Question

How does toothpaste kill bacteria that cause cavities?

Answer 1

Many toothpaste and mouthwashes contain fluoride that helps to protect the teeth against the bacterial infections that cause cavities.

Complete answer:
Our teeth are made up of the hard substance called enamel, which is primarily composed of the calcium-based mineral called hydroxyapatite. The consumption of starchy and sugary substances can cause the growth of bacteria on the surface of the teeth and as the bacteria tries to digest these substances they release the acid which can cause the demineralization of the enamel. This demineralization causes holes in the enamel and weakens the enamel. These are called cavities.

The fluoride in the toothpaste causes the remineralization of the teeth and causes the restoration of the minerals like calcium and phosphates which helps in the strengthening of the teeth. Another substance called triclosan is added to the toothpaste which is supposed to be more effective than toothpaste with fluorides.

At high concentration the triclosan at high concentrations, triclosan works by interfering with the outer membrane that protects bacteria, making it permeable so that triclosan can penetrate it and kill the microorganism. Triclosan also inhibits lipid synthesis by inhibiting the enzymes which are involved in fatty acid synthesis. Humans do not have this enzyme for lipid synthesis so the triclosan does not affect humans.

Note: The triclosan although is more effective than fluoride-containing toothpaste it is toxic to birds and fishes. Moreover, it is also considered carcinogenic by many researchers and its use is avoided by many toothpaste brands.