title: Study of the radio-opacity of base and liner dental materials using a digital radiography system.
abstract: OBJECTIVE
  This study investigated the radio-opacity of commercially available glass ionomer cements (GICs), flowable resin composites (FRCs) and calcium hydroxide cements (CHCs) and compared this with the radio-opacity of enamel, dentine and aluminium stepwedge. 16 GICs, 8 FRCs and 4 CHCs were analysed.
  
  
  METHODS
  Three sets of three samples were prepared: 1 mm, 2 mm and 3 mm thickness for GIC and FRC and 1 mm thickness for CHC. Specimens of enamel and dentine with the same thicknesses were obtained. As a control, an aluminium stepwedge was used. Radiographs were taken with a digital Kodak RVG 5000 (0.32 s, 30 cm). The images were analysed using the Image Tool(®) program (v. 2.00; The University of Texas Health Science Center, San Antonio, TV) to obtain the mean grey values.
  
  
  RESULTS
  Analysis of variance was used to investigate the significance of differences among the groups. For pairwise comparisons, the Tukey test was applied (p < 0.05). The GICs Ionomaster (Wilcos, Petrópolis, Brazil), Maxxion (FGM, Joinville, Brazil), Bioglass R (Biodinâmica, Ibiporã, Brazil), Bioglass F (Biodinâmica), Vidrion R (SS White, Rio de Janerio, Brazil) and Vidrion F (SS White), presented radio-opacity lower than that of dentine. All FRCs and CHCs studied showed radio-opacity higher than that of dentine. Vitro Fil (DFL, Rio de Janeiro, Brazil), Magic Glass (Vigodent, Rio de Janeiro, Brazil), Vitrebond (3M, Sumaré SP, Brazil), Riva Self Cure (SDI, Victoria, Australia), Riva Light Cure (SDI), Fill Magic (Vigodent), Opallis (FGM, Joinville, Brazil), Surefil SDR (Dentsply, Milford, DE), Tetric N (Ivoclar Vivadent, Schaan, Lichtenstein), Tetric (Ivoclar Vivadent), Hydro C (Dentsply, Petrópolis, Brazil), Hydcal (Technew, Madalena, Portugal) and Liner (Vigodent) showed radio-opacity similar to or greater than that of enamel for all thicknesses.
  
  
  CONCLUSIONS
  The increased thickness of the materials studied increases their radio-opacity. Some commercially available GICs used as a base and liner for restorations have a very low radio-opacity (Ionomaster, Maxxion, Bioglass R, Bioglass F, Vidrion R and Vidrion F).
authors: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, Brazil.
authors: K M
authors: KM
authors: Lachowski
authors: S B
authors: SB
authors: Botta
authors: C A
authors: CA
authors: Lascala
authors: A B
authors: AB
authors: Matos
authors: M A P
authors: MA
authors: Sobral
mesh_terms: D002126:Calcium Hydroxide / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003287:Contrast Media; D003738:Dental Cements / Q000737:chemistry; D003743:Dental Enamel / Q000000981:diagnostic imaging; D003764:Dental Materials / Q000737:chemistry*; D003804:Dentin / Q000000981:diagnostic imaging; D003819:Denture Bases; D003822:Denture Liners; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D011856:Radiographic Image Enhancement / Q000295:instrumentation; D019252:Radiography, Dental, Digital / Q000295:instrumentation / Q000379:methods; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003287:Contrast Media; D003738:Dental Cements; D003764:Dental Materials; D005899:Glass Ionomer Cements; D019279:Resin Cements; D002126:Calcium Hydroxide
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