Mirela Sanae Shinohara

Fluoride-containing adhesive: durability on dentin bonding.

OBJECTIVES To evaluate (1) the influence of fluoride-containing adhesive on microtensile bond strength (microTBS) and (2) in vitro secondary caries inhibition at the resin-dentin interface after 24 h and 3 months water-storage and (3) the degree of conversion of different adhesives after 24h 1 month. METHODS Flat surfaces of human teeth were ground and randomly assigned to six groups: (SBMP-24) Scotchbond Multi-Purpose control [SBMP], 24 h; (SE-24) SBMP etch and primer+Clearfil SE Bond adhesive [SE], 24h; (PB-24) SBMP etch and primer+Clearfil Protect Bond adhesive [PB], 24h; (SBMP-3) SBMP, 3 months; (SE-3) SBMP+SE, 3 months; and (PB-3) SBMP+PB, 3 months. To evaluate the effect of the adhesive resin alone, all teeth were etched with 35% phosphoric acid and primed with SBMP primer prior to applying the adhesive resin. Bonded assemblies were prepared for microTBS and stored in distilled water at 37 degrees C for 24h and 3 months. Sections of restored teeth of each group were exposed to an acid challenge. The specimens were sectioned, polished, and then observed with polarized light microscopy (PLM). Also, the degree of conversion (DC) of the adhesives was measured using Fourier Transform-Infrared spectroscopy (FTIR) at 24 h and 1 month, after polymerization. RESULTS microTBS values obtained in MPa (24h/3m) were: (MP) 61.5+/-10.5/52.9+/-8.9, (SE) 55.5+/-11.8/55.6+/-13, and (PB) 50.3+/-9.9/61.0+/-13.6. For interface analysis by PLM, an inhibition zone (IZ) adjacent to the hybrid layer was created only when the fluoride-containing adhesive (PB) was used. The DC in percentage (24 h, 1 month) were: (MP) 60.5+/-2.8/61.3+/-0.6, (SE) 69.6+/-1.3/70.7+/-0.05, and (PB) 53.1+/-0.4/58.3+/-1.6. SIGNIFICANCE The fluoride-containing adhesive demonstrated significant increase of bond strength values after water-storage. This material was also able to create an acid inhibition zone in dentin. There was a significant increase of degree of conversion after 1 month only for PB.

Dentin bond strength and nanoleakage of the adhesive interface after intracoronal bleaching

This study evaluated dentin bond strength (BS) and nanoleakage of non‐ and pre‐etched dentin immediately (T0,), 7 days (T7), and 14 days (T14) after bleaching. Bovine incisors (150) were selected and half of them submitted to intrapulpal dentin etching (e). Non‐ and pre‐etched dentin were subjected to the following (n = 15): no bleaching/control (C); 35% carbamide peroxide (CP); 35% hydrogen peroxide (35% HP); 25% hydrogen peroxide (25% HP); and sodium perborate (SP). Bleaching agents were applied to the pulp chamber four times within a 72‐h interval. Afterwards, pulp chamber dentin was prepared for the BS test at different evaluation times (n = 5): T0, T7, and T14. Composite blocks were built on pulp chamber and sectioned in slices. Slices were reduced to an hour‐glass shape with a cross‐sectional area of 0.8 mm2 and submitted to microtensile BS test. Two additional specimens for each group were prepared for nanoleakage evaluation by transmission electron microscopy (TEM). Results were analyzed by ANOVA (two‐way) and Dunnetts test (p < .05). BS decreased immediately after intracoronal bleaching for both sound and pre‐etched dentin (p < .05). At T14, the BS of non‐etched bleached dentin increased for all groups, whereas the pre‐etched SPe group presented BS similar to the Ce. Nanoleakage within the hybrid layer was perceptible immediately after bleaching, although a decrease in nanoleakage was observed for all groups at T14. Adhesive restorations should be performed 7–14 days after bleaching, according to the bleaching agent used. Intracoronal bleaching should be performed preferably with sodium perborate if previous dentin etching is applied.