Introduction: Root canal obliteration is the result of accelerated dentin deposition within the root canal space. The American Association of Endodontics (AAE) classifies it as a high level of difficulty, since procedural errors may occur, such as perforation, which is the creation of a communication between the duct system and the periradicular tissues.
Clinical case: Female patient referred to the Endodontics graduate program with a "previously initiated" diagnosis. Clinical and radiographic examination revealed tooth # 12 with cervical perforation, obliterated canal, and periapical lesion. The perforation was sealed with Biodentine, the canal was located using a microscope, conductometry was taken with a #08K file and instrumented with ProTaper Next; it was irrigated with 5.25% sodium hypochlorite (NaOCl). Calcium hydroxide (CaOH2) with propylene glycol was placed as intracanal medication between each appointment before finishing. It was obturated with gutta-percha from the system and AH Plus sealer.
Discussion: McCabe and Dummer (2012)  determined that procedures on teeth with root canal obliteration should be limited to cases with symptomatic and/or radiographic signs of periapical pathology. Ingle et al.  (1985) found that the second most common reason for endodontic failure is root perforation. Although, depending on the size, location, type, time and sealing material, its prognosis can be modified.
Conclusion: Tooth perforation is the most common result of iatrogenic damage during endodontic access when attempting to locate an obliterated canal. The size, location, and time that elapses from the moment of the perforation and a good sealing with biomaterials help the success of the treatment.