IADR Abstract Archives
Light-Cured Ca(OH)2 Pulp-Capping Materials Raise the Local pH to 7.8
Objectives: To determine the relationship between pH change and degradation for calcium hydroxide chelate cements and polymer based light-cured calcium hydroxide materials.
Methods: Two examples, each of chelate and light-cured calcium hydroxides, were used. Discs (5 mm diameter x 2 mm depth) were prepared for each material, light-cured on one side through a plastic film where appropriate, and weighed. They were then placed in individual volumes of 5 cm3 distilled water, removed after key intervals (5 minutes, 20 minutes, 1 hour, 4 hours, 24 hours and 48 hours), dried with a tissue, and weighed again. At the same intervals, the pH of the individual storage liquids was measured. Results for both mass change and pH were tested for significance using 1-way ANOVA followed by Tukey’s HSD test and differences at p<0.05 were considered significant.
Results: The pH around chelate Ca(OH)2 cements rose rapidly to be over 10 by 48 hours. The chelate cements initially increased in mass, but had lost substantial amounts by 48 hours. The polymer based light-cured Ca(OH)2 cements showed only minor change in pH, in both cases being just above 7.8 at 48 hours. They behaved differently from each other, with Cal LC losing mass, whereas Calcimol showed no significant change by 48 hours.
Conclusions: Degradation of chelate-type calcium hydroxide cements is essential to alter the pH of the surrounding medium. High pH is known to stimulate the formation of reparative dentine in vital teeth. We conclude that polymer based light-cured calcium hydroxide possibly do not raise pH sufficiently to do this, hence they may not be as effective for pulp capping as chelate Ca(OH)2 cements.
Methods: Two examples, each of chelate and light-cured calcium hydroxides, were used. Discs (5 mm diameter x 2 mm depth) were prepared for each material, light-cured on one side through a plastic film where appropriate, and weighed. They were then placed in individual volumes of 5 cm3 distilled water, removed after key intervals (5 minutes, 20 minutes, 1 hour, 4 hours, 24 hours and 48 hours), dried with a tissue, and weighed again. At the same intervals, the pH of the individual storage liquids was measured. Results for both mass change and pH were tested for significance using 1-way ANOVA followed by Tukey’s HSD test and differences at p<0.05 were considered significant.
Results: The pH around chelate Ca(OH)2 cements rose rapidly to be over 10 by 48 hours. The chelate cements initially increased in mass, but had lost substantial amounts by 48 hours. The polymer based light-cured Ca(OH)2 cements showed only minor change in pH, in both cases being just above 7.8 at 48 hours. They behaved differently from each other, with Cal LC losing mass, whereas Calcimol showed no significant change by 48 hours.
Conclusions: Degradation of chelate-type calcium hydroxide cements is essential to alter the pH of the surrounding medium. High pH is known to stimulate the formation of reparative dentine in vital teeth. We conclude that polymer based light-cured calcium hydroxide possibly do not raise pH sufficiently to do this, hence they may not be as effective for pulp capping as chelate Ca(OH)2 cements.