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Purpose: To determine the degree of conversion (DC), physicochemical properties, and microshear bond strength (µSBS) of experimental self-adhesive resin cements (SARCs) to dentin and yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic., Materials and Methods: Dual-curing cements were formulated with UDMA, HEMA, bis-GMA, and TEG-DMA as the organic matrix. 2MP (bis 2-(methacryloyloxy)-ethyl-phosphate) and GDMAP (1,3-glycerol dimethacrylate phosphate) were added to impart self-adhesive characteristics. A control group was formulated without self-etch methacrylates. Silanized particles were incorporated. Photoactivation was carried out using an LED light-curing unit (1200 mW/cm2) for 20 s. Infrared spectroscopy assessed the DC immediately and after 24 h. pH was analyzed in real time and recorded after 48 h. Water sorption (Wsp), water solubility (Wsl), and film thickness measurements followed ISO 4049. µSBS of the cements to dentin and Y-TZP was evaluated immediately and after 3 months of water storage. Y-TZP was also tested without a surface treatment and after tribochemical silica coating with subsequent application of a silane agent. The fractures patterns were classified as adhesive, cohesive, and mixed. Data were submitted to analyses of variance and Tukey's tests (α = 0.05)., Results: Control (91.7%) and 2MP (92.0%) groups generated the highest DC after 24 h. 2MP (pH = 3.6) showed the lowest pH followed by GDMAP (pH = 4.7) and control (pH = 6.4) after 48 h. The control cement exhibited lower Wsp (41.0 µg/mm3) and Wsl (4.3 µg/mm3) than the other groups. Film thickness was statistically similar (p = 0.266) for all cements. Control (27.0 MPa) and GDMAP (24.1 MPa) showed higher µSBS to dentin than 2MP (13.7 MPa) after water storage. Mixed fractures were predominant in dentin. For all cements, the µSBS to Y-TZP was < 3.0 MPa after water storage, independent of the surface treatment., Conclusion: The results of DC, pH, Wsp and Wsl were material dependent. Only the film thickness was statistically similar for all groups. The cement formulated with GDMAP maintained the bond strengths to dentin even after aging. However, none of the groups were able to generate satisfactory bond strength to Y-TZP, independent of the surface treatment.

Objective: To evaluate the influence of tetrahydrofuran (THF) on the resin-to-dentin microtensile bond strength (microTBS) after water storage, for 24h and 6 months, and to compare its behavior with that of traditional solvents., Methods: Seven versions of monomer/solvent mixtures (primers) were prepared using the following solvent and water combinations: (1) THF, (2) acetone, (3) ethanol, (4) water, (5) THF/water, (6) acetone/water and (7) ethanol/water. An experimental adhesive resin was also synthesized to compare adhesive systems with the different primers. Forty-two bovine incisors, randomly separated into seven groups, had their superficial coronal dentin exposed. After acid-etching and rinsing, the excess water was removed from the surface with absorbent paper. Each experimental primer was applied with agitation (30s) followed by a mild air stream (10s). The experimental adhesive resin was applied and light-activated (20s). Resin composite restorations were constructed incrementally. Restored teeth were stored in distilled water at 37 degrees C (24h) and sectioned to obtain sticks with an area of 0.5mm(2). Half the specimens were subjected to the microTBS test immediately after being cut and the other half were tested after 6 months of water storage. Data (MPa) were analyzed by two-way ANOVA (solvent type and storage time as factors) and Tukey-Kramer's test at alpha=0.05., Results: Factors and interaction showed a statistical effect. After 6 months storage, acetone groups and primers containing THF showed similar microTBS to initial means., Significance: THF seems to be a promising solvent for use in dental adhesive systems, maintaining bond strength on dentin substrate after storage.

This study verified the influence of storage and compressive loads on the microtensile bond strength (microtbs) of an adhesive system when using the conventional technique or collagen removal treatment. Twenty bovine teeth were separated into four groups: G1) adhesive system Prime & Bond NT (PBNT) in accordance with the manufacturer's instructions, G2) PBNT after deproteinization with 10% sodium hypochlorite (NaOCl), G3) PBNT in accordance with the manufacturer's instructions + 50,000 compressive cycles and G4) PBNT after deproteinization + 50,000 compressive cycles. After 24 hours, the teeth were sectioned and half of the specimens were stored in water (37 degrees C) for further evaluation (after 60 days). The failure mode was evaluated by scanning electron microscopy (SEM). The bond strength values were separately submitted to two-way ANOVA for each period and the differences among groups were determined by Tukey's test (p = 0.05). Comparisons between 24 hours and 60 days were determined by multiple paired Student's t-tests (5%). The evaluation at 24 hours revealed that deproteinization did not affect microtbs for the non-cycled groups (G1 = 47.8 +/- 4.7 and G2 = 52.4 +/- 11.32). For the groups tested after the mechanical cycles, deproteinization produced higher microtbs (G3 = 32.7 +/- 9.6 and G4 = 43.3 +/- 16.7). At 60 days, deproteinization produced higher microtbs than the manufacturers' recommendations for the cycled and non-cycled groups (G1 = 31.5 +/- 5.8; G2 = 48.8 +/- 7.7; G3 = 17.1 +/- 7.2 and G4 = 48.8 +/- 12.2). In conclusion, the deproteinized groups were less susceptible to degradation than the groups restored with the conventional technique.

Though many advances have been made in the development of dental adhesives, the immediate, or short-term, disruption created by stress — due to polymerization of resin composite restorative materials within dental cavities — is still a challenge yet to be completely solved in restorative dentistry. Therefore, the aim of this paper is to present a general overview of the subject, concerning resin composite formulations, origins of stress, clinical consequences of stress development, in vitro methods used for its measurement and methods used to reduce stress magnitudes and rates of development. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To evaluate (1) the influence of fluoride-containing adhesive on microtensile bond strength (μTBS) and (2) in vitro secondary caries inhibition at the resin–dentin interface after 24h 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], 24h; (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 μTBS and stored in distilled water at 37°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 24h and 1 month, after polymerization. Results: μTBS 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 (24h, 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. [Copyright &y& Elsevier]