Materials used for root canal obturation: technical, biological and clinical testing

Endodontic filling materials may be considered true implants as they touch and are based in vital tissues of the body, and protrude to meet the external surface directly or, more appropriately, indirectly via another surface restoration (Fig. 1). It follows that the materials must possess several different properties relative to their functions and location, ranging from biocompatibility to mechanical sealing ability. The first ‘root fillings’ were probably items wedged and fixed in root canals exposed by trauma or wear and causing pain to the individual. He, she or a helping associate would poke and scratch into the root with whatever item available, e.g. the bronze pin found in an upper canine of a roman soldier, exhumed in the Israeli desert some 1800 years after his death (1). The search for materials that would remedy the pains and problems associated with compromised pulps has been almost as haphazard up to this day. Most materials applied to other fields of dentistry have been tried also as endodontic filling materials, with variable, and at times disastrous, effects. Typically, focus has been on one particular property of the material advocated to be of primary significance for ‘success’, while disregarding other, in hindsight, more important aspects of the filling. One component of the root filling, the gutta-percha core, has however remained dominant in the various techniques and material combinations advocated for endodontic obturation for the past century and more. Silver points have had and still have proponents as an alternative, but their suitability has been questioned with reference to corrosion and clinical failures. Only during the past few years has the gutta-percha been seriously challenged by other, synthetic materials in the production of root fillings.