title: A simple mounting model for consistent determination of the accuracy and repeatability of apex locators.
abstract: OBJECTIVE
  To develop a precise and simple mounting model (MM) for evaluating apex locators and to compare the repeatability of the MM with a conventional visual method (VM).
  
  
  METHODS
  Electronic working length determination was performed in 32 maxillary central incisors using two methods: (i) the MM method and (ii) a conventional VM. The MM utilizes a micrometer to determine the distance travelled by the measuring file during working length determination. In the VM, the length of the measuring file (representing the working length) is determined visually using a caliper and a microscope at 6x magnification. Each measurement was repeated once. The repeatability of each method was evaluated by calculating the coefficient of repeatability.
  
  
  RESULTS
  The coefficient of repeatability, which includes 95% of the differences between repeated measurements, was 0.04 mm for MM compared with 0.9 mm for VM. The measurement error of MM was significantly lower than VM (0.02 and 0.4 mm respectively). There was a statistically significant difference between the means of absolute difference in repeated measurements: MM 0.01 mm (95% confidence interval (CI): 0.01; 0.02 mm) compared with VM 0.4 mm (95% CI: 0.3; 0.5 mm).
  
  
  CONCLUSIONS
  The new MM had superior repeatability in comparison with the conventional method where visual interpretation is a source of inaccurate measurement.
authors.affiliation: Department of Conservative Dentistry, School of Dental Medicine, University of Tübingen, Osterlanderstrasse 2-8, 72076 Tübingen, Germany. ashraf.elayouti@med.uni-tuebingen.de
authors.forename: A
authors.initials: A
authors.lastname: ElAyouti
authors.forename: C
authors.initials: C
authors.lastname: Löst
mesh_terms: D004582:Electronics, Medical / Q000295:instrumentation; D004867:Equipment Design; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology; D008853:Microscopy / Q000295:instrumentation; D009811:Odontometry / Q000295:instrumentation* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D018915:Root Canal Preparation / Q000295:instrumentation*; D019227:Tooth Apex / Q000033:anatomy & histology*