IFIC Review: Nutrition and Oral Health: Making the Connection

September 1998

(This publication is available online only.)
How does the mouth relate to good health? The mouth is the entry point for food and the beginning of the gastrointestinal tract. The ability to chew and swallow is a critical function required to obtain essential nutrients for the body-the building blocks of good health. The links between oral health and nutrition are many. Thus, oral health plays an integral role in assuring adequate nutritional status. (1)

Interestingly, oral health and nutrition share an interdependent and sometimes antagonistic relationship. By promoting healthy development and maintenance of the mouth's tissues and natural protective mechanisms, good nutrition promotes good oral health. In contrast, certain foods can cause plaque development increasing the risk for oral disease. How the foods are eaten can stimulate saliva flow, reducing the risk. The interactions are complex, with food and nutrition having the potential for both positive and negative effects on oral health.

In addition, the mouth serves as a window for the skilled dental practitioner to view overall health status. The regular dental examination makes it possible for your dentist to check for gum disease as well as precancerous or cancerous lesions. More sophisticated screening mechanisms can produce early warnings of stroke by displaying calcifications in the corotid artery, or chemotherapy-induced weakening of the jaw.(2)

Taking care the mouth is an important step on the road to good health. Good eating habits, regular brushing, flossing and fluoride are all part of maintaining good health.

Oral Health - What Causes Dental Caries?

Caries (often referred to as tooth decay or cavities) is a bacterial disease that is caused or hindered by many interacting factors - bacteria, saliva flow, minerals, fluoride in water supply or dentiffices, the properties of the food eaten, frequency of eating, dental care and dental hygiene.

For many years, the primary focus of oral health care has been the prevention of cavities in children with an emphasis on dietary influences on caries formation. With evolving science, specific foods no longer are being singled out as major risk factors for caries. In today's world, however, prevention focuses on fluoride, use of sealants, frequency of eating, and good oral hygiene.

All these factors interact by encouraging or discouraging the cariogenic bacteria that cause progressive destruction of tooth enamel, known as demineralization. Plaque is an almost invisible deposit of bacteria and their byproducts that constantly forms on everyone's teeth. The bacteria in plaque use carbohydrates to produce acids that can attack tooth enamel. The decaying action of the plaque bacteria depends on its ability to adhere to tooth surfaces and to hold acids on the teeth. After many such attacks, the tooth enamel may break down, forming a cavity.(3)

The Role of Saliva

Saliva has a powerful, protective role in the oral cavity where it preserves the integrity Of the soft tissues and increases the caries resistance of the dental tissues. Minerals in saliva, such as phosphorus and calcium, also play a role in helping to reform the tooth enamel, a process known as remineralization. The mechanisms of repair are not well understood and are being actively studied. Fluoride in the mouth enhances saliva's role in the remineralization process. Additionally, saliva contains other substances that serve as buffers to neutralize the acid created by bacteria. Saliva also works to help remove food particles from the mouth.

In effect, saliva is to tooth enamel what blood is to the cells of the body. just as body cells depend on the blood stream to supply nutrients, remove waste and protect the cells, enamel depends on saliva to perform similar functions.(4)

Eating Habits
Sugars (fruit sugar, milk sugar and table sugar) and cooked starches (cookies and bread, etc.), known as fermentable carbohydrates, are the only foods that can impact caries. Because carbohydrates can be used by caries -promoting bacteria to produce acid and ultimately tooth decay, eating habits rather than the foods themselves are a key factor in causing or preventing tooth decay.
Frequency of eating is important because the acids are released to work on the teeth for about twenty to forty minutes following each eating occasion. The greater the frequency of eating, the more opportunity for the acid to work. Decay occurs when periods of acid attack or challenge to the tooth (demineralization) occur more frequently than periods of recovery (remineralization).

Similarly, those foods that tend to adhere to the teeth pose greater risks of decay than those that clear the mouth quickly. Consumer perceptions of foods that stick or adhere to the teeth usually are different from reality, as the following chart demonstrates. Surprisingly, chips and crackers adhere longer than jelly beans and caramels.(5) This may be because caramels and jelly beans contain soluble sugars that are washed away more quickly by saliva than foods such as bread or crackers, that are not dispersed rapidly by saliva, and thus linger longer on the teeth.The first column on the chart shows the consumer rating of the "stickiness" of the food, while the second and third columns show the weight of the food particles remaining on the teeth, or "sticking" to the teeth, one minute and five minutes after swallowing. When consumed with beverages, these rankings may be modified.

