Abstract: Root canal therapy (RCT) is the most commonly used and effective method to treat dental pulp disease and periapical disease. However, because of root canal omission and difficult dredge, the treatments of calcified root canals often fail. Clinical diagnosis and evaluation with root canal explorations and radiologia are able to improve the success rate of root canal therapy. Additionally, root canal dredging which makes use of specialize instruments such as ultrasonic microscope, plus chemical reagents can also promote the successful rate. This article will review the research progress on the mechanism, diagnosis, evaluation and pathway establishment of the calcified root canal.

Key words: calcified canal, ultrasonic microscope technique, Nickel titanium instrument system