Effect of Tantalum Pentoxide Addition on the Radiopacity Performance of Bi2O3/Ta2O5 Composite Powders Prepared by Mechanical Milling

Abstract

Among the various phases of bismuth oxide, the high temperature metastable face-centered cubic δ phase attracts great attention due to its unique properties. It can be used as an ionic conductor or an endodontic radiopacifying material. However, no reports concerning tantalum and bismuth binary oxide prepared by high energy ball milling and serving as a dental radiopacifier can be found. In the present study, Ta2O5-added Bi2O3 composite powders were mechanically milled to investigate the formation of these metastable phases. The as-milled powders were examined by X-ray diffraction and scanning electron microscopy to reveal the structural evolution. The as-milled composite powders then served as the radiopacifier within mineral trioxide aggregates (i.e., MTA). Radiopacity performance, diametral tensile strength, setting times, and biocompatibility of MTA-like cements solidified by deionized water, saline, or 10% calcium chloride solution were investigated. The experimental results showed that subsequent formation of high temperature metastable β-Bi7.8Ta0.2O12.2, δ-Bi2O3, and δ-Bi3TaO7 phases can be observed after mechanical milling of (Bi2O3)95(Ta2O5)5 or (Bi2O3)80(Ta2O5)20 powder mixtures. Compared to its pristine Bi2O3 counterpart with a radiopacity of 4.42 mmAl, long setting times (60 and 120 min for initial and final setting times) and 84% MG-63 cell viability, MTA-like cement prepared from (Bi2O3)95(Ta2O5)5 powder exhibited superior performance with a radiopacity of 5.92 mmAl (the highest in the present work), accelerated setting times (the initial and final setting time can be shortened to 25 and 40 min, respectively), and biocompatibility (94% cell viability).

Mechanochemical synthesis of nanostructured and composite oxide ceramics: From mechanisms to tailored properties

“…By controlling the proportion of synthetic raw materials, the performance of synthetic powders is improved. Chang and coworkers 150 mechanically ball‐milled Ta 2 O 5 and Bi 2 O 3 (5:95, 1:4) in different proportions to synthesize composite powders. The addition of tantalum pentoxide shortens the grinding time to form these phases.…”

Designing Calcium Silicate Cements with On-Demand Properties for Precision Endodontics

“…Unfortunately, producing tailor-made cements is complex as attempts to optimize components and W/P (inputs) often induce trade-offs in cement properties. For example, increases in radiopacity can decrease mechanical properties or lengthen the setting time since additional radiopacifiers can only be incorporated at the expense of other powder components (Li and Coleman 2019; Lin, Lin, et al 2021). Likewise, increasing flowability lengthens the setting time, as both positively correlate with W/P (Natu et al 2015; Koutroulis et al 2019).…”

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

“…Suitable radiopacifiers to improve the performance of MTA remains an interest of research and development. For instance, previous investigations using either a physically highenergy ball milling process [15,16] or chemically wet methods such as precipitation, sol-gel, and spray pyrolysis processes [17][18][19] to modify bismuth oxide by introducing a secondary oxide have been attempted, and improvements in radiopacity performance were observed. These MTA-like cements, however, may experience tooth discoloration after clinical service due to the presence of bismuth.…”

“…By continuous milling of a single starting powder or alloying of multiple components, amorphous materials, extended solid solutions, intermetallic compounds, metastable crystalline materials, nanocrystalline powders, and quasicrystals can be synthesized [20,[22][23][24]. For instance, the high-temperature metastable δ-Bi 7.38 Zr 0.62 O 2.31 phase was synthesized by mechanically milling a Bi 2 O 3 and ZrO 2 powder mixture [15], whereas the formation of β-Bi 7.8 Ta 0.2 O 12.2 , and δ-Bi 3 TaO 7 phases can be achieved by milling binary Bi 2 O 3 and Ta 2 O 5 [16]. Corresponding radiopacities of various as-milled Bi 2 O 3 -based composite powders have been examined [15,16].…”

“…For instance, the high-temperature metastable δ-Bi 7.38 Zr 0.62 O 2.31 phase was synthesized by mechanically milling a Bi 2 O 3 and ZrO 2 powder mixture [15], whereas the formation of β-Bi 7.8 Ta 0.2 O 12.2 , and δ-Bi 3 TaO 7 phases can be achieved by milling binary Bi 2 O 3 and Ta 2 O 5 [16]. Corresponding radiopacities of various as-milled Bi 2 O 3 -based composite powders have been examined [15,16]. The effect of milling time, oxide addition, and storage environment on the radiopacity performance have been discussed.…”