title: Color stability of a resin composite: Effect of the immersion method and surface treatments.
abstract: BACKGROUND
  In vitro staining methods expose the entire specimen to staining solutions. In a real clinical situation, this is not observed, since one should consider that the bonded surface is not exposed to the oral environment. Theoretically, the clinical condition would be the best simulated if the specimens were exposed to staining solutions by partial immersion.
  
  
  OBJECTIVE
  To evaluate if different immersion methods and surface treatments influence the color stability of resin-based specimens.
  
  
  METHODS
  A stainless steel matrix was used to prepare 30 disc-shaped specimens that were randomly allocated in three groups: Without polishing, polishing with abrasive discs, and surface sealant. Half of the specimens were isolated to maintain only the upper surface exposed to staining (partial immersion) and the other half was totally immersed in coffee solution for 48 h (total immersion). The coordinates ΔE*, ΔL*, Δa*, Δb* were assessed by spectrophotometer.
  
  
  METHODS
  Two-way ANOVA and Tukey's post hoc tests (α =0.05).
  
  
  RESULTS
  Specimens submitted to partial immersion showed lower values of ΔE*, ΔL*, Δa*, Δb*, in comparison to total immersion (P = 0.000). Specimens covered by a surface sealant presented lower ΔE* values regardless of the immersion method.
  
  
  CONCLUSIONS
  Specimens totally immersed in staining solutions could in somehow overestimate the color change, once that in most clinical conditions not all of the restoration surfaces are exposed to the oral environment. Moreover, as the surface sealant application produces color change values that are clinically acceptable, it might be used in esthetic restorations as an adjunct treatment.
authors.affiliation: Department of Restorative Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: L L
authors.initials: LL
authors.lastname: Miotti
authors.affiliation: Department of Stomatology, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: G F
authors.initials: GF
authors.lastname: Nicoloso
authors.affiliation: Department of Restorative Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: L B
authors.initials: LB
authors.lastname: Durand
authors.affiliation: Department of Restorative Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: A H
authors.initials: AH
authors.lastname: Susin
authors.affiliation: Department of Stomatology, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: R O
authors.initials: RO
authors.lastname: Rocha
mesh_terms: D003124:Colorimetry / Q000379:methods*; D003188:Composite Resins / Q000737:chemistry*; D007101:Immersion; D066298:In Vitro Techniques; D008422:Materials Testing; D010895:Pit and Fissure Sealants / Q000737:chemistry*; D013053:Spectrophotometry; D013193:Stainless Steel / Q000737:chemistry; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D010895:Pit and Fissure Sealants; D013193:Stainless Steel