Apical problems--coronal solutions: how changes in access cavity design can prevent and overcome problems with curved canals.
There is no doubt that the preparation of curved canals presents one of the greatest challenges in endodontic and is fraught with potential difficulties. Canal curvature can only be seen on a radiograph in the mesio-distal plane and yet it is well known that curvature in the bucco-lingual plane is also evident in many teeth. A primary cause of failure of endodontic treatment is the persistence of microbial infection. In curved canals this is often due to procedural errors such as ledges, fractured instruments and canal blockage. Over the years a variety of techniques have been proposed for preparing these canals. Whether it is the straightforward endodontic treatment of a straight, single rooted tooth, or retreatment of a curved molar with a number of procedural errors, the access cavity has a crucial role in the achievement of successful endodontic treatment. The size and shape of the access cavity will be dictated by the degree of curvature of the canals and the objectives that have to be achieved.