How does tooth decay damage teeth?

In its simplest form, bacteria that are present on the tooth surface breaks down the Carbohydrates that you eat or drink, into an acid. This acid slowly dissolves away tooth structure. The decay process occurs quicker on the inside layer (dentin) of the tooth. That is why dental sealants work well. They seal the tiny little openings in the enamel or top layer of the tooth. Good oral hygiene and regular professional cleanings break up and remove the sticky bacterial layer that forms on the tooth surface (plaque). This helps to prevent the decay process from destroying healthy tooth structure.

Abraham Speiser
Tooth decay damages teeth due to the action of bacterial plaque on the tooth's hard structure creating a hole we call a "CAVity." (Think of a hole in a mountain as a CAVe and a tiny hole in a tooth as a CAVity.) Bacteria combine with carbohydrates in the plaque to form acids and enzymes which do the damage. 

The hard structure of teeth is made up of high concentration calcium salt (hydroxyapatite) in a protein shape scaffold called the protein matrix. In all 3 types of tooth decay.....
  • tooth decay in the pits and fissures on the biting surfaces of the teeth,
  • tooth decay on the smooth surfaces:
  1. next to the cheek/lip
  2. next to the tongue or 
  3. between the teeth and
  • tooth decay on the root surfaces..... 
… EARLY DESTRUCTION occurs when the bacteria in the plaque remove most of the calcium from the tooth’s hard structure. This results in loss of the tooth's surface luster leaving a weaker chalky surface which dentists call a white spot. A white spot is made up of low concentration calcium salt (hydroxyapatite) and protein matrix.

LATER DESTRUCTION occurs when the bacteria in the plaque continue to destroy the tooth by removing the remaining calcium salt from the white spot and breaking down the protein matrix. Nothing is left except a void. This void is a hole in the tooth called a cavity. When the cavity reaches deep in the tooth, the bacteria infect the dental pulp which contains a nerve and blood vessels. The result is pain (a toothache) and infection (an abscess.)
The dental science of "cariology" (study of tooth decay) has greatly expanded in knowledge, in recent years. Initially, earlier scientists established that the acidic bacterial metabolic waste products (when the bacteria go to the bathroom) actually dissolve mineralized tooth structure. We now know the process is even more complex.

Numbers of proteolytic enzymes (chemicals which breakdown proteins) are also contained in these bacterial waste products (i.e. trypsin, chimotripsin, hyaluronidases, various collagenases, etc.). These chemicals are highly effective in further breaking down & destroying the dentin, the tooth structure under the protective enamel.

Thus, it's essential we maintain this outer protective shell of tooth structure, enamel. Once enamel is physically violated, by tooth decay, fractures, etc., one's inner tooth structure (dentin) becomes vulnerable.
Tooth decay is the destruction of enamel. It occurs when foods containing carbohydrates (sugars and starches) such as milk, pop, raisins, cakes or candy are frequently left on the teeth. That's because bacteria that live in the mouth thrive on these foods, producing acids as a result. Over a period of time, these acids destroy tooth enamel, resulting in tooth decay.

You can prevent tooth decay by regularly visiting the dentist, brushing twice a day with a fluoride toothpaste and cleaning between your teeth with dental floss daily.

My answer won't really be any different than the others above, but it's hard for any dentist to turn away from this particular question. Decay (caused by bacteria) will weaken a tooth, causing pits and holes to form (which we call "cavities"). Left untreated, this will eventually cause a tooth to break, and/or lead to infection.

David Jin, DDS
Decay, by definition is "to decline from sound or prosperous condition; to decline in health, strength, or vigor; to undergo decomposition." 

For a tooth, decay = rotting of that tooth's structure.
Decay destroys the enamel matrix of the tooth, which acts like a protective layer over the more sensitive inner parts of the tooth, -- the dentin and pulp. Once decay penetrates enamel it creeps into the dentin and if left unchecked will go all the way to the pulp. People may not even feel small areas of decay. Dentists use instruments and radiographs (x-rays) to detect early decay that might not be visible to the eye. If treated early, damage to the tooth is minimal and may require just a simple filling. If decay continues to the dentin layer, patients will sometimes report pain when eating sweets and cold sensitivity, but some may not notice anything unusual. If the decay reaches the pulp where the nerve and blood supply to the tooth are, it causes the nerve to become inflamed and/or die which can result in severe throbbing pain and extreme sensitivity to heat and biting pressure. This also may create an infection that causes facial swelling. These advanced areas of decay require root canals and crowns to restore the tooth or extraction of the tooth entirely. When we catch decay early, damage to the tooth is minimal and less expensive to treat.

Tooth decay damages teeth by creating cavities, i.e. holes, in teeth. This weakens the integrity of the tooth, which may lead to a fracture if not repaired properly. Decay can also cause pain as it approaches the center, or pulp, of the tooth. This is where the "nerve" is located.

