This study investigated the relationship between the solubility, salivary sorption, and degree of conversion of dimethacrylate-based polymeric matrixes. Six polymeric matrixes produced by mixing bis-GMA, TEGDMA and UDMA dimethacrylate monomers were studied. Photoactivation was induced by camphoroquinone/ethyl N,N-dimethyl-4-aminobenzoate. The specimens were light-cured using an irradiance of 850 mW/cm(2) for 20 s. The solubility and sorption (microg/mm(3)) were measured after immersion in artificial saliva (neutral pH) for 7 days. The degree of conversion (%) was obtained by using a FT-IR spectrometer equipped with an attenuated total reflectance crystal (ATR). The degree of conversion varied from 39.15 +/- 6.30 to 65.57+/- 4.80, and was influenced by the viscosity of the monomers present in the polymeric matrixes. The solubility of polymeric matrixes varied between 13.64 +/- 0.39 and 25.08 +/- 0.83, and was strongly influenced by the degree of conversion (Pearson, r = -0.9587, p < 0.01). No correlation was found between salivary sorption and the degree of conversion (p = 0.3918). Salivary sorption was only dependent on the chemical and physical structures of the monomers presented in the polymeric matrixes.

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This study evaluated the influence of dentin deproteinization with NaOCl on the microshear bond strength (microSBS) and the nanoleakage patterns of three dentin bonding systems (DBS). Occlusal dentin surfaces, obtained from extracted noncarious human molars, were divided into two experimental groups, according to dentin surface treatment: Group I-37% H(3)PO(4)/15s and Group II-37% H(3)PO(4)/15s + 10% NaOCl/1 min. The dentin surfaces were bonded with one of the following DBS: Scotchbond Multipurpose-SBMP, Prime & Bond NT-PB and Clearfil SE Bond-SE. After 1 week storage in water at 37 degrees C, the specimens were subjected to the microSBS test. The data were analyzed by two-way ANOVA and Student-Newman-Keuls' test (p = 0.05). The nanoleakage was evaluated using scanning electron microscopy (SEM) in backscattered electron imaging regime. No significant difference in microSBS between dentin treatments was found for SBMP. For PB, microSBS increased after NaOCl dentin treatment. SE showed a reduction in microSBS in deproteinized specimens. SEM analysis showed different nanoleakage patterns for each DBS. Irrespective of dentin treatments, all SBMP specimens showed nanoleakage. SE did not show nanoleakage with the two dentin treatments. PB showed nanoleakage within the hybrid layer only in acid-etched specimens. The influence of dentin deproteinization was dependent on the dentin bonding system formulation.

This study evaluated the influence of organic acids present in the oral biofilm on the microtensile bond strength (μTBS) of adhesive systems to human dentin. Sixty occlusal dentin surfaces were wet ground with 600 grit SiC abrasive paper and divided into four groups according to the adhesive systems: Scotchbond Multipurpose (SMP), Adper Single Bond 2, Adper Scotchbond SE (ASE), and Clearfill SE Bond (CSE). After the adhesive systems were applied, a block of resin composite was built up on the dentin surfaces. After 24 h storage in distilled water at 37°C, the teeth were perpendicularly cut to obtain beams (1 mm(2)). For each adhesive system, the beams were divided into three groups according to storage media: artificial saliva (AS); propionic acid (PA), and lactic acid (LA). After 7 days storage at 37°C, the beams were submitted to μTBS testing. The μTBS ranged from 36.0 ± 1.6 (ASE-PA) to 52.5 ± 1.2 (CSE-AS). For all adhesive systems, the μTBS values after storage in PA were lower than those in AS. Except for the SMP, the values of μTBS after storage in LA were lower than those in AS. The adhesive ASE presented the lowest values of μTBs in the three media. The acids present in the oral biofilm may affect the bond strength of adhesive systems to human dentin.

It was concluded that tooth brushing with dentifrices with high concentration of NaF and CPP-ACPF cream was not able to prevent enamel erosion in simulated oral environment.