title: Cleaning effectiveness and shaping ability of rotary ProTaper compared with rotary GT and manual K-Flexofile.
abstract: OBJECTIVE
  To compare the cleaning efficacy and shaping ability of engine-driven ProTaper and GT files, and manual preparation using K-Flexofile instruments in curved root canals of extracted human teeth.
  
  
  METHODS
  45 canals of maxillary and mandibular molars with curvatures between 25 degrees and 40 degrees were divided into three groups. The groups were balanced with regard to the angle and the radius of canal curvature. Canals in each group were prepared to an apical size of 25 with either the rotary ProTaper or GT system, or manually with K-Flexofile using the modified double-flared technique. Irrigation was done with 2 mL 2.5% NaOCl after each instrument and, as the final rinse, 10 mL 2.5% NaOCl then 10 mL 17% EDTA and finally 5 mL distilled water. The double-exposure radiographic technique was used to examine for the presence of apical transportation. The time required to complete the preparation, as well as any change in working length after preparation were recorded. The roots were then grooved and split longitudinally. The amounts of debris and smear layer were evaluated at the apical, middle and coronal regions under the scanning electron microscope. Data were analyzed either parametrically with the F-test or non-parametrically using the Kruskal-Wallis test, where appropriate.
  
  
  RESULTS
  Two GT files but none of the K-Flexofile and ProTaper instruments separated. For debris removal, the ProTaper group achieved a better result than GT (P < 0.05) but not the K-Flexofile group at all three regions (apical, middle and coronal). K-Flexofiles produced significantly less smear layer than ProTaper and GT files only in the middle third of the canal (P < 0.01). Both NiTi rotary instruments maintained the original canal shape better than the K-Flexofiles (P < 0.05) and required significantly less time to complete the preparation.
authors.affiliation: Department of Endodontics, School and Hospital of Stomatology, Wuhan University, Key Laboratory for Oral Biomedical Engineering, Ministry of Education, China.
authors.forename: Sheng-Bo
authors.initials: SB
authors.lastname: Liu
authors.forename: Bin
authors.initials: B
authors.lastname: Fan
authors.forename: Gary S P
authors.initials: GS
authors.lastname: Cheung
authors.forename: Bing
authors.initials: B
authors.lastname: Peng
authors.forename: Ming-Wen
authors.initials: MW
authors.lastname: Fan
authors.forename: James L
authors.initials: JL
authors.lastname: Gutmann
authors.forename: Ya-Ling
authors.initials: YL
authors.lastname: Song
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
authors.forename: Zhuan
authors.initials: Z
authors.lastname: Bian
mesh_terms: D003722:Dental Alloys; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D008963:Molar; D009532:Nickel; D011859:Radiography; D018915:Root Canal Preparation / Q000295:instrumentation*; D016369:Smear Layer; D013193:Stainless Steel; D014025:Titanium
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium