Patients who do not practice good oral hygiene develop tooth decay from decomposing food particles and the resulting plaque which builds up on the teeth. Acid found in fruits, fruit juices, some vegetables, and all soft drinks, sugars found in food and beverages, and decaying food particles begin to eat away at the tooth enamel. As the protective enamel weakens, holes form in the enamel and allow the acids, sugars, and decaying food particles to eat their way further into the tooth. The result of this is caries, which is a cavity or hole in the tooth.
There are two types of fillings mainly used in cavities, amalgam and composite. The location of the cavity greatly determines which type of filling is used. Dental amalgam is that familiar silver colored filling and it is a stable metal alloy which combines elemental mercury, silver, tin and copper. Dental amalgam is very durable and resistant to wear. It is also less expensive than gold or composite fillings.
Composite fillings are made of plastics and are white, making them much less noticeable in the patient's mouth. The material comes in a range of colors so the dentist is usually able to match your tooth color. The most commonly used composite filling is made of a composite quartz resin and contains a light sensitive agent. The resin remains pliable while the dentist is working with it. After he or she has completed their work to their satisfaction, the dentist will use a small gun like device which shines an intense light on the composite filling and instantly hardens the material. The usual length of time required to cure each layer of the filling is forty seconds. The patient can eat immediately following a composite filling. Some composite material is considered to be hard enough to withstand the force of chewing on the back teeth.
In general, composite fillings are used to fill cavities located between teeth, on front teeth, on any tooth visible when smiling, and on any tooth readily visible when talking. Amalgam fillings are generally recommended for back teeth. Patients with composite fillings to do not experience the heat and cold sensitivity associated with metal alloy fillings.
Some patients are opting for removal of all old fillings to be replaced with composite fillings for cosmetic reasons. I saw several cases of this during the years I worked in the dental field. Unless the dentist can justify the replacement of a filling, though, dental insurance usually will not cover the new filling. Many companies will only pay benefits equal to that of an amalgam filling on a back tooth but will pay for composite fillings on front teeth.
Regardless of the location of a cavity, the dentist must first remove the decay from the area to be filled. The dentist will usually administer a local anesthetic to numb the tooth and the gum area in which they will be working. Patients with a high anxiety level may opt for use of nitrous oxide, known as laughing gas. Actual removal of the decay is accomplished by use of dental drills and micro air abrasion. A dental laser is sometimes used.
To gain access to a cavity between teeth the dentist will place a metal band around an adjoining tooth which can be tightened with tension. This temporarily opens a small space between the teeth in which to work. This same type band is often used around the tooth being filled if the cavity is in the top of the tooth to isolate the tooth being worked on. The dentist will place rolls of gauze in the mouth to help keep the inner cheek out of the way while working. The gauze also helps to catch the patient's saliva and any blood that may come from the gum in the area being worked on.
A composite can be bonded to the tooth in thin layers. This allows the dentist to preserve more of the natural tooth. If the decay is close to a nerve, the dentist will apply a special liner to protect the nerve. A bond resin must be applied to the tooth in order for the composite to adhere to the tooth. A special material that opens the pores of the tooth's dentin and roughens the surface of the exposed enamel is applied. The bond resin is a more fluid version of the material in the composite and is also hardened and cured with the light in the same manner the composite is. The dentist builds the filling up with the composite material in thin layers. After completion of the filling, the dentist will have the patient bite down on articulating paper to check their bite in the same manner they do amalgam fillings. The dentist will then adjust the height of the filling. When the bite is determined to be correct, the dentist will polish the tooth. This same bonding method may be used to build up a tooth in order to support a crown.
Though more expensive than amalgam fillings, composite fillings can be well worth the cost in terms of self esteem. If you desire composite fillings, discuss the possibility with your dentist. The dentist can evaluate the amount and location of decay in the tooth and the location of the tooth itself to determine the best course of treatment.