CAD/CAM dentistry, (Computer-Aided Design and Computer-Aided Manufacturing in dentistry), is an area of dentistry utilizing CAD/CAM technologies to produce different types of dental restorations, including crowns, veneers, inlays and onlays, fixed bridges, dental implant restorations and orthodontic appliances.
Typically CAD/CAM dental restorations are milled from solid blocks of ceramic or composite resin closely matching the basic shade of the restored tooth. Metal alloys may also be milled or otherwise digitally produced. After decayed or broken areas of the tooth are corrected by the dentist, an image (scan) is taken of the prepared tooth and the surrounding teeth. This image, called a digital impression, draws the data into a computer. Then proprietary software is used to create a replacement part for the missing areas of the tooth, essentially creating a virtual restoration. This is called reverse engineering. The software sends this virtual data to a milling machine where the replacement part for the defect (the dental restoration) is carved out of a solid block of ceramic or composite resin. Stains and glazes are fired to the surfaces of the milled ceramic crown or bridge to correct the otherwise monochromatic appearance of the restoration. The resulting restoration can then be adjusted in the patient’s mouth and cemented or bonded in place. Depending on the restorative material, cementing/bonding surface areas on the tooth and the restoration may be respectively etched and silanized. Resin cement is then used to fuse the restoration to the prepared tooth, completing the restorative treatment process.
A Crown or bridge, also known as a fixed partial denture, is a dental restoration used to replace a missing tooth by joining permanently to adjacent teeth or dental implants.
Types of bridges may vary, depending upon how they are fabricated and the way they anchor to the adjacent teeth. Conventionally, bridges are made using the indirect method of restoration.
A bridge is fabricated by reducing the teeth on either side of the missing tooth or teeth by a preparation pattern determined by the location of the teeth and by the material from which the bridge is fabricated. In other words, the abutment teeth are reduced in size to accommodate the material to be used to restore the size and shape of the original teeth in a correct alignment and contact with the opposing teeth.
The materials used for the bridges include gold, porcelain fused to metal, or in the correct situation porcelain alone. The amount and type of reduction done to the abutment teeth varies slightly with the different materials used. The recipient of such a bridge must be careful to clean well under this prosthesis.