Dental laboratories make, alter and repair custom-made dental appliances to prescriptions from dentists and other dental professionals. They usually work behind the scenes rather than providing treatment directly to patients. A prescription sets out the design, materials and fit required, often using impressions, scans, measurements or models supplied by the dental practice. Typical work includes crowns, bridges, veneers, inlays, dentures and implant-supported restorations. Laboratories may also produce orthodontic retainers and other appliances, sports mouthguards and night guards. Technicians use materials such as ceramics, metals and acrylics, and may combine traditional bench techniques with digital design, 3D printing and computer-aided milling. Dental technicians in the UK are regulated by the General Dental Council, which maintains the professional register.