dental Cavity-DentalCaries

Bacteria found in the mouth and the presence of sugars cause tooth decay. The bacteria "eat" the sugars in the mouth, releasing acidic byproducts that de-mineralize, or soften the teeth. Over time, demineralization can cause a hole, or cavity in the teeth. That is why it is very important to brush your teeth at least twice each day. By removing the bacteria and sugars from your teeth, you can arrest the de-mineralization and, possibly prevent the formation of cavities.

Oftentimes, cavities are treated with fillings. Fillings are placed in the mouth by removing the decayed tooth structure, then filling the space with some durable material such as amalgam (silver fillings) or composite (tooth colored fillings). Very large cavities, or cavities that cause extreme pain and sensitivity can sometimes require root canal treatment. This is necessary when bacteria from the cavity reach the pulp (center) of the tooth where the blood vessels and nerves are found.

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 sugar 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.

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.

4. Brushing your teeth DOES help prevent dental caries. 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. This does not mean that sugar is evil and that you must make a choice between eating sweet foods and keeping your teeth. Sugar at normal mealtimes does almost no damage 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.

Before proceeding further, it is important that you understand that sugar is one of the four major factors that effect the health of the teeth. The sugar habits
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 tends to be the frequency of exposure. Thus, if 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 and doing a bit of work, 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 some of it leaving a coating of acid on the teeth. This acid remains active for about twenty minutes at which time you take another sip starting the whole thing again. One can, or bottle may last a whole day, but that can contains enough sugar to cause huge damage to your teeth. Note that if you drank an entire case of Coke in the space of 20 minutes, that case of soda would constitute only one discreet 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 that 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.  information about the toxicity of artificial sweeteners like Nutrasweet®, saccharine and Splenda®, click here.

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.  Since the acid caused by carbonation does NOT spend enough time in the mouth to damage the teeth, the experiment would say nothing at all about the effects of soda on the teeth.  However, it says a great deal about the wisdom of storing nails in full bottles of soda.

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 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.

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 is characterized by children, generally under the age of 3 who are put to bed with a baby bottle filled, usually with fruit juice 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. 

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.

The first step in restoring a tooth is to determine the extent of decay. We do this with an x-ray. To the left, you see a large area of decay in the bottom tooth, second from the right. The bright areas in the teeth are all old amalgam fillings. The decay is seen as the dark area to the left of the amalgam in that tooth. The dark area in the center of the teeth are where the nerves are located. You can see that the decay has gotten very close to the nerve. (Learn about X-rays; click here.)

This picture shows what the tooth looks like before it is restored. The hole to the back of the tooth, just behind the amalgam is apparent to the naked eye. The X-ray above shows the actual extent of the decay.

After the patient has been made numb, the tooth is prepared with a high speed handpiece removing all the old fillings, and all the decayed areas in the tooth.

After the tooth is completely clean, all the holes are filled with light cured composite, and the tooth is carved to resemble the form it had before the decay occurred. This tooth looks wonderful now, but it is important to remember that the original decay was very close to the nerve, and it is not possible to guarantee that the nerve will not become inflamed and start to swell causing a toothache later.

The image on the left is a simplified diagram of a cross section of a tooth.  The white covering on the tooth is called enamel.  It really is white in color, but somewhat translucent and allows the color of the underlying structures to shine through.   It is also very hard and quite resistant to acid attack.  The brownish yellow material underlying the enamel is called dentin, and it too is hard, but it is much less hard than enamel.  The dentin has a density like that of hard bone.  It is much less resistant to acid attack.  Underlying the dentin is the nerve of the tooth.  The nerve is actually a complex organ.  In a healthy state, it is pink and soft, like the lining of your mouth, and is composed of blood vessels, connective tissue and, of course, nerve fibers.  The dentin is permeated with thousands of tiny tubules which run perpendicularly from the nerve to the enamel/dentin interface, and also to the outer surface of the root in areas which are not covered by enamel.  These tubules are filled with fluid.  The fluid is actually contained within tiny projections from cells that line the inside of the nerve space.  These cells are part of the nerve complex and are called odontoblasts.    Touching the living dentin produces movement of the fluid in the tubules which transmits impulses back to the nerve making the dentin sensitive to any type of direct stimulus.  Because of the presence of these tubules, the dentin is actually quite permeable to fluids.

The image on the right is a picture of an actual tooth which has been attacked by decay.  It has been stained to better show the structures within the tooth.  Originally, the tooth was adjacent to two other teeth which made contact with this one at the positions shown by the yellow arrows. Since teeth can move slightly when pressure is applied to them, such as when a person chews or clenches his teeth, the teeth can rub together at the contact points.  The combination of acid attack from sugar soaked plaque, plus the friction of the constant rubbing of the teeth at the contact points produces tiny holes in the enamel.  The contact on the left side of the tooth shows how acid plus friction can produce a hole in the enamel.  This one has not yet penetrated through to the dentin.  The contact on the right shows what happens when the enamel has been breached allowing the decay to penetrate into the dentin.  Note that while the hole in the enamel is relatively small, the decay has rapidly progressed within the dentin to a much larger extent due to the relative softness and permeability of the dentin as compared with the enamel.   The decay has a tendency to spread along the dentinal tubules from the enamel surface toward the nerve from which the tubules arise.

