Caries

Facts about tooth decay

1. If there were no fermentable sugars in your diet, you would never get a single cavity. This applies even to the rare person who's teeth are in fact "soft". This also holds even if you never brush your teeth! I once treated a woman who's teeth were soft enough to absorb overall color from normal foods. The enamel was so soft that while preparing the teeth for crowns, the diamond bur cut through them like they were made of hard chalk! Believe it or not, she had never had a single cavity! The reason for this was that she had been told as a child that her teeth were especially susceptible to decay and to avoid sugar as much as possible. She was also a consistent brusher because of the yellow cast to her teeth. I placed crowns on her teeth due to their appearance, not because they were decayed.

2. Very, very few people actually have "soft teeth". The number probably runs in the range of a small fraction of a percent of the population!

The image at the head of this page, as well as the one to the right shows normal, healthy teeth that have become carious (decayed) due to a habit involving multiple exposures to sugar, usually liquid, throughout the day, day after day. A look at the patient's gums shows little redness around the teeth. This is a sign that this patient has been brushing his teeth conscientiously. To see pictures of the results of poor oral hygiene (lack of normal brushing and cleaning between the teeth once a day), see my page on gum disease.
3. Almost everyone who is prone to caries has a specific habit in which one form of sugar or another soaks the teeth many, many times a day. These sugar habits account for perhaps 95% of all caries! If you can identify the habit, and substitute a diet drink, or a non sugared food in its place, the decay simply stops where it is.
I'll go further into some of the specific sugar habits later in this piece, but for now, understand that the epidemic of tooth decay in America was caused by the sudden availability of sugared food products and had this seminal event never happened, the poor fellow pictured here would not have been featured on this page! Click on the image to the right to see how this mouth was restored.	Since people keep asking me if the above case can be repaired, please click on the image to see the case in progress.

Don't get discouraged if you have this type of problem. The images below show some standard dentistry repairing serious decay with simple fillings. Note that only the four central teeth have been repaired so far.

Q. But even diet soda contains acid from the carbonation (carbonic acid) as well as citric acid and even other forms of acid added to enhance the flavor. Since these acids occur in diet soda as well as in sugared soda, why is it that diet soda doesn't cause decay??

A. All the non sugar related acids in soda (including carbonic acid) are so soluble in water that they are washed off the teeth almost immediately before they can cause much decalcification of the tooth structure. On the other hand, the sugar in regular soda is very sticky and remains on the teeth for a long time. In addition, the bacteria in plaque use sugar as a raw material to create dextrans which are the molecular units composing the viscous sticky stuff that makes plaque adhere to the teeth. The dextrans have the property of absorbing more sugar which is turned into acid by the plaque bacteria causing the plaque to remain acidic for twenty minutes or more after each exposure to sugar.

I have never tried to dissolve a nail in a bottle of Coke, but if it did dissolve, it would be from the prolonged exposure of the iron to the carbonic acid from the carbonation in the soda, and not from the sugar. If a diet soda is drunk in the ordinary way, the carbonic acid caused by carbonation does NOT spend enough time in the mouth to damage the teeth. However if a patient habitually engages in soda-swishing, which is the habit of swishing the soda around in the mouth for prolonged periods before swallowing in order to remove the carbonation (because the carbonation hurts the throat), then over many years, the acids in even diet soda can cause serious erosion of the enamel and exposed dentin. Note that this form of erosion is NOT the same as decay. Decay is caused by bacterial action while erosion is caused by direct acid attack. Of course, soda swishing with regular sugared soda causes rampant decay as well as serious tooth erosion.

4. Brushing your teeth DOES help prevent tooth decay! In order for the sugar to have the negative effect it does on the teeth, the bacteria (germs) that live in plaque must metabolize (digest) it to produce a dilute ACID which is the agent that does the real damage to the teeth. These germs live in your mouth and double their number about every 20 minutes. By brushing your teeth, you are reducing their number, and hence the amount of acid produced. This in turn reduces the rate of decay. Unfortunately, even if your oral hygiene is very good, millions of germs remain behind, and continue to reproduce throughout the day leaving plenty of them around to turn the multiple swigs of sugar into acid. In the presence of reasonable oral hygiene, multiple exposures of the teeth to sugar still produces decay, but much more slowly than if the teeth are not kept clean.

