Composite fillings are a mixture of acrylic resin and finely ground glasslike particles that produce a tooth-colored restoration. Composite fillings provide good durability and resistance to fracture in small-to-mid size restorations that need to withstand moderate chewing pressure. Less tooth structure is removed when the dentist prepares the tooth, and this may result in a smaller filling than that of an amalgam (silver filling). Composites can also be "bonded" or adhesively held in a cavity, often allowing the dentist to make a more conservative repair to the tooth.
In teeth where chewing loads are high, composite fillings are moderately resistant to wear, but less so than amalgam fillings. The cost is moderate and depends on the size of the filling and the technique used by the dentist to place it in the prepared tooth. The time required to place a composite filling is usually longer than what is required for an amalgam filling. Composite fillings require a cavity that can be kept clean and dry during filling and they are subject to stain and discoloration over time.