The physicochemical and biological properties of calcium silicate-based cement (CS) associated to microparticulated (micro) or nanoparticulated (nano) zirconium oxide (ZrO 2 ) were compared with CS and bismuth oxide (BO) with CS. The pH, release of calcium ions, radiopacity, setting time, and compression strength of the materials were evaluated. The tissue reaction promoted by these materials in the subcutaneous was also investigated by morphological, immunohistochemical, and quantitative analyses. For this purpose, polyethylene tubes filled with materials were implanted into rat subcutaneous. After 7, 15, 30, and 60 days, the tubes surrounded by capsules were fixed and embedded in paraffin. In the H&E-stained sections, the number of inflammatory cells (ICs) in the capsule was obtained. Moreover, detection of interleukin-6 (IL-6) by immunohistochemistry and number of IL-6 immunolabeled cells were carried out. von Kossa method was also performed. The differences among the groups were subjected to Tukey test (p 0.05). The solutions containing the materials presented an alkaline pH and released calcium ions. The addition of radiopacifiers increased setting time and radiopacity of CS. A higher compressive strength in the CS 1 ZrO 2 (micro and nano) was found compared with CS 1 BO. The number of IC and IL-6 positive cells in the materials with ZrO 2 was significantly reduced in comparison with CS 1 BO. von Kossa-positive structures were observed adjacent to implanted materials. The ZrO 2 associated to the CS provides satisfactory physicochemical properties and better biological response than BO. Thus, ZrO 2 may be a good alternative for use as radiopacifying agent in substitution to BO.

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Objective. The aim of this study was to evaluate the compressive strength and setting time of MTA and Portland cement (PC) associated with bismuth oxide (BO), zirconium oxide (ZO), calcium tungstate (CT), and strontium carbonate (SC). Methods. For the compressive strength test, specimens were evaluated in an EMIC DL 2000 apparatus at 0.5 mm/min speed. For evaluation of setting time, each material was analyzed using Gilmore-type needles. The statistical analysis was performed with ANOVA and the Tukey tests, at 5% significance. Results. After 24 hours, the highest values were found for PC and PC + ZO. At 21 days, PC + BO showed the lowest compressive strength among all the groups. The initial setting time was greater for PC. The final setting time was greater for PC and PC + CT, and MTA had the lowest among the evaluated materials (P < 0.05). Conclusion. The results showed that all radiopacifying agents tested may potentially be used in association with PC to replace BO.

The aim of this study was to evaluate some properties of the calcium silicate materials Mineral Trioxide Aggregate (MTA) and Portland cement (PC) with microparticulated (micro) and nanoparticulated (nano) zirconium oxide (ZrO 2 ) or niobium oxide (Nb 2 O 5 ). The experimental materials: White PC (PC), MTA-Angelus ® (MTA), PC+ZrO 2 micro, PC+ZrO 2 nano, PC+Nb 2 O 5 micro and PC+Nb 2 O 5 nano were submitted to radiopacity and pH evaluations. Furthermore, the antimicrobial activity against different microorganisms was assessed by agar diffusion test. MTA presented higher radiopacity than other materials. However, all materials except PC presented higher radiopacity than recommended by ISO/ADA. MTA promoted higher pH values in all analyzed periods (p≤0.05). At the initial periods, PC and PC+ZrO 2 micro showed pH similar to MTA. All materials showed antimicrobial activity against the evaluated microorganisms. In conclusion, ZrO 2 and Nb 2 O 5 could be alternative radiopacifiers to be added to calcium silicate materials.