Impact of immediate and delayed light activation on self-polymerization of dual-cured dental resin luting agents.
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.
Moraes
Rafael R
RR
Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, SP, Brazil. moraesrr@gmail.com
Faria-e-Silva
André L
AL
Ogliari
Fabrício A
FA
Correr-Sobrinho
Lourenço
L
Demarco
Flávio F
FF
Piva
Evandro
E
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
D003188:Composite Resins; D003738:Dental Cements