In this chapter detailed description of filling/ obturation of the finished and sterilized root canal system is given. Filling technique of root canal with ‘gutta-percha’ or ‘silver cone’, and ‘cements’ or using other techniques is well covered. Various root canal cements/sealants’ with their ‘ingredients’, brand names and the names of their manufacturers are given in a table-form, covered under heading of name of cement, manufactured by, composition, advantages, disadvantages. A summary is also given for root canal filling with GP point or silver cone and cement for quick recapitulation and better remembrance of the readers. The use of finger-spreaders for better and complete spreading of cement into all side walls of the root canal under the process of filling/obturation is covered. How and when the final restoration should be given in a RCTed tooth is also described. A repair of tissues that follows root canal treatment is also given. Possible causes of failure in ‘endodontic treatment’ are given step wise in 6 points. The RCT in previously “irradiated” patients of cancer both for maxilla and mandible is also given.