Enamel: your teeth's natural defense

A woman drinking from a mug by a sunny window A woman drinking from a mug by a sunny window A woman drinking from a mug by a sunny window

Your teeth are protected by enamel, a very hard, thin coating. To maintain a healthy smile, you need to protect your enamel from decay, excess wear and acid erosion. Learn more about what causes damage to enamel and how you can keep your enamel strong with good dietary choices and proper dental hygiene.

What is enamel?

Enamel is the most visible layer of a tooth. It is also the hardest and most mineralized substance in the human body, composed of about 95 to 98 percent calcium and phosphate ions that form strong hydroxyapatite crystals. It protects the much softer inner layer of teeth, called the dentin, from the forces of wear, bacteria and acids that cause decay and acids from all other sources, primarily food, beverages and your stomach acid. Enamel also shields the very temperature-sensitive dentin from painful contact with hot and cold foods and drinks. Because it contains no living cells, enamel cannot regrow. Once it wears away, it’s gone. Under the right conditions though, early damage can be repaired.

The thin layer of enamel needs to last a lifetime, but it is constantly under pressure from a variety of forces. Tooth wear is mainly the result of three processes: (1) attrition, including wear through tooth-to-tooth contact resulting from bruxing or clenching; (2) abrasion, which is wear produced by something other than another tooth, like toothbrushing or chewing on hard substances, such as the sand and grit in chewing tobacco or holding a pipe stem between your teeth; and (3) erosion, where the teeth are exposed to non-tooth decay-related acids from inside or outside the body. Inside acids can include stomach acids from persons with frequent gastric reflux (GERD), other gastrointestinal disorders, or frequent vomiting in people with bulimia. The most common sources of outside acids are acidic beverages such as carbonated soft drinks, fruit juices, energy and sports drinks, wine, beer and other alcohols, and foods such as fruits, condiments, tomatoes and pickles, to name a few. 

What causes enamel erosion?

Enamel erosion is separate from the tooth decay process, which also damages enamel through acid-producing bacteria. Erosion refers to enamel or dentin wear from the acidic foods and drinks in our diet, from stomach acid in persons with conditions such as gastric reflux, bulimia or anorexia, and from certain medications and other external sources of acid exposure. Enamel erosion is characterized by acid-mediated surface softening which, if frequent or long-lasting, can progress to irreversible loss of enamel surface.

Research shows that low pH is the primary factor in a beverage or food's erosive potential. Normal pH of saliva is around pH7, and research has shown that foods and drinks with a pH below approximately 5.5 can cause erosive effects. Most fruit juices, carbonated sodas, flavored waters, teas, energy and sports drinks, and alcoholic beverages are considered extremely erosive. There is a dose-response relationship between the daily consumption of acidic drinks and dental erosive wear, so the sensible use of these type drinks is appropriate. There are other important factors that can determine how your teeth will be affected by erosive foods and beverages. These include anything that affects saliva amount, composition and flow rate, tooth surface structure, and oral hygiene habits, including brushing and fluoride exposure and chewing and grinding habits.

Most experts believe that during the last 15-20 years there has been a significant increase in the prevalence and severity of erosive tooth wear, particularly in adolescents and young adults, largely linked to the high rate of consumption of soft drinks, including fruit juice and carbonated drinks, by this age group. A combination of erosion and abrasion or attrition accelerates this wear, and a tooth surface softened from erosion is more susceptible to destruction from bruxing or clenching or the abrasion from overly vigorous brushing. The most common sites for tooth erosion are on the chewing surfaces of molars and the inside surfaces of the upper front teeth, but depending on the individual, it also can be found on most tooth surfaces.

Erosive damage to the permanent teeth occurring during childhood can compromise the dentition for the person’s entire lifetime and may require repeated expensive fillings and other dental treatment. So, it is important to understand the destructive forces at work and the preventive behaviors that can protect your teeth. Saliva plays a critical role in the protection of enamel from erosion by acid and provides the components of a protective coating called the “acquired pellicle,” which covers the enamel.  It also promotes remineralization of the enamel surface following acid attack, by supplying calcium, phosphate and fluoride ions that can help replace the minerals that are being lost due to the acid. Anything that dehydrates, or dries your mouth, will leave you far more susceptible to both erosion and tooth decay. Dry mouth can occur due to many health conditions, including diabetes, stroke or autoimmune disorders, like Sjogren’s syndrome. Other common causes of dry mouth include hundreds of common over-the-counter and prescription medications, as well as recreational drugs, alcohol use, dehydration, smoking, snoring and mouth breathing.

