorane-based composite. Material and Methods. Specimens were made with silorane-based composite (Filtek P90, 3M ESPE) and assigned to the treatments: control (light-cured); aluminum oxide discs (Sof-Lex, 3M ESPE); diamond-impregnated silicone tips (Astropol, Ivoclar Vivadent); aluminum oxide-impregnated silicone tips (Enhance, Dentsply). Half of the specimens were finished/polished immediately and the rest after 7 days. Surface roughness (Ra, μm; n = 20) and Vickers microhardness (50 g; 45 s; n = 10) were measured. Cavities were prepared in bovine incisors and filled with Filtek P90. The fillings received immediate or delayed finishing/polishing (n = 10) and were subjected to dye penetration test (0.5% basic fuchsin, 24 h). Data were analyzed by ANOVA and Scheffe, Kruskal-Wallis, and Mann-Whitney tests (p < 0.05). Results. The finishing/polishing system significantly influenced roughness and microhardness (p < 0.0001). For enamel, microleakage was not affected by the finishing/polishing system (p = 0.309). For dentin, Sof-Lex discs and Astropol points promoted greater microleakage than Enhance points (p = 0.033). Conclusion. Considering roughness, microhardness, and microleakage together, immediate finishing/polishing of a silorane-based composite using aluminum oxide discs may be recommended.

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