title: Histologic evaluation of canal and isthmus debridement efficacies of two different irrigant delivery techniques in a closed system.
abstract: BACKGROUND
  This study compared canal and isthmus debridement efficacies between side-vented needle irrigation (SNI) and continuous ultrasonic irrigation (CUI) in the mesial root of mandibular first molars with narrow isthmuses using a closed-canal design.
  
  
  METHODS
  Micro-computed tomography scanning was used to select 20 teeth, each containing a narrow isthmus. Each root was sealed at the apex; embedded in polyvinylsiloxane to simulate a closed-canal system; and instrumented to size 40, 0.04 taper. Final irrigation was performed with either SNI or CUI (N = 10). Masson trichrome-stained sections were prepared from demineralized roots at 10 canal levels between 1.0 and 2.8 mm from the anatomic apex. The areas and debris occupied by the canals and isthmus were measured using ImageJ software (National Institutes of Health, Bethesda, MD) and statistically analyzed using repeated-measures analysis.
  
  
  RESULTS
  Overall, a significant difference was identified between SNI and CUI in the amount of debris remaining in the isthmus (P = .006) but not in the canal (P = .940). There was significantly more debris in the most apical three canal levels (1.0-1.4 mm) regardless of the irrigation technique (P < .001). The isthmus harbored significantly less debris in the CUI group between isthmus levels 1.0 to 2.2 mm when compared with SNI (P < .001 and P = .029). Neither technique removes debris completely from the canal or isthmuses.
  
  
  CONCLUSIONS
  Compared with SNI, CUI removes significantly more debris from narrow isthmuses of mandibular mesial roots.
authors.affiliation: U.S. Army Dental Activity, Fort Gordon, Augusta, Georgia, USA.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Adcock
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Sidow
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Looney
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Kathleen
authors.initials: K
authors.lastname: McNally
authors.forename: Kimberly
authors.initials: K
authors.lastname: Lindsey
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
mesh_terms: D001391:Azo Compounds; D002614:Chelating Agents / Q000008:administration & dosage; D004396:Coloring Agents; D003786:Dental Pulp Cavity / Q000473:pathology*; D004492:Edetic Acid / Q000737:chemistry; D004801:Eosine Yellowish-(YS); D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008334:Mandible; D008739:Methyl Green; D008963:Molar / Q000473:pathology; D009339:Needles; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D012973:Sodium Hypochlorite / Q000008:administration & dosage; D007507:Therapeutic Irrigation / Q000295:instrumentation; D019227:Tooth Apex / Q000473:pathology; D016896:Treatment Outcome; D014465:Ultrasonics / Q000295:instrumentation; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D001391:Azo Compounds; D002614:Chelating Agents; D004396:Coloring Agents; D012388:Root Canal Irrigants; C017768:trichrome stain; D008739:Methyl Green; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D004801:Eosine Yellowish-(YS)