  We examine the influence of density on the transition between chain and
spiral structures in planar assemblies of active semiflexible filaments,
utilizing detailed numerical simulations. We focus on how increased density,
and higher P\'eclet numbers, affect the activity-induced transition spiral
state in a semiflexible, self-avoiding active chain. Our findings show that
increasing the density causes the spiral state to break up, reverting to a
motile chain-like shape. This results in a density-dependent reentrant phase
transition from spirals back to open chains. We attribute this phenomenon to an
inertial effect observed at the single polymer level, where increased
persistence length due to inertia has been shown in recent three-dimensional
studies to cause polymers to open up. Our two-dimensional simulations further
reveal that a reduction in the damping coefficient leads to partial unwinding
of the spirals, forming longer arms. In suspension, interactions among these
extended arms can trigger a complete unwinding of the spirals, driven by the
combined effects of density and inertia.
