title: Comparison of alternative image reformatting techniques in micro-computed tomography and tooth clearing for detailed canal morphology.
abstract: BACKGROUND
  Micro-computed tomography (MCT) shows detailed root canal morphology that is not seen with traditional tooth clearing. However, alternative image reformatting techniques in MCT involving 2-dimensional (2D) minimum intensity projection (MinIP) and 3-dimensional (3D) volume-rendering reconstruction have not been directly compared with clearing. The aim was to compare alternative image reformatting techniques in MCT with tooth clearing on the mesiobuccal (MB) root of maxillary first molars.
  
  
  METHODS
  Eighteen maxillary first molar MB roots were scanned, and 2D MinIP and 3D volume-rendered images were reconstructed. Subsequently, the same MB roots were processed by traditional tooth clearing. Images from 2D, 3D, 2D + 3D, and clearing techniques were assessed by 4 endodontists to classify canal configuration and to identify fine anatomic structures such as accessory canals, intercanal communications, and loops.
  
  
  RESULTS
  All image reformatting techniques in MCT showed detailed configurations and numerous fine structures, such that none were classified as simple type I or II canals; several were classified as types III and IV according to Weine classification or types IV, V, and VI according to Vertucci; and most were nonclassifiable because of their complexity. The clearing images showed less detail, few fine structures, and numerous type I canals. Classification of canal configuration was in 100% intraobserver agreement for all 18 roots visualized by any of the image reformatting techniques in MCT but for only 4 roots (22.2%) classified according to Weine and 6 (33.3%) classified according to Vertucci, when using the clearing technique.
  
  
  CONCLUSIONS
  The combination of 2D MinIP and 3D volume-rendered images showed the most detailed canal morphology and fine anatomic structures.
authors.affiliation: Department of Conservative Dentistry, Dental Research Institute, Seoul National University Dental Hospital, Seoul National University School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Ki-Wook
authors.initials: KW
authors.lastname: Lee
authors.affiliation: Department of Conservative Dentistry, Dental Research Institute, Seoul National University Dental Hospital, Seoul National University School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yeun
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Division of Restorative Dentistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Canada.
authors.forename: Hiran
authors.initials: H
authors.lastname: Perinpanayagam
authors.affiliation: Private Practice, Changwon, Republic of Korea.
authors.forename: Jong-Ki
authors.initials: JK
authors.lastname: Lee
authors.affiliation: Department of Conservative Dentistry, Dental Research Institute, Seoul National University Dental Hospital, Seoul National University School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yeon-Jee
authors.initials: YJ
authors.lastname: Yoo
authors.affiliation: Department of Conservative Dentistry, Jukjeon Dental Hospital, College of Dentistry, Dankook University, Jukjeon, Republic of Korea.
authors.forename: Sang-Min
authors.initials: SM
authors.lastname: Lim
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Seok Woo
authors.initials: SW
authors.lastname: Chang
authors.affiliation: Department of Industrial Engineering, Pusan National University, Pusan, Republic of Korea.
authors.forename: Byung-Hyun
authors.initials: BH
authors.lastname: Ha
authors.affiliation: Division of Endodontology, Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Conservative Dentistry, Dental Research Institute, Seoul National University Dental Hospital, Seoul National University School of Dentistry, Seoul National University, Seoul, Republic of Korea. Electronic address: kum6139@snu.ac.kr.
authors.forename: Kee-Yeon
authors.initials: KY
authors.lastname: Kum
mesh_terms: D000328:Adult; D000368:Aged; D002244:Carbon; D004396:Coloring Agents; D003648:Decalcification Technique; D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data; D021621:Imaging, Three-Dimensional / Q000379:methods / Q000706:statistics & numerical data; D008437:Maxilla; D008875:Middle Aged; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D018915:Root Canal Preparation / Q000379:methods*; D019227:Tooth Apex / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D019237:Tooth Cervix / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D004396:Coloring Agents; C028433:chinese ink; D002244:Carbon
keywords: 3-dimensional volume rendering; Canal configuration; MB root canal; MinIP technique; classification; clearing technique