A dental filling is a restorative treatment used to repair tooth structure damaged by decay (a cavity). The process involves removing the decayed material and filling the resulting space to prevent further damage and restore the tooth’s function and shape. Not all fillings are white; modern dentistry offers a choice between aesthetic, tooth-colored options and more traditional, silver-colored materials.
Defining Tooth-Colored Materials
The most common “white” filling material is composite resin, a mixture of acrylic plastic and finely ground glass-like particles. Dentists can color-match this material precisely to the surrounding tooth structure, providing an aesthetically pleasing restoration. Composite resins are widely used for both highly visible front teeth and posterior teeth.
Placement of a composite resin filling is an adhesive process, meaning the material chemically bonds to the tooth structure. A mild acid gel is applied to the tooth surface to create microscopic roughness, followed by a bonding agent. The putty-like resin is then layered into the cavity and hardened instantly using a high-intensity curing light. The dentist then shapes and polishes the final restoration.
Another tooth-colored option is glass ionomer cement, made from a blend of acrylic and glass. While not as durable as composite resin, it possesses the unique property of releasing fluoride over time, which helps protect the tooth from further decay. Glass ionomer is often selected for small cavities in non-load-bearing areas or in pediatric dentistry due to its ease of application.
The Role of Traditional Fillings
Traditional fillings are metallic options, most notably dental amalgam, which has a silver appearance. Amalgam is an alloy composed of mercury, silver, tin, and copper, forming a strong, durable, and cost-effective restorative material. It is recommended for restoring chewing surfaces on back teeth, such as molars, where the filling must withstand significant biting forces.
Gold fillings, or cast gold restorations, are another non-white, metallic option. Although expensive, gold is incredibly durable and biocompatible, often lasting 20 years or more with proper care. Unlike amalgam, a gold filling is custom-fabricated in a dental laboratory and cemented into the prepared cavity during a separate appointment.
Both amalgam and gold fillings are selected for their longevity and proven ability to hold up under the pressure of chewing and grinding. Their mechanical properties make them a preferred choice for large restorations in the posterior region of the mouth.
Functional Differences Between Filling Types
A significant difference between filling types lies in the method of cavity preparation. Amalgam fillings require the dentist to prepare a specific shape that mechanically locks the material in place, often requiring the removal of more healthy tooth structure. Conversely, composite resin restorations rely on adhesive bonding, allowing for a more conservative treatment that preserves the natural tooth.
Amalgam fillings have a longer lifespan than composite restorations, often lasting between 10 and 15 years, compared to five to ten years for composite fillings. Amalgam’s strength and resistance to wear suit it for high-stress areas. However, its metallic composition can expand and contract with temperature changes, potentially stressing the surrounding tooth over time.
The placement procedure also differs, as composite fillings are more technique-sensitive and require the area to be kept completely dry during the multi-step bonding and curing process, making the appointment longer. Amalgam placement is quicker and less sensitive to moisture contamination. Composite fillings are also more expensive than amalgam due to material costs and the increased time and precision required for application.