Several factors influence the performance, durability, longevity, and expense of dental restorations, including: The components used in the filling material The amount of tooth structure remaining Where and how the filling is placed The chewing load that the tooth will have to bear The length and number of visits needed to prepare and adjust the restored tooth Before your treatment begins, your doctor will discuss with you all of your options and help you choose the best filling for your particular case. In preparation for this discussion it may be helpful to understand the two basic types of dental fillings — direct and indirect. Direct fillings are fillings placed into a prepared cavity in a single visit. They include silver amalgam, glass ionomers, resin ionomers, and composite (resin) fillings. The dentist prepares the tooth, places the filling, and adjusts it in one appointment. Indirect fillings generally require two or more visits. They include inlays, onlays, and veneers fabricated with gold, base metal alloys, ceramics, or composites. They are used when a tooth has too much damage to support a filling but not enough to necessitate a crown. During the first visit, the dentist prepares the tooth and makes an impression of the area to be restored. The dentist then places a temporary covering over the prepared tooth. The impression is sent to a dental laboratory, which creates the dental restoration. At the next appointment, the dentist cements the restoration into the prepared cavity and adjusts it as needed.