Discoloration Improvement by Mechanically-Milled Binary Oxides as Radiopacifier for Mineral Trioxide Aggregates

Hsiu Na Lin, Ling Chi Wang, May Show Chen, Pei Jung Chang, Pin Yu Lin, Alex Fang, Chin Yi Chen, Pee Yew Lee, Chung Kwei Lin

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Mineral trioxide aggregates (MTA) have been widely used in endodontic treatments, but after some time, patients suffer tooth discoloration due to the use of bismuth oxide (Bi2O3) as a radiopacifier. Replacement of Bi2O3 with high energy ball-milled single (zirconia ZrO2; hafnia, HfO2; or tantalum pentoxide, Ta2O5) or binary oxide powder was attempted, and corresponding discoloration improvement was investigated in the present study. Bi2O3-free MTA is expected to exhibit superior discoloration. The radiopacity, diametral tensile strength, and discoloration of MTA-like cements prepared from the as-milled powder were investigated. Experimental results showed that MTA-like cements prepared using Ta2O5 exhibited a slightly higher radiopacity than that of HfO2 but had a much higher radiopacity than ZrO2. Milling treatment (30 min to 3 h) did not affect the radiopacities significantly. These MTA-like cements exhibited superior color stability (all measured ΔE00 < 1.0) without any perceptible differences after UV irradiation. MTA-like cements prepared using ZrO2 exhibited the best color stability but the lowest radiopacity, which can be improved by introducing binary oxide. Among the investigated samples, MTA-like cement using (ZrO2)50(Ta2O5)50 exhibited excellent color stability and the best overall performance with a radiopacity of 3.25 mmAl and a diametral tensile strength of 4.39 MPa.

Original languageEnglish
Article number7934
Issue number22
Publication statusPublished - Nov 2022


  • binary oxide
  • discoloration
  • hafnia
  • mechanical milling
  • mineral trioxide aggregates
  • radiopacifier
  • radiopacity
  • tantalum pentoxide
  • zirconia

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics


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