5. Tooth decay is a major contributor to chronic bad breath!

It is essential to control your tooth decay in order to get your bad breath under control. However, tooth decay is not the only contributor to halitosis. Click here to learn about all the forms of bad breath, and how you can treat them

The sugar habits and sugar myths

If you seem to get a lot of cavities, then you almost certainly have a sugar habit. By that I mean that you tend to expose your teeth to something sweet numerous times throughout the day. The key here is the frequency of exposure, not the actual amount of sugar in the foods eaten or drunk.

Say you buy one can of (sugared) soda (or even natural fruit juice) and then sip it throughout the day, taking a sip, putting it down, then picking it up for another sip twenty minutes later.
Each sip allows the sugar to coat your teeth.
The bacteria in your mouth metabolize the sugar turning it into acid.
This acid remains active for about twenty minutes at which time you take another sip starting the whole sugar/acid cycle over again.
One bottle, or can may last a whole day, but that bottle contains enough sugar to cause huge damage to your teeth.
Note that even if you drank an entire case of Coke in the space of 20 minutes, that case of soda would constitute only one discrete exposure and would do minimal damage to your teeth. (Potato chips and other non sweet carbohydrates are NOT major causes of tooth decay. This mythology springs from anecdotes like the one presented later in this page.)

In order to fully taste the soda, the sugar must contact the teeth. Sipping through a straw does not prevent contact of the sugar with the teeth, because if it did, it would also prevent your tasting the soda which would take the fun out of drinking it in the first place.

Drinking Diet Coke, Diet Mountain Dew, Diet Pepsi, Diet Kool-Aid or any other artificially sweetened drink does not cause any decay at all, because artificial sweeteners are not metabolized into acid by the germs in your mouth. For information about the toxicity of artificial sweeteners like Nutrasweet®, saccharine and Splenda®, click here.

Finally, it is not just soda that is involved in the sugar habit/tooth decay syndrome. Below is a short list of some of the surprising habits that I have run into over the years, and every one of them was the reason that the patient needed a lot of dental work.

1. Unsweetened fruit juices used in the same way as Coke described above does the same thing to your teeth. Fruit juices contain natural sugar which is just as fermentable as table sugar. Many of our patients work in a local juice bottling factory. They can drink all the juice they want as a perk of the job. Many of them begin to develop major tooth decay only after beginning work there because of the simple availability of all that sugar.

2. One woman prided herself on never using sugar, but she needed three very carious teeth extracted, three root canals and numerous fillings. I kept asking her what type of foods she ate. "Fresh fruit, vegetables, and other wholesome things. Oh yes, and herbal tea. " I sweeten it with a tablespoon of HONEY". How often did she drink her tea? "All day long" she told me. Honey is just concentrated sugar made by bees.

3. Another vegetarian patient came to me with rampant decay. After much indignant denial about eating or drinking sugared foods, I discovered that she ate RAISINS throughout the day. Fresh fruit does not stick to the teeth and rarely is involved in the sugar habit syndrome, but raisins and other dried fruit are very much like gumdrops as far as the teeth are concerned. The sticky raisin paste remains on the teeth long after the raisin is eaten, and releases sugar into the saliva for quite a long time.

4. Another older man who I had been treating for years came into the office one day with cavities starting in almost all of his teeth. He had never had a single cavity for years, but now he had lots of them. It turns out that he had recently retired and had been spending a lot of time at the VFW with a bunch of guys who all drank copious amounts of Mountain Dew. They had all long ago lost their teeth and were wearing dentures. But my patient had acquired the habit by associating with his new friends, and almost acquired their dentures as well.

5. A pair of identical twins was brought into Tufts dental clinic while I was there. One twin had perfect teeth without a single cavity. The other had rampant decay all over his mouth. Being from the same family, they both ate the same things at each meal (mom was adamant that she gave them almost no sweets) and being identical twins, they were genetically identical, so neither one should have been any more susceptible to cavities than the other. No one could pry out of the twins any differences in their eating habits. Finally, one of my older professors cornered the two of them and after much prodding finally discovered that the cavity prone one liked to suck on bread balls. "Bread balls?? What are bread balls?" "Well you take the soft middle out of a slice of bread, ball it up real tight and suck on it!" Bread is not sweet. How could that cause cavities? Actually, bread is made of starch which normally does not cause decay, but when kept in the mouth for a long time, an enzyme in the saliva called amylase begins to break down the starches into their constituent parts, and those parts are simply sugar. Try it sometime. If you keep a piece of bread in your mouth for a while it begins to taste sweet. This is not to imply that bread, potato chips or other starchy foods are major causes of tooth decay. The sugar is released if the starch is kept in the mouth for a long time without being swallowed.

