Chemistry around us: toothpaste
To protect your teeth from cavity-causing bacteria, it is advisable to brush them after every meal. But what exactly happens in your mouth when you do that?
The cleaning effect comes from abrasives, which are small particles in the toothpaste, such as silicate compounds, calcium carbonate or calcium sulfate. These abrasive materials have microscopically small edges that help scrub away the plaque – a tough layer of bacteria that cause tooth decay – from your teeth when you brush. This process is facilitated by surfactants, surface-active substances that create foam – just as they do in shower gel and shampoo – and ensure that the toothpaste is evenly distributed so that the hard-to-reach spots also get clean.
But toothpaste should not just clean your teeth, it should also protect them. It therefore includes other ingredients, such as sodium fluoride or stannous fluoride. Because tooth enamel is largely made up of calcium, it can form bonds with the fluoride, making the enamel harder and protecting it from acids and cavity-causing bacteria. This protection has to be regularly renewed – ideally after every meal.