title: Micro-CT evaluation of the efficacy of hard-tissue removal from the root canal and isthmus area by positive and negative pressure irrigation systems.
abstract: OBJECTIVE
  To evaluate the removal of accumulated hard-tissue debris (AHTD) from the root canal system of mandibular molars by positive and negative pressure irrigation systems, using micro-CT imaging analysis.
  
  
  METHODS
  Mandibular molars with a single canal in the distal root and 2 canals connected by an isthmus in the mesial root were matched based on similar morphological dimensions using micro-CT evaluation and assigned to 2 experimental groups (n = 20 mesial and 10 distal canals), according to the irrigation protocol: apical positive (conventional irrigation) or negative (EndoVac system) pressure. Changes in root canal volume and surface area as well as percentage of uninstrumented canal wall surface and accumulated hard-tissue debris (AHTD) after canal preparation were compared statistically using the independent sample t-test and Mann-Whitney U-test, with the significance level set at 5%.
  
  
  RESULTS
  Volume, surface area and percentage of static voxels in either mesial or distal root canal systems were not significantly different between groups before or after root canal preparation (P > 0.05). After preparation, AHTD was not observed in the distal canal of both groups. However, in the mesial root canal system, the conventional irrigation group was associated with a significantly higher median percentage of AHTD (11.48%; IQR: 5.9-22.6; range: 1.86-41.98) than the EndoVac group (3.40%; IQR: 1.5-7.3; range: 0.82-12.84) (P < 0.05).
  
  
  CONCLUSIONS
  Neither irrigation protocol succeeded in rendering the mesial canal system free of AHTD; however, apical negative pressure irrigation resulted in lower levels of AHTD than conventional irrigation.
authors.affiliation: Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil. marcoversiani@yahoo.com.
authors.forename: M A
authors.initials: MA
authors.lastname: Versiani
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: F R F
authors.initials: FR
authors.lastname: Alves
authors.affiliation: Department of Health, Dentistry Division, Southwest State University of Bahia, Jequié, Brazil.
authors.forename: C V
authors.initials: CV
authors.lastname: Andrade-Junior
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: M F
authors.initials: MF
authors.lastname: Marceliano-Alves
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: J C
authors.initials: JC
authors.lastname: Provenzano
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: I N
authors.initials: IN
authors.lastname: Rôças
authors.affiliation: Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: M D
authors.initials: MD
authors.lastname: Sousa-Neto
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: J F
authors.initials: JF
authors.lastname: Siqueira
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D003765:Models, Dental; D008963:Molar / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D012388:Root Canal Irrigants; D018915:Root Canal Preparation / Q000379:methods*; D014092:Tooth Root / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography
chemical_list: D012388:Root Canal Irrigants
keywords: apical negative pressure; hard-tissue debris; isthmus; mandibular molar; micro-computed tomography; root canal irrigation