Food Consumer Rating Dry weight (mg) of
retained food particles
Time After Swallowing
1 Min. 5 Mins.
Caramels 1 16 0
Jelly beans 2 7 1
Chocolate-caramel peanut bars 3 26 1
Chocolate-caramel bars 4 15 0.1
Hot fudge sundaes 5 0 0
Peanutbutter crackers 6 59 9
Dried figs 7 37 2
Milk chocolate bars 8 0.3 0
Raisins 9 4 0.2
Granola bars 10 61 22
Source: Kashket, S., Van Houte, J., Lopez, L.R. and Stocks, S. Lack of correlation between food retention on the human dentition and consumer perceptions of food stickiness. Journal of Dental Research, 1991. Vol. 70. No. 10. Pp 1314-1319
Figure 1: Consumer perception of food stickiness compared with actual retention.(5)

High carbohydrate containing foods produce less acid when eaten with a meal than when eaten alone because saliva production is increased during a meal to help neutralize acid production and clear food from the mouth. A small piece of cheese at the end of the meal can help combat the acids produced from carbohydrate foods during the meal.

Lack of Access to Dental Care

Few data exist on access to dental care, but a 1987 report by the National Center for Health Statistics showed that only 5 percent of children in the United States under age 2 had ever seen a dentist. There has been a profound decrease in caries over the past two decades - a drop from a mean of 18 to 8 decayed, missing or filled surfaces among 17-year-olds -and half of 5 to 17 year old children in the country were free of dental decay. However, data suggest that socioeconomic status plays a role in caries development. "Closer examination .... disclosed there was a marked polarization in the distribution of caries among children - 20 percent have 60 percent of the decay .... it is the have-nots that have most of the dental disease. "(6)

Population-wide use of dental sealants remains low. However, between the 1986-87 and 1988-94 National Health and Nutrition Examination Surveys (NHANES 11 and NHANES 111), use of dental sealants more than doubled. Sealants are plastic films painted onto the chewing surfaces of teeth to protect them from decay. The NHANES III survey found sealants on the primary teeth of less than 2 percent of children, and the permanent teeth of 19 percent of children and adolescents. Use of sealants on permanent teeth was three times as common in white children (22 percent had "Sealants) as in African American children (8 percent) or Mexican American youngsters (7 percent).(7)

Baby Bottle Tooth Decay

Baby bottle tooth decay, sometimes known as nursing caries, is a dental condition in which theteeth of an infant or young child are severely damaged. It is caused by frequent prolonged exposure of a child's teeth to liquids containing sugars. Even lactose (the milk sugar found in cow's milk, formula milk and breast milk) can cause decay when in prolonged contact with the teeth. Bottles containing juices or other liquids containing sugars are the most common cause.

Normal feeding is not a problem because the liquids clear from the mouth quickly. But offering a child a bottle containing sweet liquid many times a day as a pacifier, or allowing a child to fall asleep with a bottle of formula or juice during naps or bedtime can lead to serious dental problems.

Simple steps taken by parents and caretakers can prevent or alleviate the problem, according to Dr. Steven Moss, a pediatric dentist at New York University. The steps, according to Moss, are:

After each feeding, wipe the child's teeth and gums with a damp washcloth or gauze pad to remove plaque.
Begin brushing your. child's teeth with a soft toothbrush and a pea-shaped amount of fluoride toothpaste as soon as the first tooth erupts.
If your child needs a comforting bottle at nap time or during the night, fill a nursing bottle with water rather than formula, Juice, milk or sweetened liquids. You could also give the child a clean pacifier recommended by your dentist or pediatrician.
Start visits to a dentist or pediatric dentist when the child is between six and twelve months of age. Such visits help assure the child's teeth are developing normally and that sealants, if indicated, are applied as the child grows. Make appointments regularly.'

