Cavity Fillings

A filling is a way to restore a tooth damaged by decay back to its normal function and shape. When a dentist gives you a filling, he or she first removes the decayed tooth material, cleans the affected area, and then fills the cleaned out cavity with a filling material.

By closing off spaces where bacteria can enter, a filling also helps prevent further decay. Materials used for fillings include gold, porcelain, a composite resin (tooth-colored fillings), and an amalgam (an alloy of mercury, silver, copper, tin and sometimes zinc).

How Will I Know if I Have a Cavity?

This may sound a bit surprising to most people, but the large majority of cavities are completely painless. This is because the outer enamel has no nerves. It is only when the cavity enters the underlying dentin that the cavity may begin to feel sensitive. The most common cavity symptoms are an increased sensation to cold, sweet foods or beverages. A cavity is often responsible for a broken tooth. The cavity weakens the tooth, especially when it forms under a tooth filling or a tooth cusp, and can easily cause a fracture when biting down.
Patients are sometimes taken off guard when they learn that they have a few cavities but they don’t have any symptoms. It is far better to treat a small cavity than to wait until they have symptoms; such as pain. By the time there are symptoms, the cavity may have spread to infect the dental pulp, necessitating a root canal procedure or a tooth extraction to eliminate the infection. Always remember that most dental problems are insidious — that is, they sneak up on you. Regular dental exams, at least twice a year, will greatly reduce the likelihood that a dental cavity will go undetected and spread, causing toothache pain and infecting the dental pulp.

How Do Dentists Detect Cavities?

Cavities are detected a number of ways. The most common are clinical (hands-on) and radiographic (X-ray) examinations. During a clinical exam, the dentist uses a handheld instrument called an explorer to probe the tooth surface for cavities. If the explorer “catches,” it means the instrument has found a weak, acid damaged part of the tooth — a dental cavity. Dentists can also use a visual examination to detect cavities. Teeth that are discolored (usually brown or black), can sometimes indicate a dental cavity.
Dental X-rays, especially check-up or bitewing X-rays, are very useful in finding cavities that are wedged between teeth, or under the gum line. These “hidden” cavities are difficult or impossible to detect visually or with the explorer. In some cases, none of these methods are adequate, and a dentist must use a special disclosing solution to diagnose a suspicious area on a tooth.

How Fillings Work

The treatment of dental cavities goes back centuries, but it was not until 1875 that Dr. G.V. Black first described an organized approach to their treatment. His systematic methods are still used today, primarily for the placement of silver (amalgam) dental fillings. Dr. Black advocated removing the decayed part of the tooth, and extending the tooth preparation to include certain grooves and other surfaces. This process, called “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 is able to be probed with an explorer, it has undergone cavitation and requires treatment. Early dental cavities that have not spread to the dentin or have undergone cavitation should not be treated, as they can be healed or re-mineralized with fluoride.
The goal of treating cavities involves two basic principals: removing the decayed portion of the tooth and rebuilding the missing tooth structure with a filling material. The dentist usually begins the procedure with an injection of local anesthetic (usually Xylocaine®). The tooth is isolated from the rest of the mouth, and in most cases, a high-speed dental drill is needed to remove the decay and prepare the tooth for the filling. Depending on which material is used, the dentist will vary the tooth preparation accordingly. After the tooth has been prepared, a liner is often used to reduce tooth sensitivity. Common liners include Gluma®, Copalite® varnish and Dycal®.
Dycal is a compound containing calcium hydroxide, and is used in deep cavities to stimulate the dentin to regenerate and protect the dental pulp. In deeper fillings, a base is used in addition to the liner. Common bases used under dental fillings are glass ionomer cement and zinc phosphate cement. 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, but 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 rebuilding the tooth.
After a tooth has been filled, it is not unusual for the tooth to be sensitive for a day or two. In general, the deeper the filling, the more likely the tooth will have prolonged sensitivity, especially to cold food or beverages. Most fillings should be completely comfortable within two weeks. In some cases, the filling will be built up too high, and a second appointment is needed to shave down the filling to a comfortable level. If sensitivity lasts more than two weeks, it may indicate that there is a void under the filling. Prolonged discomfort may also indicate a tooth that has an infected pulp, and requires root canal therapy.

How Can I Prevent Cavities?

The easiest way to prevent cavities is by brushing your teeth and removing plaque at least three times a day, especially after eating and before bed. Flossing at least once a day is important to remove plaque between your teeth. You should brush with a soft-bristled toothbrush, and angle the bristles about 45 degrees toward the gum line. Brush for about the length of one song on the radio (three minutes). It’s a good idea to ask your dentist or hygienist to help you with proper brushing methods.
Reducing the amount and frequency of eating sugary foods can reduce the risk of forming cavities. If you are going to drink a can of sweetened soda, for instance, it is better to drink it in one sitting, than sip it throughout the day. Better yet, drink it through a straw in one sitting, to bypass the teeth altogether. Getting to the dentist at least twice a year is critical for examinations and professional dental cleanings.
To reduce the incidence of cavities, use toothpaste and mouthwash that contains fluoride. Fluoride is a compound that is added to most tap water supplies, toothpastes, and mouth rinses to reduce cavities. Fluoride becomes incorporated into our teeth as they develop and makes them more resistant to decay. After our teeth are formed, fluoride can reverse the progress of early cavities, and sometimes prevent the need for corrective dental treatments.
The recent drop in the number of cavities is largely due to the addition of fluoride to our drinking water. Mass water fluoridation is 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 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 are very susceptible to cavities, your dentist can use high concentration, in-office fluoride treatments and prescribe a fluoride supplement, either as a gel, tablets or drops. In some cases, customized trays can be used while you sleep to deliver higher doses of fluoride and help strengthen teeth to prevent cavities.
A dental procedure called sealants can also help reduce cavities on the top and sides of back teeth (occlusal, buccal and lingual surfaces). A sealant is a white resin material that blankets the tooth, protecting the vulnerable pits and fissures of the tooth. Sealants are routinely placed on children’s teeth to prevent cavities on their newly developing molars. The use of sealants to prevent cavities is also a cost-effective way to reduce the incidence of cavities on adults as well. Sealants are generally not used on teeth that already have fillings.
People who have a dry mouth are at risk for developing cavities, and can have their dentist prescribe artificial saliva and mouth moisturizers, as well as recommend chewing sugarless gum to stimulate saliva production. Finally, an antiseptic mouthwash containing chlorhexidine gluconate such as Peridex® can also be useful in killing bacteria associated with dental caries.