INTRACANAL PH CHANGES OF CALCIUM HYDROXIDE PASTES EXPOSED TO CARBON-DIOXIDE IN-VITRO

It has been suggested that the main benefit of using calcium hydroxide as an intracanal medicament lies in its bactericidal effect, provided that the pH of the paste is above 12.5. The purpose of this study was to measure changes in the pH of several calcium hydroxide pastes seal ed in root canals for 30 days. Sixty-two extracted, single-rooted huma n teeth were endodontically prepared using K-files up to size 60. The teeth were separated at random into six equal groups to be filled with either Calxyl, Hydrocalcium, or a paste made by mixing calcium hydrox ide powder with either distilled water, camphorated p-monochlorophenol , local anesthetic solution, or Solvidont, Cavidentin was used to seal the coronal orifice of the teeth that were placed individually in via ls containing 10 mt distilled water, Five vials of each group were exp osed to air at room temperature, whereas the other five vials were exp osed to carbon dioxide in a closed container, The pH of the paste in t he root canal was measured after 30 days, There was no significant (p > 0.01) change in the pH (mean 13.11) of the pastes placed in teeth be fore and after exposure to air, whereas the pH of the pastes in teeth exposed to carbon dioxide was significantly (p < 0.01) reduced (mean 1 2.54), There was no significant difference in pH between the six prepa rations, After 30 days of exposure to carbon dioxide, they still maint ained a purportedly bactericidal pH within the root canal.