Properties of Dental Composite

Dental composite is a synthetic resin, typically acrylic-based, that contains inorganic fillers such as glass and quartz, according to TheFreeDictionary.com. Composites are used for dental restorations, particularly those used in the front teeth, because they are tooth-colored and thus esthetically pleasing, reports "Torres and Ehrlich Modern Dental Assisting." This material has several properties that make it a suitable choice for patients, but it also can cause some problems.

Manipulation/Radiographic Properties

• Composites can be shaped to the anatomy of a tooth easily. In addition, dental composite can be sustained in the mouth's environment and can be bonded directly to a tooth's surface, according to "Torres and Ehrlich Modern Dental Assisting."

  Composite resins also show up on dental radiographs, which are used to help dentists diagnose oral problems in patients, reports "Dental Materials: Properties and Manipulation." On a radiograph, composites typically are radiopaque, which means radiation does not easily pass through them. As a result, they appear white or light gray when compared with dentin--a material that makes up the main portion of a tooth's structure. On the contrary, composites appear radiolucent--or dark--on a radiograph when compared with enamel, the hardest material in the body, which makes up the crown of the tooth.

Thermal Properties

• A composite restoration has a lower thermal conductivity than do metallic restorations such as gold alloy or amalgam--silver-colored restorations, according to "Dental Materials: Properties and Manipulation." For this reason, composites offer good thermal insulation for the dental pulp--the part of the root of a tooth that contains nerves and blood vessels. This is an advantage, as patients who receive metallic instead of composite restorations on portions of their teeth can experience sensitivity to oral temperature changes.

  On the contrary, composites have a higher thermal expansion than tooth structure does, which means composites easily can change dimensions as temperature changes in the mouth. This can pose a problem because when restorations expand, oral fluids can leak between a composite and the tooth.

Strength Properties

• Composites work best in the front teeth where biting forces are low. Still, composites can be used in the back teeth, even though they are less durable than metallic restorations. However, dental composites can be problematic in that they can wear down from abrasive tooth brushing and chewing, and also can wear as the composite material degrades in the mouth, according to "Dental Materials: Properties and Manipulation." For this reason, products created to serve as composites for the back teeth usually have higher wear resistance than those manufactured for use in the front teeth.