title: Fitness of gutta-percha cones in curved root canals prepared with reciprocating files correlated with tug-back sensation.
abstract: BACKGROUND
  The purpose of this study was to evaluate the gutta-percha-occupied area (GPOA) and the relationship between GPOA and tug-back sensations in canals instrumented with reciprocating files.
  
  
  METHODS
  Twenty curved canals were instrumented using Reciproc R25 (VDW, Munich, Germany) (group R) and WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) (group W), respectively (n = 10 each). The presence or absence of a tug-back sensation was decided for both of #25/.08 and #30/.06 cones in every canal. The percentage of GPOA at 1-, 2-, and 3-mm levels from the working length was calculated using micro-computed tomographic imaging. The correlation between the sum of the GPOA and the presence of a tug-back sensation was also investigated. The data were analyzed statistically at P = .05.
  
  
  RESULTS
  A tug-back sensation was present in 45% and 100% canals for #25/.08 and #30/.06 cones, respectively, with a significant difference (P < .05). At the 2- and 3-mm levels, #30/.06 cones produced significantly higher GPOA in groups R and W (P < .05). The sum of the GPOA score was significantly higher in the samples with a strong tug-back sensation (P < .05); however, there was no significant difference between the 2 cone types for this correlation (P > .05).
  
  
  CONCLUSIONS
  Under the conditions of this study, the tug-back sensation can be a definitive determinant for indicating higher cone fitness in the curved canal regardless of the cone type.
authors.affiliation: Department of Dentistry, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
authors.forename: Heeyoung
authors.initials: H
authors.lastname: Yoon
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, Korea.
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Baek
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, Korea.
authors.forename: Kee-Yeon
authors.initials: KY
authors.lastname: Kum
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Pusan National University Dental Hospital, Yangsan, Korea.
authors.forename: Hyeon-Cheol
authors.initials: HC
authors.lastname: Kim
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Daejeon Hospital, WonKwang University, Daejeon, Korea.
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Moon
authors.affiliation: Private Practice, Irvine, California; Department of Endodontics, Loma Linda University, School of Dentistry, Loma Linda, California.
authors.forename: Denny Y
authors.initials: DY
authors.lastname: Fang
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, Korea. Electronic address: jimin525@snu.ac.kr.
authors.forename: WooCheol
authors.initials: W
authors.lastname: Lee
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000187:drug effects; D006171:Gutta-Percha / Q000737:chemistry*; D006801:Humans; D009532:Nickel; D012387:Root Canal Filling Materials / Q000737:chemistry; D012389:Root Canal Obturation / Q000379:methods*; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D012677:Sensation; D013193:Stainless Steel; D014025:Titanium; D055114:X-Ray Microtomography
chemical_list: D012387:Root Canal Filling Materials; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D006171:Gutta-Percha; D014025:Titanium
keywords: Cone fitness; gutta-percha occupying area; reciprocating file; tug-back sensation