title: Chemical and antimicrobial properties of calcium hydroxide mixed with irrigating solutions.
abstract: OBJECTIVE
  Chemical and antimicrobial effects of paste-like suspensions of calcium hydroxide (Ca(OH)2) powder with chlorhexidine (CHx), sodium hypochlorite (NaOCl) or iodine potassium iodide (IPI) solutions were tested and compared to conventional Ca(OH)2/saline paste.
  
  
  METHODS
  Equivalent mixtures of Ca(OH)2 with irrigating solutions were compared to conventional Ca(OH)2/saline paste for their ability to raise the pH in root dentine. Ca(OH)2 pastes were compacted into prepared root canals of single-rooted extracted human teeth. Changes in root pH over time were recorded with a microelectrode placed in standardized wells within root surfaces. Antimicrobial efficacy of test solutions and pastes against Enterococcus faecalis and Candida albicans was assayed using an agar diffusion test.
  
  
  RESULTS
  The ability of Ca(OH)2 to raise the pH in the root dentine was maintained when using mixtures of Ca(OH)2 with CHx, NaOCl or IPI (Kruskal-Wallis, P > 0.05). Mixtures of Ca(OH)2 with the test solutions had similar antimicrobial properties as equivalent mixtures with saline (anova, P > 0.05). The efficacy of CHx was reduced when mixed with Ca(OH)2. No additive antiseptic effects were recorded between Ca(OH)2 and IPI or Ca(OH)2 and NaOCl.
  
  
  CONCLUSIONS
  Ca(OH)2 is a strong alkali, whose pH is not changed when adding weak acids or alkalis in aqueous suspensions. Under the conditions of this study, mixing Ca(OH)2 powder with the test irrigating solutions did not provide an increased antimicrobial effect compared to a conventional Ca(OH)2/saline medication.
authors.affiliation: Division of Endodontology, Department of Preventive Dentistry, Cariology, and Periodontology, Center for Dental Medicine, University of Zürich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Haenni
authors.forename: P R
authors.initials: PR
authors.lastname: Schmidlin
authors.forename: B
authors.initials: B
authors.lastname: Mueller
authors.forename: B
authors.initials: B
authors.lastname: Sener
authors.forename: M
authors.initials: M
authors.lastname: Zehnder
mesh_terms: D000704:Analysis of Variance; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001641:Bicuspid; D002126:Calcium Hydroxide / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003481:Cuspid; D003786:Dental Pulp Cavity / Q000187:drug effects; D004338:Drug Combinations; D013293:Enterococcus faecalis / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D005779:Immunodiffusion; D017613:Iodine Compounds / Q000494:pharmacology; D012387:Root Canal Filling Materials / Q000494:pharmacology*; D012388:Root Canal Irrigants / Q000494:pharmacology*; D018709:Statistics, Nonparametric
chemical_list: D000891:Anti-Infective Agents, Local; D004338:Drug Combinations; D017613:Iodine Compounds; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; C439385:iodine potassium iodide; C010882:chlorhexidine gluconate; D002126:Calcium Hydroxide; D002710:Chlorhexidine