Iatrogenic perforations are caused by an instrument breaching the apex or wall of the root canal; probably the most common occurrence is during the preparation of a post space (Fig. 6). Partial or complete closure by hard tissue may be induced with calcium hydroxide, provided the perforation is not too large, lies within the crestal bone and does not communicate with the oral cavity.
Treatment should begin as soon as possible, adopting the same procedure as for root-end induction. Closure of perforations using calcium hydroxide takes considerably longer than root-end induction in most cases. An alternative technique, if the perforation can be visualised with the use of a surgical microscope, would be direct repair with mineral trioxide aggregate.
If foreign bodies in the form of root-filling materials, cements or separated instruments have been extruded into the tissues, healing with calcium hydroxide is unlikely to occur and a surgical approach is recommended (Part 11).