  Dynamical chiral-symmetry breaking in QCD is studied with the Schwinger-Dyson
(SD) formalism based on lattice QCD data, i.e., LQCD-based SD formalism. We
extract the SD kernel function $K(p^2)$ in an Ansatz-independent manner from
the lattice data of the quark propagator in the Landau gauge. As remarkable
features, we find infrared vanishing and intermediate enhancement of the SD
kernel function $K(p^2)$. We apply the LQCD-based SD equation to thermal QCD
with the quark chemical potential $\mu_q$. We find chiral symmetry restoration
at $T_c \simeq 100{\rm MeV}$ for $\mu_q=0$. The real part of the quark mass
function decreases as $T$ and $\mu_q$. At finite density, there appears the
imaginary part of the quark mass function, which would lead to the width
broadening of hadrons.
