What Is Dental Erosion?

Teeth are essential components of the digestive system, enabling us to cut and grind our food into smaller pieces so that we can swallow it more easily. Each tooth consists of four main layers. The tooth pulp is the innermost layer and contains connective tissue, blood vessels, and nerves. Cementum is a layer that covers the root of the tooth (the part of the tooth that is not exposed to the environment inside the mouth) and helps to anchor it in the jaw. Dentin is the main supporting structure of the tooth and is made of a bone-like matrix that protects the nerves in the pulp. It sits directly under the final layer, the enamel.

Tooth enamel forms a shiny, hard protective layer around the crown (the part of the tooth that is exposed above the gums) to protect it from damage and the effects of bacteria in the mouth that can cause small openings or holes called “cavities”. It is highly mineralized, with 95% of it consisting of calcium and phosphorus bound together in small crystals called hydroxyapatite that are extremely strong.

Although enamel is the hardest substance in the body it is unable to regenerate if it becomes damaged because there are no living cells in the tooth to replace it. Physical factors such as everyday wear and tear and teeth grinding can contribute to dental erosion (the gradual destruction of tooth enamel), leading to the inner layers of the teeth becoming exposed and increasing the chance of cavities developing. Chemical factors can also cause dental erosion. For example, sugary foods can interact with bacteria in dental plaque (a sticky substance that continuously builds up on the teeth) leading to the production of acid.

How Does pH Affect Tooth Enamel?

pH is a numerical scale, ranging from 0 to 14, that describes how acidic or alkaline a substance is. A pH of 7 describes a substance that is neutral (is neither acidic nor alkaline), while a pH less than 7 describes one that is acidic, with the acidity increasing as the pH approaches 0. Conversely, a pH greater than 7 describes an alkali with the strength of alkalinity increasing as the pH approaches 14. In the mouth, acid produced by bacteria in plaque or in acidic foods and drinks softens the enamel, and can dissolve the hydroxyapatite crystals within it if the pH drops below 5.5. It has been reported that the ability of tooth enamel to dissolve increases by 10-fold with each one-unit decrease in pH.

Why Are Many Soft Drinks Acidic?

Acids either occur naturally in drinks or are added to enhance their flavor or improve their shelf life. For example, citrus juices naturally contain citric acid, but it may also be added to other drinks to increase the tanginess of the flavor or to act as a preservative. Phosphoric acid is added to some soft drinks for similar reasons. In addition, fizzy drinks get their fizziness as a result of carbon dioxide being dissolved in water under pressure in a process that forms a weak solution of carbonic acid (resulting in a tingly sensation on your tongue when you drink them).

It would be wrong to think that the presence of acids in soft drinks is always a bad thing. Ascorbic acid, another name for vitamin C, is commonly found on lists of ingredients and has several important functions in the body including keeping cells healthy, wound healing, and the maintenance of healthy skin, bones and blood vessels.

 What Did This Study Investigate?

Over recent years, increased consumption of soft drinks and fruit juices has been linked to rising rates of a wide range of health conditions that include type 2 diabetes, obesity, and the development of osteoporosis later in life. In the UAE, it has been estimated that each resident consumes an average of 103 liters of soft drinks per year, and the country is one of the top five countries in the world in terms of juice consumption per person. The high rate of acidic drink consumption in the UAE has been reported to be having a significant effect on the dental health of the country’s citizens, with over 50% of 5-year-old preschool children showing signs of tooth damage caused by the enamel starting to dissolve.

The authors of this study analyzed 306 different soft drinks that are sold in the UAE, including fizzy drinks, energy drinks, sparkling water, iced teas, juices, non-alcoholic malt beverages, coconut water, and sports drinks. They measured the pH of each drink three times using a pH meter and classified them as mildly erosive (pH 4 or more), erosive (pH between 3 and 3.99), or extremely erosive (pH less than 3).

What Did the Study Find?

The authors of the study reported that 88% of the drinks tested had a pH of less than 4, with 51% classified as erosive and 37% as extremely erosive. The most acidic drink tested, a fizzy drink, had a pH of only 2.32, although the type of drink with the lowest average pH was non-alcoholic malt beverages (pH 2.99). In addition to the pH of a drink, there is some evidence that the type of acid added or naturally occurring in it may be linked to the amount of erosion that may occur, with citric acid having been reported previously to be more aggressive than phosphoric acid.

In this study, citric, phosphoric, ascorbic, and malic acids were the acids most frequently present according to the ingredients labels. Phosphoric acid was found in both fizzy and energy drinks, citric acid was found combined with pantothenic acid in energy drinks, malic acid (which contributes to the sour taste of some foods and drinks) was mainly present in sparkling water or combined with juices containing citric acid, and ascorbic acid was mainly found in juices and malt beverages.

Take Home Message for Patients

Reducing your consumption of soft drinks can benefit the health of your teeth because it will lessen the amount of time that your enamel is exposed to high levels of acidity. If you do consume a soft drink, drinking it through a straw can help to keep it away from the teeth. In addition, if you decide to brush your teeth after having a soft drink it is important to wait 30 minutes to 1 hour before doing so. This is because it takes around this length of time for the saliva in the mouth to return the environment back to being neutral. If you brush your teeth before this happens, the acidity in the mouth may mean that the enamel is still slightly soft, increasing the chance of physical erosion.