Introduction
Digital technology is changing how restorations are made. The central method is CAD/CAM (computer-aided design and computer-aided manufacturing), introduced in the mid-1980s by Mörmann and Brandestini in Zurich. A restoration is designed on a screen and then made by a machine.
How CAD/CAM works
- Scanning: the tooth preparation, the impression or the plaster model is scanned, and the data goes to a computer.
- Design: software is used to create a virtual restoration.
- Milling: at a command, computer-controlled grinders cut the block under water cooling, in just a few minutes.
- Finishing: the restoration is sintered if needed, then stained, glazed or polished.
Zirconium dioxide and CAD/CAM
Fully sintered zirconia is so hard that milling it is slow and wears out the grinders quickly. So blocks of compacted powder are used instead, which are about as hard as plaster and mill much faster. The restoration is then sintered in a special furnace at 1350 to 1550 °C.
Titanium
Casting titanium is expensive because of its high melting temperature and chemical reactivity. CAD/CAM avoids these problems, so it is increasingly used to shape titanium.