Zirconium oxide and niobium oxide used as radiopacifiers in a calcium silicate‐based material stimulate fibroblast proliferation and collagen formation

Aim To evaluate the influence of the addition of microparticulate (micro) and nanoparticulate (nano) zirconium oxide (ZrO 2 ) and niobium pentoxide (Nb 2 O 5 ) to a calcium silicate‐based cement ( CS ) on the subcutaneous healing process in rats compared with MTA Angelus™. Methodology In each rat, two polyethylene tubes filled with the following materials: (i) MTA ; (ii) CS + ZrO 2 micro; (iii) CS + ZrO 2 nano; (iv) CS + Nb 2 O 5 micro or (v) CS + Nb 2 O 5 nano were implanted subcutaneously; empty polyethylene tubes were used in the Control group. After 7, 15, 30 and 60 days, the specimens ( n = 5 per group in each period) were fixed and embedded in paraffin. Masson's trichrome sections were used to obtain the volume density of the inflammatory cells (Vv IC ) and fibroblasts (VvFb). The sections were also stained with Picrosirius‐red to calculate the birefringent collagen content. Fibroblast growth factor‐1 ( FGF ‐1) was detected by immunohistochemistry, and the number of immunolabelled cells was obtained. The data were subjected to two‐way anova followed by Tukey's test ( P ≤ 0.05). Results At all periods, the Vv IC was significantly lower ( P < 0.001) in all the CS and Control groups than in the MTA group. At all periods, the VvFb was reduced significantly ( P = 0.023) in the MTA group in comparison with the other groups. In addition, the number of immunolabelled cells in the capsules of the CS groups was significantly higher ( P < 0.001) than in the MTA group at all time‐points. Conclusions The experimental materials ( CS + ZrO 2 and CS + Nb 2 O 5 ) induced fibroblast proliferation and accelerated the regression of the inflammatory reaction. However, the addition of nanoparticulate radiopacifiers did not improve the biological properties of a calcium silicate‐based cement when compared to microparticulate agents.