“Saliva contains components that can directly attack bacteria which cause decay, and it is also rich in calcium and phosphates that help to remineralise tooth enamel.”
“Saliva contains antimicrobial components, as well as minerals that can help rebuild tooth enamel after attack by acid-producing, decay-causing bacteria.” – U.S. Surgeon General’s Report
1. Where does saliva come from?
- Saliva is produced in the salivary glands.
- The average production of saliva is 1.5 litres per day, or 45 litres per month.
- This might seem to be a lot of saliva, but remember it is being produced continuously for 24 hours of every day.
- There are three pairs of salivary glands in the mouth:
- The parotid salivary glands are in the cheeks, between the ear and nose.
- The submandibular salivary glands are on the floor of the mouth, in the area of the lower molar teeth.
- The sublingual salivary glands are under the tongue.
2. What are the functions of saliva?
- Saliva plays a vital role in several important oral functions:
- Eating: Unless food is moistened by saliva it cannot be properly tasted or chewed.
- Swallowing: Dry food is difficult to swallow. It could tear the lining of the throat. Liquid is needed to be able to swallow.
- Speech: Speaking dries the mouth. Despite the normal presence of saliva, speakers often need to sip water when they make long speeches. Normal speech would be impossible without saliva.
- Digestion: Food that is not chewed and moistened by saliva is difficult for the stomach to process.
- It plays an important role in the prevention of tooth decay.
- It may be used to test for diseases such as cancer and HIV.
3. How does saliva prevent tooth decay and gum disease?
- The flow of saliva helps to wash away food debris.
- It is alkaline, and so it helps to neutralise mouth acids and reduce decay.
- It helps to protect the teeth from erosion caused by acids in the diet.
- The saliva dilutes the strength of the acid.
- Saliva slows or inhibits plaque growth and calculus formation.
- This reduces the risk of gum disease.
- The calcium content of saliva can help to reverse the early stages of decay. This is called remineralisation.
4. What influences the flow of saliva?
- The flow of saliva is stimulated by the act of chewing.
People who are too frail to chew properly are unable to produce enough saliva for a healthy mouth.
- The smell, taste, sight, or even the thought of food also stimulates salivary flow.
5. What is xerostomia?
- This is a persistently dry mouth caused by a reduced production of saliva.
- It is not the ordinary dry mouth that can be cured by a glass of water.
- It has many causes:
- Inadequate chewing.
- Medication such as anti-histamines, anti-depressants and drugs to reduce blood pressure.
- Mouth breathing.
- Fatigue and anxiety.
- Diseases such as diabetes or HIV.
- Ageing does not cause dry mouth. It is present in the elderly only when it is a symptom of a disease.
6. What are the effects of dry mouth?
- Dry mouth causes a great deal of discomfort such as:
- Dryness and a slight burning feeling in the mouth.
- Difficulty with speaking and swallowing.
- Bad breath (halitosis).
- Increased tooth decay.
- Increased gum disease (gingivitis and periodontitis).
- Difficulty with dentures, as saliva is essential for the suction needed to keep dentures firm and stable.
- Cracking of the lips and corners of the mouth.
7. What treatment is there for a persistently dry mouth?
- Your dentist or doctor will advise you along the following lines:
- It is very important to stimulate the salivary glands by vigorous chewing.
- Eat foods that require chewing.
- Sugarless chewing gum will stimulate the salivary glands.
- Regular sips of water, or sucking ice can provide temporary relief.
- Artificial saliva can be sprayed into the mouth several times a day.
- Mouthwashes, lozenges and toothpastes can help to relieve the dryness.
- When the cause of the dry mouth is a medical condition, you will be referred to your doctor for advice and treatment.
- Sialogogues can stimulate the flow of saliva. Ask your doctor or dentist about them.