Methods: The procedures consisted of:
A. Monitoring of pH of a 5ml physiological saline solution (PBS, 37¢ªC) exposed to specimens (n=5) of each brand for 3w.
B. Specimens retrieved from A, immersed in fresh PBS, and pH measured for 1 w. Triplicate tests were performed for all pH tests.
C. Specimens (n=2) from B were washed, dried, and examined by SEM and EDXA.
D. Precipitates collected from solution containing GPCH were analyzed by XRD.
Results: The near neutral pH (7.2) of PBS exposed to GP remained unchanged with time. However, in contact with GPCH, it rose to 11.32 ± 0.15 within 1d, and was constant for the test period. The test solution in procedure B was found to be moderately alkaline and constant at pH = 10.42 ± 0.11.
GPCH specimens immersed in PBS were covered with adherent reaction products and produced precipitates in solution. The surface reaction products contained mainly Ca, P, and O. The precipitates were identified as carbonated HA, the mineral constituent of teeth structure. None of the above phenomena were observed with GP.
Conclusions: In a physiological saline solution, GP is inert. GPCC, on the other hand, is highly active. Its activity is demonstrated in its ability to create an alkaline environment and to induce mineralization. Since these properties are crucial to wound healing and repair, GPCH may be more effective than GP in root canal therapy [J Endo, 28, 10, 697, 2002].