6. One elderly woman had a dry mouth, so she began sucking on cough drops all day long and discovered that within a year of beginning the habit, her teeth, which had always been a prized possession began turning black and breaking out.

7. One patient liked to reward herself at the end of a long day with a little Claret, a sweet brandy. She would pour her little shot glass and sip on it all evening until bedtime. After two years, her formerly good teeth were in need of total reconstruction.

8. Nursing bottle syndrome (most recently called early childhood caries) is characterized by children, generally under the age of 3 who are put to bed with a baby bottle filled, usually with fruit juice (all natural juices contain lots of fermentable sugars) or sweetened milk. The pattern is severe decay of the front top teeth. If the bottle contained only water, or an artificially sweetened drink such as Crystal Lite or artificially sweetened Kool-Aid, the teeth would not be affected. No mom does this on purpose to her child, but it is quite common because mom simply doesn't know that the sugar in the bottle would do this. Click on the image to the right to see more images of nursing bottle syndrome.

9. Chewing tobacco is cured in sugar! People who chew a lot of tobacco generally have rampant decay! In areas where chewing tobacco is popular, there is not only a great deal of decay, but also a lot of badly stained teeth. Chewing tobacco is quite acidic and tends to etch the surface of the teeth in the same way that the dentist does when he puts dilute acid on a tooth to etch the surface in preparation for bonding a filling. The etching process causes a microscopically rough surface on the enamel ideal for allowing stains to hide out from toothbrushes. Since the tobacco juice is also dark brown, the stain not only coats the surface of the enamel on the teeth, but it also penetrates into the nooks and crannies etched into the surface by the acid. This means that the staining becomes permanent.

10. Honey does cause tooth decay! Honey is considered a refined sugar because 96% of the dry matter in honey is composed of fructose, glucose and sucrose. Honey also has the highest calorie content of all sugars with 65 calories/tablespoon, compared to the 48 calories tablespoon found in table sugar. Honey actually decays teeth faster than table sugar, partly because it is very sweet, and partly because it is sticky and remains on the teeth longer than other refined sugars.

Recently, however, scientific evidence has come to light showing that some types of raw honey contain enzymes which kill bacteria. Indeed, some studies have shown that certain types of honey, when applied directly to wounds, can reduce the risk that the wound will become infected. In other words, honey can have antiseptic properties which could affect its cariogenicity (decay producing properties). In fact, I have received one letter from a fellow who spent a number of summers processing honeycomb. He tells me that he has chewed pieces of honeycomb throughout the day for years without getting cavities. This is probably true, but only for certain types of honey.

Honey contains an enzyme that produces hydrogen peroxide, and which is believed to be the main reason for its antimicrobial activity. Unfortunately, the antimicrobial activity of various types of honey may differ as much as a hundred fold depending on the specific substrate (flowers) from which the bees make their honey. Manuka honey seems to be especially high in the appropriate enzyme. The Manuka shrub is native to New Zeeland, so if you live "Down Under" you are more likely to find this type of honey available in stores. The type of commercial honey you buy in North American and European supermarkets is made up from mixed batches collected from multiple sources and the concentration of the appropriate enzyme is likely to be fairly dilute. My correspondent who had been chewing honeycomb over the course of years without ill effects for his teeth happened to live in New Zeeland and had been processing Manuka honey.

One anecdote may help to dispel the myth that honey will not harm the teeth. The term "honey bear" refers to two species of bear which prefer to raid beehives for honeycomb. Bears who habitually feast on honey are the only wild animals which have the dubious distinction of suffering from tooth decay when NOT in captivity.

Sugar (in moderation) is NOT evil!

Make no mistake. Excessive exposure of the teeth to sugar WILL cause tooth decay. On the other hand, sugar at normal mealtimes does almost no damage to the teeth whatsoever because the exposure to the sugar is not prolonged and the other foods you are eating at the same time tend to wash the sugar off the teeth. Fresh fruit is rarely a problem even though it contains natural sugars because of the detersive (washing) effect of the fruit fibers.

