Evaluation of various forms of calcium hydroxide in the monitoring of microleakage

Abstract

Calcium hydroxide has been shown to be an effective medium for the in vivo microleakage testing of amalgams. The purpose of this study was to determine the relative effectiveness of several forms of calcium hydroxide in the measurement of this clinical problem. It was also the purpose of this study to determine whether a relationship exists between the pH of the Ca(OH) 2 liner and its ability to detect microleakage. Standardized Class V preparations were generated on the buccal surfaces of extracted molars. The axial walls of the preparations were based either with Dycal, Dycal VLC, Pulpdent Liquid, or pure Ca(OH) 2. A series of teeth without a calcium hydroxide base served as the negative control. All teeth were restored with a spherical amalgam and kept in de-ionized water. The surfaces of the restorations were then subjected to 20 mL of 2°C water for a period of one min. After three min, a color-indicating pH paper was positioned over the restored area for detection of the presence of hydroxyl ions atthe amalgam/tooth interface. Regardless of the form of calcium hydroxide, all indicated extensive microleakage immediately after insertion of the restoration. In all cases, the number of samples generating positive results for leakage decreased over a period of time. The rate of decrease, however, was substantially dependent upon the form of calcium hydroxide used as well as its pH. The reagent grade of Ca(OH) 2 generated the greatest percentage of positive results for the longest duration.