To understand the mechanism of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) hydrolysis, we investigated the degradation of 2-methacryloyloxyethyl dihydrogen phosphate (MEP), because the MEP molecule has the methacryloxy and phosphate ester portions of MDP but, unlike the latter, is water-soluble. The MEP-N-methcryloyl glycine (NMGly), MDP-NMGly, and MDP-2-hydroxyethyl methacrylate (HEMA) primers were designed, stored for different periods, and then analyzed. Our null hypotheses were that (1) the mechanism of MDP hydrolysis differs from that of MEP and (2) the type of hydrophilic monomer--NMGly or HEMA--has no effect on the MDP hydrolysis rate. Similar to the production of methacrylic acid (MA) and 2-hydroxyethyl dihydrogen phosphate (HEP) during MEP hydrolysis, MDP produced MA and 10-hydroxydecyl dihydrogen phosphate (HDP) during hydrolysis. However, the rate of MDP hydrolysis depended on the type of hydrophilic monomer: Compared with HEMA, NMGly significantly increased the rate of MDP hydrolysis.
It is well-known that self-etching primers can be altered. However, the effects from altered primers on the dentin bond durability have yet to be thoroughly identified. In this study, we examined the effects from 5 altered Liquid A primers in different stages of degradation-where 2-hydroxyethylmethacrylate (HEMA) and 10-methacryloyloxydecyl dihydrogen phosphate (MDP), used in Liquid A primers, were altered by the hydrolysis of the methacryloxy ester portion in the HEMA and MDP-on the hybrid layer's quality and dentin bond durability. The hypothesis was that degradation stages of altered Liquid A primers have no effect on the hybrid layer's quality and on dentin bond durability. Bond strengths, obtained after thermo-cycling, were strongly dependent on the degradation stage of the altered Liquid A primer. Alterations of self-etching primers reduced dentin bond durability and decreased the created hybrid layer's quality.
In this study, a dual-curing type composite resin cement that included a photo-initiator and two accelerators was designed. In particular, special emphasis was made on addressing questions on the effects from different amounts of additional accelerators on the flexural strength of the designed experimental composite resin cement, as well as on the tensile bond strength of the bracket bonded onto the enamel surface by the experimental composite resin cement.When 0.25 mass% of the p-tolydiethanolamine and sodium p-toluenesulfinate were added, the maximum flexural strength was obtained for the chemical-cured and dual-cured experimental composite resin cement. The dual-cured experimental composite resin cement's flexural strength value was in the mid-range of the values exhibited from the commercial resin cements. However, the dualcured experimental composite resin cement exhibited noticeably high tensile bond strength when compared with the results obtained with the commercial resin cements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.