Calcium Hydroxide is widely used in endodontics for a number of purposes. Its antimicrobial properties are attributed to its high pH (basic), destructive effects on bacterial cell walls and ability to dissolve organic tissue. It is used routinely as an intracanal medicament. It is also used for apexification, apexigenesis, treatment of root resorption.
Ca(OH)2 used in endodontics is made with Ca(OH)2 powder, a vehicle and a radiopacifier. Most common radiopacifiers are barium sulfate, bismuth or compounds containing iodine or bromine. While radiopacifiers make the calcium hydroxide more visible radiographically, some radiopacifiers are known to resorb at a slower pace, sometimes making it difficult to see the subtle changes.
While the control of a paste material at the apex of a canal can be very difficult, the resorptive properties of calcium hydroxide make it a very forgiving material. Extrusion of calcium hydroxide past the apex of a tooth is not uncommon. In fact, there are some who would recommend deliberate extrusion in the case of a large, chronic periapical lesion to help in the healing of such a lesion.
Calcium hydroxide (Ultracal - Ultradent - 35% Ca(OH)2 with barium sulfate) was used during treatment of this tooth to control exudate prior to obturation. A significant amount was extruded past the apex in close approximation to the maxillary sinuses during the endodontic treatment.
14 months later, the patient returned for treatment of #14. Our recall radiograph of #15 shows complete resorption of Ca(OH)2. The patient had no complaints and is in full function.
Hasan Orucoglu, Funda Kont Cobankara, "Effect of Unintentionally Extruded Calcium Hydroxide Paste Including Barium Sulfate as a Radiopaquing Agent in Treatment of Teeth with Periapical Lesions: Report of a Case", Journal of Endodontics, July 2008 (Vol. 34, Issue 7, Pages 888-891)