A dental filling fills a hole in a tooth that used to have natural tooth structure. That hole can be created by tooth decay or even when part of the tooth breaks off. While “fillings” can be made of tooth-colored ceramic or plastic, they can also be made from metal like gold or silver-colored dental amalgam. Most of the time, when dentists talk about fillings, we are talking about composite resin (“plastic”) and dental amalgam that are placed directly into the tooth while it is in the mouth, or direct restorations. In contrast, gold or ceramic “fillings” are referred to as indirect restorations, a term that also applies to crowns, onlays, and bridges.
Direct restorations are best used to address minor problems in teeth, like minor cavities or chips. Some of the problems with plastic or amalgam fillings are that they tend to be weaker than indirect restorations, may not have optimal shape and contours, may have incomplete seals against the tooth, and may not be as durable as indirect restorations. The bigger the filling, the less likely a direct restoration is to succeed for more than a few years.
Amalgam and composite fillings are typically less costly than indirect restorations. Sometimes, dentists will repair teeth with large direct restorations as an economical alternative to indirect restorations, but the compromises should be clearly understood by the patient. It may actually make more financial sense to invest money in optimal treatment than to patch and repair several times over several years, causing some degree of injury to the tooth multiple times. Sometimes, however, direct restorations may be the most appropriate treatment, even if they are large. For example, if a person is very prone to dental disease, then the investment in direct restorations may not be wise until the disease process has been controlled.
The choice of whether a filling should be a direct restoration or indirect restoration should be made after a thorough discussion between the patient and the dentist about the benefits and risks of each option. Unfortunately, many insurance companies will only pay for “the lowest costly alternative” rather than for the best treatment option. Fortunately, modern filling materials often can provide very nice restorations when used appropriately.