title: Influence of dentin from the root canal walls and the pulp chamber floor on the pH of intracanal medicaments.
abstract: BACKGROUND
  The objective of this study was to evaluate the alterations in the pH of calcium hydroxide (Ca[OH]2), 2% chlorhexidine (CHX) gel, and their combination after adding dentin powder from the root canal walls and the pulp chamber floor.
  
  
  METHODS
  Ca(OH)2 paste, 2% CHX gel, and their combination were examined. Dentin powder was obtained from the root canal walls and the pulp chamber floor of bovine teeth and added as 1.8% to the volume of the medications. The pH values of the mixtures were assessed immediately after preparation, after 24 hours, and on days 7 and 14. Data were analyzed statistically by analysis of variance and the Student's t test (P = .05).
  
  
  RESULTS
  pH values of Ca(OH)2 were always above 12 in the presence or absence of dentin powder during the 14 days of the study. A significant decrease in pH values of Ca(OH)2 was observed after 14 days when dentin from the root canal wall was added (P < .001). The pH values of CHX gel were significantly increased by the presence of dentin (P = .001). The t test showed a significant difference in the increase of the pH values when the different dentin types were added (P = .002). The pH of the Ca(OH)2 and CHX gel combination was not influenced by dentin powder from the root canal walls, and a reduction was observed after 14 days, exactly like in the control group. The pH values of the combination did not alter after 14 days when pulp chamber floor dentin was added.
  
  
  CONCLUSIONS
  The different dentin types variably affect the pH of Ca(OH)2 paste, 2% CHX gel, and their combination in the studied periods.
authors.affiliation: Department of Endodontics, Dental School, University of Athens, Athens, Greece.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Agrafioti
authors.forename: Nestoras E
authors.initials: NE
authors.lastname: Tzimpoulas
authors.forename: Evangelos G
authors.initials: EG
authors.lastname: Kontakiotis
mesh_terms: D000818:Animals; D002126:Calcium Hydroxide / Q000737:chemistry; D002417:Cattle; D002710:Chlorhexidine / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D003804:Dentin / Q000502:physiology*; D004338:Drug Combinations; D006863:Hydrogen-Ion Concentration; D012388:Root Canal Irrigants / Q000737:chemistry*; D013997:Time Factors
chemical_list: D004338:Drug Combinations; D012388:Root Canal Irrigants; D002126:Calcium Hydroxide; D002710:Chlorhexidine