title: Effect of exponential polymerization on color stability of resin-based filling materials.
abstract: OBJECTIVE
  To investigate the influence of a halogen light curing device used with constant or exponential polymerization mode on the color stability of contemporary resin-based filling materials.
  
  
  METHODS
  Eight samples of Charisma (CH), Durafill (DU), Definite (DE), and Dyract AP (DY) each were light-cured with constant power or with soft-start mode (Translux Energy) for 20, 40 or 60s. The CIE-Lab-values (L(*), a(*), b(*)) were measured prior to and after performing dry aging, water aging or a Suntest (EN ISO 7491) and Delta L-, Delta a-, Delta b-, and Delta E-values were calculated.
  
  
  RESULTS
  Statistical analysis (GLM and repetition of measures) showed significant changes (p<0.05) of the color values for each material's curing mode and time after each of the aging processes. Four-way ANOVA revealed significant differences (p<0.05) between Delta L-, Delta a-, Delta b-, and Delta E of the materials in dependence on the curing time and mode and aging condition. Exponentially-cured DU was the most color-unstable material after aging in water followed by the 20s exponentially cured DE and CH samples. After the Suntest, DY showed significant bleaching (negative Delta b) and the largest Delta E for all curing times and modes followed by the DE samples. DU and CH were the most color-stable materials in this test.
  
  
  CONCLUSIONS
  The extent of discoloration depends on the (a) curing time, (b) curing mode, (c) aging condition, and (d) material. For the constant curing mode, 40s curing time for the exponential 60s seems to be appropriate.
authors.affiliation: Heinrich-Heine-University, Medical Faculty, Centre of Dentistry, Department of Operative and Preventive Dentistry and Endodontics, Moorenstr. 5, Geb. 18.13, D-40225 Düsseldorf, Germany. Ralf.Janda@uni-duesseldorf.de
authors.forename: R
authors.initials: R
authors.lastname: Janda
authors.forename: J-F
authors.initials: JF
authors.lastname: Roulet
authors.forename: M
authors.initials: M
authors.lastname: Latta
authors.forename: M
authors.initials: M
authors.lastname: Kaminsky
authors.forename: St
authors.initials: S
authors.lastname: Rüttermann
mesh_terms: D000704:Analysis of Variance; D003116:Color; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D003793:Dental Restoration, Permanent; D004356:Drug Storage; D006219:Halogens; D008027:Light; D016014:Linear Models; D008422:Materials Testing; D044367:Phase Transition; D013997:Time Factors
chemical_list: D003188:Composite Resins; D006219:Halogens