RESUMO
The behavior of water-soluble photoinitiators with crown ethers in dental adhesives is unknown. This study investigated the effect of sodium acylphosphine oxide (APO-Na) with crown ether in a hydrophobic adhesive on adhesion to teeth. Sodium 2,4,6-trimethylbenzoyl-phenylphosphine oxide (TMPO-Na = APO-Na) was synthesized in 67.1% yield and identified by 1H NMR. APO-Na was dissolved in hydrophobic resins in the presence of a crown ether (ionophore effect). Thirty kinds of experimental single-step adhesives comprising APO-Na, CE, Bis-GMA, 6-methacryloyloxyhexyl phosphonoacetate (6-MHPA), and 4-methacryloyloxyethyl trimellitic acid (4-MET) were thereby prepared. Shear bond strength to unetched ground teeth was measured at a crosshead speed of 1.0 mm/min, and the data were analyzed by ANOVA. The shear bond strength results of bonding resins containing APO-Na with 18-crown-6-ether (CE-6) were significantly higher than that without CE-6 (control) (p<0.05). Higher bond strength values [for enamel: BR24 at 19.3 (3.2) MPa; for dentin: BR29 at 20.2 (4.7) MPa] were achieved with the adhesives containing APO-Na, CE-6, 6-MHPA, and 4-MET. Therefore, it was found that APO-Na with CE-6 contributed to the efficient bonding performance of single-step adhesive to teeth. However, in view of the biosafety hazard posed by crown ethers, the search is still on for reagents that are biologically safer than crown ethers--but with ionophor effects--to be used in dental adhesives.
Assuntos
Éteres de Coroa/síntese química , Colagem Dentária , Cimentos Dentários/síntese química , Esmalte Dentário/ultraestrutura , Dentina/ultraestrutura , Fosfinas/síntese química , Acilação , Animais , Bis-Fenol A-Glicidil Metacrilato/química , Bovinos , Resinas Compostas/química , Éteres de Coroa/química , Lâmpadas de Polimerização Dentária , Cimentos Dentários/química , Análise do Estresse Dentário/instrumentação , Interações Hidrofóbicas e Hidrofílicas , Ionóforos/química , Metacrilatos/química , Fosfinas/química , Ácidos Fosfínicos/química , Ácido Fosfonoacéticos/química , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química , Cimentos de Resina/síntese química , Cimentos de Resina/química , Resistência ao Cisalhamento , Solubilidade , Ácidos Tricarboxílicos/química , Água/químicaRESUMO
The behavior of microencapsulated polymerization initiators in dental adhesives is unknown. This study investigated the effects of new microencapsulated initiators in novel, multi-purpose, PMMA-type adhesive resin on the bonding performance and polymerization reactivity. Microencapsulated BPO and 1,3,5-trimethylbarbituric acid (TMBA) with PEMA as a shell polymer were quantitatively synthesized at 97-98% yield with 30-54 microm diameter. Adhesive-MC (comprising the synthesized microcapsules) and Adhesive-BR (comprising bare BPO and bare TMBA) were prepared and stored at 5 degrees C, 23 degrees C, and 40 degrees C for two months. MMA monomer was used as a solvent for the microcapsules. At the starting period, there were no significant differences between Adhesive-MC and Adhesive-BR in shear bond strength to enamel or dentin treated with or without surface treatment agent (p<0.05); moreover, their curing times (tc=304 seconds) were almost the same. After two months' storage at 40 degrees C, Adhesive-BR degraded in bond strength and showed markedly delayed polymerization reactivity as storage period progressed. In direct contrast, it was found that Adhesive-MC still retained its capabilities for adhesion to gold alloy and initiation of radical polymerization (p<0.05).
