title: [Root canal therapy of resinified teeth with surgical operating microscope and ultrasonic instruments].
abstract: OBJECTIVE
  To evaluate the role of surgical operating microscope and ultrasonic instruments in endodontic treatment of patients who underwent previous resinifying therapy.
  
  
  METHODS
  63 premolars and molars that had been treated with resinifying therapy before were selected for root canal therapy. The coronal portion of resinified root canals were negotiated with ultrasonic instruments under surgical operating microscope, and the apical portion was managed with small size hand files and 15% EDTA. The root canals of all cases were shaped by Nickel-Titanium rotary instruments Hero 642, and obturated with lateral condensation technique. The negotiation of root canal system, instrument fracture, alterations of canal morphology, and operation time were recorded. The efficiency of preparation and obturation was analyzed by radiographs before and after treatment.
  
  
  RESULTS
  The root canals of 54 teeth were negotiated, enlarged and obturated, with a success rate of 85.7%. No complications were found, such as vertical fracture, ledge, perforation and instrument separation. Good result of treatment was achieved in the 54 cases.
  
  
  CONCLUSIONS
  The use of surgical operating microscope and ultrasonic instruments is proved to be effective in negotiation of coronal portion of the resinified root canals. Nevertheless, the use of ultrasonic instruments in apical or curved portion of root canals is not encouraged.
authors: Department of Endodontics, Guanghua College of Stomatology, Sun Yat-sen University, Guangzhou 510055, Guangdong Province, China.
authors: Qiong
authors: Q
authors: Xu
authors: Jun-qi
authors: JQ
authors: Lin
authors: Sui
authors: S
authors: Mai
authors: Jian-wei
authors: JW
authors: Liu