title: Evaluation of Root Canal Dentin Erosion after Different Irrigation Methods Using Energy-dispersive X-ray Spectroscopy.
abstract: BACKGROUND
  The purpose of this study was to examine the level of erosion in root dentin caused by different irrigation methods and protocols.
  
  
  METHODS
  Thirty-five extracted upper molar teeth were instrumented and divided into 7 groups to undergo treatment by different methods: negative control, GentleWave System (Sonendo Inc, Laguna Hills, CA), and syringe needle irrigation following different protocols. The teeth were instrumented to size #25/.08 or #30/.09 for needle irrigation groups and to ProTaper size S1 for the GentleWave group under 5% sodium hypochlorite (NaOCl). The needle irrigation groups were subjected to final rinses of 2 minutes of 3% NaOCl + 2 minutes of 8% EDTA (3% N2 + 8% E2), 2 minutes of 3% NaOCl + 2 minutes of 8% EDTA + 1 minute of 3% NaOCl (3% N2 + 8% E2 + 3% N1), 2 minutes of 5% NaOCl + 2 minutes of 17% EDTA (5% N2 + 17% E2), 2 minutes of 5% NaOCl + 2 minutes of 17% EDTA + 1 minute of 5% NaOCl (5% N2 + 17% E2 + 5% N1), and 5 minutes of 5% NaOCl + 5 minutes of 17% EDTA + 5 minutes of 5% NaOCl (5% N5 + 17% E5 + 5% N5), respectively. The root canal surface was observed by scanning electron microscopy, and the dentin composition was analyzed by continuous line scanning for 300 μm into dentin using energy-dispersive X-ray spectroscopy.
  
  
  RESULTS
  A slight but statistically significant decrease of calcium and an increase of carbon was measured in the 5% N2 + 17% E2 group in comparison with the control; no significant difference was found among GentleWave, 3% N2 + 8% E2, and 5% N2 + 17% E2 (P > .05). A final 1-minute rinse with 3% or 5% NaOCl reduced calcium and phosphorus to a significantly lower level than in groups without a 1-minute final rinse (P < .05). Final irrigation with 5% NaOCl for 5 minutes removed almost all calcium and phosphorus. Scanning electron microscopy showed canal wall erosion when an additional final irrigation with NaOCl was done.
  
  
  CONCLUSIONS
  NaOCl followed by final EDTA irrigation performed either by syringe needle or the GentleWave System caused minimal dentin erosion. Erosion was measured as increased loss of calcium and phosphorus in samples in which additional final irrigation was performed using NaOCl after EDTA.
authors: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada.
authors: Zhejun
authors: Z
authors: Wang
authors: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada; Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan.
authors: Hazuki
authors: H
authors: Maezono
authors: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada.
authors: Ya
authors: Y
authors: Shen
authors: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada. Electronic address: markush@dentistry.ubc.ca.
authors: Markus
authors: M
authors: Haapasalo
mesh_terms: D002118:Calcium; D002244:Carbon / Q000032:analysis; D003786:Dental Pulp Cavity / Q000737:chemistry* / Q000473:pathology*; D003804:Dentin / Q000737:chemistry / Q000648:ultrastructure; D004492:Edetic Acid / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008963:Molar; D009339:Needles; D010758:Phosphorus; D012388:Root Canal Irrigants / Q000627:therapeutic use*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D012390:Root Canal Therapy / Q000379:methods; D012973:Sodium Hypochlorite / Q000008:administration & dosage / Q000627:therapeutic use; D013052:Spectrometry, X-Ray Emission / Q000379:methods*; D013499:Surface Properties; D013594:Syringes; D007507:Therapeutic Irrigation / Q000295:instrumentation* / Q000379:methods*; D013997:Time Factors; D014077:Tooth Erosion; D014092:Tooth Root / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D012388:Root Canal Irrigants; D010758:Phosphorus; D002244:Carbon; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D002118:Calcium
keywords: Dentin; EDTA; GentleWave; erosion; irrigation; sodium hypochlorite