Related Experiment Video
Updated: Aug 26, 2026

Concurrent Quantification of Cellular and Extracellular Components of Biofilms
Published on: December 10, 2013
[Comparison of effect on S.mutans producing acid ability between organic weak acid and fluoride]
Cai-lian Zhu1, Zheng Liu, Jiang-yun Sheng
1Shanghai Research Institute of Stomatology, Ninth People's Hospital, Shanghai Second Medical University, Shanghai 200011, China.
Objective:
To figure out the effects of organic weak acids, benzoate, citric acid and malic acid on the main cariogenic bacteria S.mutans Ingbritt. To evaluate the possibility of above weak acids as anti-caries reagents.
Methods:
S.mutans Ingbritt was inoculated into tryptic soy broth containing different concentrations of fluoride, benzoate, citric acid and malic acid, grew in anaerobic conditions at 37 degrees centigrade for 48h. The final pH values of suspension were measured.
Results:
Fluoride had best inhibitory effect on S.mutans Ingbritt in low concentrations, whereas other 3 weak acids, benzoate, citric acid and malic acid could inhibit S.mutans Ingbritt in a higher concentrations. The order of effectiveness was fluoride>malic acid>benzoate>citric acid.
Conclusion:
Fluoride has the best inhibitory effect on S.mutans producing acid ability. Though weak acids benzoate, malic acid and citric acid in high concentration had different inhibitory effects on S.mutans Ingbritt, however high concentration of organic acids can make enamel demineralization.
Related Concept Videos
Acid Strength and Molecular Structure
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
Substituent Effects on Acidity of Carboxylic Acids
Molecular Structure and Acidity
The size effect explains the change in atomic size on acidity. When comparing the acids formed from elements that belong to the same column in the periodic table, their atomic sizes...
Acidity and Basicity of Carboxylic Acid Derivatives
The relative acidic strength of the derivatives can be explained based on the extent of resonance stabilization of the conjugate base. The...
Calculating pH Changes in a Buffer Solution
Weak Acid Solutions
