title: Evaluation of the radiopacity of calcium silicate cements containing different radiopacifiers.
abstract: OBJECTIVE
  To identify the suitable ratio of alternative radiopacifiers to impart the necessary radiopacity to calcium silicate cements (CSC) and assess the purity of the radiopacifying agents.
  
  
  METHODS
  Alternative radiopacifying materials for incorporation into CSC included barium sulphate, titanium oxide, zinc oxide, gold powder and silver/tin alloy. The chemical composition of the alternative radipacifying materials and bismuth oxide, which is used in mineral trioxide aggregate (MTA), was determined using energy dispersive X-ray analysis. In addition, using an aluminium step-wedge and densitometer, the radiopacity of each material was evaluated as recommended by international standards. The optical density was compared with the relevant thickness of aluminium (Al). A commercial MTA and CSC were used as controls. Statistical analysis comparing the radiodensity of the different cements to MTA was performed using anova with P = 0.05 and post hoc Tukey test.
  
  
  RESULTS
  All percentage replacements of bismuth oxide, gold and silver-tin alloy powder, and the 25% and 30% replacements with barium sulphate and zinc oxide had radiopacities greater than 3 mm thickness of aluminium (Al) recommended by ISO 6876 (2002). The 25% replacement of cement with gold powder and 20% replacement of cement with silver/tin alloy powder exhibited radiopacity values of 8.04 mm Al and 7.52 mm Al, respectively, similar to MTA (P > 0.05). The cement replaced with 20% bismuth oxide showed a radiopacity of 6.83 mm Al, lower than MTA (P = 0.003).
  
  
  CONCLUSIONS
  Silver/tin alloy and gold powder imparted the necessary radiopacity to a calcium silicate-based cement. Barium sulphate was also a suitable radiopacifier together with a lower concentration of silver/tin alloy and gold powder that achieved the radiodensity recommended by ISO 6876. Further research is required to investigate the broader properties of the calcium silicate-based cement with the different radiopacifiers.
authors.affiliation: Department of Building and Civil Engineering, University of Malta, Msida, Malta. josette.camilleri@um.edu.mt
authors.forename: J
authors.initials: J
authors.lastname: Camilleri
authors.forename: M G
authors.initials: MG
authors.lastname: Gandolfi
mesh_terms: D017610:Calcium Compounds; D003287:Contrast Media; D003738:Dental Cements / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D017640:Silicates; D013052:Spectrometry, X-Ray Emission
chemical_list: D017610:Calcium Compounds; D003287:Contrast Media; D003738:Dental Cements; D017640:Silicates; C031293:calcium silicate