title: Apical limit and working length in endodontics.
abstract: Establishing the working length is an important step in endodontic treatment as inaccurate length determination may lead to failure. There is an ongoing debate regarding the extent of the apical limit of root canal preparation. This controversy is based upon different clinical opinions concerning the distance between the end point of the root canal preparation and the periodontal tissues. In this paper, we review the different schools of thought for working length determination, and how apex locators work and how they must be used for optimal accuracy. The reliability of these devices has been proven; the price is moderate and apex locators are now part of the basic armamentarium in the achievement of quality and predictable endodontic treatment.
  
  
  CONCLUSIONS
  The technique of determining the working length from a single radiograph remains empirical, and apex locators should be considered an essential aid in establishing working length.
authors.affiliation: University of Birmingham School of Dentistry and University of Paris 7, France.
authors.forename: Stephane
authors.initials: S
authors.lastname: Simon
authors.forename: Pierre
authors.initials: P
authors.lastname: Machtou
authors.forename: Nick
authors.initials: N
authors.lastname: Adams
authors.forename: Phillip
authors.initials: P
authors.lastname: Tomson
authors.forename: Philip
authors.initials: P
authors.lastname: Lumley
mesh_terms: D017097:Electric Impedance; D055615:Electrical Equipment and Supplies; D006801:Humans; D009811:Odontometry / Q000295:instrumentation*; D019239:Practice Patterns, Dentists'; D011859:Radiography; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D019227:Tooth Apex / Q000033:anatomy & histology* / Q000000981:diagnostic imaging