Construction Of Separated Instrument's Model And Management Of Intracanal Broken Instruments' Removal With Microsonic Technique

Instrument separation in root canal preparation is one of the most difficult complication in Root canal therapy. Existence of Separated Instrument influences the completion of root canal therapy successfully, We should remove it completely . Because of all kinds of factors' influence, the intracanal separated instruments' removal are very difficult. Someone reports the successful rate of the intracanal separated instrument is 55% - 79%. There are many methods to remove them, including the braiding technique, ,the Endo extractor technique, the Masserann-Kit and ultrasonic technique. Recently, the use of the dental operating microscope in endodontics and in combination with ultrasonic tips has proved helpful to remove separated instruments from root canals. In our research, we construct the Separated Instrument's Model, then removal them with microsonic technique and compare the method and difficulty, in order to help us carry out clinical therapy successfully.Part One : Experimental Research1 Analysis of the Separated Instrument's Characterin Root Canal PreparationMaterials and Methods: 221 extracted permanent teeth(500 root canals) were randomly divided into two groups(250 root canals each group),then one K or H-type hand file from small to large number was selected and inserted into the root canal until the file was seen at the apical foramen , then clockwise rotating it for 10min. If it was broken , recorded it's time. If it was not broken ,...