title: Accuracy of electronic apex locators in comparison to actual length--an in vivo study.
abstract: OBJECTIVE
  The measurement precision of four electronic apex locators (Root ZX, Morita, Tokyo, Japan; Endy, Loser, Leverkusen, Germany; Justy II, Hager-Werken, Duisburg, Germany; Endox Lysis, Milan, Italy) was examined in the present in vivo study.
  
  
  METHODS
  The root canal length of 40 single-rooted and multi-rooted teeth was determined with the four devices prior to tooth extraction. To determine the actual root canal length, the apical third was longitudinally sectioned, the root canal instrument was positioned and the apex was examined using a microscope.
  
  
  RESULTS
  The average measurement deviation (+/-SD) in relation to the apical constriction was 0.3 mm (+/-0.6) for the Root ZX, 0.7 mm (+/-1.0) for the Endy, 0.2 mm (+/-0.7) for the Justy II and 1.3 mm (+/-1.7) for the Endox. The limit of +/-0.5 mm from the apical constriction was attained by the Root ZX in 78%, by the Endy in 67%, by the Justy II in 80% and by Endox in 31% of all measurements.
  
  
  CONCLUSIONS
  The latest generation of apex locaters provide the clinician with an accurate and useful adjunct for the determination of root canal length.
authors.affiliation: Department of Restorative Dentistry, Ludwig-Maximilians University, Goethestrasse 70, D-80336 Munich, Germany. chaffner@dent.med.uni-muenchen.de
authors.forename: C
authors.initials: C
authors.lastname: Haffner
authors.forename: M
authors.initials: M
authors.lastname: Folwaczny
authors.forename: K
authors.initials: K
authors.lastname: Galler
authors.forename: R
authors.initials: R
authors.lastname: Hickel
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D004582:Electronics, Medical / Q000295:instrumentation; D004867:Equipment Design; D006801:Humans; D008853:Microscopy; D009811:Odontometry / Q000295:instrumentation*; D018915:Root Canal Preparation / Q000295:instrumentation; D019227:Tooth Apex / Q000033:anatomy & histology*; D019553:Tooth, Nonvital / Q000473:pathology