Tooth decay (commonly called a cavity) is damaging because it creates holes that weaken the tooth structure. When the damage is small, your dentist can easily fix it. Sometimes decay can be so destructive that it penetrates all the way into the center of the tooth, attacking the nerve. This is a much more serious and complicated problem. The best way to catch decay early (when it's small) is to visit your dentist for regular check-ups.

Tooth decay affects teeth and your overall health in several ways. We are all familiar with the term "cavity" which brings up an image of a hole in the tooth. What is actually happening inside a cavity is a knot of bacteria has set up shop so to speak and they are dissolving away the tooth structure with their waste products from the food you feed them. But cavities are but one of the problems caused by tooth decay. The waste products (toxins) they create also strip away the cells protecting your gum tissue. This "skin" covering your gums protects you from infection by these same and other bacteria. If left untreated the tooth decay can give rise to bone and tooth loss and the spread of bacteria throughout your body affecting your heart and other vital organs and if you are pregnant, your unborn child. In addition to the many health-related problems tooth decay can cause, the social and personal hygiene issues are extremely important in today's society. To have rotted, missing and stained teeth can devastate your chances for a job, a date or a sales presentation!

A simple cavity disrupts the self-cleansing contours of the teeth that are naturally present. A "filling" returns the tooth to proper function, contour and even beauty in many cases. Dental treatment however is expensive compared with preventive, maintenance care. So cavities can affect you pocketbook too. In summary, tooth decay damages far more than your teeth and the disease pathway decay follows is far more complicated than a simplistic cartoon of germs eating away at the tooth. Tooth decay is easily prevented and difficult to treat, so partner up with a dentist you trust and keep your teeth and your health all your life!
Tooth decay enters through the enamel layer first.  Once the bacteria enter through the enamel the next layer in the tooth is the dentin, once that dentin layer is weakened, the whole integrity of the tooth is weakened. The more extensive destruction to the dentin layer the more the tooth is weakened.
Tooth decay is not, technically, the process whereby the teeth are damaged but decay is the result of the damage caused by the effects of acids on the teeth. Teeth are formed from two different sorts of building blocks. First there is a part called the organic portion. This part is mainly formed from protein and has a consistency similar to leather- sort of tough and flexible. To this organic framework is added the hard mineral portion. This mineral portion consists mainly of calcium and phosphorous and is what makes enamel the hardest material found in the human body. While the enamel and other portions of the tooth are very hard and resistant to wear and breakage they are still vulnerable to being dissolved by acids. Bacteria found in the plaque on teeth eat sugars from our diet and produce many waste products from it. One of the main waste products is acid which, along with other acids in our diet, slowly dissolves the minerals from the enamel. As the mineral is lost the organic portion is exposed. This part, being softer and more porous will crumble or wear producing the cracks and holes that we call cavities. It is also darker in color and stains as well giving the cavity its characteristic brown or black color (although other colors are possible).

Unfortunately we currently have no way of re-mineralizing any but the most minimal damaged enamel and dentine. Therefore, in order to treat these cavities, we must clean out this damaged, infected tooth structure and replace it with a 'filling'. We are striving to catch these cavities earlier and earlier in order to have more success at re-mineralization procedures. This is one more reason to visit your dentist regularly.

Tooth decay causes a hole in a tooth. The hole can weaken the tooth, and it can break and abscess. If treated early, the tooth can be fixed with a filling. If treated later, the tooth may need a root canal (filling of the root) or a crown. If left untreated, the tooth decay can lead to loss of the tooth.

Tooth decay is a bacterial infection of the tooth that softens the enamel of the tooth until it begins to chip away. This ultimately leads to a hole in the tooth. As the decay deepens, the nerve of the tooth is damaged leading to excruciating pain and further infection that spreads to other parts of the body.
Tooth decay or caries is usually caused by a bacterial infection most commonly consisting of Streptococcus mutans and Lactobacillus. The bacteria accumulate on the teeth and process food debris while excreting acids which break down the surface of the teeth. This break down will eventually lead to an opening into the inner part of the tooth (a cavity) that must be repaired with a filling or other restoration to restore the tooth to normal function. The routine removal of all of the food debris, or plaque, with good brushing and flossing techniques is the best way to prevent this damage.
Think of putting an axe to the base of a strong tree- the deeper the axe penetrates, the weaker the tree. Tooth decay acts in the same manner, so the greater the amount of decay, the greater the chance that the tooth will fracture. In addition, the closer the decay gets to the nerve in the center of the tooth, the greater the chance of a toothache.
Decay starts when the outer layer of enamel is penetrated creating a hole, or cavity, in the tooth. This initial step occurs when bacteria in plaque create enough acidity to demineralize enamel, softening it, and eventually destroying a section of it.

