Why is the pH of saliva important?

pH of saliva

A pH is the hydrogen ion concentration in a solution. Every fluid has a pH, and the pH of body fluids determines your health status. A deranged pH is indicative of a disease going on in the body. Let’s get into the details of the pH of saliva.

what is the Composition and amount of saliva produced daily

Saliva is composed of 99% water and 1% proteins and salt. An average of 0.5-1.5 liter of saliva is produced daily. The saliva produced between meals is 0.3-0.4 ml/min. Its production falls to 0.1 ml/min during sleep and increases to 4 -5 ml/min while eating.

Saliva is filtered from the blood but is less concentrated than plasma. The autonomic nervous system influences the quality of saliva. The parasympathetic nervous system is activated when you relax, and activation of this nervous system produces watery saliva. However, the sympathetic nervous is activated during stress and stimulates thick stringy saliva. 

What do pH values indicate?

A pH determines the number of hydrogen ions present in a fluid. Based on the concentration of hydrogen ions, fluids are classified into acidic, basic, and neutral. The pH values fall between 0-14 where

  • A ph between 0-6.9 shows an acidic medium 
  • A pH between 7.1-14 displays a basic medium 
  • A pH of 7 indicates a neutral medium (equal hydrogen and hydroxyl ions).

Acidic fluids have a higher concentration of hydrogen ions. The concentration of hydrogen ions in a fluid show strength of an acid, For instance, coca-cola contains strong acids such as phosphoric and citric acid with a pH of 2.6-2.7, whereas the pH of cow’s milk is 6.7-6.9 because of the presence of lactic acid, a weak acid. 

What is the normal pH of saliva?

The pH of human saliva is in the range of 6.7-7.6. A healthy saliva is near to neural pH with few acidic molecules. 

The pH of blood is 7.35-7.45. The pH at this level is ideal for many biological processes, one of the most important being the oxygenation of blood. Saliva is filtered from the blood, so vast variations in salivary pH values indicate problems with blood pH. 

Saliva is mainly produced by three large salivary glands, submandibular (60%), parotid (30%), and sublingual (5%). Only 7% of saliva is produced by small (minor) salivary glands scattered throughout the mouth. Their protein-rich saliva forms a protective layer on the mouth lining, keeping it moist at all times. 

A salivary pH of 7 indicates healthy teeth and gum status. The gum disease and dental cavities are unlikely to thrive in a neutral oral environment.

A prolonged decrease in salivary pH is a sign of acidemia (high acid in the blood) and predisposes you to dental cavities, gum disease, and bad breath. A low salivary pH favors the replication of gram-negative anaerobic bacteria by utilizing the environmental acid and producing more acidic products. The produced acid and enzymes destroy the gums and play a role in initiating or aggravating existing gum disease. 

What is the pH of mouth?

The pH of the oral cavity is maintained near neutrality by saliva. In healthy individuals, resting mouth pH doesn’t fall below 6.2. Saliva keeps the mouth neutral by two mechanisms:

  • Washes away acid-producing carbohydrates from the teeth and removes acid produced by bacteria
  • Acids produced by sugary beverages are buffered by the buffering agents in the saliva. 

Why is the pH of saliva important?

The pH of saliva has a fundamental impact on your dental health. The acidic saliva creates an acidic environment in the mouth that dissolves the highly mineralized tooth enamel.

As the oral pH drop to 4, the enamel erodes. There is a tenfold increase in enamel erosion for every unit decrease in pH. So, at pH 2, there is 100 fold increase in enamel erosion. Consuming cola softens the enamel and removes it if you brush your teeth soon after the drink or grind your teeth. 

The enamel erosion exposes the underlying dentin. Dentin exposure leads to tooth sensitivity on exposure to air, hot or cold drinks and foods. Moreover, the teeth appear yellow due to loss of enamel. 