Numerous controlled studies have shown that dietary sugar (in moderate amounts) is not associated with an increase in the incidence of heart disease, cancer, autoimmune diseases or other chronic medical problems. Even type 2 diabetes is not caused by sugar. The people who get it have a genetic predisposition to it (it is caused by genes and runs in the family). Eating sweets or the wrong kinds of food does not cause diabetes, link 2,

Type 2 diabetes is triggered in genetically susceptible individuals by obesity, lack of exercise and increasing age. Persons with the genetic predisposition and who fit the age, obesity and exercise profile may develop a resistance to insulin. The receptors on cells in the body that normally respond to the action of insulin fail to be stimulated by it due to a genetic variation in the somatic receptors. This is known as insulin resistance. In response to this, more insulin may be produced, and this over-production exhausts the insulin-manufacturing cells in the pancreas.
Type 2 diabetics can often avoid the symptoms by reducing or deleting sugar from their diet and increasing exercise. The confusion in the public's mind between the cause of the disease (genetics, obesity and age), and the effect that sugar has on persons who have the disease is the origin of the myth that sugar is the cause of type 2 diabetes.

The US Food and Drug Administration has this to say about sugar:

Over the last several decades, sugar has taken on the villain's role in the American diet. General sugar-bashing has led to "sugarphobia", and the unfounded fear that eating refined sugar causes many health problems, including heart disease, diabetes, anxiety, fatigue, depression, hyperactivity, and even criminal behavior.

But, in fact, added sugar at current levels is not detrimental to health. According to the landmark 1986 FDA Report of Sugars Task Force, sugar, when consumed in normal or moderate quantities, cannot be linked to any disease, nor does it create a dependency. (Click here for the link.)

America's obesity epidemic

Having stated the case for sugar in moderation, I will now qualify this assertion by stating the obvious. The amount of sugar, in the form of high fructose corn syrup has skyrocketed since 1980 when the US government started its war on fat. Virtually all low fat products are fortified with high fructose sugars simply because otherwise nobody would buy them due to their rather unsatisfying taste. In addition, the consumption of various sodas (Coke and Pepsi especially), sports drinks, iced teas, flavored waters and juices of all sorts has increased almost exponentially over the last thirty years. Virtually everyone knows someone who is addicted to soda or Gatorade, or is addicted themselves. All of these products are sweetened with high fructose sugars.

Sucrose, (table sugar), is a disaccharide, a single molecule made up of one glucose molecule joined to one fructose molecule. The body metabolizes it by breaking up the sucrose molecule into its constituent parts and metabolizing each one directly. The glucose can be metabolized directly by all the cells in the body as a source of energy without further processing. Fructose must first be processed in the liver before it becomes useful to the body. Some of its metabolites can lead to gout, high blood pressure, liver disease and cardiovascular disease in addition to obesity. High fructose corn syrup is much less expensive than other types of caloric sweeteners, and is also 73% sweeter than sucrose, which is why manufacturers use it.

There's an old saying; "In for a penny, in for a pound!" This applied with a vengeance as the government began its anti-fat public service campaign and then applied pressure on food manufacturers to offer low fat alternatives. Once the manufacturers began to fortify their products with high fructose sugars (this includes breads and other products you don't usually associate with sugar), Americans became accustomed to the taste and this eventually forced all the manufacturers to increase the sugar content of their products, even those that were not "low-fat". Needless to say, this has not been good for public health overall. (You can tell that I am NOT a fan of government social engineering projects. Not only did the government prove to be wrong about low fat diets, but its meddling helped to bring about the current obesity epidemic.)

Don't be fooled by junk science!

Modern popular culture is permeated with myths accusing ordinary foods of causing various diseases. These myths are based on the distortion and misuse of scientific studies that are themselves often flawed and later disproved. These studies are publicized by groups with economic, political, or even religious agendas. Science moves forward, but interest groups with agendas do not.

For people who would like to relieve themselves of the enormous guilt they are supposed to feel because they enjoy particular foods, are overweight, or otherwise do not "live up to" the physical and behavioral standards imposed by television personalities and health food gurus, I would strongly recommend that they become regular readers of the JunkFoodScience blog. It is written by Sandy Szwarc, BSN, RN, CCP . She is a registered nurse, journalist and a serious researcher who advises science and policy institutes on health issues.

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