title: Comparison of four electronic root canal length measurement devices.
abstract: OBJECTIVE
  The objective of this study is to evaluate the performance of four electronic root canal length measurement devices (ERCLMDs) [Root ZX, Raypex 6, ProPex II, and VDW Gold with ERCLMD] in wet and dry root canals with different major foramen diameters, in association with three file positions within the final 1 mm of canals.
  
  
  METHODS
  Fifty roots were divided into five groups that were instrumented apically to the terminus diameter using K-files 15, 20, 30, 40, and 60. ERCLMD measurements were made when the file tip was at major foramen, 0.5 mm and 1.0 mm short of the foramen, when the apex touched to the surface of saline or was immersed 3 mm into saline, and when the canal was dry or was irrigated with saline. The differences between the electronic lengths and the actual lengths were calculated. The data were analyzed using the three-, two-, and one-way ANOVA and the LSD test (p < .05).
  
  
  RESULTS
  Overall, the four ERCLMDs demonstrated 12.8% unstable and beyond the foramen measurements (11.3%). About 85% of the beyond the foramen measurements had foramen diameters 0.40 and 0.60. ERCLMD comparisons related to the file positions in the foramen diameters showed significant differences between ERCLMDs in each foramen diameter (p < .05).
  
  
  CONCLUSIONS
  All ERCLMDs provided highly accurate measurements within the final 1 mm of the foramen. Wet or dry canals and apex conditions did not adversely affect the accuracy of the ERCLMDs' readings. ProPex II located the file positions in the teeth with different foramen diameters more accurately than the other ERCLMDs.
authors.affiliation: a Department of Endodontics, Faculty of Dentistry , İstanbul Aydın University , İstanbul , Turkey.
authors.forename: Rüstem Kemal
authors.initials: RK
authors.lastname: Sübay
authors.affiliation: b Okmeydanı Dental Hospital , İstanbul , Turkey.
authors.forename: Özlem
authors.initials: Ö
authors.lastname: Kara
authors.affiliation: c Department of Oral Surgery, School of Dentistry , İstanbul University , İstanbul , Turkey.
authors.forename: Melike Ordulu
authors.initials: MO
authors.lastname: Sübay
mesh_terms: D000704:Analysis of Variance; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D004867:Equipment Design; D006801:Humans; D009811:Odontometry / Q000295:instrumentation; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D019227:Tooth Apex / Q000033:anatomy & histology; D014092:Tooth Root / Q000033:anatomy & histology*
keywords: Electronic root canal length measurement device; apical foramen; apical foramen diameter; working length