title: Impact of immediate and delayed light activation on self-polymerization of dual-cured dental resin luting agents.
abstract: This study investigated the impact of immediate and delayed light activation on self-polymerization of a model dual-cured luting agent. The material presented the following components: base paste - 2,2-bis[4-(2-hydroxy-3-methacryloxyprop-1-oxy)phenyl]propane/triethylene glycol dimethacrylate (TEGDMA), camphorquinone, dimethyl-p-toluidine, butylated hydroxytoluene (BHT), glass fillers; catalyst paste - bisphenol-A ethoxylated dimethacrylate/TEGDMA, benzoyl peroxide, BHT, fillers. The pastes were mixed and seven polymerization scenarios tested: immediate light activation using low (5Jcm(-2)) or high (20Jcm(-2)) energy dose; delayed light activation (after 2min - short delay) using low or high dose; delayed light activation (after 10min - long delay) using low or high dose; and self-polymerization only. The degree of conversion (DC) and rate of polymerization (R(p)) were evaluated for 30min by real-time infrared spectroscopy. The lowest DC was detected for the self-polymerized and immediate-low dose groups, whereas the immediate-high dose and short delay-high dose groups showed the highest values. For the self-polymerized and immediate-high dose samples, R(p)(max) was detected after approximately 7s, whereas this took approximately 14s for the immediate-low dose group. R(p)(max) for the immediate-high dose group was higher than for the self-polymerized sample, which in turn was higher than for the immediate-low dose group. R(p)(max) for the short delay groups was higher than for the long delay groups. In conclusion, the extent of self-polymerization was influenced by the light dose reaching the material, which was dependent on high radiant exposure for optimal polymerization and the moment at which the light was applied; the short delay increased the DC for lower doses, while also generally decreasing the R(p) for all scenarios.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, SP, Brazil. moraesrr@gmail.com
authors.forename: Rafael R
authors.initials: RR
authors.lastname: Moraes
authors.forename: André L
authors.initials: AL
authors.lastname: Faria-e-Silva
authors.forename: Fabrício A
authors.initials: FA
authors.lastname: Ogliari
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.forename: Flávio F
authors.initials: FF
authors.lastname: Demarco
authors.forename: Evandro
authors.initials: E
authors.lastname: Piva
mesh_terms: D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects*; D003738:Dental Cements / Q000737:chemistry* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D055119:Elastic Modulus / Q000528:radiation effects; D006244:Hardness / Q000528:radiation effects; D006245:Hardness Tests; D008027:Light; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D010777:Photochemistry / Q000379:methods; D011829:Radiation Dosage; D013314:Stress, Mechanical; D013499:Surface Properties / Q000528:radiation effects
chemical_list: D003188:Composite Resins; D003738:Dental Cements