title: Hard-tissue debris accumulation created by conventional rotary versus self-adjusting file instrumentation in mesial root canal systems of mandibular molars.
abstract: OBJECTIVE
  To evaluate the accumulation of hard-tissue debris when using the Self-adjusting File (SAF) system in mesial roots of mandibular molars with isthmuses and to compare it with that occurring when the ProTaper file system was used.
  
  
  METHODS
  Forty extracted human mandibular molars with joining mesial root canals and an isthmus between the two canals were randomly assigned to two experimental groups and scanned using micro-computed tomography. Root canals in the control group (N = 20) were instrumented using the ProTaper rotary system until F3. Irrigation with 1 mL of 3% NaOCl solution was applied after each instrument. Root canals in the experimental group (N = 20) were prepared using the SAF for 4 min, with continuous irrigation (3% NaOCl, 4 mL min(-1)). After rescanning, canals in both groups were further irrigated with 5 mL of 17% EDTA for 2 min. After final scanning, the per cent value of total canal system volume filled with hard-tissue debris was calculated. Statistical analysis was performed using Mann-Whitney U-test; the alpha-type error was set at 1%.
  
  
  RESULTS
  Instrumentation of the root canals with ProTaper left 10.1% (IQR 5.2) of the total canal system volume filled with hard-tissue debris while preparation with the SAF left 1.7% (IQR 1.6). This difference was highly significant (P < 0.0001). After subsequent EDTA irrigation, these values were significantly reduced (P < 0.01) to 7.9% (IQR 4.1) and 1.3% (IQR 0.8) in the ProTaper and SAF groups, respectively.
  
  
  CONCLUSIONS
  Preparation with the SAF system resulted in less hard-tissue debris accumulation in isthmus-containing root canal systems compared with instrumentation with ProTaper rotary files.
authors.affiliation: Division of Preventive Dentistry, Periodontology, and Cariology, University of Zürich Center of Dental Medicine, Zürich, Switzerland. frank.paque@zzm.uzh.ch
authors.forename: F
authors.initials: F
authors.lastname: Paqué
authors.forename: A
authors.initials: A
authors.lastname: Al-Jadaa
authors.forename: A
authors.initials: A
authors.lastname: Kfir
mesh_terms: D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D004492:Edetic Acid / Q000627:therapeutic use; D004867:Equipment Design; D006801:Humans; D008334:Mandible; D008422:Materials Testing; D008963:Molar / Q000648:ultrastructure*; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013997:Time Factors; D019227:Tooth Apex / Q000648:ultrastructure; D014732:Vibration; D055114:X-Ray Microtomography
chemical_list: D012388:Root Canal Irrigants; D004492:Edetic Acid; D012973:Sodium Hypochlorite