CEREC crowns are manufactured by using CAD-CAM technology. (Computer-assisted design—Computer-assisted manufacture). This process is similar to scanning a document and then printing it. The teeth are scanned and the image is transferred to the computer. The dentist can then fill the virtual tooth preparation on the screen and then a milling machine cuts the filling or crown from a block of ceramic. This is done within 20 or 30 minutes per crown. The ceramic is then either glazed or polished and then glued onto your tooth. This technology is marketed as a one-visit crown and there is no need for a temporary restoration and you save on expensive laboratory fees. My criticism to the marketing is that patients requiring five crowns will be required to wait a very long time. Wearing a temporary crown for a week or two is not such an inconvenience and CEREC crown prices are never less than lab fabricated crowns. We use a similar process with “lava” 3M crowns. These are also CAD-CAM, but there are a number of differences. The impression is taken with a silicon impression material, as opposed to a scanner. The patient goes home with temporary crowns. A plaster model is made and then scanned into the computer. The margins are far more precise, because the scanner reads the plaster margins of a die, as opposed to an oral environment where you have tissue interference. The “lava” milling center which is a machine that fills an entire room and costs at least 4 or 5 times more than CEREC, cuts a thin layer of zirconia to fit the die. This zirconia layer is then sintered for 11 hours in a furnace, the end result being far stronger than any CEREC. Other porcelains are then layered onto the zirconia to complete the crown. The advantage is that different colours can be added into the crown to make it look life-like. This is beneficial for front teeth. The crown fit is checked under magnification, before it is released to the dentist. Lab fabricated crowns are precisely made without any time restrictions of waiting patients.