Effect of Insufficient Light Exposure on Polymerization Kinetics of Conventional and Self-adhesive Dual-cure Resin Cements.
OBJECTIVE
The purpose of this study was to investigate the influence of insufficient light exposure on the polymerization of conventional and self-adhesive dual-cure resin cements under ceramic restorations.


METHODS
Two conventional dual-cure resin cements (Rely-X ARC, Duolink) and two self-adhesive resin cements (Rely-X U200, Maxcem Elite) were polymerized under different curing modes (dual-cure or self-cure), curing times (20 and 120 seconds), and thickness of a ceramic overlay (2 and 4 mm). Polymerization kinetics was measured by Fourier transform infrared spectroscopy for the initial 10 minutes and after 24 hours. Data were analyzed using mixed model analysis of variance (ANOVA), one-way ANOVA/Student-Newman-Keuls post hoc test, and paired t-test (α=0.05).


RESULTS
When light-curing time was set to 20 seconds, the presence of the ceramic block significantly affected the degree of conversion (DC) of all resin cements. Especially, the DC of the groups with 20 seconds of light-curing time under 4 mm of ceramic thickness was even lower than that of the self-cured groups at 24 hours after polymerization (p<0.05). However, when light-curing time was set to 120 seconds, a similar DC compared with the group with direct light exposure (p>0.05) was achieved in all dual-cure groups except Maxcem Elite, at 24 hours after polymerization.


CONCLUSIONS
For both conventional and self-adhesive dual-cure resin cements, insufficient light exposure (20 seconds of light-curing time) through thick ceramic restoration (4 mm thick) resulted in a DC even lower than that of self-curing alone.
Y
Y
Jang
J L
JL
Ferracane
C S
CS
Pfeifer
J W
JW
Park
Y
Y
Shin
B D
BD
Roh
D017438:Bisphenol A-Glycidyl Methacrylate; D055117:Curing Lights, Dental; D001840:Dental Bonding / Q000379:methods*; D006244:Hardness; D007700:Kinetics; D008422:Materials Testing; D058567:Photoinitiators, Dental; D011092:Polyethylene Glycols; D058105:Polymerization; D011109:Polymethacrylic Acids; D019279:Resin Cements / Q000737:chemistry*; D055116:Self-Curing of Dental Resins; D017550:Spectroscopy, Fourier Transform Infrared
C515955:Maxcem; D058567:Photoinitiators, Dental; D011109:Polymethacrylic Acids; C462240:RelyX ARC; C587242:RelyX U200; D019279:Resin Cements; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate