title: Effect of staining solutions and repolishing on color stability of direct composites.
abstract: OBJECTIVE
  The purpose of this study was to assess the color change of three types of composite resins exposed to coffee and cola drink, and the effect of repolishing on the color stability of these composites after staining.
  
  
  METHODS
  Fifteen specimens (15 mm diameter and 2 mm thick) were fabricated from microhybrid (Esthet-X; Dentsply and Filtek Z-250; 3M ESPE) and high-density hybrid (Surefil; Dentsply) composites, and were finished and polished with aluminum oxide discs (Sof-Lex; 3M ESPE). Color of the specimens was measured according to the CIE L*a*b* system in a reflection spectrophotometer (PCB 6807; BYK Gardner). After baseline color measurements, 5 specimens of each resin were immersed in different staining solutions for 15 days: G1 - distilled water (control), G2 - coffee, G3 - cola soft drink. Afterwards, new color measurement was performed and the specimens were repolished and submitted to new color reading. Color stability was determined by the difference (ΔE) between the coordinates L*, a*, and b* obtained from the specimens before and after immersion into the solutions and after repolishing.
  
  
  RESULTS
  There was no statistically significant difference (ANOVA, Tukey's test; p>0.05) among the ΔE values for the different types of composites after staining or repolishing. For all composite resins, coffee promoted more color change (ΔE>3.3) than distilled water and the cola soft drink. After repolishing, the ΔE values of the specimens immersed in coffee decreased to clinically acceptable values (ΔE<3.3), but remained significantly higher than those of the other groups.
  
  
  CONCLUSIONS
  No significant difference was found among composite resins or between color values before and after repolishing of specimens immersed in distilled water and cola. Immersing specimens in coffee caused greater color change in all types of composite resins tested in this study and repolishing contributed to decrease staining to clinically acceptable ΔE values.
authors.affiliation: Department of Dental Materials and Prosthodontics, Ribeirão Preto Dental School, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Fabrício Mariano
authors.initials: FM
authors.lastname: Mundim
authors.forename: Lucas da Fonseca Roberti
authors.initials: Lda F
authors.lastname: Garcia
authors.forename: Fernanda de Carvalho Panzeri
authors.initials: Fde C
authors.lastname: Pires-de-Souza
mesh_terms: D002253:Carbonated Beverages; D003069:Coffee / Q000737:chemistry; D003116:Color; D004396:Coloring Agents / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing / Q000379:methods*; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D013053:Spectrophotometry; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D003069:Coffee; D004396:Coloring Agents; D003188:Composite Resins; D003764:Dental Materials; C466112:Esthet-X; C444701:Filtek Z250; C403464:SureFil packable composite; D014867:Water