2TheApex: Endodontically treated teeth not restored with a crown are 6 times more likely to be lost.A good restoration is just as important to the success of root canal treatment treatment as the quality of obturation. (1) While it has been shown that the dentin of endodontically treated teeth is not more brittle than their vital counterparts, they often experience a reduction in overall strength from loss of tooth structure. (2) Loss of even one marginal ridge, such as in an MO or DO preparation, can reduce the strength of a posterior tooth by 46%, loss of both marginal ridges results in a 63% reduction, while a conservative endodontic access will only reduce the strength of the tooth by about 5%. (3) A crown may not be indicated for every tooth following root canal treatment, however Aquilino showed that teeth not restored with a crown were lost 6 times more frequently than those restored with a crown. (4)1: Ray, H. A., and M. Trope. "Periapical status of endodontically treated teeth in relation to the technical quality of the root filling and the coronal restoration."International Endodontic Journal 28.1 (1995): 12-18.2: Sedgley, Christine M., and Harold H. Messer. "Are endodontically treated teeth more brittle?." Journal of Endodontics 18.7 (1992): 332-335.3: Reeh, Ernest S., Harold H. Messer, and William H. Douglas. "Reduction in tooth stiffness as a result of endodontic and restorative procedures." Journal of Endodontics 15.11 (1989): 512-516.4: Aquilino, Steven A., and Daniel J. Caplan. "Relationship between crown placement and the survival of endodontically treated teeth." The Journal of prosthetic dentistry 87.3 (2002): 256-263.