title: Reciprocating root canal technique induces greater debris accumulation than a continuous rotary technique as assessed by 3-dimensional micro-computed tomography.
abstract: BACKGROUND
  The ability of single-file, reciprocating instruments to remove inorganic debris is uncertain. By using micro-computed tomography (microCT), this study compared the 3-dimensional distribution, quantity, and density of remaining inorganic debris in the mesial root of mandibular molars after instrumentation. A single reciprocating file was compared with a multifile rotary instrumentation technique.
  
  
  METHODS
  Teeth were selected for instrumentation using reciprocating or rotary instruments (n = 19). Teeth were scanned using microCT before and after instrumentation. Through shape recognition and superimposition image analysis techniques, remaining inorganic tissue debris was identified, quantified, and visualized 3-dimensionally, mapping debris to its location. The use of a density phantom enabled the debris density to be calculated, giving a measure of compactness.
  
  
  RESULTS
  After single-file instrumentation, an average of 19.5% debris remained in the canal compared with 10.6% with the multifile technique (P = .01) and at an average density of 1.60 g/m(3) compared with 1.55 g/m(3) for the multifile system (P > .05). Isthmuses, protrusions, and irregularities in the canal wall were repeatedly seen at the locations of debris accumulation.
  
  
  CONCLUSIONS
  In canals with a high prevalence of isthmuses and protrusions, using multifile rotary systems may be preferred over reciprocating files because it can yield cleaner canals with less debris accumulation.
authors.affiliation: Physical Sciences of Imaging in the Biomedical Sciences, University of Birmingham, Edgbaston, Birmingham, UK. j.p.robinson@pgr.bham.ac.uk
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Robinson
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Lumley
authors.forename: Paul R
authors.initials: PR
authors.lastname: Cooper
authors.forename: Liam M
authors.initials: LM
authors.lastname: Grover
authors.forename: A Damien
authors.initials: AD
authors.lastname: Walmsley
mesh_terms: D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D003804:Dentin / Q000000981:diagnostic imaging; D018130:Diamond / Q000737:chemistry; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D019047:Phantoms, Imaging; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D012388:Root Canal Irrigants; D018130:Diamond; D012973:Sodium Hypochlorite
keywords: Debris; micro–computed tomography; reciprocate movement; root canal preparation