Radiopacity and Material Interaction With Dentine of Selected Dental Materials

Objectives: The aim of this laboratory study was to investigate the stability of various radiopacifiers used in different restorative and endodontic materials, by assessing their radiopacity in function, their interaction with dental structures, and ion release.
Methods: Six restorative materials, Grey MTA Plus (Avalon Biomed), Neo MTA Plus (Avalon Biomed), Fuji IX (GC Europe), ChemFil (Dentsply DeTrey), TheraCal (Bisco), and light curable calcium hydroxide liner (Produit Dentaires SA) were assessed. Disc-shaped specimens (diameter 6 mm, thickness 2 mm) were prepared according to the manufacturer's instructions. The specimens were X-rayed together with an aluminum stepwedge. The grey scale values were obtained by analysing data with a software (ImageJ) after the radiographs were scanned. Extracted human teeth were restored with the restorative materials and X-rayed before and after thermo-cycling to asses for differences in radiopacity. SEM/EDX analysis was performed to identify radiopacifiers in each of the six different materials and also to investigate the interaction of these materials with dentine. ICP-OES (inductively coupled plasma optical emission spectrometry) analysis was performed to observe any ions release (leachable matter) by the test materials after immersion of 1, 7, 14, and 28 days.


Results: The ranking of the highest to the lowest radiopacity of the 2 mm thick discs were: Grey MTA Plus, Neo MTA Plus, Fuji IX, TheraCal, light curable calcium hydroxide liner and ChemFil. The elements that would increase the material radiopacity included bismuth for MTA Plus, tantalum for Neo MTA Plus. The glass ionomers exhibited the presence of strontium while the Thercal and light curable calcium hydroxide had additions of barium and zirconium. All materials tested exhibited a reduction in radiopacity after thermo-cycling. They all leached out mainly calcium.


Conclusions: MTA-based restorative materials exhibited the highest radiopacity. The materials studied released varying amount of leachable matter.