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Purpose: The purpose of this study was to investigate the effect of priming time on bovine enamel and dentin adhesion promoted by self-etching primer systems. Materials and Methods: Two commercial self-etching primer systems, Clearfil SE Bond (SE) and Unifil Bond (UB), were used. Bovine enamel and dentin were treated with each system with various priming times (5, 20, and 60 seconds), and the tensile bond strength was measured. Scanning electron microscopic (SEM) observation was also performed to examine the effect of priming time on the morphology of the resin-tooth interface. Results: The tensile bond strength to enamel ranged from 10.6 to 14.3 MPa, and no statistically significant difference was detected among products or priming times. To dentin, UB showed the statistically significantly lowest tensile bond strength when primed for 5 seconds, 6.9 ± 1.1 MPa, but there was no significant difference between the groups primed for 20 and 60 seconds, 13.5 ± 4.1 MPa and 13.8 ± 4.6 MPa, respectively. SE created tensile bond strengths ranging from 13.9 to 15.7 MPa and showed no effect of priming time on dentin adhesion. SEM observation revealed that resin penetrated into both enamel and dentin more deeply with extension of priming time. Conclusion: Priming times longer than those recommended by the manufacturers did not influence the tensile bond strength to enamel and dentin when using two commercial self-etching primers. In contrast, a shortened priming time, 5 seconds, carried a risk of decreasing dentin adhesion, although it had no adverse effect on enamel adhesion. [ABSTRACT FROM AUTHOR]

Purpose: To compare nanoleakage patterns of an unfilled (OS; One-Step), a 6 wt% spherical silica-filled (OSs; One-Step Plus) and a 15 wt% glass-filled (OSg) version of a two-step, acetone-based self-priming adhesive. Permeability of bonded dentin treated with OS and OSs was also examined. Methods: Deep, coronal dentin from extracted third molars were etched and bonded using these adhesives. One-mm thick sections were immersed in 50 wt% ammoniacal silver nitrate (pH 9.5) for 24 hours. Unstained, undemineralized sections were examined by TEM. The permeability of dentin bonded with OS and OSs were investigated at 20 cm of H2O hydrostatic pressure and compared with the osmotic conductance determined with 4.8 M CaCl2 at zero hydrostatic pressure. Composite-dentin beams bonded with OS, OSs and OSg that were fractured after microtensile bond testing were examined by SEM. Results: Two types of nanoleakage patterns were recognized along the resin-dentin interfaces. The reticular type consisted of discontinuous islands of silver deposits and was exclusively seen in hybrid layers. The spotted type consisted of isolated silver grains and was evident throughout the hybrid and adhesive layers in OS. These two patterns were seen to variable extents in the two filled adhesive versions OSs and OSg and their distribution was independent of one another. OS and OSs bonded dentin were permeable to fluid filtration. However, part of this fluid movement was due to the permeability of the adhesive layer, as demonstrated by osmotic fluid conductance in the absence of hydrostatic pressure. Fractographic analysis revealed denuded collagen fibrils within fractured hybrid layers that were indicative of incomplete resin infiltration. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of disodium dihydrogen ethylenediamine tetraacetate dihydrate (EDTA) conditioning prior to the application of adhesive systems on the bond strength of resin composite to dentin. Methods: 80 bovine teeth were ground with 600-grit SiC paper to obtain flat dentin surfaces. Half of the specimens were conditioned with 0.5 mol EDTA aqueous solution (pH 7.4) for 60 seconds, water-rinsed and air-dried, and the other half were used without any treatment. The specimens were randomly divided in four groups of 10 each. The dentin surfaces were treated with each of two "all-in-one" adhesive systems (One-up Bond F, OB; Reactmer Bond, RB), a self-e tching priming system (Clearfil SE Bond, SE), and a total-etch one-bottle bonding system (Single Bond, SB). For SB, the adhesive was applied on EDTA-conditioned dentin without H3PO4 etching. Then a layer of resin composite was place d and light-cured for 40 seconds. The tensile bond strength was measured and the resin-dentin interface was observed using a scanning electron microscope. Results: The mean and standard deviation of tensile bond strength in MPa to ground dentin were 9.3±3.5/OB, 11.6±2.0/RB, 23.2±4.9/Sb and 19.7±4.1/SB. Bond strengths to EDTA-conditioned dentin were 15.0±3.0/OB, 16.8±3.6/RB, 22.8±5.2/SE and 19.4±5.1/SB. Duncan's Multiple Range test revealed that the EDTA-conditioned dentin showed significantly higher tensile bond strength than the non-conditioned one for "all-in-one" adhesive systems (P< 0.05) but no significant difference was found for the self-etching priming and total-etch one-bottle bonding systems. At the resin-dentin interface, EDTA-conditioned specimens formed thicker hybrid layers than non-conditioned ones for all systems except for SB. