title: [Research on cleaning rate of the C-shaped canal treated by manual or rotary endodontic file combined with ultrasonic rinsing].
abstract: OBJECTIVE
  To evaluate the cleaning effect of the C-shaped canal treated by manual K file and ProTaper rotary endodontic file combined with ultrasonic cleaning, and find a better cleaning program for the C-shaped root canal.
  
  
  METHODS
  Fifty mandibular second molars were randomly divided into 5 groups: K file group, K file+ultrasonic rinsing group, ProTaper group, ProTaper+ultrasonic rinsing group and the control group. After initial shaping and cleaning, the mandibular second molars were soaked in formalin and stained. Under microscopy, the cleaning rate of necrotic tissue and cutting area were observed and analyzed. The data was processed with SPSS 17.0 software package.
  
  
  RESULTS
  The cleaning rates of the treated groups were significantly higher than that of the control group (P<0.05); In each treatment group, the cleaning rate of the apex was significantly lower than that of the crown and central part (P<0.05); The cutting score of ProTaper+ultrasonic cleaning group was lower than that of the other treatment groups; The cutting score of the K file+ultrasonic rinsing group was significantly lower than that of the K file group (P<0.05); The cutting score and cleaning rate were negatively correlated (r=-0.712, P=0.000 ), the linear regression was the cleaning rate =98.325-4.325 × wall cutting score (R=0.454, P<0.05).
  
  
  CONCLUSIONS
  In the process of shaping and cleaning of C-shaped canal, it is recommended that the ProTaper nickel-titanium rotary endodontic file should be chosen to clean the top of the taproot pipe and combined with ultrasonic rinsing to achieve better results.
authors.affiliation: Department of Oral Medicine, Affiliated Hospital of Binzhou Medical College. Binzhou 256603;China.E-mail:wangjingsdbz@126.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.forename: Qing-shan
authors.initials: QS
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Rong
authors.forename: Jiu
authors.initials: J
authors.lastname: Wang
mesh_terms: D003722:Dental Alloys; D003762:Dental Instruments; D003786:Dental Pulp Cavity; D006801:Humans; D008963:Molar; D009532:Nickel; D018915:Root Canal Preparation; D014025:Titanium; D014465:Ultrasonics
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium