title: Apical Transportation, Centering Ratio, and Volume Increase after Manual, Rotary, and Reciprocating Instrumentation in Curved Root Canals: Analysis by Micro-computed Tomographic and Digital Subtraction Radiography.
abstract: BACKGROUND
  This study aimed to evaluate apical transportation (AT), centering ratio (CR), and volume increase (VI) produced after instrumentation of mesiobuccal canals of maxillary molars with hand files, rotary, and reciprocating instruments using micro-computed tomographic (micro-CT) imaging and to demonstrate the ability of digital subtraction radiography (DSR) to evaluate AT.
  
  
  METHODS
  Forty-five canals were randomly assigned to either group K, manual K-files; PTN, ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland); or Rec, Reciproc (n = 15 for each group) for preparation. Master apical files were #25, X2 (#25/06), and R25 (#25/08), respectively. Micro-CT imaging was used to measure AT (mm) and CR (mm) at 3 different locations (1, 4, and 7 mm from the apex). VI (mm3) was measured for each root third and for the whole canal. DSR (mesiodistal and buccolingual projections) was used to measure AT at 1 mm from the apex.
  
  
  RESULTS
  AT and CR values were statistically similar across the groups at 1, 4, and 7 mm. AT results obtained for the different locations were similar within each group; CR, in turn, showed statistically lower values at 1 mm. VI was statistically similar in all groups. Both DSR and micro-CT imaging showed that AT always occurred on the outside of canal curvature. The highest mean value obtained for AT was 0.215 mm.
  
  
  CONCLUSIONS
  AT, CR, and VI were similar for the K, PTN, and Rec groups. AT results were clinically irrelevant. DSR was as effective as micro-CT imaging in AT analysis and could be considered as an alternative method for assessing this outcome.
authors.affiliation: Department of Restorative Dentistry, Universidade Luterana do Brasil, Canoas, Rio Grande do Sul, Brazil.
authors.forename: Caroline
authors.initials: C
authors.lastname: Zanesco
authors.affiliation: Department of Conservative Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Marcus Vinicius Reis
authors.initials: MV
authors.lastname: Só
authors.affiliation: Department of Restorative Dentistry, Universidade Luterana do Brasil, Canoas, Rio Grande do Sul, Brazil.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Schmidt
authors.affiliation: Department of Surgery and Orthopaedics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Vania Regina Camargo
authors.initials: VR
authors.lastname: Fontanella
authors.affiliation: Department of Conservative Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. Electronic address: regrazziotin@gmail.com.
authors.forename: Renata
authors.initials: R
authors.lastname: Grazziotin-Soares
authors.affiliation: Department of Restorative Dentistry, Universidade Luterana do Brasil, Canoas, Rio Grande do Sul, Brazil.
authors.forename: Fernando Branco
authors.initials: FB
authors.lastname: Barletta
mesh_terms: D003762:Dental Instruments; D006801:Humans; D008437:Maxilla; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D019252:Radiography, Dental, Digital; D011897:Random Allocation; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D019227:Tooth Apex / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D055114:X-Ray Microtomography
keywords: Apical transportation; micro–computed tomographic imaging; reciprocating; shaping ability