title: Influence of coloring procedure on flexural resistance of zirconia blocks.
abstract: BACKGROUND
  The white color of zirconia limits the possibility of a natural-looking restoration. Industrially precolored blocks and green-stage coloring liquids are used to obtain shaded zirconia. Several authors have reported that pigments may negatively affect the mechanical characteristics of the material.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to investigate the effect of a recently marketed coloring system on the flexural strength (σ), Weibull characteristic strength (σ0), and Weibull modulus (m) of a zirconia for computer-aided design/computer-aided manufacturing (CAD/CAM) systems.
  
  
  METHODS
  Noncolored white blocks (In-Ceram YZ), industrially precolored blocks (In-Ceram YZ col. LL1p), and green-stage infiltration-shaded blocks in 4 colors (In-Ceram YZ Coloring Liquids) were tested. Industrially precolored specimens (n = 30) were assigned to the PREC group. Noncolored specimens were divided into 5 groups (n = 30). Group CNTR was not treated (control). Groups INF-N, INF-L, INF-M, and INF-I were subject to green-stage infiltration (neutral, light, medium, and intense, respectively). Specimens were tested in a 3-point bending apparatus following ISO 6872:2008 specifications. Data were analyzed by 1-way ANOVA.
  
  
  RESULTS
  The calculated flexural strengths (MPa) were CNTR 1232.56 ± 103.91; PREC 1215.16 ± 141.42; INF-N 1280.72 ± 160.10; INF-L 1218.92 ± 78.63; INF-M 1153.71 ± 176.80; and INF-I 1248.46 ± 111.73. No statistically significant differences were found among the tested groups (P = .195).
  
  
  CONCLUSIONS
  Unlike what has been reported for other combinations of zirconia and coloring liquids, the coloring technique tested in the present study did not negatively influence the flexural characteristics of the tested zirconia.
authors: Tutor, Department of Medical Biotechnologies, University of Siena, Siena, Italy. Electronic address: maurizio.sedda@gmail.com.
authors: Maurizio
authors: M
authors: Sedda
authors: Research Professor, Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors: Alessandro
authors: A
authors: Vichi
authors: Tutor, Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors: Michele
authors: M
authors: Carrabba
authors: Tutor, Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors: Alessandro
authors: A
authors: Capperucci
authors: Senior Lecturer, Eastman CPD, UCL Eastman Dental Institute, London, United Kingdom.
authors: Chris
authors: C
authors: Louca
authors: Dean, Professor, Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors: Marco
authors: M
authors: Ferrari
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003116:Color; D004396:Coloring Agents / Q000737:chemistry; D017076:Computer-Aided Design; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D055119:Elastic Modulus; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D018583:Pliability; D013314:Stress, Mechanical; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D003764:Dental Materials; C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D015040:Zirconium