  We briefly review some of the models used to describe DNA denaturation
dynamics, focusing on the value of the dynamical exponent $z$, which governs
the scaling of the characteristic time $\tau\sim L^z$ as a function of the
sequence length $L$. The models contain different degrees of simplifications,
in particular sometimes they do not include a description for helical
entanglement: we discuss how this aspect influences the value of $z$, which
ranges from $z=0$ to $z \approx 3.3$. Connections with experiments are also
mentioned.
