title: Ageing of silorane-based and methacrylate-based composite resins: effects on translucency.
abstract: OBJECTIVE
  Verify if media and time of storage affect the translucency of a silorane-based composite (Filtek P90) compared to two methacrylate-based composites (Z350 and ROK), and compare two methods of translucency evaluation.
  
  
  METHODS
  Specimens were divided into two groups (n=7) according to the storage media (deionized water or red wine). With a spectrophotometer (SP60) in reflectance mode, the CIE L*a*b* parameters and opacity percentage readings were conducted at baseline, 24h, 30 days, and 180 days. Data were analyzed using two-way repeated measures ANOVA and Tukey (p<0.05). Pearson correlation measured the relationship between translucency parameter and opacity percentage.
  
  
  RESULTS
  When stored in water, P90 showed an increase, whereas Z350 decreased in translucency. ROK did not exhibit any tendency over time. When stored in wine, the translucency of all materials decreased. A negative relationship was found between translucency parameter and opacity percentage. When stored in water, the a* values for P90 decreased, whereas Z350 and ROK showed values increasing over time. When stored in wine, the L* parameter tended to decrease over time, an effect that was less intense for P90. Moreover, the b* parameter for P90 decreased, whereas methacrylate-based composites increased over time.
  
  
  CONCLUSIONS
  P90 was more stable in red wine than the other materials and became more translucent in water whether metacrilate-based materials became more opaque. Both media as well as storage time affected the translucency of the materials tested. Translucency could be measured with both methods tested.
  
  
  CONCLUSIONS
  Silorane-based composites seemed to be more stable than methacrylate-based composites in red wine and became more translucent over time in water, which was different than methacrylate-based composites. More studies are needed to clarify silorane-based composites performance.
authors.affiliation: Post-Graduate Program in Dentistry Sciences, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. marinakaizer@terra.com.br
authors.forename: Marina da Rosa
authors.initials: Mda R
authors.lastname: Kaizer
authors.forename: Pâmela Gutheil
authors.initials: PG
authors.lastname: Diesel
authors.forename: André
authors.initials: A
authors.lastname: Mallmann
authors.forename: Letícia Borges
authors.initials: LB
authors.lastname: Jacques
mesh_terms: D003124:Colorimetry; D003188:Composite Resins / Q000737:chemistry*; D004356:Drug Storage; D049449:Luminescence; D008163:Luminescent Measurements / Q000379:methods; D008422:Materials Testing; D008689:Methacrylates; D055620:Optical Phenomena; D012833:Siloxanes; D013053:Spectrophotometry; D013997:Time Factors; D014867:Water; D014920:Wine
chemical_list: D003188:Composite Resins; D008689:Methacrylates; D012833:Siloxanes; D014867:Water