title: Effect of various digital processing algorithms on the measurement accuracy of endodontic file length.
abstract: OBJECTIVE
  The aim of this study was to compare the accuracy of endodontic file lengths after application of various image enhancement modalities.
  
  
  METHODS
  Endodontic files of three different ISO sizes were inserted in 20 single-rooted extracted permanent mandibular premolar teeth and standardized images were obtained. Original digital images were then enhanced using five processing algorithms. Six evaluators measured the length of each file on each image. The measurements from each processing algorithm and each file size were compared using repeated measures ANOVA and Bonferroni tests (P = 0.05). Paired t test was performed to compare the measurements with the true lengths of the files (P = 0.05).
  
  
  RESULTS
  All of the processing algorithms provided significantly shorter measurements than the true length of each file size (P < 0.05). The threshold enhancement modality produced significantly higher mean error values (P < 0.05), while there was no significant difference among the other enhancement modalities (P > 0.05). Decrease in mean error value was observed with increasing file size (P < 0.05).
  
  
  CONCLUSIONS
  Invert, contrast/brightness and edge enhancement algorithms may be recommended for accurate file length measurements when utilizing storage phosphor plates.
authors.affiliation: Department of Oral Diagnosis and Radiology, School of Dentistry, Ege University, Izmir, Turkey.
authors.forename: Betül Ilhan
authors.initials: BI
authors.lastname: Kal
authors.forename: B Güniz
authors.initials: BG
authors.lastname: Baksi
authors.forename: Nesrin
authors.initials: N
authors.lastname: Dündar
authors.forename: Bilge Hakan
authors.initials: BH
authors.lastname: Sen
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D001641:Bicuspid; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D009811:Odontometry / Q000379:methods*; D019252:Radiography, Dental, Digital; D015203:Reproducibility of Results; D018915:Root Canal Preparation / Q000295:instrumentation*; D018709:Statistics, Nonparametric; D014092:Tooth Root / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014963:X-Ray Intensifying Screens