A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns are often needed when a large cavity threatens the ongoing health of a tooth. They are typically bonded to the tooth using a dental cement. Crowns can be made from many materials, which are usually fabricated using indirect methods. Crowns are often used to improve the strength, longevity or appearance of teeth.
Your dentist prepares the tooth by removing the outermost layer of tooth and/or filling material into a short flattened pylon shape and takes an impression which is sent to a lab to fabricate the crown outside of the mouth. Your dentist will also make a provisional crown for your use while the lab does its work. The permanent crown is then inserted at a later dental appointment.
Using this indirect method of tooth restoration allows use of strong restorative materials requiring time consuming fabrication methods requiring intense heat, such as casting metal or firing porcelain which would not be possible to complete inside the mouth. Many patients choose to have their crown fabricated with gold because of the similar expansin properties of natural teeth.
A bridge, also known as a fixed partial denture, is a dental restoration used to replace a missing tooth by permanently joining to adjacent teeth or dental implants.
A bridge is made by reducing the teeth on either side of the missing tooth or teeth. An impression is taken for the lab, and a temporary bridge is made for your use while the lab makes the permanent bridge. Then you return for the cementation appointment.
The teeth supporting the bridge on either side are called the "abutments" and the replaced missing teeth are called "pontics". A bridge cannot connect from a natural tooth abutment to a dental implant abutment. Two dental implants are required for a bridge where this function is required.
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. Patients are instructed how to and must be careful to clean the abutment teeth and gums well under the bridge.
A veneer is a thin layer of restorative material placed over the front of a tooth surface, either to improve the aesthetics of a tooth, or to protect a damaged tooth surface. There are two main types of material used to fabricate a veneer, composite and dental porcelain. A composite veneer may be directly placed (built-up in the mouth), or indirectly fabricated by a dental technician in a dental laboratory, and later bonded to the tooth. A porcelain veneer may only be indirectly fabricated in the same way a crown is made.
Today, with improved cements and bonding agents, they typically last 10 or more years. They may have to be replaced in time due to cracking, leaking, chipping, discoloration, decay, shrinkage of the gum line and damage from injury or tooth grinding.
*There are two fees associated with crowns, bridges, porcelain veneers, dentures and other oral appliances. The dentist’s fee and a lab fee for their materials and services.