title: Translucency and masking ability of various composite resins at different thicknesses.
abstract: BACKGROUND
  Optical properties of the composite resins, concerning their translucency and thickness, are affected by discolored tooth structure or inherent darkness of the oral cavity.
  
  
  OBJECTIVE
  This study aimed to compare the translucency parameter (TP) of five different composite resins in different thicknesses and to evaluate their masking ability in black backgrounds.
  
  
  METHODS
  Five brands of composite resins; Gradia (GC) and Crystalline (Confi-dental) in opaque A2 (OA2), Vit-l-escence (Ultradent) in opaque snow (OS), Herculite XRV (Kerr) and Opallis (FGM) in dentin A2 (DA2) shades were selected to enroll the study. Color coordinates of each composite were determined at 0.5, 1, and 1.5 mm thicknesses on a white backing, the backing of material itself and a black backing were calculated by using a spectrophotometer to evaluate the translucency parameter (TP) of the study materials. The masking ability was also calculated from the specimens on the material itself and on black backing. The values under 2 were estimated as imperceptible. One-way ANOVA, T-test and Tukey HSD were employed for statistical analysis.
  
  
  RESULTS
  The masking ability values, recorded for the 1.5 mm-thick specimens, were in the range of imperceptible except for the Herculite. There was no difference in TP values of the materials at 1.5 mm thickness. Opaque snow shade of Vit-l-escence and opaque A2 shade of Gradia showed lower TP values in comparison with the other 1 and 0.5 mm-thick materials and this difference was statistically significant (p< 0.05).
  
  
  CONCLUSIONS
  In relatively thin thicknesses (≤1mm), these opaque/dentin shade composite resins could not mask the black background color.
authors.affiliation: Oromaxillofacial Developmental Disease Research Center, Dept. of Operative Dentistry, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Farideh
authors.initials: F
authors.lastname: Darabi
authors.affiliation: Oromaxillofacial Developmental Disease Research Center, Dept. of Periodontology, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Golpar
authors.initials: G
authors.lastname: Radafshar
authors.affiliation: Oromaxillofacial Developmental Disease Research Center, Dept. of Operative Dentistry, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Tavangar
authors.affiliation: Oromaxillofacial Developmental Disease Research Center, Dept. of Operative Dentistry, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Davaloo
authors.affiliation: Dentist, Private Practice, Tehran, Iran.
authors.forename: Aref
authors.initials: A
authors.lastname: Khosravian
authors.affiliation: MS in Nursing Education, Oromaxillofacial Developmental Disease Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Nastaran
authors.initials: N
authors.lastname: Mirfarhadi
keywords: Composite resins; Masking; Thickness; Translucency