Self-ligating brackets: present and future.

Recently, there has been a resurgence in the use of self-ligating (SL) brackets, which were introduced in the early 20th century. From a synthesis of both in-vitro and in-vivo evidence-based literature, we present general concepts, principles, and axioms. The references to "active" and "passive" SL brackets are explained and juxtaposed in relation to their perceived advantages and disadvantages. We also present new concepts in regard to the future of SL brackets: combination bracket system, hybrid system, and selective use of SL brackets.