The pH of our mouth changes throughout the day. It is dependent on food and drink that we consume, saliva flow, and general health factors. The lower the pH the more acidic the mouth is, which has effects on the dental enamel, dentine, gums and soft tissues. For optimal oral health, a neutral pH (7) or slightly alkaline is desirable.
The pH of the mouth determines what bacteria grow in the mouth as different bacteria grow at different pH and most grow in a pH range of 5.0-6.5. A combination of bacteria and an acidic environment leads to dental decay and gum disease.
Soft drinks (pH 2.3- about 4), lemon (pH =2), apple cider vinegar (pH 2.5-3), citrus juices (3-3.5), pickled foods (4-4.6) and many other dietary staples are acidic. Even bottled water has a pH of around 5.5. Acid reflux also lowers the oral pH. Tooth enamel starts dissolving or losing its mineral at pH 5.5 and the softer dentine dissolves at 6.7. This leads to dental erosion where the teeth become worn down, the enamel is thin and weak, teeth are sensitive and they chip easily.
Alkaline water has been popular recently and usually has a pH of 8.5-9. While pH above 7 encourages remineralisation of the teeth, too high a pH can lead to flaking of the enamel.
It is the balance between the food and drink we consume, the protective properties of saliva, good dental care and pH control that prevent dental decay and erosion.