title: Comparison of stabilities in translucency, fluorescence and opalescence of direct and indirect composite resins.
abstract: OBJECTIVE
  To evaluate translucency, fluorescence and opalescence stabilities of direct and indirect composite resins after aging.
  
  
  METHODS
  One direct (16 shades) and two indirect composite resins (16 and 26 shades) were investigated. Resins were filled in a mold (1 mm thick) and light cured; post-curings were performed for indirect resins. Color was measured before and after 5,000 cycles of thermocycling on a reflection spectrophotometer in reflectance and transmittance modes to calculate parameters for translucency (TP), fluorescence (FL) and opalescence (OP). Differences in the changes of TP, FL and OP after aging by the type of resin were determined by t test, and those were also determined by one-way ANOVA with the factor of the brand or the shade group (P < 0.05).
  
  
  RESULTS
  Changes in TP, FL and OP were -1.2 to 0.7, -0.2 to 0.4 and -0.6 to 1.3, respectively, for direct resins; and were -2.0 to 1.8, -0.9 to 0.4 and -2.9 to 3.7, respectively, for indirect resins. Changes in TP were not significantly different by the type of resin, but those in FL and OP were different (P = 0.05). Changes in optical parameters were influenced by the brand or the shade group of the resins (P < 0.05).
  
  
  CONCLUSIONS
  Stabilities in optical properties of resins varied depending on type, brand or shade group. Aging significantly affected fluorescence and opalescence, but not translucency, of indirect resins compared to those of direct resins.
authors.affiliation: Chinese Academy of Sciences, Beijing, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Yu
authors.forename: Young-Keun
authors.initials: YK
authors.lastname: Lee
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D004355:Drug Stability; D005453:Fluorescence; D008027:Light; D008689:Methacrylates / Q000737:chemistry; D055620:Optical Phenomena; D013053:Spectrophotometry
chemical_list: D003188:Composite Resins; C507124:Estelite sigma; D008689:Methacrylates; C477352:Sinfony composite resin; C110370:belleGlass