Now the decay has passed the hard outer enamel and can reach the softer dentin. Once into dentin, decay will progress much faster as it spreads and destroys more tooth structure. If untreated the decay will eventually infect the nerve of the tooth. In most cases, cavities will cause no pain until this final stage of invading the nerve, or pulp, of the tooth. This is when pain and swelling, ie an abscess, can occur.
Teeth will actually melt away. Tooth decay can come in a wide variety of colors from white, brown, orange and black. Acids are created either directly from certain beverages, foods and snacks or indirectly as a waste byproduct from the bacteria in your mouth that consumes carbohydrates. The acids developed destroy teeth by breaking down the enamel rods which are the hardest material in your body. Once it breaks through the enamel, it can stay there if we can arrest it by starving the acid monsters or it can progress to the softer inner parts of the tooth - the dentin. Once it is there, it can rapidly progress to the blood and nerve supply.

Tooth decay in its early form may not necessarily hurt or become sensitive which leads to the wonderful idea of having your dentist check for early signs. It is never as easy to fix something when it is in the early stages of disease which can greatly reduce the cost of allowing it to progress to a larger and more costly process.
Tooth decay is the damaging result of harmful bacteria that has been on a tooth surface long enough to cause trouble. Plaque, that sticky substance that accumulates on teeth, contains bacteria that can produce acids that attack enamel, the hard outer layer of the tooth. This starts the decay process. Once the enamel is weakened, the decay spreads into the dentin, or softer tooth structure inside the tooth. Tooth decay destroys tooth structure, makes teeth initially sensitive to cold and sweets, but as the decay progresses, it starts to affect the nerve which is at the inner most part of the tooth. The nerve becomes irritated, at which point a toothache can begin. If not treated by a dentist, and the decay is not removed, it can permanently damage the nerve and kill it. If caught early enough, teeth with decay can be treated and repaired with a filling or restoration. If not attended to, the decay can cause enough tooth destruction to require a crown or root canal, or ultimately even cause tooth loss.

The mouth is a chemistry lab that allows the flow of calcium in and out of your teeth. When bacteria (plaque) are attached to your tooth and are fed sugars, they produce acids that take calcium out of your tooth. Along with home care and the removal of the plaque, your saliva is a defense system to replace calcium from this acid attack and stop the decay process. If your home care is poor, the plaque is allowed to take more and more calcium  out of your tooth. Initially, the beginning of a cavity is rough in texture and turns a white color. In this form, the tooth can be repaired by calcium replacement and considered reversible. However, over time if this continues, a hole or cavity is formed and bacteria can hide from normal cleaning techniques. This damage of the tooth decay is now irreversible and must be repaired by a dentist with a filling.

Teeth decay as a result of bacteria digesting food particles that is left over on teeth to breakdown tooth structure. It usually starts as a small hole in the tooth. Although as bacteria get further inside the tooth they do more damage since the inner part of the tooth (dentin layer) is much softer than the outer enamel layer. So once the bacteria gets to the inside layer it starts to destroy the tooth from the inside out. At this point it may not look like a big hole from outside but if left without treating, it will literally go on till the whole tooth is gone.
Tooth decay is formed when acid demineralizes your teeth. Bacteria in our mouths break down food particles into acid and then acid then softens your enamel and dentin (the inside layer of your teeth). The teeth become so soft that the tooth structure beings to dissolve creating a very large cavity. 
Certain bacteria in the mouth feed on sugars you consume. Their harmful bi-products produced demineralize enamel, the hard, white outer covering of the tooth, leading to holes or pits in the tooth. Once the decay extends to the inner layer of the tooth, it spreads at a greater rate. The decay makes the tooth soft, causing the tooth to breakdown.  

Tooth Decay damages teeth by dissolving the hard outer part of the tooth (enamel). Tooth decay occurs when the tooth loses its density or strength which allows bacteria to have an easier way to get to your underlying structure (dentin/nerve), which leads to sensitivity. You always want to treat decay as soon as possible so little problems do not become big ones! Always remember, prevention is the key!

Rita Medwid

Tooth decay weakens a healthy tooth. A weaken tooth will start to pit and a cavity or hole will result. Like a worm in an apple, the decay will travel and spread. The tooth can begin to hurt to cold and sweets. Once the decay travels to the nerve, you will have pain with chewing, or feel an aching pulse inside your tooth. This can begin from something so simple as a diet coke or Gatorade. Anything that has citric or phosphoric acid will dissolve the enamel. Also, GERD, gastric reflux, and bulimia will eat away at the healthy tooth structure. Once bacteria sets into the weakened area, you can have further problems with gum disease. The bad gums will negatively affect your health. From strokes to diabetes, it is important to talk with your dentist. 