Dental Caries - A Disease in Decline

The Fluoride Factor

Far and away the most important factor in reducing caries during the last two decades has been the widespread introduction of fluoride into water supplies as well as fluoridation of toothpaste. Precisely how fluoride works to treat and, in effect, prevent formation of dental cavities is still being studied, but the. evidence of effectiveness is overwhelming?

Widespread use of fluoride is credited with a dramatic decline in dental caries during the last 20 years in the United States, according to a survey by the National Institute of Dental Research (NIDR). The number of cavity-free children has increased from 28 percent in the early 1970s to 55 percent in the permanent teeth of 5 to 17 year olds in the 1988-94 National Health and Nutrition Examination Survey (NHANES III).(10) An increase in the number of people who regularly visit their dentist and an overall improved diet are also cited as factors in the decline of dental caries, says the NIDR.(11)

Despite the overwhelming scientific evidence of the benefits of fluoride, it has had its share of critics. Dental fluorosis - small, chalky, opaque areas on the surface of the teeth - is a concern of critics. This condition has been observed in communities when systemic fluorides are available in greater than optimal amounts for lengthy periods. A 1991 Public Health Service Review of the benefits and risks of fluoride concluded that the risks were minimal compared with the benefits, especially when water supplies were fluoridated according to government recommendations.

Other Oral Health Problems

Three forms of tooth wear may affect the teeth. When teeth wear through tooth to tooth contact this is termed attrition. Abrasion results from the application of external mechanical factors such as incorrect toothbrushing. Dental erosion is defined as the loss of hard tooth tissue caused by acids other than those produced by bacteria involved in dental caries. Tooth wear is similar to caries only in that a large number of factors combine to determine if an individual is at risk.

Some factors in dental erosion are internal and are seen in persons suffering gastric reflux or eating disorders - when acid enters the mouth from the stomach though regurgitation or vomiting. Other determinants are external with acids entering the mouth through the consumption of acidic foods, drinks or medicines. Both external and internal factors may be involved and the picture is often complicated by the contribution of the other forms of tooth wear, namely attrition and abrasion, especially in adults. Severe tooth wear is quite rare.

Acidic foods and drinks include fruits (especially citrus fruits) and their Juices, vinegary foods such as pickles, and fruit based or carbonated soft drinks. Unusual eating or drinking habits such as sucking on segments of citrus fruits (as athletes may do) and swishing or holding drinks in the mouth may be a greater factor in tooth erosion than the amount consumed.

Saliva is the key protective factor in the mouth to protect the teeth against erosion as well as against caries. Saliva flow is stimulated when acids enter the mouth as saliva neutralizes and dilutes the acid and clears it from the mouth. Therefore, the teeth are more at risk when saliva flow is low - as in some elderly people, in athletes who are mouth breathing or as a result of medications such as antihistamines. (12)

Periodontal disease is a widespread infectious disorder that destroys the supporting tissues of the teeth. Seen primarily in adults, it is initiated by plaque. Nutrient deficiencies may play a role in bringing about the condition, but good oral hygiene and regular visits to the dentist are the primary preventive procedures.(1)

New Directions in Oral Health Research

Over the last forty years, dental health researchers have shifted their focus from specific foods, such as candy, to the role of carbohydrates in general (starches and sugars), as well as to examining how eating habits influence plaque build-up. With fluoride now recognized as a dental caries combatant, future research and preventive measures are expected to focus on:

Ways in which dentists can utilize the routine dental visit as a screening mechanism to provide early warnings of eating disorders, of cancer, or of soft tissue problems pointing to osteoporosis. Some contemporary dentists now use the routine teeth cleaning as a time to administer a special x-ray of the carotid artery that can detect future risk of stroke or of chemotherapy-induced weakening of the jaw structure.
The role of nutrients (such as vitamin A and protein) on salivary gland structure and function, and the implications of deficiencies.
The role of antioxidants (such as vitamin E and carotene) on protective mechanisms against periodontal damage.(13)
The diet and lifestyle risk factor of tobacco and alcohol in the etiology of oral cancer. Additional research is needed on such protective factors as antioxidant nutrients.
Formation of new partnerships among dentists, pediatric dentists, dental hygienists and dietitians in oral health screening, nutrition screening and counseling.
Influence of aging, malnutrition and skeletal diseases such as osteoporosis on oral soft tissues in the elderly.
Decreased saliva flow in the elderly.

