title: In vivo comparison of working length determination with two electronic apex locators.
abstract: OBJECTIVE
  To compare the accuracy of two electronic apex locators (EALs) in the same teeth in vivo.
  
  
  METHODS
  The working lengths in 20 teeth with a single canal were determined with two different EALs (Root ZX; J. Morita Corporation, Tokyo, Japan and Raypex 5 VDW, Munich, Germany) before extraction. When the first EAL was used the files were advanced until the display indicated the 'apical constriction'. The files were then fixed in removable and replaceable light curing composite patterns. The procedure was repeated in the same tooth with the second EAL and a different file. The teeth were then extracted and the apical 4 mm of the root canals were exposed. After that the apical parts with the repositioned files in the canals were digitally photographed under a light microscope. On the images the minor diameter and the major foramen of each sample were marked and the respective distances of the file tips from these positions were measured with a computer program. Subsequently the values of the two groups of EALs were compared using a paired sample t-test.
  
  
  RESULTS
  The minor foramen was located within the limits of +/-0.5 mm in 75% of the cases with the Root ZX and in 80% of the cases with Raypex 5. The paired sample t-test showed no significant difference between the EALs regarding determination of the minor foramen.
  
  
  CONCLUSIONS
  The use of EALs is a reliable method for determining working length. The differences between the two EALs were not statistically significant.
authors.affiliation: Department of Operative Dentistry and Periodontology, University School and Dental Hospital, Albert-Ludwigs-University Freiburg, Freiburg i. Br., Germany. thomas.wrbas@uniklinik-freiburg.de
authors.forename: K T
authors.initials: KT
authors.lastname: Wrbas
authors.forename: A A
authors.initials: AA
authors.lastname: Ziegler
authors.forename: M J
authors.initials: MJ
authors.lastname: Altenburger
authors.forename: J F
authors.initials: JF
authors.lastname: Schirrmeister
mesh_terms: D000328:Adult; D000368:Aged; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D017097:Electric Impedance; D004582:Electronics, Medical; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008875:Middle Aged; D009811:Odontometry / Q000295:instrumentation*; D019227:Tooth Apex / Q000033:anatomy & histology*