title: [Effects of different instruments in root-end preparation: scanning electron microscopic evaluation].
abstract: OBJECTIVE
  To evaluate the effects of retrograde preparation between ultrasonic retrotips and traditional slow-speed handpiece.
  
  
  METHODS
  27 maxillary second bicuspid teeth with two canals and one isthmus were divided randomly into 3 groups with 9 in each. The root-end preparations were made respectively using ultrasonic diamond tip Berutti and NiTi tip RE2, ultrasonic #40K file and slow-speed handpiece with NO.2 round bur. The postoperative epoxy resin replicas were examined under scanning electron microscope for further evaluating the number and type of the micro-cracks, the quality of cavity margin. SPSS13.0 software package was used for Kruskal-Wallis test.
  
  
  RESULTS
  The number of micro-crack of ultrasonic instruments were significantly less than that of slow-speed handpiece(P=0.002).The type of micro-cracks has no significant difference between the two techniques(P=0.657). On the quality of cavity margin, the slow-speed handpiece group had significant inferior to the ultrasonic #40K file group(P=0.039); there was no significantly difference between the ultrasonic Berutti and RE2 group and the slow-speed handpiece group (P=0.136); there was no significant difference between the two ultrasonic groups (P=0.637).
  
  
  CONCLUSIONS
  Ultrasonic instrument is feasible in the root-end preparation.
authors.affiliation: Department of Cariology and Endodontology, College of Stomatology, Guangxi Medical University, Nanning 530021, Guangxi Province, China. zhangpingjuan123123@126.com
authors.forename: Ping-juan
authors.initials: PJ
authors.lastname: Zhang
authors.forename: Wen-xia
authors.initials: WX
authors.lastname: Chen
authors.forename: Qi-xin
authors.initials: QX
authors.lastname: Zeng
authors.forename: Fang-fang
authors.initials: FF
authors.lastname: Xie
mesh_terms: D001047:Apicoectomy; D001641:Bicuspid; D018130:Diamond; D006801:Humans; D008855:Microscopy, Electron, Scanning; D018915:Root Canal Preparation; D014464:Ultrasonic Therapy
chemical_list: D018130:Diamond