title: Ex vivo assessment of irrigant penetration and renewal during the cleaning and shaping of root canals: a digital subtraction radiographic study.
abstract: OBJECTIVE
  To assess radiographically irrigant penetration in the root canal system of curved roots during root canal shaping procedures ex vivo.
  
  
  METHODS
  Thirty extracted mandibular molar teeth with moderate to severe curvature were used. A special aiming device was used to guarantee that each successive radiograph was taken with the same positioning. The mesiolingual canal of each tooth was instrumented using the ProTaper system. For each step of the shaping procedure, two irrigation modalities were repeated in the same order. Active irrigation consisted of a 0.5-mL flush of sodium diatrizoate solution (Hypaque 50%) immediately followed by agitation with a size 08 K-file. Passive irrigation consisted of a 0.5-mL flush of sodium hypochlorite solution delivered with a syringe through a 27-gauge notched tip needle. A digital radiograph was taken after each modality and stored on computer for subsequent digital subtraction and measures of the depths of irrigant penetration. Comparisons were performed within an analysis-of-variance framework in a repeated-measures approach.
  
  
  RESULTS
  The penetration of irrigants was significantly greater for each successive step of the shaping procedure when the two modalities were analysed separately (P < 0.001). The difference between the two modalities was statistically significant for each step of the shaping procedure (P < 0.0001).
  
  
  CONCLUSIONS
  Shaping root canals improved both penetration and exchange of irrigant inside the root canal system. Complete renewal of the solution was impossible to achieve with a conventional syringe delivery system and a limited volume of solution. Recapitulation with a K-file after flushing improved irrigant penetration.
authors.affiliation: Department of Endodontics and Restorative Dentistry, School of Dentistry, Paris 7-Denis Diderot University, Paris, France. bronnec.endo@gmail.com
authors.forename: F
authors.initials: F
authors.lastname: Bronnec
authors.forename: S
authors.initials: S
authors.lastname: Bouillaguet
authors.forename: P
authors.initials: P
authors.lastname: Machtou
mesh_terms: D000704:Analysis of Variance; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D003806:Dentin Permeability; D003973:Diatrizoate / Q000008:administration & dosage; D006801:Humans; D008963:Molar; D019252:Radiography, Dental, Digital; D012388:Root Canal Irrigants / Q000008:administration & dosage; D018915:Root Canal Preparation / Q000379:methods*; D012973:Sodium Hypochlorite / Q000008:administration & dosage; D018709:Statistics, Nonparametric; D013382:Subtraction Technique; D007507:Therapeutic Irrigation / Q000379:methods
chemical_list: D012388:Root Canal Irrigants; D003973:Diatrizoate; D012973:Sodium Hypochlorite