A composite resin is a tooth-colored mixture filled with glass (silicon dioxide). Composite resin mimics the color and texture of natural teeth. Bonding utilizes a composite resin to close gaps, restore, reshaped, or recolor your smile. Tooth-colored fillings are used to replace old silver mercury fillings, decayed, cracked, and chipped teeth. They are also used on gums that show signs of recession and abfractions. After preparing the tooth, the composite resin is placed inside the prep, and with the aid of a curing light the filling is harden. Your filling will then be strong, durable, and ready to use.