title: Exploiting the potential of free software to evaluate root canal biomechanical preparation outcomes through micro-CT images.
abstract: OBJECTIVE
  To propose an automated image processing routine based on free software to quantify root canal preparation outcomes in pairs of sound and instrumented roots after micro-CT scanning procedures.
  
  
  METHODS
  Seven mesial roots of human mandibular molars with different canal configuration systems were studied: (i) Vertucci's type 1, (ii) Vertucci's type 2, (iii) two individual canals, (iv) Vertucci's type 6, canals (v) with and (vi) without debris, and (vii) canal with visible pulp calcification. All teeth were instrumented with the BioRaCe system and scanned in a Skyscan 1173 micro-CT before and after canal preparation. After reconstruction, the instrumented stack of images (IS) was registered against the preoperative sound stack of images (SS). Image processing included contrast equalization and noise filtering. Sound canal volumes were obtained by a minimum threshold. For the IS, a fixed conservative threshold was chosen as the best compromise between instrumented canal and dentine whilst avoiding debris, resulting in instrumented canal plus empty spaces. Arithmetic and logical operations between sound and instrumented stacks were used to identify debris. Noninstrumented dentine was calculated using a minimum threshold in the IS and subtracting from the SS and total debris. Removed dentine volume was obtained by subtracting SS from IS.
  
  
  RESULTS
  Quantitative data on total debris present in the root canal space after instrumentation, noninstrumented areas and removed dentine volume were obtained for each test case, as well as three-dimensional volume renderings.
  
  
  CONCLUSIONS
  After standardization of acquisition, reconstruction and image processing micro-CT images, a quantitative approach for calculation of root canal biomechanical outcomes was achieved using free software.
authors.affiliation: Faculdade de Odontologia, Departamento de Odontopediatria e Ortodontia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: A A
authors.initials: AA
authors.lastname: Neves
authors.affiliation: Escola de Ciências da Saúde, Universidade do Grande Rio, Duque de Caxias.
authors.forename: E J
authors.initials: EJ
authors.lastname: Silva
authors.affiliation: Polícia Militar do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: J M
authors.initials: JM
authors.lastname: Roter
authors.affiliation: Faculdade de Odontologia, Universidade Federal Fluminense, Niterói, Brazil.
authors.forename: F G
authors.identifier: http://orcid.org/0000-0001-9972-6861
authors.initials: FG
authors.lastname: Belladona
authors.affiliation: Programa de Engenharia Nuclear, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: H D
authors.initials: HD
authors.lastname: Alves
authors.affiliation: Programa de Engenharia Nuclear, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: R T
authors.initials: RT
authors.lastname: Lopes
authors.affiliation: Departamento de Engenharia de Materiais, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: S
authors.initials: S
authors.lastname: Paciornik
authors.affiliation: Escola de Ciências da Saúde, Universidade do Grande Rio, Duque de Caxias.
authors.forename: G A
authors.initials: GA
authors.lastname: De-Deus
mesh_terms: D000465:Algorithms; D006801:Humans; D008334:Mandible; D008963:Molar / Q000000981:diagnostic imaging* / Q000601:surgery*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D018915:Root Canal Preparation / Q000379:methods*; D012984:Software; D055114:X-Ray Microtomography
keywords: canal instrumentation; micro-CT; root canal preparation