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of drying methods used in scanning electron microscopy on the thickness of the hybrid layers created by several different adhesive systems. Methods: A total etch dry bonding system, (Photobond), a three-step bonding adhesive system, (Scotchbond Multipurpose), a wet-bonding adhesive system (All-Bond 2) and a self-etching primer system (Mac Bond II) were used in this study. To permit measurement of the thickness of the hybrid layer, the resin-dentin interfaces were polished and etched briefly to remove polishing debris followed by immersion in 10% NaOCl for 4 hours. Half of the specimens in each group were subjected to fixation and critical-point drying followed dental bondby gold sputter-coating. The remaining specimens were allowed to air dry prior to gold sputter-coating. SEM observations were carried out to determine the structure and thickness of the hybrid layers. Remits: The thickness of hybrid layers were affected by the drying methods with the critical-point drying methods producing the thickest hybrid layers (P< 0.05). The thickest hybrid layers were created by Photobond, with Scotchbond Multi-Purpose and All-Bond 2 producing intermediate thickness hybrid layers, among the total etch systems. The thinnest hybrid layer among all of the adhesive systems was produced by the self-etching primer, Mac Bond II. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the microtensile bond strength (µTBS) of a self-etching pruning adhesive system to normal, caries-affected and caries-infected dentin, and to observe the ultrastructure of the resin-dentin interface by transmission electron microscopy (TEM). Materials gad Methods: Twelve extracted human molar teeth with deep occlusal caries were stained with caries detector solution and ground flat occlusally. The red-stained soft dentin was classified as caries-infected. The surrounding discolored dentin was classified as caries-affected dentin. The surrounding normal dentin served as a control. The entire flat surface was bonded with Clearfil Liner Bond 2V (CV) and covered with resin composite to form a composite crown 5 mm high. One day later the specimens were serially sectioned vertically into multiple slabs 0.8 mm thick. Under microscopic observation, the specimens were divided into normal or caries-infected or caries-affected dentin. These regions were isolated by cutting away the remaining dentin to form hour-glass shapes with the smallest surface area at the test site. After measuring the areas, the specimens were fixed to a microtensile tester and pulled under tension to failure. Additional slabs that were not used for bond strength tests were processed for TEM. Bond strength data were analyzed by Kruskal-Wallis one-way ANOVA and Student-Newman-Keuls multiple comparisons. Results: The µTBS of CV to normal, caries-affected and caries-infected dentin were 45 ± 10 MPa, 30 ± 10 MPa. 10 ± 5 MPa, respectively. TEM images showed that CV formed thin hybrid layers that were less than 1 urn thick in normal dentin, but that were between 6-8 µm thick in canes-affected dentin. Bacteria were only sparsely observed in the dentin tubules of bonded caries-affected dentin. However, in caries-infected dentin, an unusual interface was seen in which carious bacteria within disorganized non-banded collagen Fibrils could be seen embedded by the adhesive. The hybrid layer in caries-infected dentin was found to be 30-60 µm thick. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of phosphoric acid etching prior to the application of self-etching primer on the adhesion of resin composite to tooth substrates. Materials and Methods: Bovine teeth were randomly divided in four groups of 20 samples each. Tooth surface conditions were as follows: Group 1: enamel ground with 600-grit SiC paper; Group 2: ground enamel was etched with 35% phosphoric acid gel for 15 seconds, water-rinsed and completely dried; Group 3: ground dentin; Group 4: dentin etched using the same method as Group 2. The samples in each group were divided in two subgroups of 10 each, UniFil Bond (UB) and Clearfil SE Bond (SE) were applied as adhesive systems with self-etching primers, and a layer of resin composite (AP-X) was placed and light-cured for 40 seconds. The tensile bond strengths (TBS) were measured and the resin-tooth interfaces were observed with scanning electron microscopy. Results: The mean TBS values were 11.2 MPa (Group 1-UB), 14.3 MPa (Group 1-SE ), 16.3 MPa (Group 2-UB), 20.5 MPa {Group 2-SE), 13.4 MPa (Group 3-UB), 16.7 MPa (Group 3-SE), 9.3 MPa (Group 4-UB) and 12.6 MPa (Group 4-SE). Two-way ANOVA and Scheffe's F test showed that the enamel etching significantly increased the TBS values hut dentin etching significantly decreased the TBS values. [ABSTRACT FROM AUTHOR]