title: Optical behavior of dental zirconia and dentin analyzed by Kubelka-Munk theory.
abstract: OBJECTIVE
  To use the Kubelka-Munk theory to evaluate the scattering (S), absorption (K) and transmittance (T) of non-colored and colored dental zirconia systems and human (HD) and bovine (BD) dentins.
  
  
  METHODS
  Two zirconia systems were used: ZC- ZirCAD (Ivoclar Vivadent) and LV-LAVA (3M ESPE). Specimens from each ceramic system were divided into 3 groups (n=5): ZC1 and LV1 (non-colored); ZC2 and LV2 colored to shade A1, and ZC3 and LV3 colored to shade A3. Five human and bovine anterior teeth were flattened and polished through 1200 grit SiC paper to expose the superficial buccal dentin. All samples were prepared to a final thickness of 0.5 mm. Diffuse reflectance was measured against white and black backgrounds, using a spectroradiometer in a viewing booth with D65 illuminant and d/0° geometry. S and K coefficients and T were calculated using Kubelka-Munk's equations. Data was statistically analyzed using Kruskal-Wallis, Mann-Whitney tests, and VAF coefficient.
  
  
  RESULTS
  Spectral distributions of S, K and T were wavelength dependent. The spectral behavior of S and T was similar to HD (VAF≥96.80), even though they were statistically different (p≤0.05). The spectral behavior of K was also similar to HD, except for LV1 (VAF=38.62), yet all ceramics were statistically different from HD (p≤0.05). HD and BD showed similar values of S and T (p>0.05).
  
  
  CONCLUSIONS
  The dental professional should consider the optical behavior differences between the zirconia systems evaluated and the human dentin to achieve optimal esthetics in restorative dentistry.
authors.affiliation: Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva s/n, 18071 Granada, Spain; Post-graduate Program in Dentistry, Dental School, University of Passo Fundo, Brazil.
authors.forename: Oscar E
authors.initials: OE
authors.lastname: Pecho
authors.affiliation: Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva s/n, 18071 Granada, Spain; Houston Center for Biomaterials and Biomimetics, School of Dentistry, University of Texas, 7500 Cambridge St., Houston, TX 77054, USA.
authors.forename: Razvan
authors.initials: R
authors.lastname: Ghinea
authors.affiliation: Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva s/n, 18071 Granada, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Ionescu
authors.affiliation: Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva s/n, 18071 Granada, Spain.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Cardona
authors.affiliation: Post-graduate Program in Dentistry, Dental School, University of Passo Fundo, Brazil.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Della Bona
authors.affiliation: Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva s/n, 18071 Granada, Spain; Houston Center for Biomaterials and Biomimetics, School of Dentistry, University of Texas, 7500 Cambridge St., Houston, TX 77054, USA. Electronic address: mmperez@ugr.es.
authors.forename: María del Mar
authors.initials: Mdel M
authors.lastname: Pérez
mesh_terms: D000818:Animals; D002417:Cattle; D002516:Ceramics / Q000737:chemistry*; D003116:Color; D003804:Dentin / Q000737:chemistry*; D004955:Esthetics, Dental; D006801:Humans; D055095:Optics and Photonics; D012542:Scattering, Radiation; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015040:Zirconium; C028541:zirconium oxide
keywords: Absorption coefficient; Scattering coefficient; Transmittance; Zirconia