[Treatment of a canal with a "C" configuration].

The prevalence of "C" shaped root canals in the second mandibular molars is relatively low, but diagnosis and treatment of these canals are sometimes difficult. Through clinical cases, the authors emphasize on the importance of preoperative X-rays and describe convenient preparation techniques. Some "C" shaped canals are difficult to interpretate because of the thickness of bone trabeculae, and a "C" shaped canal must be suspected when the roots are fuse and/or very close each other.