title: The influence of varying layer thicknesses on the color predictability of two different composite layering concepts.
abstract: OBJECTIVE
  Optical properties of teeth are mimicked by composite layering techniques by combining a relatively opaque layer (dentin) with more translucent layers (enamel). However, the replacing material cannot always optically imitate the tooth when applied in the same thickness as that of the natural tissues. The natural layering composite system is available in 2 concepts: (1) dentin (D) and enamel (E) have the same shade but with different translucencies; (2) D and E have different shades where E is always the same high translucent shade. The objective was to evaluate the influence of varying thicknesses of E and D composites on the overall color and on the translucency for both concepts.
  
  
  METHODS
  For each concept three composite brands were tested; Concept 1: Clearfil Photo Bright (Kuraray), Herculite XRV Ultra (Kerr), Venus Diamond (Heraeus Kulzer); Concept 2: Amaris (VOCO), CeramX Duo (DENTSPLY) and Point4 (Kerr). Two specimens of each shade (A1-A3) per composite were made of standardized thicknesses with a poly-acrylic mold and Teflon cover, making 36 specimens of wedge-like dimension. The L*a*b* values were measured three times against a white and black background (n=216). Student's t-tests revealed significant levels between the average ΔE* values of the 3 areas for each composite.
  
  
  RESULTS
  Statistically significant differences (p<0.05) were found for all thicknesses and for all shades between the concepts. Concept 2 showed greater variations in ΔE* with increased thicknesses.
  
  
  CONCLUSIONS
  Concept 2 composites are more sensitive to layer thickness changes, which implicates less predictability in a daily clinical routine.
authors.affiliation: Department of Oral Function and Restorative Dentistry, Academic Center for Dentistry Amsterdam, Amsterdam, The Netherlands. Electronic address: G.Khashayar@acta.nl.
authors.forename: G
authors.initials: G
authors.lastname: Khashayar
authors.affiliation: Department of Oral Function and Restorative Dentistry, Academic Center for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Dozic
authors.affiliation: Department of Oral Function and Restorative Dentistry, Academic Center for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: C J
authors.initials: CJ
authors.lastname: Kleverlaan
authors.affiliation: Department of Oral Function and Restorative Dentistry, Academic Center for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: A J
authors.initials: AJ
authors.lastname: Feilzer
authors.affiliation: Department of Oral Function and Restorative Dentistry, Academic Center for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Roeters
mesh_terms: D003116:Color; D003188:Composite Resins
chemical_list: D003188:Composite Resins
keywords: Color measurement; Composite layering techniques; Dental materials; Restorative dentistry; Spectrophotometry; Tooth build-up; Tooth color; Translucency