According to WebMD, a dental crown is a tooth-shaped cap that is cemented over an entire tooth. They can be used for various reasons; for example, to strengthen a weakened tooth due to decay, to restore a broken tooth, to correct discolored or misshapen teeth, to hold a dental bridge in place, or to cover a dental implant. Permanent crowns are created with a variety of materials, including metal, porcelain-fused-to-metal, resin, or ceramic.

The traditional dental crown procedure requires two trips to the dentist's office. During the first visit, the patient's tooth is examined and prepared. This may involve X-rays, filing down the tooth, and taking an impression of the teeth with paste or putty, WebMD explains. The patient also receives a temporary crown during the first appointment. The impressions are sent to a dental laboratory where the crown is made in two to three weeks. The patient then receives the crown on their second visit to the dentist's office.

According to Alan Ripps, D.M.D., a professor of operative dentistry and biomaterials at Louisiana State University School of Dentistry, the first dental crown appointment can take up to two hours and the second up to an hour; but a new dental crown procedure practiced by Dr. Ripps and his team is reducing the time spent in the dentist's office to one visit lasting less than two hours. Within 15 minutes the patient's crown is cut and prepared by a machine. Within an hour and a half, the crown is cemented into place. The new procedure frees the need for a temporary crown and is just as accurate as other methods, Dr. Ripps says.

To create an accurate crown, a three dimensional image of the tooth is created for the machine to read. The tooth is prepped with a special material that translates to the computer the X-Y coordinates of the tooth, including each gradation and axis.

According to Dr. Ripps, the cost for the patient is about the same; but for the dentist, it can be expensive. The machine can cost around $100,000 and the blocks used to make the crowns are an additional fee.

The blocks cost around $20 to $30 a piece, but must be purchased in multiples of five or ten blocks. They also come in a variety of sizes and colors.

"To have a good variety, you would have to have a nice investment up front," Dr. Ripps says. The procedure can be affordable for a doctor who performs a substantial amount of crown procedures each month, but may be too expensive for a dentist just starting a practice.