Global Perspectives

Dramatic declines in tooth decay are being seen around the world as well. The World Health Organization Oral Health Programme has set a Year 2000 Goal of three or less decayed, missing or filled teeth by age 12. To date, over 100 countries have achieved that goal. Those countries where fluoride is widely available show the sharpest declines. (14)
See Chart below.

Zoom in on this image

Figure 2: The global decline in caries for a section of countries over a 20-year period. (15,16)

Key Definitions

Caries - Scientific name for dental cavities. It is both singular and plural.
Cariogenic - Capable of promoting the development of caries (cavities). Describes any food containing sugars or cooked starches that can be used to form acid by bacteria living in plaque on teeth.
Cavity - The hole occurring in the outer surface of the tooth enamel.
Cooked starches - Contained in cooked foods such as pasta, rice, bread, potatoes, chips, crackers and baked goods.
Demineralization - The process by which minerals are leached out of tooth enamel. This occurs when the bacteria in plaque produces acids that can attack tooth enamel.
Enzyme - A protein which acts as a catalyst in promoting one or more of the many chemical reactions in the body. Enzymes in saliva help dissolve cooked starches into sugars so they become soluble and can clear the mouth or be fermented by plaque bacteria.
Fermentable carbohydrates - Any sugar or cooked starch that can be metabolized by oral bacteria to produce acid.
Fructose - A simple sugar found in honey and fruits.
Glucose - A simple sugar, also known as dextrose, found in many foods.
Plaque - An invisible, sticky film that forms on teeth, giving them a "fuzzy feel." Plaque contains bacteria which can ferment sugars and cooked starches in foods to form acid.
Remineratization - The process by which the minerals from saliva enter the tooth surface to repair it.
Starch - A carbohydrate polymer composed of glucose molecules. All starches are broken down in the body to the simple sugar glucose before they can be used.
Sucrose - The scientific name for table sugar, a mixture of the two simple sugars, glucose and fructose.

References

The American Dietetic Association. ADA Reports: Position of the American Dietetic Assocation: Oral Health and Nutrition. 1996 J.Am. Diet. Assoc. 96: 184-189.
Carter, L.C., A.D. Holler, et. al. 1997. Use of Panoramic Radiography Among An Ambulatory Dental Population to Defect Patients at Risk of Stroke. J. Am. Dent. Assoc. 128: 978-983.
American Dental Association. 1990. Diet and Dental Health.
Moss, S. 1997. The Relationship Between Diet, Saliva and Baby Bottle Tooth Decay. Int. Dent Jnl. 46: 399-402 (Suppl) 8.
Kashket, S., J. Van Houte, L.R. Lopez and S. Stocks. 1991. Lack of Correlation Between Food Retention on the Human Dentition and Consumer Perception of Food Stickiness. J. Dent. Res., 70/10: 1314-1319.
Mandel, I.D., American Dental Association. Caries Prevention: Current Strategies, New Directions. J. Am. Dental Assoc. 127:477-488.
National Institute of Dental Research. 1996. News release, March/96
American Dental Association. 1989. Baby Bottle Tooth Decay. 166.
Public Health Service. Review of Fluoride: Benefits and Risks. February 1991.
National Institute of Dental Research. News releases. March 11, 1996 and June 21, 1988.
International Food Information Council. 1997. Food Insight, January/February 8.
Imfeld, T., 1995. Etiology, Mechanisms and Implications of Dental Erosion: Dental Erosion. Definition, classification and links. September. 151-155.
Levitch, L.C., et al: 1994. Non-carious Cervical Lesions. Jnl of Dentistry, 22:195-207.
World Health Organization. 1995. The Oral Health Programme: Dental Caries Levels at 12 Years. May.
World Health Organization. 1995. Oral Health Global Indicator for 2000 Dental Caries Levels at 12 Years. WHO, Geneva.
Hescot, P., Roland, E. 1993. Dental Health in France. DMF Scores for 6, 9 and 12 Years Old. French Union for Oral Health (UFSBD).