Impact of zr-doped bi₂o₃ radiopacifier by spray pyrolysis on mineral trioxide aggregate

Mineral trioxide aggregates (MTA) have been developed as a dental root repair material for a range of endodontics procedures. They contain a small amount of bismuth oxide (Bi2O3) as a radiopacifier to differentiate adjacent bone tissue on radiographs for endodontic surgery. However, the addition of Bi2O3 to MTA will increase porosity and lead to the deterioration of MTA’s mechanical properties. Besides, Bi2O3 can also increase the setting time of MTA. To improve upon the undesirable effects caused by Bi2O3 additives, we used zirconium ions (Zr) to substitute the bismuth ions (Bi) in the Bi2O3 compound. Here we demonstrate a new composition of Zr-doped Bi2O3 using spray pyrolysis, a technique for producing fine solid particles. The results showed that Zr ions were doped into the Bi2O3 compound, resulting in the phase of Bi7.38Zr0.62O12.31. The results of materials analysis showed Bi2O3 with 15 mol % of Zr doping increased its radiopacity (5.16 ± 0.2 mm Al) and mechanical strength, compared to Bi2O3 and other ratios of Zr-doped Bi2O3. To our knowledge, this is the first study of fabrication and analysis of Zr-doped Bi2O3 radiopacifiers through the spray pyrolysis procedure. The study reveals that spray pyrolysis can be a new technique for preparing Zr-doped Bi2O3 radiopacifiers for future dental applications.