Plaque Inhibition by a Combination of Zinc Citrate and Sodium Lauryl Sulfate

Abstract

Bacteriological tests demonstrated an additive inhibitory effect of ZnCl₂ and sodium lauryl sulfate (SLS) on in vitro growth of Streptococcus sobrinus OMZ 176 and of Streptococcus sanguis ATCC 10556. As measured by atomic absorption spectrophotometry, the solubility of zinc citrate increased in the presence of SLS. After 48 h, the concentration of solubilized zinc from aqueous solutions of 5.0 mM zinc citrate was 12.0 mM versus 14.4 mMin the presence of 34.7 mM SLS. The plaque-inhibiting properties of aqueous solutions of 12.0 mM Zn²⁺ from zinc citrate, 34.7 mM SLS, and 14.4 mM Zn²⁺ from zinc citrate in combination with 34.7 mM SLS were examined in 7 volunteers. Plaque accumulations were assessed by using a method earlier described after 3 days of twice daily mouthrinses with 10 ml test solution, during which period no mechanical oral hygiene was performed. Compared to placebo, SLS and zinc citrate increased the frequency of plaque index score 0 by 52.9 and 98.3%, respectively, and SLS gave 36.9% and zinc citrate 55.7% less surfaces with scores 2 or 3 (p < 0.05 in all cases). The combination of zinc citrate and SLS gave a threefold increase of plaque index score 0 and a 70.5 % reduction of scores 2 or 3 (p < 0.05).

Effects of Mouthrinses with Triclosan, Zinc Ions, Copolymer, and Sodium Lauryl Sulphate Combined with Fluoride on Acid Formation by Dental Plaque in vivo

“…The MIC value obtained for SLS with S. mutans and S. sanguis in a defined microdilution test system was within the range previously reported [Giertsen et al, 1989]. Triclosan was about 10 times more effective than SLS, a relative efficacy similar to that observed by Wade and Addy [1992] against a variety of oral microorganisms using an agar dilution method.…”

“…Combinations of zinc ions with chlorhexidine [Giertsen et al, 1988], with SLS [Giertsen et al, 1989], or with triclosan [Saxton, 1986;Bradshaw et al, 1993] may exert either additive or synergistic growth-inhibitory effects on plaque microorganisms due to complementary modes of action. These effects probably also relate to increased intracellular uptake of zinc ions following perturbation of membrane integrity.…”

“…The antibacterial effect of PG alone was also tested. Each well was inoculated with 75 Ìl inoculum of the bacteria diluted 1:1,000 in broth to a final dilution of 1:2,000 [Giertsen et al, 1988[Giertsen et al, , 1989. The outermost wells were not used to avoid errors due to evaporation.…”

“…A volume of 25 Ìl of one of the agents (final concentration MIC and one dilution step above and below MIC) was added to each of serial dilutions of the other agent (75 Ìl). Aliquots of 50 Ìl inoculum of the bacteria diluted 3:2,000 in broth were dispensed to obtain a final dilution of inoculum of 1:2,000 [Giertsen et al, 1988[Giertsen et al, , 1989.…”

“…SLS inhibits growth of a range of oral bacteria in vitro, including Streptococcus sobrinus and Streptococcus sanguis, and it retards slightly plaque formation in humans [Giertsen et al, 1989]. Observed plaque-inhibitory effects of triclosan-containing oral hygiene formulations may be attributable partially to their content of SLS [Waaler et al, 1993].…”