Saliva contains the ingredients to make and repair teeth: Calcium (Ca), phosphate (PO4), hydroxide (OH–) and sodium (Na).
Saliva works in a number of ways to combat the acid in a food or drink:
- As saliva has a pH of around 7, it can make the food or drink less acidic.
- It can dilute the acid so there is less of it
- The acid content of a drink and the action of chewing food can stimulate more saliva to be produced
- Once mixed with the food or drink, it is swallowed, clearing them from the mouth
- It can ‘buffer’ the acids, meaning it keeps the pH inside the mouth near neutral, even if there is an acidic food or drink present. The main buffer is hydrogen carbonate (HCO3–). The amount of this will increase when stimulated by the smell or anticipation of a food or drink
Saliva also helps make a layer over the teeth called the ‘pellicle’
- This is mostly made up of proteins and minerals
- The pellicle acts as a barrier between the enamel and acidic foods and drinks, reducing the rate at which enamel can dissolve when exposed to these. Read more about how acid affects your teeth.
- The pellicle is reduced by tooth brushing, which is one reason why it is important not to brush soon after eating or drinking or to consume acidic foods or drinks shortly after brushing and not to brush too many times a day. After tooth brushing, it takes about 2 hours for the pellicle to build up again
Hara AT, Zero DT. The Potential of Saliva in Protecting Against Dental Erosion. In: Lussi A, Ganss C (eds): Erosive Tooth Wear. Monogr Oral Sci. Basel, Karger, 2014, vol 25, pp 197–205. DOI: 10.1159/000360372.
Hannig M, Hannig C. The Pellicle and Erosion. In: Lussi A, Ganss C (eds): Erosive Tooth Wear. Monogr Oral Sci. Basel, Karger, 2014, vol 25, pp 206–214. DOI:10.1159/000360376).
Kaidonis J, Townsend G. The ‘sialo–microbial–dental complex’ in oral health and disease. Ann Anato 2016;203:85–89