[ effect of addition of calcium hypochlorite disinfectant on setting expansion and surface hardness of dental stone]

ABSTRACT

Addition of disinfectants to dental stones is one method to prevent cross-contamination between patients and laboratory personnel. This study aimed to evaluate the effect of addition of calcium hypochlorite disinfectant on setting expansion and surface hardness of dental stone. In this experimental study, calcium hypochlorite aqueous solution with 0.5% concentration was added to type V dental stone. Setting expansion was measured by extensometer in millimeter and surface hardness was measured by Rockwell hardness test machine. Data were statistically analyzed using t-test with 0.05 level of significance. The mean setting expansion values were 2.49 +/- 0.0017 mm and 0.27 +/- 0.0094 mm in the test and control groups, respectively and had a statistically significant difference. The mean Rockwell hardness number was 74 +/- 1.93 and 85 +/- 3.09 in the test and control groups, respectively with no statistically significant difference. Setting expansion and surface hardness of type V dental stone increased and decreased, respectively by the addition of 0.5% calcium hypochlorite. Thus, this disinfection method needs modification for routine use in the laboratory setting: