Had root canal filled with ketac-endo on 2/8/99. Pt kept experiencing pain until 4/17/99, of which time apical surgery with retrograde filling was performed, symptoms subsided as soon as new cement (irm) was introduced with the surgery. Rptr writes, "i have been using crcs as the material of choice for my sealer for over 9 years. I have never experienced any unusual problems with this material. In the middle part of 1998 i decided to switch to ketac-endo, as this material showed promise in terms of not disrupting today's bonding agents. I used this material cautiously in about 40 or so cases. I began using this material on a limited basis in the latter part of 1997. In the early part of 1999 some of the pts who received this filler returned to my office with complaints ranging from sore gums to swelling. One of the pts who was treated in 1997 returned in 1998. After careful evaluation i have concluded the following: 1. Perfectly filled root canals with gross apical lesions. Absolutely no defects found with the obturation of the root systems. The ketac-endo filler appeared to be toxic to the surrounding bone tissue. 2. Type 3 furcation bone loss in upper first molars. These pts had no history of periodontal problems pre-op. The ketac-endo appeared to be toxic to the surrounding bone and periodontium. I have re-treated some of these cases with apicoectomies as well as regular re-treatments. I have re-filled these teeth with crcs and have re-achieved normal healing. I have noted upon retrieval of the gutta percha that was filled with ketac-endo that the odor of the root system was putrid and necrotic, despite the excellent obturation. I have stopped using ketac-endo and have not had any further problems. I have never observed or experienced any of the above mentioned problems with any of the crcs filled root canals that i have performed in the last ten years. Furthermore, the successful re-treatments with crcs had led me to conclude that ketac-endo is toxic to the human body and should be removed from the list of accepted dental materials. I have contacted espe, yet they have not been able to provide me with any documentation fo their lab protocols and testing of this material. They had me sent them the remaining ketac-endo for testing. I have none of the material available any more at the office. Their lab results have not been documented and they deny any problems. ".