We consider the behaviour of two coupled symmetric electronic minibands in the presence of an AC intense field. Symmetric coupled minibands are realized as dimerization procedures. The minibands are emulated by a tight-binding finite chain, whereas the interaction with an AC field is described by a time-independent Hamiltonian. We follow the evolution of dressed minibands, non perturbatively, in a wide frequency range. For one dimerization procedure, a transition between both limits can be systematically followed and a dynamic breakdown is unambigously identified. The most striking effect that may occur is a field-induced analog of an insulator-metal transition due to the suppression of a Peierls-like instability.