The pH of the mouth and tooth decay

To chew food we need essential structures: teeth. They are part of our survival, our body's nutrition depends on this factor, so it is necessary to take proper care to conserve them.
This concern with oral hygiene has not emerged recently, since Antiquity (2000 a. C) there are already reports of the Egyptians using the abrasive mixture of powdered pumice stone and vinegar to clean the teeth. But what is pumice?
Pumice is a mixture of oxides made up of 70% Silicon Oxide (SiO₂) and 30% Aluminum Oxide (Al₂O₃).

Pumice stone

When it comes to the composition of teeth, the mineral hydroxyapatite is the main constituent, whose formula is Ca₅(DUST₄)₃Oh. Hydroxyapatite is partially soluble in acidic solutions, which can lead to tooth decay.

The carbohydrate-protein called mucin forms a film on the teeth: the Biofilm (plaque). The important thing is that this plaque is removed by brushing, because it traps food particles causing tooth decay.
Bacteria in our saliva ferment the carbohydrates we eat, and produce lactic acid. Therefore, the pH of the mouth is below 4.5 (acidic). The reaction of the acid with hydroxyapatite forms a salt that is soluble in H

₂The therefore starts from Hydroxyapatite and dissolves, which will favor the appearance of small cavities in the teeth.

There are factors that further aggravate the problem, such as the disease bulimia (a disorder caused by eating a large amount of food followed by vomiting), which causes the hydrochloric acid existing in the stomach eliminated along with vomiting, further reduce the pH, reaching 1.5 (very acid).
Another aggravating factor for oral health is the smoking habit. Cigarettes can cause from stains on the teeth to lip cancer, in addition, nicotine influences pigmentation, leaving the smile yellow.
But there are alternatives that help fight dental corrosion, such as periodic application of fluoride. Fluoride ions (F^-) present in fluorine transform hydroxyapatite into fluorapatite which protects teeth even more, as it is less soluble in acids.
Liria Alves
Graduated in Chemistry
Brazil School Team

Physicochemical - Chemistry - Brazil School

Source: Brazil School - https://brasilescola.uol.com.br/quimica/o-ph-boca-deterioracao-dos-dentes.htm