In this work, we study the thermodynamic behavior of heavy-flavored meson matter in the framework of $(sigma,omega)$-meson-exchange model in relativistic mean field theory. We find a decreasing of the effective masses of $D$ and $B$ mesons as the tem
perature increases. By using the effective mass and maximum value of dissociation temperatures available from lattice QCD, the masses of the bound states $D bar{D}$ and $B bar{B}$ are estimated in 2 MeV for both molecules. For the $B$-meson matter, the pressure presents an exotic behavior, being negative for temperatures above 6.6 times the deconfinement transition temperature $T_c$. In addition, the ratio of pressure to energy density is similar to the value predicted for systems that behave as dark energy matter.
