Dental cavities, also known as carries, have been around for thousands of years. However, the problem has been steadily increasing over time. For example, scientists have discovered fossilized remains of men and women from the Iron Age in @Warwickshire, @England. These remains showed a cavity rate of only about 8 percent. When the scientists examined today's Warwickshire inhabitants, they found a remarkably high cavity rate of 48 percent. The culprit is most likely a modern diet, which consists, in large part, of highly processed, sugar-containing foods.
Dental cavities are caused by a combination of carbohydrate-containing foods and bacteria that normally live in our mouths. While there are many different types of bacteria, there are only a few that contribute to cavity formation. These bacteria reside in a film that continuously forms on and around our teeth. We call this film plaque. The bacteria use carbohydrates for food, producing acid in the process. The acid causes the @pH (a measure of acidity) on the tooth surface to drop. Before eating, the pH in the mouth is about 6.2 to 7.0, slightly more acidic than water. After eating sugary foods and other carbohydrates, the pH drops. At a pH of 5.2 to 5.5 or below, the acid begins to dissolve the hard enamel that forms the outer coating of the teeth. As the enamel wears away, a cavity results.
Cavities can spread beyond the surface enamel, invading the softer dentin located directly beneath. It can also move to the nerve and blood supply of the tooth contained within the pulp, leading to abscesses and infections.
Cavities can form on the biting surfaces of the back teeth -- the molars and premolars. In these locations they usually cause pits and grooves. These are thin areas of enamel that contain recesses. They can easily trap food and plaque. As the trapped bacteria continue to produce acid, the pits enlarge to form wider grooves and finally hole. Once worn through the enamel, they can invade the underlying dentin.
Cavities can also form on the front teeth, or on the back (lingual) areas of the teeth, where there is a smooth surface. In a smooth surface cavity, the acid must travel through the entire thickness of the enamel.
And as we get older, certain body change can themselves lead to tooth decay. For example, the gums can recede from the teeth, exposing the roots to plaque. The roots are covered with cementum, which is softer than enamel. This makes them more susceptible to decay, and the majority of people over age 50 have some form of tooth-root decay.
Also common in older people is decay around the edges of previous fillings. Over time these fillings can weaken, leading to cracks around the edges. Bacteria accumulate in these tiny, hard-to-reach cracks, promoting decay.
The treatment of dental cavities goes back centuries. But it was not until 1875 that @G.@V. Black, a dentist at @Northwestern University Dental School, first described an organized approach to their treatment. His methods are still used today. Dr. Black removed the parts of the teeth that were decayed. He then extended the tooth preparation to include not only the cavity, but also certain other grooves and surfaces. This process, "extension for prevention," is considered prudent because it provides the tooth with some protection from further decay in the future.
Most cavities discovered during a dental examination will need to be treated. In general, if a cavity has broken through the enamel and is into the underlying dentin, or if it is able to be penetrated with a dental instrument, requires treatment. Early dental cavities -- ones that have not spread to the dentin -- can simply be re-mineralized with fluoride or filled with amalgam. If the decay has spread further into the tooth structure, it can lead to gum disease. This needs to be treated more aggressively, with scaling and planing, flap surgery, or even a root canal.
The goal of treating cavities involves two basic principals: first, removing the decayed portion of the tooth; second, rebuilding the missing tooth structure with a filling material. The dentist usually begins with an injection of a local anesthetic. The tooth is isolated from the rest of the mouth. Then a high-speed dental drill is used to remove the decay. Next, the dentist will prepare the tooth. A liner is often used to reduce tooth sensitivity. In deeper fillings, a base is used in addition to the liner. The main purpose of the base is to insulate the tooth from temperature changes in the mouth. The dentist and patient can then choose a number of different materials to fill the tooth. The most common are silver (amalgam), white (resin), porcelain, or gold. These materials are layered on top of the liner or base to finish the process of repair.
After a tooth has been filled, it is not unusual for the area to be sensitive for a day or two. In general, the deeper the filling, the more likely the tooth will be sensitive. Most fillings should be completely comfortable within two weeks. In some cases, the filling will be built up too high, causing a rough area or an improper bite. In these cases, a second appointment will be needed to shave down the filling to a comfortable level. If sensitivity lasts more than two weeks, it may indicate that there is an abscess under the filling; an x-ray will show the abscess as a space. Prolonged discomfort may also indicate a tooth that has an infected pulp; more extensive work, such as a root canal, will have to be performed.
