Rui Vicente Oppermann

Effect of Some Polyvalent Cations on the Acidogenicity of Dental Plaque in vivo

The effect of different metal ions on the acidogenicity of dental plaque was investigated. It was found that mouthrinsing with 20 mM solutions of SnF2, ZnCl2, AlCl3 and FeCl3 inhibited the metabolic activity of dental plaque for periods up to several hours, whereas the same concentration of MgCl2 showed no such effect but on the contrary tended to increase the acid-formation potential. Sodium chloride (40 mM) had no measurable effect.

Accumulation of Cu and Zn in human dental plaque in vivo.

The rentention of copper and zinc in dental plaque in vivo after repeated mouth rinses with aqueous solutions of salts of these elements was measured by neutron activation analysis. The reduction in a

The in vivo effect of glucose solutions containing Cu+ + and Zn+ + on the acidogenicity of dental plaque

A series of experiments were performed to evaluate the lowest concentration of copper or zinc effective in reducing the acidogenicity of dental plaque in vivo when applied simultaneously with a carbohydrate challenge. The effect of a combination of sub-effective concentrations of these metals was also determined. The results showed a significant reduction in acid production in plaque challenged with glucose solutions containing 0.25 mM CuSO4 or 5.0 mM Zn (C2H3O2).2 as compared to glucose solutions alone. Neither 0.1 mM copper sulphate nor 2.5 mM zinc acetate reduced the acidogenicity of plaque significantly, whereas a combination of these subeffective concentrations was effective. The low metal concentrations causing reduction in acid formation in this study may be explained by the inhibiting substances reaching the bacteria at the same time as the substrate. The synergistic effect of the combination of low concentrations of copper and zinc is consistent with the view that these metals effect dental plaque by the same mechanisms.

The effect of some cationic antiseptics on the acidogenicity of dental plaque in vivo

Two series of experiments were performed in order to compare the ability of different cationic antiseptics to inhibit the acid production in plaque. In addition an attempt was made to evaluate the influence of oral retention on the acid-inhibiting properties of these agents. In one series of experiments acid production, following sucrose applications on plaque, was measured in situ prior to and at given time intervals after rinsing with the individual agents. In a second series the effect of eluting the antiseptics retained in the oral cavity by means of 5 consecutive acetic acid (6 mM) rinses was evaluated. The results showed that chlorhexidine (0.5 mM) was more effective than benzalkonium chloride (1 mM) and piperazine (1 mM). Cetylpyridinium chloride (1 mM) was the least effective. Acidic elution markedly reduced the inhibitory effect of single rinses of chlorhexidine (0.5 mM), benzalkonium chloride (1 mM) and the cetylpyridinium chloride (1 mM). This effect was less pronounced with a higher concentration (2.2 mM) of chlorhexidine. The results gave support to the view that retention of an agent in the mouth and in plaque is of significance for its ability to inhibit acid production of dental plaque.