title: [The sizes of measurement files on the accuracy of electronic apex locator].
abstract: OBJECTIVE
  To investigate the different sized measurement files on the accuracy of electronic apex locator (EAL) in vitro.
  
  
  METHODS
  Alginate and extracted single-Ccanalled tooth were used to mimic the situation in vivo. Forty-one teeth were used. EAL Raypex 5 was applied to determine the length of the canals by 10#-40# K files. Experimental measurements and the distances (IF value) between experimental and ideal actual measurements under the same measurement environment were recorded. Paired sample F test was applied to analyze the results by using SPSS 10.0 software package.
  
  
  RESULTS
  The results showed that at the allowance of + or - 0.5mm, the accuracy ratios were 85.4%(10#),75.6%(15#),85.4%(20#),90.2%(25#),73.2%(30#),68.3%(35#) and 63.4%(40#), respectively. While at the allowance of +0.5--1.0mm, the accuracy ratios were 87.8%(10#),87.8%(15#),90.2%(20#),97.6%(25#),97.6%(30#),97.6%(35#) and 87.8%(40#), respectively. Statistical analysis showed that there was no significant difference in accuracy between each group(P>0.05).
  
  
  CONCLUSIONS
  The results suggested that it be advisable to improve the accuracy of the EAL by measuring the working length one more time with 25# K file during the preparation under this experimental environment.
authors.affiliation: Institute of Stomatology, People's Hospital, Yunyang Medical College, Shiyan 442000, Hubei Province, China. nmn888@163.com
authors.forename: Li
authors.initials: L
authors.lastname: He
authors.forename: Tu-qiang
authors.initials: TQ
authors.lastname: Hu
authors.forename: Ping
authors.initials: P
authors.lastname: Bu
authors.forename: Li-ling
authors.initials: LL
authors.lastname: Pan
authors.forename: Jian-qin
authors.initials: JQ
authors.lastname: Lin
mesh_terms: D003786:Dental Pulp Cavity; D006801:Humans; D009811:Odontometry; D018915:Root Canal Preparation; D019227:Tooth Apex