Abstract
ObjectiveApplications of resin luting agents and high-power light-emitting diodes (LED) light-curing units (LCUs) have increased considerably over the last few years. However, it is not clear whether the effect of reduced exposure time on cytotoxicity of such products have adequate biocompatibility to meet clinical success. This study aimed at assessing the effect of reduced curing time of five resin luting cements (RLCs) polymerized by high-power LED curing unit on the viability of a cell of L-929 fibroblast cells.Material and MethodsDisc-shaped samples were prepared in polytetrafluoroethylene moulds with cylindrical cavities. The samples were irradiated from the top through the ceramic discs and acetate strips using LED LCU for 20 s (50% of the manufacturer's recommended exposure time) and 40 s (100% exposure time). After curing, the samples were transferred into a culture medium for 24 h. The eluates were obtained and pipetted onto L-929 fibroblast cultures (3x104 per well) and incubated for evaluating after 24 h. Measurements were performed by dimethylthiazol diphenyltetrazolium assay. Statistical significance was determined by two-way ANOVA and two independent samples were compared by t-test.ResultsResults showed that eluates of most of the materials polymerized for 20 s (except Rely X Unicem and Illusion) reduced to a higher extent cell viability compared to samples of the same materials polymerized for 40 s. Illusion exhibited the least cytotoxicity for 20 s exposure time compared to the control (culture without samples) followed by Rely X Unicem and Rely X ARC (90.81%, 88.90%, and 83.11%, respectively). For Rely X ARC, Duolink and Lute-It 40 s exposure time was better (t=-1.262 p=0,276; t=-9.399 p=0.001; and t=-20.418 p<0.001, respectively).ConclusionThe results of this study suggest that reduction of curing time significantly enhances the cytotoxicity of the studied resin cement materials, therefore compromising their clinical performance.
Highlights
Resin cements are widely used in the luting of composite resin or porcelain inlays, porcelain laminate veneers, resin bonded metallic prosthesis and ceramic restoratives using Computer aided design and manufacturing (CAD/CAM)19.Different types of light-curing units (LCUs) have been proposed for the photopolymerization of light activated restorative materials including conventional quartz tungsten halogen (QTH) lights and new photoactivation techniques, such as intermittent light23, plasma arc curing (PAC)25 and, more recently, a new technology employing light-emitting diode (LED)14 or laser27.Solid-state LEDs use junctions of doped semiconductors (p-n junctions) based on gallium nitride to emit blue light
Cells The cells used for the experiments were L-929 mouse fibroblasts (L-929 An2 HÜKÜK 95030802; Food and Mouth Disease Institute, Ankara, Turkey) in conformity with the ISO 10993-513 standard
The cytotoxic effect of the tested materials and exposure times on the cell survival rates were evaluated by two-way analysis of variance
Summary
Resin cements are widely used in the luting of composite resin or porcelain inlays, porcelain laminate veneers, resin bonded metallic prosthesis and ceramic restoratives using Computer aided design and manufacturing (CAD/CAM)19.Different types of light-curing units (LCUs) have been proposed for the photopolymerization of light activated restorative materials including conventional quartz tungsten halogen (QTH) lights and new photoactivation techniques, such as intermittent light, plasma arc curing (PAC) and, more recently, a new technology employing light-emitting diode (LED) or laser27.Solid-state LEDs use junctions of doped semiconductors (p-n junctions) based on gallium nitride to emit blue light. Resin cements are widely used in the luting of composite resin or porcelain inlays, porcelain laminate veneers, resin bonded metallic prosthesis and ceramic restoratives using Computer aided design and manufacturing (CAD/CAM). Different types of light-curing units (LCUs) have been proposed for the photopolymerization of light activated restorative materials including conventional quartz tungsten halogen (QTH) lights and new photoactivation techniques, such as intermittent light, plasma arc curing (PAC) and, more recently, a new technology employing light-emitting diode (LED) or laser. Solid-state LEDs use junctions of doped semiconductors (p-n junctions) based on gallium nitride to emit blue light. The spectral output of blue LEDs falls between 450 and 490 nm, so these units are effective for curing materials with camphorquinone photo-initators. LED units do not require a filter, have a long life span, and do not produce as much heat as quartz-tungsten halogen devices.
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