CEREC use CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) technology, incorporating a camera, computer and milling machine in one instrument. The dentist uses a special camera to take an accurate picture of the damaged tooth. This optical impression is transferred and displayed on a color computer screen, where the dentist uses CAD technology to design the restoration. Then CAM takes over and automatically creates the restoration while the patient waits. Finally,The dentist bonds the new restoration to the surface of the old tooth.