Effect of different photoinitiators and reducing agents on cure efficiency and color stability of resin-based composites using different LED wavelengths.
OBJECTIVE
To evaluate the effect of photoinitiators and reducing agents on cure efficiency and color stability of resin-based composites using different LED wavelengths.


METHODS
Model resin-based composites were associated with diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide (BAPO) or camphorquinone (CQ) associated with 2-(dimethylamino) ethyl methacrylate (DMAEMA), ethyl 4-(dimethyamino) benzoate (EDMAB) or 4-(N,N-dimethylamino) phenethyl alcohol (DMPOH). A narrow (Smartlite, Dentisply) and a broad spectrum (Bluephase G2, Ivoclar Vivadent) LEDs were used for photo-activation (20 J/cm(2)). Fourier transform infrared spectroscopy (FT-IR) was used to evaluate the cure efficiency for each composite, and CIELab parameters to evaluated color stability (ΔE00) after aging. The UV-vis absorption spectrophotometric analysis of each photoinitiator and reducing agent was determined. Data were analyzed using two-way ANOVA and Tukey's test for multiple comparisons (α=0.05).


RESULTS
Higher cure efficiency was found for type-I photoinitiators photo-activated with a broad spectrum light, and for CQ-systems with a narrow band spectrum light, except when combined with an aliphatic amine (DMAEMA). Also, when combined with aromatic amines (EDMAB and DMPOH), similar cure efficiency with both wavelength LEDs was found. TPO had no cure efficiency when light-cured exclusively with a blue narrowband spectrum. CQ-systems presented higher color stability than type-I photoinitiators, especially when combined with DMPOH.


CONCLUSIONS
After aging, CQ-based composites became more yellow and BAPO and TPO lighter and less yellow. However, CQ-systems presented higher color stability than type-I photoinitiators, as BAPO- and TPO-, despite their higher cure efficiency when photo-activated with corresponding wavelength range.


CONCLUSIONS
Color matching is initially important, but color change over time will be one of the major reasons for replacing esthetic restorations; despite the less yellowing of these alternative photoinitiators, camphorquinone presented higher color stability.
Department of Restorative Dentistry, School of Dentistry, Oregon Health & Sicence University, 2730 SW Moody Avenue, 97201, Portland, OR, USA; Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Av. Limeira, 901, Areião, 13414-903, Piracicaba, SP, Brazil. Electronic address: dayoli87@gmail.com.
Dayane Carvalho Ramos Salles
DC
de Oliveira
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Av. Limeira, 901, Areião, 13414-903, Piracicaba, SP, Brazil.
Mateus Garcia
MG
Rocha
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Av. Limeira, 901, Areião, 13414-903, Piracicaba, SP, Brazil.
Alexandre
A
Gatti
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Av. Limeira, 901, Areião, 13414-903, Piracicaba, SP, Brazil.
Americo Bortolazzo
AB
Correr
Department of Restorative Dentistry, School of Dentistry, Oregon Health & Sicence University, 2730 SW Moody Avenue, 97201, Portland, OR, USA.
Jack Liborio
JL
Ferracane
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Av. Limeira, 901, Areião, 13414-903, Piracicaba, SP, Brazil.
Mario Alexandre Coelho
MA
Sinhoret
D000180:Acrylic Resins / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D002164:Camphor / Q000031:analogs & derivatives / Q000737:chemistry; D003116:Color; D003188:Composite Resins / Q000737:chemistry; D055117:Curing Lights, Dental / Q000145:classification*; D008027:Light; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D010720:Phosphines / Q000737:chemistry; D058567:Photoinitiators, Dental / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry; D019163:Reducing Agents / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D000180:Acrylic Resins; D003188:Composite Resins; C090257:Foundation composite resin; D008689:Methacrylates; D010720:Phosphines; D058567:Photoinitiators, Dental; D011140:Polyurethanes; D019163:Reducing Agents; C513703:Vivadent; D017438:Bisphenol A-Glycidyl Methacrylate; D002164:Camphor; C044646:phosphine; C049840:2-(dimethylamino)ethyl methacrylate; C553149:camphorquinone
Artificial accelerated aging; Color change; Degree of conversion; Light-curing; Light-curing unit