title: The relationship between leachability of polymerization initiator and degree of conversion of visible light-cured resin.
abstract: Recently, polymerization-initiator-induced radicals have been identified as a biohazard as well as residual monomers. The present investigation was conducted to clarify the leaching behavior of the polymerization initiator and to measure the relationship between the leached amount of polymerization initiator and the degree of conversion of visible light (VL)-cured resin. Moreover, determining a suitable ratio of polymerization initiator to the base monomer according to the above relationship was carried out. The base monomer (UDMA/TEGDMA) was activated with varying concentrations of polymerization initiator (CQ/DMPT, CQ/DMAEMA) from 0.3-0.9 wt%, respectively, which were exposed to light for 40 s. Gas chromatograph mass spectrometry (GCMS) was carried out to evaluate the leached amount of polymerization initiator. The degree of conversion (DC) of the cured sample was estimated using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. As the result, it was recognized that the leachability of the polymerization initiator (CQ, DMPT, and DMAEMA) depended on the degree of conversion of the VL-cured resin. Therefore, the optimal concentration of polymerization initiator can be determined from the relation between the degree of conversion and the leached amount of polymerization initiator, which is about 0.6 wt% for CQ/DMPT (1:1 in weight) and 0.5 wt% for CQ/DMAEMA (1:1 in weight) relative to the UDMA/TEGDMA (1:1 in weight) monomer.
authors.affiliation: Department of Operative Dentistry, Hiroshima University, Faculty of Dentistry, Hiroshima, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Moin Jan
authors.forename: Y
authors.initials: Y
authors.lastname: Nomura
authors.forename: H
authors.initials: H
authors.lastname: Urabe
authors.forename: M
authors.initials: M
authors.lastname: Okazaki
authors.forename: H
authors.initials: H
authors.lastname: Shintani
mesh_terms: D003738:Dental Cements / Q000737:chemistry* / Q000528:radiation effects; D005609:Free Radicals; D008401:Gas Chromatography-Mass Spectrometry; D008027:Light; D008689:Methacrylates / Q000737:chemistry* / Q000494:pharmacology / Q000528:radiation effects; D009994:Osmolar Concentration; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000528:radiation effects; D011108:Polymers; D011109:Polymethacrylic Acids / Q000737:chemistry* / Q000528:radiation effects; D019163:Reducing Agents / Q000494:pharmacology; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013729:Terpenes / Q000494:pharmacology; D014052:Toluidines / Q000494:pharmacology; D014520:Urethane / Q000031:analogs & derivatives / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D003738:Dental Cements; D005609:Free Radicals; D008689:Methacrylates; D017319:Photosensitizing Agents; D011108:Polymers; D011109:Polymethacrylic Acids; D019163:Reducing Agents; D013729:Terpenes; D014052:Toluidines; C426022:dimethylacryloxyethyl 2,2,4-trimethylhexamethylene diurethane; C020946:triethylene glycol dimethacrylate; D014520:Urethane; D011092:Polyethylene Glycols; C048339:camphoroquinone; C049840:2-(dimethylamino)ethyl methacrylate; C015835:dimethyl-4-toluidine