Unfortunately, some prescription and over-the-counter drugs can cause dry mouth.  Drugs which are most likely to produce dry mouth are the older style antihistamines, and antidepressants, as well as diet drugs, blood pressure medications, decongestants and cancer treatment drugs.  Patients with chronically dry mouths tend to experience a shift in the normal balance of bacterial flora present in the mouth.  The type of germs that come to predominate in patients with dry mouth are also the ones which produce the most acid when the patient eats sugar, so even normal amounts of sugar at mealtimes may cause serious decay.  

Unfortunately, chronic users of most illegal recreational drugs also suffer from lifestyle issues that are associated with their drugs of choice, as well as dry mouth and side effects from some of the drugs themselves which make the user crave sugar. 

• This combination of factors combines to produce rampant decay and a condition known as Acute Necrotizing Ulcerative Gingivitis (ANUG) which is really an acute form of  form of gum disease.  There is speculation about the possibility that the drug itself directly produces some of the tooth destruction since it is somewhat caustic by itself.  However, the drug is in direct contact with the teeth for only a very short time and is quite water soluble.  Considering the large amounts of fluids a meth addict must drink to satisfy his thirst, I believe that it would be washed off rather quickly and the drug's direct corrosive effects are probably fleeting and weak compared with the well documented destruction produced by the combination of dry mouth and copious amounts of liquid sugar.   Bruxing also contributes to the severity and distribution of the decay.  With the increasing popularity of methamphetamines, this syndrome has become increasingly prevalent and has become a major health concern, especially in prison populations.

Tetracycline---It used to be common for physicians to prescribe Tetracycline to young children under the age of six for earaches.  This drug, unfortunately, incorporates itself into actively growing dermal structures, and teeth are dermal structures.  Tetracycline incorporated into developing teeth tends to leave an overall gray cast in the enamel, and this is frequently accented with darker horizontal lines which are a permanent source of embarrassment to the patient when he or she grows up. This drug is rarely used on children today for this reason.  This condition is known as tetracycline stain.  Unfortunately, tetracycline stain does not respond to dental bleaching very well.  

Dilantin  (phenytoin)--A drug used to treat seizures in epileptics--can cause swelling of the gums (gingival hyperplasia), especially in persons who do not brush their teeth regularly.  The image to the right shows what the combination of poor oral hygiene and Dilantin can do to a patient's gums.  Better oral hygiene would have reduced the enlargement of the gingiva.  A limited number of other types of drugs can also cause this problem, although to a lesser extent.  They include blood pressure medications in the calcium channel blocker category (Cardizem), birth control and hormone replacement drugs (Progestogen) and immunosupressive agents such as cyclosporine.  In general, this type of gingival enlargement can be prevented by good hygiene, but once it occurs, the only way to eliminate it is through surgical removal of the excess tissue, a procedure called gingivectomy.

Does sugarless gum or candy prevent decay?
Until recently, the idea that sugarless gum would actually prevent tooth decay was based on the fact that sugar substitutes do not promote decay, and the gum base itself has a detersive effect which means that the mechanical action of chewing gum tends to remove some plaque from teeth.  All gums have detersive qualities.  This quality is fairly marginal, and does not substitute for brushing and flossing.  Regular sugared gum will promote decay since the presence of the sugar induces acid which remains on the teeth for the full time that the gum tastes sweet, plus an extra 20 minutes.  Sugarless gum sweetened with sorbitol, manitol or  other non sugar sweeteners will not promote decay.

The US army is quite impressed with the cavity fighting qualities of xylitol and has recommended the following regimen to help keep their soldiers' teeth in good shape:

Dry mouth syndrome

A number of conditions and drugs tend to cause chronic dry mouth.  They include the normal ageing process, Sjorgren's syndrome, and numerous prescription and non prescription drugs such as antihistamines and decongestants.  Numerous psychiatric drugs including lithium and thorazine as well as drugs used to produce drowsiness and assist in falling asleep also can cause chronic dry mouth.  Many illegal recreational drugs such as those mentioned above  cause dry mouth

Plaque is composed of a range of species of bacteria, and the relative number of each species of plaque organisms is highly dependent on the exact chemical and physical composition of the saliva in the mouth.  Dry mouth causes a drastic change in the composition of the plaque reducing the populations of some species and increasing the populations of others.  Unfortunately, this shift in floral composition tends to cause an overgrowth of organisms which produce acidic waste products, especially when sugar is abundant.  Of course, the acid in plaque is the actual agent that produces tooth decay.  This generally means that people with chronically dry mouths tend to get rampant decay in their teeth.

