title: Influence of exposure parameters on the detection of simulated root fractures in the presence of various intracanal materials.
abstract: OBJECTIVE
  To investigate how the exposure parameters used when producing CBCT scans affect diagnostic accuracy when detecting simulated vertical root fractures and how various filling materials affect image quality.
  
  
  METHODS
  A total of 160 extracted single-rooted human teeth were divided into four groups based on the materials within the root canals: unrestored, gutta-percha, metallic post and fibreglass post. Half of the sample of each group was selected for the induction of vertical root fractures. Each tooth was placed in an empty socket of a dry skull which was scanned on a CBCT unit (9000 3D scanner; Kodak Dental Systems, Carestream Health, Rochester, NY, USA) using the following exposure parameters: 74 kV/12 mA; 74 kV/10 mA; 74 kV/8 mA; 74 kV/6.3 mA; 70 kV/12 mA; 70 kV/10 mA; 70 kV/8 mA; 70 kV/6.3 mA. Two observers assessed all images using a 5-point confidence scale for fracture detection and a 4-point score for the presence of artefacts. Sensitivity, specificity, accuracy and area under ROC curve were compared by two-way anova and Tukey's test. Artefact formation was evaluated by descriptive statistics.
  
  
  RESULTS
  There were no significant differences in the sensitivity (P = 0.370), specificity (P = 0.660), accuracy (P = 0.084) and area under the ROC curve (P = 0.674) values amongst the various exposure parameters within the same group. There were some significant differences when the groups were compared for each intracanal material. The sensitivity and accuracy of the group containing metallic posts were significantly lower than the unrestored and fibreglass post groups (P ≤ 0.017).
  
  
  CONCLUSIONS
  The variations in exposure parameters did not interfere with the diagnosis of vertical root fractures, independent of the root canal restorative status. Metallic posts were associated with greater artefact formation and compromised the diagnostic performance. It is possible to decrease the kVp/mA settings to reduce the probability of biological effects due to radiation, without losing diagnostic accuracy.
authors.affiliation: Department of Oral Diagnosis, Paraíba State University, Campina Grande, Brazil.
authors.forename: M G O
authors.initials: MGO
authors.lastname: Pinto
authors.affiliation: Department of Oral Diagnosis, Paraíba State University, Campina Grande, Brazil.
authors.forename: K A
authors.initials: KA
authors.lastname: Rabelo
authors.affiliation: Department of Oral Pathology, Radiology & Medicine, The University of Iowa, Iowa City, IA, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Sousa Melo
authors.affiliation: Department of Oral Diagnosis, Federal University of Bahia, Salvador, Brazil.
authors.forename: P S F
authors.initials: PSF
authors.lastname: Campos
authors.affiliation: Division of Radiology, Department of Health Technology and Biology, Federal Institute of Bahia, Salvador, Brazil.
authors.forename: L S A F
authors.initials: LSAF
authors.lastname: Oliveira
authors.affiliation: Department of Oral Diagnosis, Paraíba State University, Campina Grande, Brazil.
authors.forename: P M
authors.initials: PM
authors.lastname: Bento
authors.affiliation: Department of Oral Diagnosis, Paraíba State University, Campina Grande, Brazil.
authors.forename: D P
authors.initials: DP
authors.lastname: Melo
mesh_terms: D054893:Cone-Beam Computed Tomography; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging; D005898:Glass; D006171:Gutta-Percha; D006801:Humans; D011857:Radiographic Image Interpretation, Computer-Assisted; D014082:Tooth Fractures / Q000175:diagnosis / Q000000981:diagnostic imaging*; D014092:Tooth Root / Q000000981:diagnostic imaging / Q000293:injuries*
chemical_list: C009753:fiberglass; D006171:Gutta-Percha
keywords: artefacts; cone beam computed tomography; vertical root fracture