Today’s post looks at the complex process required to construct a dental crown. Dental crowns can be constructed with metal, ceramic (porcelain), plastics, or varying combinations of these. We will describe the process used to create a porcelain crown, though the steps are similar to those used for other materials.
As far as beauty goes, today’s high-quality crowns are just as pleasing and natural looking as authentic teeth. (A crown that looks like a white Chiclet and sticks out like a sore thumb is not a high-quality crown from Mt. Vernon Center For Dentistry.)
When one of our Mt. Vernon Center For Dentistry patients needs a crown, a dental assistant makes an impression of all the teeth. The impression is sent to a laboratory where the plaster teeth are separated. The individual tooth mold in need of restoration is scanned into a computer to have the precise dimensions to send to the factory.
The technologically-advanced factory has a computerized machine that will then pour plaster into cylindrical molds, creating blanks. Once hardened, the process of making the tooth from the plaster blanks begins.
The machine then takes the scanned data from the impression and begins milling out the contours found in the scan. The finished tooth is not to scale, being 20% to 30% larger than necessary. This enlargement is to allow for material shrinkage that will later occur.
The machine then dips the plastered tooth into liquid ceramic. The ceramic hardens and gives the tooth a gleaming, natural finish that is indistinguishable from a genuine tooth. The machine then starts a new process of orienting the tooth with others. This time, ceramic powder is poured into new molds over the plaster tooth. The molds are put on a rod and then plunged into a water-filled chamber. Once the chamber lid is closed, water pressure increases, solidifying each ceramic tooth.
The restoration is then chiseled to perfectly match the plastered tooth that is inside. This tooth becomes the ceramic shell of the crown and is easily lifted off the plastered tooth.
This shell, or coping, will then be exposed to a high temperature for increased stability. It also shrinks to the proper size when exposed to the high temperature. Once finished, a plastic replica of the original tooth is created from the computer scan. The new shell is then tested for precise fitting over the tooth.
The shell then leaves the factory for the lab, where layers of colored porcelain are painted on it. A skilled ceramist – an artist in every sense of the word – may apply up to 15 layers of porcelain to perfectly match the variations in the surrounding teeth. This labor-intensive process accounts for much of the cost of a high-quality crown.
The crown is then fired to making the porcelain more solid throughout. More hand contouring follows, as required, and then is finished with a clear, ceramic gloss.
All of this work results in a fantastic crown for one of our patients!