Compounding this problem is the natural tendency of persons who suffer from dry mouth to sip sweet drinks and suck on hard candy all day long as a way of promoting moisture in the mouth.  The combination of dry mouth plus copious amounts of sugar throughout the day causes serious decay in these people, especially the elderly.  This combination of dry mouth and excessive sugar usage causing rampant decay is called "dry mouth syndrome"

The greatest advance in dentistry concerning dry mouth syndrome has been the discovery that hard candies and chewing gum containing xylitol can actually inhibit tooth decay.   Since the presence of sweet and sour things in the mouth can help promote the production of saliva, sucking on hard candies artificially sweetened with xylitol can be a real lifesaver for these people.  

There are several pharmacological ways of dealing with dry mouth.  They are as follows:

1. Biotene dry mouth toothpaste and gum: pleasant taste and widely accepted.
2. Neutral Sodium Fluoride gel (Thera-Flur-N or Prevident gel): Following brushing and flossing place 6 to 8 drops in the applicator and wear for six minutes.  Spit out. do not swallow gel.  Do not eat or drink or rinse mouth for 30 minutes.
3. Neutral Sodium Fluoride toothpaste (Prevident 5000): After brushing and flossing, place a small amount on toothbrush and brush teeth.  Spit out, but do not rinse.  Avoid eating or drinking for 30 minutes.
4. Oral balance gel:  Best for nighttime use, but can be applied anytime.
5. Pilocarpine (Salagen) 5 mgm tablets: a prescription drug taken three times a day.  Useful in most cases of dry mouth, but in severe cases of Sjorgren's syndrome, in which the salivary glands may have atrophied it may not produce saliva.  No drug can force the production of saliva if the glands are no longer functional.  This drug may cause diarrhea in some patients.
6. Saliva Stimulant Tablets (Salix 30): Not a shelf item in drug stores; order according to NDC Code # 20186-2130-00 
7. Saliva Substitutes: These are simply squirted into the mouth when desired.  The effects are short term but they can be helpful. Saliva substitutes are generally available over the counter at pharmacies. They include the following brand names, but other brands are available:
   1. Phys total care
   2. Rosane
   3. Salivart
8. Xylitol mints, candies and gum (Google search):  This most recent of discoveries may well revolutionize the care and treatment of people who have dry mouth syndrome, but still have functioning saliva glands.  They stimulate the production of saliva and inhibit decay. You can purchase these online at various sites.

The major artificial sweeteners used today are aspartame  (Equal® and Nutrasweet®), saccharine(Sweet 'n Low® is the largest selling brand), and sucralose (Splenda®).  All three of these have been lambasted by various health groups who claim that they are toxic and cause untold misery in anyone foolhardy enough to use them.   Let me set the record straight.  Saccharine was invented in 1879 and has been in constant use in the United States since the early 1960s.  During that time  no evidence that it has caused an increase in any human disease, including cancer has come to light .  Likewise aspartame (Nutrasweet®) was invented in 1965.  It also has been in use for more than 30 years and there has been no evidence of toxicity.  Both of these sweeteners have been in massive use throughout the world since their introduction into the mass market.  They are both sanctioned by the US food and drug administration.  Imagine the huge quantities of diet soda and other prepared foods containing these compounds that have been consumed by literally billions of people during that time.  Now ask yourself how dangerous they could be if they have been used for that long with no indication of a public health hazard.  

Sucralose (Splenda®) was discovered in 1976 by researchers working under the auspices of Tate & Lyle Ltd., a large British sugar refiner.  In 1980, Tate & Lyle arranged with Johnson & Johnson, the world's largest health care company, to develop sucralose. Johnson & Johnson formed McNeil Specialty Products Company in 1980 to commercialize sucralose. Sucralose has been in use commercially in Canada since 1991and was approved for consumption in the United States in 1998.  It has been in use In the US since that time, and has been approved for use in 50 other countries.  It is derived from sugar and has the advantage of sweetening with few calories and, generally no effect on the teeth.  It has the added advantage of being useful in cooking, unlike aspartame which tends to break down in heat.  A small percentage of people note a bitter aftertaste while eating foods prepared with sucralose.  Most find that it tastes just like sugar.

As for the scare mongers who are constantly trying to persuade the population that any new innovation is bad for your health, please read this article by Steve Milloy.  He is a public health expert, a fellow at the Cato institute and author of the excellent site "junkscience.com". The article is the sad story of cyclamates, a wonderful artificial sweetener that WAS banned in the late 60's because of these people.  The science used to ban this product was based on feeding huge quantities of the sweetener to rats over long periods of their lives (analogous to a human drinking 350 cans of diet coke every day for twenty years), and then creating panic in the public sector with scare tactics.