The easiest way to prevent cavities is by brushing and flossing your teeth, removing plaque before it builds up. Dentists recommend brushing at least three times a day. It is especially important to brush after eating and before going to bed. Flossing at least once a day is important to remove plaque that accumulates in the hard-to-reach spaces between your teeth. You should brush with a soft bristled toothbrush. Angle the bristles about 45 degrees toward the gum-line. Brush for about 3 minutes. You should also visit your dentist at least twice a year for examinations and professional cleanings.
Another good way to prevent cavities is by reducing the amount and frequency of sugary foods you consume. In addition, use toothpaste and mouth rinse (not mouthwash -- most simply cover bad breath and may actually contain sweeteners) that contain fluoride. Fluoride is a mineral found naturally in all water sources. It re-mineralizes the enamel surface where acid has begun to eat it away. As a result, it can not only reduce the number of cavities, but it can also help to repair the early stages of tooth decay, even before it becomes visible to a dentist. In short, it creates a tooth surface that's resistant to further decay.
For the last fifty or so years, many communities have also added fluoride to their drinking water. Mass water fluoridation is one of the most cost-effective measure available to reduce the incidence of tooth decay. The @Environmental @Protection @Agency has determined that the acceptable tap water concentration for fluoride is 0.7 to 1.2 parts per million. Much higher levels are not valuable, as they have been associated with chalky white discolorations of the teeth known as fluorosis.
If you live in an area that does not have fluoride, or you are very susceptible to cavities, your dentist can use high concentration, in-office fluoride treatments and prescribe a fluoride supplement. Supplements are available as gels, tablets, or drops. In some cases, customized trays can be used while you sleep to deliver higher doses of fluoride and help strengthen your teeth.
Sealants can also help reduce cavities on the top and sides of the back teeth. Sealants are formed of a white resin material that blankets the tooth, protecting the vulnerable pits and fissures. They are often used on children's teeth to prevent cavities on their newly developing molars, and they can serve as another cost-effective way to reduce the incidence of cavities on adults, as well. They are generally not used on teeth that already have fillings.
There is one other way to help prevent cavities. Dry mouth (also known as @xerostomia) is a condition where you don't produce enough saliva. It not only leaves a dry, sticky feeling in your mouth and on your tongue, but it can lead to tooth decay. Saliva serves two purposes. First, it helps to digest food. And second, it helps to prevent tooth decay and infection by destroying bacteria and fungi in the mouth. Sometimes dry mouth can be caused by medications. In those cases, doctors try to adjust the dose. Artificial saliva (kind of like eye drops, only for the mouth) may also be useful. And dentists recommend that you keep your mouth moist by sipping water throughout the day, and by avoiding spicy and salty foods and caffeine, which has a drying effect.
Left untreated, simple tooth decay and cavities can become more serious, leading to infections in the pulp that lies beneath the tooth surface and sometimes causing a painful pocket of pus, also known as an abscess, to develop. When it reaches this stage, the decay is referred to as periodontal disease, or simply gum disease, and it is the primary cause of tooth loss in adults over 35. Such decay attacks not only the gums, but also the bone and other tooth-supporting structures.
The earliest stage of periodontal disease is called gingivitis, and since many people don't experience any significant pain or discomfort at this stage, if you don't see your dentist regularly you may have the disease for years before getting the proper. The lack of any warning pain makes it especially important to brush and floss every day and to look for other signs of its progression. These include tender, swollen gums, or gums that bleed, particularly when you brush or floss your teeth; gums that turn a dark reddish color, a receding gum line, pain when you chew, tartar buildup on the tooth surface, and overly sensitive teeth. If you experience any of these, you should see a dentist as soon as possible.
If the gingivitis remains untreated, the infection can spread from the gums into the ligaments and bone that support the teeth. This may cause the teeth to become loose and eventually to fall out, a condition known as periodontitis.
Dentists diagnose gum disease with a combination of an oral examination and dental X-rays. In the examination, they will use a probe to measure the space between the teeth and the gums. In a normal mouth, a V-shaped groove runs between the two, measuring at most three millimeters deep, but if pockets form, the probe will push deeper into the gum tissue, and how deep it goes is a good indicator of how far the infection has progressed. They will then use the X-rays to determine if any of the underlying bone has been lost.
The good news is that you can prevent most cases of gum disease simply by brushing and flossing properly every day.
