title: [Continuous observation of canal aberrations in S-shaped simulated root canal prepared by hand-used ProTaper files].
abstract: OBJECTIVE
  To observe the formation of canal aberrations in S-shaped root canals prepared by every file of hand-used ProTaper.
  
  
  METHODS
  Fifteen S-shaped simulated resin root canals were selected. Each root canal was prepared by every file of hand-used ProTaper following the manufacturer instruction. The images of canals prepared by S1, S2, F1, F2 and F3 were taken and stored, which were divided into group S1, S2, F1, F2 and F3. One image of canal unprepared was superposed with the images of the same root canal in these five groups respectively to observe the types and number of canal aberrations, which included unprepared area, danger zone, ledge, elbow, zip and perforation. SPSS12.0 software pakage was used for Fisher's exact probabilities in 2x2 table.
  
  
  RESULTS
  Unprepared area decreased following preparation by every file of ProTaper, but it still existed when the canal preparation was finished. The incidence of danger zone, elbow and zip in group F1 was 15/15, 11/15, 4/15, respectively, which was significantly higher than that in group S2(2/15,0,0) (P<0.001). Ledge appeared after prepared by F2, and increased sharply in group F3. None perforation was found in all groups.
  
  
  CONCLUSIONS
  The incidence of canal aberrations begins to increase after prepared by finishing files of ProTaper.The presence of unprepared area suggests that it is essential to rinse canal abundantly during complicated canal preparation and canal antisepsis after preparation.
authors.affiliation: Department of Stomatology, Taihe Affiliated Hospital, Yunyang Medical College, Shiyan 442000, Hubei Province, China. xialingyun200810@163.com
authors.forename: Ling-yun
authors.initials: LY
authors.lastname: Xia
authors.forename: Wei-dong
authors.initials: WD
authors.lastname: Leng
authors.forename: Min
authors.initials: M
authors.lastname: Mao
authors.forename: Guo-biao
authors.initials: GB
authors.lastname: Yang
authors.forename: Yong-gang
authors.initials: YG
authors.lastname: Xiang
authors.forename: Xin-mei
authors.initials: XM
authors.lastname: Chen
mesh_terms: D003786:Dental Pulp Cavity; D006801:Humans; D009532:Nickel; D018915:Root Canal Preparation; D014025:Titanium
chemical_list: D009532:Nickel; D014025:Titanium