  The effect of color screening on the formation of a heavy quark-antiquark
($Q\bar{Q}$) bound state--such as the $J/\psi$ meson--is studied using a
constituent-quark model. The response of the nuclear medium to the addition of
two color charges is simulated directly in terms of its quark constituents via
a string-flip potential that allows for quark confinement within hadrons yet
enables the hadrons to separate without generating unphysical long-range
forces. Medium modifications to the properties of the heavy meson, such as its
energy and its mean-square radius, are extracted by solving Schr\"odinger's
equation for the $Q\bar{Q}$ pair in the presence of a (screened)
density-dependent potential. The density dependence of the heavy-quark
potential is in qualitative agreement with earlier studies of its temperature
dependence extracted from lattice calculations at finite temperature. In the
present model it is confirmed that abrupt changes in the properties of the
$J/\psi$-meson in the hadronic medium ({\it plasma}), correlate strongly with
the deconfining phase transition.
