title: Measuring the radiopacity of luting cements, dowels, and core build-up materials with a digital radiography system using a CCD sensor.
abstract: OBJECTIVE
  This study assessed the radiopacity of five luting cements, five dowels, and five core build-up materials using two target distances.
  
  
  METHODS
  Materials were analyzed using a modified version of ISO protocol 4049. samples 1 mm thick were digitally radiographed alongside a stepwedge of aluminum alloy 1100 using a Trophy RVG-4 CCD sensor and 70 kVp X-ray generator. The gray-scale values of the stepwedge and sample were converted to X-ray absorbencies. The relationship between X-ray absorbance and aluminum thickness was linear for thicknesses less than 10 mm and followed a power-law relationship above 10 mm. These relations were used to convert the absorbencies of the samples into aluminum thicknesses. The radiopacity data was subjected to ANOVA/Student-Newman-Keuls testing.
  
  
  RESULTS
  All materials were more radiopaque than equivalent thicknesses of aluminum. Each product category contained a wide range of radiopacities. Syringe-dispensed materials tended to be less radiopaque than materials dispensed by mechanically assisted syringe or mixed by hand (p < 0.01). Target distance did not affect the measured radiopacity so long as the exposure time was suitably adjusted (p= 0.86).
  
  
  CONCLUSIONS
  All luting cements and core materials met or exceeded the ISO minimums. The tested metal-reinforced glass ionomer core build-up materials were extremely radiopaque. Some publications suggest that excessively radiopaque core materials can hinder a clinician's ability to spot voids or marginal defects.
authors.affiliation: Essential Dental Laboratories, the research arm of Essential Dental Systems, NJ 07606, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Rasimick
authors.forename: Steven
authors.initials: S
authors.lastname: Gu
authors.forename: Allan S
authors.initials: AS
authors.lastname: Deutsch
authors.forename: Barry Lee
authors.initials: BL
authors.lastname: Musikant
mesh_terms: D003738:Dental Cements / Q000737:chemistry*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D011176:Post and Core Technique / Q000295:instrumentation*; D019252:Radiography, Dental, Digital / Q000379:methods*
chemical_list: D003738:Dental Cements