Efficacy of Ultrasonic Vibration in Retrieving Broken Endodontic Instruments and its Effect on the Root Canal Remaining Dentin Thickness.

Abstract

Optimal cleaning and shaping is a prerequisite for successful root canal treatment. Unfortunately procedural errors such as instrument separation may interfere with that, if such accident occurred proper evaluation of the case is mandatory. There are several factors governing the success of retrieval of broken files, many studies discussed the effects of retained instruments on the outcome of endodontic treatment, several approaches are available which include obturating above the level of separated instrument, bypassing and including the instrument in the root canal filling, retrieving the instrument or finally the surgical approach. Risks should be properly assessed, as one of the most dangerous risks is overcutting dentin so as not to withstand the forces of obturation and future functioning of the tooth leading to root fracture or perforation, hence preoperative CBCT is important to determine the amount of dentin, where the file is located exactly, the expected amount of dentin to be lost, and where to operate safely, also visualization of the broken fragment is very important so a dental operating microscope should always be included in the armamentarium. The current study was conducted in order to compare the efficiency of ET25, and E7 ultrasonic tips (manufactured from different materials) in retrieval of broken instruments in mesial canals of lower first molars. Forty human mandibular first molars with mesial root canals exhibiting curvatures of less than 30 degrees according to Schneider's method were selected and divided into two equal groups. Four mm fragments of Size 25 K-files were intentionally separated inside the mesial canals, and removal procedures were done by one of the tested types of ultrasonic tips.