title: Demineralization of resected root-ends with methylene blue dye.
abstract: OBJECTIVE
  This study evaluated the ability of methylene blue solutions of different concentration, pH, and time exposure to remove the smear layer from resected root-ends.
  
  
  METHODS
  Resected root-ends were treated with either 2% methylene blue dye for intervals of 5 to 11 minutes or 1% methylene blue for 7 to 9 minutes and examined with a scanning electron microscope for smear layer removal. Two minute applications of saline solution and 50% citric acid served as controls.
  
  
  RESULTS
  All methylene blue solutions were found to be ineffective in removing the smear layer at all time intervals tested. An experimental solution of 1% methylene blue in 50% citric acid was found to predictably remove the smear layer during a 2 minute application and retained all the favorable staining characteristics of the dye. Fifty percent citric acid solutions applied for 3 minutes appeared to overdemineralize the root-end and gave poorer results than 2 minute applications.
  
  
  CONCLUSIONS
  Smear layer removal was pH dependent. Methylene blue solutions are clinically unsuitable for smear layer removal.
authors.affiliation: Department of Endodontology, Oregon Health Sciences University, Portland, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Morgan
authors.forename: J C
authors.initials: JC
authors.lastname: Baumgartner
mesh_terms: D000328:Adult; D000368:Aged; D019343:Citric Acid / Q000494:pharmacology; D003648:Decalcification Technique; D003804:Dentin / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008751:Methylene Blue / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D018915:Root Canal Preparation / Q000379:methods*; D016369:Smear Layer; D013499:Surface Properties / Q000187:drug effects; D019227:Tooth Apex / Q000187:drug effects / Q000601:surgery
chemical_list: D019343:Citric Acid; D008751:Methylene Blue