The antimicrobial effects of a saturated calcium hydroxide solution, a
nd in combination with 10% and 2 0% detergent, were evaluated on Strep
tococcus faecalis, Streptococcus sanguis, Streptococcus mutans, Strept
ococcus salivarius, Neisseria sp., diphtheroid, Staphylococcus aureus,
Lactobacillus sp., Staphylococcus epidermidis, Bacillus subtilis and
Candida albicans. The saturated calcium hydroxide solution was effecti
ve against only four of the 11 microorganisms studied over a 60-min ex
posure time. The calcium hydroxide solutions containing detergent kill
ed all 11 test organisms over a 30-min exposure time. This difference
was statistically significant (P < 0.01). No statistically significant
difference in antimicrobial action was found between the 10% and 20%
detergent calcium hydroxide solutions (P > 0.01). However, the low sur
face tension (46.5 x 10(-3) Nm-1) and high pH (10.8) of the calcium hy
droxide solution with 20% detergent establish it as the more effective
solution.