Although dental hard composite resins contain various additives that improve color tones and adhesiveness, the biological safety of the additives have not been extensively investigated. We examined the influence of fluorescent and coloring pigments, which are commom additives to hard composite resin for dental crowns, on colony formation, proliferation, DNA synthesis and protein synthesis of culture cells in addition to cytotoxicity. The coloring pigment inhibited colony formation, proliferation and protein synthesis whereas the fluorescent pigment had no effect on the cultured cells. Further, the low concentration of both pigments significantly enhanced DNA synthesis but did not induce apoptosis or necrosis of the culture cells.

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This paper evaluated improvement of the polysiloxane layer at the silica-resin interface. Water resistance and durability of mixtures of 3-methacryloyloxypropyltrimethoxysilane (3-MPS) and novel silane coupling agents, i.e. synthesized 3-methacryloyloxypropyl-2-(perfluoro) ethyldimethoxysilane (MAnF2S2M, n=4, 6, 8) with a hydrophobic fluoroalkyl and a methacryloyl group, were evaluated. The concentration of each silane solution was adjusted with ethanol at 2 mass%, then glass plates were silanized with mixed silanes, and the resin composite was adhered. The specimens were stored in deionized water for 30, 90 days, or thermally stressed. The contact angles of the resin monomer mixture (50% Bis-GMA, 50% TEGDMA) to glass plates modified with each silane were measured. The silane mixture containing 3-MPS and MA4F2S2M at 20mol% or 40mol% showed the highest tensile bond strengths and lowest contact angles.

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This study examined the influence of long-term storage of bonding agents and etching agent treatment conditions in one-step bonding agent on the enamel and dentin bond strength. The bonding systems used were all the one-step type. Bovine and resin composite were used as the experimental materials. The bonding agents were stored at room temperature. The time periods examined were 1 and 180 days. Sample surfaces were pre-treated with phosphoric acid (PAT) or citric acid (CAT) and the no pre-treatment (NON) group served as a contrary. As a result, there was no significant difference in the bond strength of bonding agents stored for 1 day in the NON group or that stored for 180 days in PAT and CAT. However, those stored for 180 days in the NON group showed significantly decreased bond strength after 1day. For bonding agent stored for 180 days, the bond strengths in PAT and CAT were significantly greater than that in the NON group.

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