Enamel erosion has been reported in all age groups; however, dentin erosion is likely to be age- dependent and results from increased levels of gingival recession, root exposures, and other accumulated risk factors. Indeed, as increasing numbers of people are retaining their teeth throughout their lifetime, gingival recession has become a more prominent issue. Gingival recession exposes root dentin to the oral environment, which increases the opportunity for acidic-erosive challenges to the dentin and abrasive brushing habits. This exposed and eroded dentin can then be subject to tooth sensitivity and root decay, leading to the eventual need for fillings, root canals and possibly tooth loss.

Factors that erode enamel

There are many substances, habits and health conditions associated with erosion or the dissolving of the tooth surface:

  • Soft drinks, fruit drinks, energy and sports drinks, wine, beer, spirits, and acidic foods, including fruits, pickles and tomatoes
  • Dry mouth (xerostomia), a condition in which there is not enough saliva to wash away harmful acids or provide the necessary calcium and phosphate ions to remineralize the tooth surface
  • Related conditions, such as gastric reflux disease or bulimia, that cause stomach acid to frequently enter the mouth
  • Medication side effects due to acidic makeup or interference with saliva production
  • Defects in enamel surfaces that are more susceptible to acid, due to tooth structure determined by genetics
  • Mechanical sources, like friction, caused by bruxism or wear from overly abrasive toothpaste or aggressive brushing, particularly with a hard-bristled toothbrush
  • Occupational factors, such as exposure to industrial acid vapors
  • Constant chlorine exposure (e.g., for swimmers)

 

Signs of enamel erosion

Signs of erosion, particularly in children and adolescents, can be subtle and difficult to detect, and some signs may not be readily visible to the individual. Regular visits to the dentist can help to identify and track erosive changes in tooth appearance. Some signs are more obvious as erosion progresses:

  • Sensitivity to hot or cold foods that causes a jolt of pain upon contact
  • Dull or discolored teeth that appear to be turning more yellow
  • Cracks and chips that cause jagged edges along the teeth
  • Cupping, or indentations on the surface of teeth, particularly surfaces where you bite or chew
  • Smooth, shiny areas on biting surfaces

How to protect tooth enamel

Try these tips to protect your enamel:

 

  • Limit soft drinks, energy and sports drinks, juices, alcohol and other acidic drinks
  • Drink plenty of water to keep the mouth moist
  • Avoid bad food or drink habits, such as sucking on acidic fruits like lemons or limes, swishing or holding acidic drinks in your mouth, and prolonged sipping of drinks throughout the day
  • Swish your mouth with water thoroughly after eating or drinking acidic foods or beverages 
  • Rinse your mouth with water after throwing up or burping stomach acid into the mouth; mix in a teaspoon of baking soda, if available
  • Wait at least an hour to brush your teeth after you have had acidic foods or beverages to allow the minerals in your saliva to help reharden the teeth surfaces
  • Consume milk or cheese at the end of a meal to help neutralize acids
  • Choose a toothpaste and mouthwash that contain fluoride to strengthen tooth enamel by helping the calcium and phosphate to remineralize teeth
  • Gently brush at least twice a day and use a soft-bristle brush
  • Try to limit between-meal snacks and acidic beverages
  • Avoid whitening products with a low pH
  • Chew sugar-free gum to stimulate saliva
  • Ask your dentist if topical fluorides or at-home fluoride rinses will benefit your situation
  • Tell your dentist if you suffer from bulimia, frequent acid reflux or GERD, alcoholism or other problems that cause stomach acids to frequently enter your mouth
  • Talk to your physician and dentist, if you suffer from dry mouth, as saliva is critical to tooth health
  • Check with your physician for treatment if you have acid-creating conditions like bulimia

Studies show the occurrence of enamel and dentin erosion is high and still growing in populations across the world. Even when erosive wear occurs in its milder forms, it is a matter of concern, as it may compromise your otherwise healthy dentition in later life. The erosive wear process is complicated and modified by many chemical, behavioral, tooth, saliva and other associated processes in the mouth. This explains why there is a wide variation in erosion in people that may appear to have similar diets and conditions. Get regular dental care. If you have risk factors and show any signs of erosive wear, it is important to intervene early to help keep your teeth healthy for a lifetime.  

 

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