title: CBCT for the assessment of second mesiobuccal (MB2) canals in maxillary molar teeth: effect of voxel size and presence of root filling.
abstract: OBJECTIVE
  To compare detection of the second mesiobuccal (MB2) canal in maxillary molar teeth using cone-beam computed tomography (CBCT) with different voxel sizes against conventional radiographic examination when the MB1 was unprepared, prepared and filled.
  
  
  METHODS
  Radiographic examination and 0.2-, 0.25- and 0.3-mm CBCT (n = 89) were performed in 3 stages: S1, no first mesiobuccal (MB1) canal preparation or filling; S2, after MB1 preparation and filling; and S3, after MB1 root canal filling removal and canal repreparation. Images were analysed using the i-Cat software. After RE and CBCT acquisition in S3, all the samples were clarified to directly visualize the presence of the MB2 canal. All images were analysed by a blinded, previously calibrated examiner. Accuracy, specificity and sensitivity were compared using analysis of variance (P < 0.05 level of significance).
  
  
  RESULTS
  MB2 root canals were detected in 67% of the samples. Overall, radiographic examination was associated with lower mean accuracy values for detecting MB2 than CBCT regardless of the MB1 condition. The MB1 root canal condition did not influence MB2 detection in 0.2-mm voxel images. The presence of root fillings in the MB1 canals reduced the detection of MB2 canals, especially in the 0.3- and 0.25-mm voxel-size images (P < 0.05).
  
  
  CONCLUSIONS
  CBCT was associated with higher mean values of specificity and sensibility than radiographic examination for the detection of MB2 canals. When endodontic retreatment is necessary removal of the root filling prior to the CBCT examination eliminates artefacts, thereby permitting the use of the 0.3-mm voxel protocol that has good diagnostic performance and lower radiation dose.
authors: Department of Surgery and Orthopedics, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. mari_vizzotto@yahoo.com.br
authors: M B
authors: MB
authors: Vizzotto
authors: P F
authors: PF
authors: Silveira
authors: N A
authors: NA
authors: Arús
authors: F
authors: F
authors: Montagner
authors: B P F A
authors: BP
authors: Gomes
authors: H E D
authors: HE
authors: da Silveira
mesh_terms: D016477:Artifacts; D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data*; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data*; D008437:Maxilla / Q000000981:diagnostic imaging*; D008963:Molar / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement; D012387:Root Canal Filling Materials / Q000737:chemistry*; D018915:Root Canal Preparation / Q000379:methods; D012680:Sensitivity and Specificity; D012984:Software; D019227:Tooth Apex / Q000000981:diagnostic imaging
chemical_list: D012387:Root Canal Filling Materials
keywords: Cone-beam computed tomography; diagnosis; endodontics