Tooth decay is caused by acid releasing bacteria that form due to the buildup of sugars in the mouth. It's the acid that erodes and eats away at the enamel. Once the protective layer of enamel is gone, tooth decay will continue to advance further into the tooth. If left untreated, tooth decay can lead to pain, infection, and possible tooth loss. That's why it is best to clean out and restore your teeth immediately when tooth decay is present.

Tooth decay causes damage to healthy tooth structure by making the tooth softer and weaker or unhealthy. If the unhealthy part is left untreated it only gets bigger and causes more of the tooth to become affected. It is best to treat tooth decay or cavities (cavitations) early to prevent the need for more invasive treatment. For example, if the decay reaches the Nerve inside the tooth then the Tooth will need Root Canal treatment.   

Tooth decay creates softer, less stable tooth structure. Unless treated, the decay keeps growing and will eventually reach the dental pulp at the center of the tooth. This is often when you will first feel symptoms such as pain. By the time the decay has reached this level, it is beyond a simple filling and you will need a root canal.

The softer decay can also allow teeth to break or fracture. This is especially true if heavy pressure is put on part of a tooth that is undermined by decay. The softer section does not support the rest of the tooth.

Tooth decay is caused by bacteria that eats away at tooth structure causing a hole or cavitation in the tooth. Cavities can appear as dark spots or broken areas of the tooth. Some decay can only be detected on radiographs or x-rays, so it is very important to let the dentist take periodic x-rays even if you don't feel like anything is wrong with your teeth. Tooth decay damages the teeth as the cavities grows larger. Teeth can darken, chip, break, become painful, and progress into the nerve of the tooth requiring a root canal to treat it. Small cavities can often be treated with a filling and larger cavities may require a stronger restoration like inlays, onlays, or crowns. Teeth may require removal if decay has damaged a majority of the tooth.

Biofilm is a sticky substance that forms on the tooth that if usually removed by proper tooth brushing techniques. Biofilm is a thin layer of bacteria which sticks to the tooth structure which takes twenty four hours form. If it is not removed from the tooth structure and gingival tissues, the bacteria consumes sugars in the form of sucrose. The bacteria then excrete acid. This acid will dissolve tooth structure slowly over a period of time.

At first there are no symptoms to the tooth because it just dissolves enamel which is the outer layer of the tooth. This area has no communication with the nerve or pulp chamber. It is not until the decay reaches the dentinal tubule under the enamel layer that you start getting sensitivity in the form of hot and cold sensitivity. Decay is a chronic disease that happens over a long period. When a tooth starts hurting it time for serious treatment.

Your best way to protect the tooth from major damage is to go to your dentist for regular checkups. He or she will examine you to find tooth decay or gum disease. If they find the disease when it is just beginning it is often a simple treatment.

What happens if tooth disease is allowed to progress, it can turn into a toothache. The ache can be dull or sharp where it hurts upon percussion (tapping on it). A dull ache is usually a sign of gum disease. A throbbing usually is a sign of irreversible nerve damage. In this case the nerve has to be removed from the tooth in root canal therapy or the tooth needs to be extracted.

The way the nerve is affected is by the acidic byproduct of the sucrose consumption by the bacteria. This infects the nerve or pulp of the tooth. The pulp of the tooth is nerve tissue like you have in spinal column supported with nutrients in the blood vessels. The bacteria and their byproducts infect this tissue and the tissues need to be removed. There are only two ways to remove them. One is through extraction and the other is through root canal therapy.

In conclusion, if you don't go to the dentist every six months, you are putting yourself at risk. Waiting until it hurts results in more complicated treatment and often can result in tooth loss. If you don't have insurance coverage for dental, don't let that keep you from the dentist. A cleaning and dental exam is your best insurance policy and often times less expensive than insurance premiums.
Tooth decay damages teeth by creating pits and holes -- generally known as cavities. You can end up with cavities if you eat too many sweets or you don't brush and floss your teeth properly.

Bacteria live in your mouth, and they feed off the sugar from food that's left behind on your teeth after you eat. Bacteria produce acid, which combines with food particles and saliva to form a sticky film called plaque. Plaque erodes the protective enamel on your teeth and allows cavities to form. Over time, the bacteria move deeper into your teeth and the cavities get bigger and bigger if you don't get them filled. Eventually, cavities can become so big that your tooth starts to hurt. Untreated tooth decay can even make a tooth fall out.
Jonathan B. Levine, DMD
Decay is very goal-oriented: its focus is to destroy a tooth. How? By blasting through that tooth, layer by layer. It starts at the top with the enamel and works its way inward from there. If it reaches as deeply as the pulp, which is where the tooth's nerve lives, that's when it hurts so badly that it can wake you up faster than any nightmare.
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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.