The pH of saliva and dental caries – how are they both related

Another adverse consequence of low salivary pH is the development of dental cavities. Enamel forms a barrier against oral bacteria and other harmful substances in the mouth. Enamel erosion due to prolonged exposure of acidic saliva makes teeth more prone to bacterial penetration. Dentin lacks the toughness to protect the teeth as enamel does. Dentin comprises 40-45% mineral, 30% organic matrix, and 20-25% water by volume, whereas enamel constitutes 92% minerals, 6% water, and 2% organic matrix. 

Enamel erosion roughens the tooth surface and lets plaque and bacteria cling to the tooth surface and initiate the process of tooth decay. The smooth polished enamel doesn’t allow bacteria to adhere to it and is frequently washed away by saliva. Also, the salivary proteins, bicarbonates, and phosphates neutralize the acid and provide lost minerals such as calcium, phosphate, and fluoride from saliva to the teeth, a process known as remineralization.

Furthermore, the worn-out eroded enamel is more prone to damage by toothbrush bristles. 

If you experience teeth erosion (rough yellow teeth), sensitivity, and cavities in multiple teeth despite good oral hygiene, you must see a dentist for further evaluation. 

Low pH of saliva and gum disease 

A prolonged acidic environment favors the replication of gram-negative anaerobic bacteria by utilizing the environmental acid and producing more acidic products. The produced acid (lactic acid, butyric acid, and aspartic acid) and enzymes destroy the gums and play a role in initiating or aggravating existing gum disease. 

An experiment on how drinks affect the pH of saliva

You can test the pH of your saliva at home by the following experiment. For that, you need pH strips, which are readily available in the pharmacy or online. Follow the below instructions:

  • Don’t eat or drink anything two hours before the test. Eating or drinking can affect the accuracy of test results. 
  • Swallow or spit the saliva from the mouth and let the mouth fill with saliva again. Collect the saliva in a spoon. 
  • Take out your pH strip and place it in the saliva, and wait for 15 seconds. 
  • Now match the color of your strip with the given color chart to determine your saliva’s pH. 

How to restore your saliva’s pH?

You can restore your salivary pH in several ways. However, first, you need to know about the pH of your saliva so you can work accordingly to tip its scale towards the healthy value. 

Also, it is essential to understand that saliva is filtered from the blood. It is a representation of blood. Any derangement in blood pH can affect the salivary pH. So, it would be best to fix the blood pH first to restore salivary pH. See your GP or dentist if you develop cavities or sensitivity in several teeth in a short stretch of time despite regular oral hygiene practices.  

If your blood pH is normal, you can work on your saliva to return it to its normal values. You can incorporate the following measures into your lifestyle:

  • Quit sugar beverages. These include cola, soft drinks, fruit juices, etc., and replace them with plain water. If you can’t quit, then lower the frequency of your intake because it takes 20-30 mins to neutralize the acid produced after a sugary meal. 
  • Consumption of alkaline foods: green leafy and root vegetables are alkaline, and three to 3-5 servings of salads should be consumed three times a day. These include spinach, kale, parsley, broccoli, asparagus, artichokes, carrots, sprouts, and sea vegetables 
  • Avoid acid-producing foods: Avoid high acid-producing foods such as peanuts, walnuts, cashews, berries, chocolate, white sugar, white bread, pasta, beef, pork, and shellfish. 

Frequently asked questions

Is saliva acidic?

Yes, saliva becomes acidic if you consume many acid-producing foods. Also, people with metabolic acidosis have acidic saliva. 

What is the pH of saliva before meal?

The resting pH of the mouth ranges between 6.7 to 7.4 and doesn’t fall below 6.2. 

Does eating sugar increase the pH of saliva?

No, it doesn’t. The sugar intake decreases the pH of saliva. Oral bacteria break down simple sugars in the diet such as glucose into organic acids that lower the salivary pH. 

What does 6.2 pH of saliva mean?

This is the lower limit of salivary pH. This is a borderline reading and is considered healthy for the oral environment. A chronic decrease in pH values below 6.2 often requires further investigation to find the cause. 

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