title: Accuracy of five electronic foramen locators with different operating systems: an ex vivo study.
abstract: OBJECTIVE
  The aim of this study was to evaluate, ex vivo, the precision of five electronic root canal length measurement devices (ERCLMDs) with different operating systems: the Root ZX, Mini Apex Locator, Propex II, iPex, and RomiApex A-15, and the possible influence of the positioning of the instrument tips short of the apical foramen.
  
  
  METHODS
  Forty-two mandibular bicuspids had their real canal lengths (RL) previously determined. Electronic measurements were performed 1.0 mm short of the apical foramen (-1.0), followed by measurements at the apical foramen (0.0). The data resulting from the comparison of the ERCLMD measurements and the RL were evaluated by the Wilcoxon and Friedman tests at a significance level of 5%.
  
  
  RESULTS
  Considering the measurements performed at 0.0 and -1.0, the precision rates for the ERCLMDs were: 73.5% and 47.1% (Root ZX), 73.5% and 55.9% (Mini Apex Locator), 67.6% and 41.1% (Propex II), 61.7% and 44.1% (iPex), and 79.4% and 44.1% (RomiApex A-15), respectively, considering ±0.5 mm of tolerance. Regarding the mean discrepancies, no differences were observed at 0.0; however, in the measurements at -1.0, the iPex, a multi-frequency ERCLMD, had significantly more discrepant readings short of the apical foramen than the other devices, except for the Propex II, which had intermediate results. When the ERCLMDs measurements at -1.0 were compared with those at 0.0, the Propex II, iPex and RomiApex A-15 presented significantly higher discrepancies in their readings.
  
  
  CONCLUSIONS
  Under the conditions of the present study, all the ERCLMDs provided acceptable measurements at the 0.0 position. However, at the -1.0 position, the ERCLMDs had a lower precision, with statistically significant differences for the Propex II, iPex, and RomiApex A-15.
authors.affiliation: Sobral School of Dentistry, Federal University of Ceará, Fortaleza, CE, Brazil. bcv@ufc.br
authors.forename: Bruno Carvalho de
authors.initials: BC
authors.lastname: Vasconcelos
authors.forename: Michelli de Medeiros
authors.initials: Mde M
authors.lastname: Bueno
authors.forename: Suyane Maria
authors.initials: SM
authors.lastname: Luna-Cruz
authors.forename: Marco Antonio Hungaro
authors.initials: MA
authors.lastname: Duarte
authors.forename: Carlos Augusto de Oliveira
authors.initials: CA
authors.lastname: Fernandes
mesh_terms: D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D004582:Electronics, Medical / Q000295:instrumentation; D006801:Humans; D009811:Odontometry / Q000295:instrumentation*; D009929:Organ Size; D012016:Reference Values; D015203:Reproducibility of Results; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D018709:Statistics, Nonparametric; D019227:Tooth Apex / Q000033:anatomy & histology*