The color of a cavity filling is determined by the material a dentist uses to restore lost tooth structure. Fillings seal the tooth after decay is removed, preventing further bacterial invasion and restoring function. The material choice dictates whether the restoration blends invisibly with the natural tooth or has a distinct metallic appearance. Modern dentistry offers various options, each with a unique composition and color influencing its suitability for different areas of the mouth.
Tooth-Colored Filling Materials
The most common tooth-colored option is composite resin, a mixture of acrylic plastic and finely ground glass particles tinted to match surrounding teeth. This material is popular for its highly aesthetic results, especially for restorations in visible areas like the front teeth. Dentists achieve a seamless appearance using standardized color-matching systems, such as the VITA Classical Shade Guide, which categorizes shades based on hue, intensity (chroma), and lightness (value).
Shade selection is performed under natural light for the most accurate match to the patient’s existing enamel. The composite resin is applied in layers and hardened using a specialized blue light, a process called light-curing.
Another tooth-colored option is glass ionomer cement, made from fluoro-aluminosilicate glass powder and liquid polyacrylic acid. It is generally less translucent than composite resin. Glass ionomer is often selected for specific applications, such as small lesions near the gum line or in children’s teeth, because it releases fluoride.
Metallic Filling Materials
Metallic options are traditional, non-aesthetic materials. Silver amalgam appears dark gray or silver in the mouth. Amalgam is an alloy composed of approximately 50% liquid mercury mixed with a powdered blend of silver, tin, and copper. This combination creates a durable, long-lasting, and highly visible restoration.
Another metallic option is gold alloy, which is distinctly yellow. Pure gold is rarely used because it is too soft, so it is alloyed with metals like silver and palladium to increase strength. These metallic materials are reserved for posterior teeth, such as molars and premolars. This placement is due to the immense forces of chewing requiring maximum material strength, and the filling’s color being less noticeable.
Factors Influencing Material Choice
A dentist’s selection of a filling material depends on an evaluation of several clinical factors. Location is a primary consideration; visible front teeth typically receive composite resin, while back teeth handling heavy chewing forces benefit from the superior strength of silver amalgam. The size of the decay also plays a significant role, as larger restorations often require the greater fracture resistance offered by amalgam or gold.
Composite resin fillings require a completely dry environment during placement because they bond directly to the tooth structure, making them technique-sensitive. Conversely, amalgam is more forgiving of moisture during placement and is known for its durability in high-stress areas. Cost is another factor, with amalgam typically being the most affordable option, while gold and certain tooth-colored materials are more expensive.