The patient came to the clinic with pain and swelling in the lower right premolar-molar region. On examination and RVG (radiograph), one could see incomplete root canal treatment in lower right 1 st molar and lower right 2 nd premolar with periapical lesion (inflammation, infection) was seen. When the crown of the molar was removed and the canals cleaned, a perforation on the pulpal floor made by the previous dentist could be seen. ProRoot MTA (Mineral Trioxide Aggregate from Dentsply) was placed in the perforation. MTA is a special root canal repair material. The root canal treatment of both the teeth was performed. The teeth were reinforced with cosmetic screw post followed by a core build up. On the teeth, the Porcelain fused to metal crowns were placed. Immediate improvement was seen. The pain disappeared and the size of the periapical lesion began to decrease. A year later after the retreatment, the tooth is totally asymptomatic and the periapical lesion has almost disappeared.

In event of failure of a previously done root canal treatment, the tooth may have to be re treated.

The chances of success increases dramatically when the procedure is done with the help of Operating Surgical Microscope.