Crowns are designed to protect a tooth from breaking by covering the tooth on four sides, top, back, front, and two sides. They are recommended by our Salisbury dentists if a tooth breaks, is in danger of breaking, has extensive decay, or has had a root canal. Crowns can be made from metal (precious, semiprecious, non-precious), porcelain fused to metal, porcelain alumina, porcelain zirconia, dilithium silicate porcelain, plastic, or all feldspathic porcelain. A crown is made by removing tooth structure to compensate for the thickness of the crown. The thicker the crown, the more removal of tooth. In this way the crown will be about the same size as the original tooth. Cast metal crowns have been used in dentistry for over 100 years. They do not break and are not abrasive to the opposing teeth. However, they are not esthetic, and therefore, are used in non-visible posterior areas. Delmarva Dental Services only uses precious metal for their all-metal crowns since it is the best. Porcelain crowns are made of different types of porcelains. The most popular is porcelain fused to metal crowns. They are tooth colored with a metal framework under the porcelain for strength. They have been the predominate porcelain crown for over 50 years in the U.S. Newer metal free frameworks have been developed such as feldspathic, alumina, zirconium, and dilithium silicate. The most natural looking crowns are E-max (dilithium sulfate). They are also very strong. Felspathic and alumina porcelain crowns are weaker and sometimes break. Zirconium porcelain crowns and porcelain fused to metal are stronger and are less likely to break. Porcelain crowns can wear the opposing teeth and should be highly polished. All plastic crowns are not used much in dentistry because they tend to lose their shine and wear significantly over time and do not offer many advantages over porcelain.
A fixed bridge is a replacement for missing teeth. It consists of an attachment of one or more fake teeth attached to the teeth next to the space. Therefore, it requires at least one tooth on each side of the space. It is characterized in several ways; the number of teeth involved, the design, and the materials used. The number of teeth involved is the sum of the number of fake teeth and the number of tooth attachments. For example, a three-unit bridge would consist of one fake tooth and two tooth attachments. The more teeth involved the more costly the bridge. The fake tooth is the same regardless of the bridge design, but the attachment to the tooth varies in three ways. In a full coverage bridge, the attachment covers the adjacent teeth entirely like a crown or cap. The attachments fit in the adjacent teeth like fillings in an inlay bridge. With a bonded or Maryland bridge, the attachments are exterior to the adjacent teeth. The following materials are used in bridges: all metal, all porcelain, porcelain fused to metal, plastic, and zirconium. At Delmarva Dental Services we have experience in all of these types of bridges. Fixed bridges have a 70 percent success rate over 15 years.
All Porcelain (Zirconium) Bridge
This type of bridge is the newest type bridge. It contains no metal and is stronger than porcelain fused to metal bridge. It is best for the lighter shades of teeth or when lighter porcelain veneers are also being done. It also requires the removal of tooth structure of the adjacent teeth but not as much as porcelain fused to metal bridge.
Porcelain Fused To Metal Bridge
This type of bridge has been the most popular for the last 40 years. It is tooth colored and the metal is hidden. The metal reinforces the porcelain, making it stronger. The success rate of bridges is about 70 percent after 15 years. The lesser number of units (shorter bridge) the greater the success rate. Different quality of metals can be used with the porcelain: precious, semiprecious, and non-precious. Precious bonds the best with porcelain. Delmarva Dental Services has been using precious metal in their porcelain fused to metal bridges since 1981. The advantages of this type of bridge are its low fracture rate, high retention rate, low wear rate, years of proven success, and relative esthetics. Most dental laboratories are well versed in its fabrication. The disadvantages are the wear of the natural teeth that oppose the bridge. It also requires the reduction of the adjacent teeth by 2 millimeters.
This is a fixed bridge with a fake tooth and is held to the adjacent teeth with exterior metal, plastic, or porcelain retainers (like wings) that wrap around the teeth. The retainers are usually not visible. The fake tooth can be porcelain, plastic, metal, or porcelain fused to metal. The appliance is cemented via the retainers to the teeth. It is a conservative bridge in that very little of the adjacent tooth structure is removed during the procedure. Since the retainers do not fully cover the adjacent teeth, it is not as retentive as a full coverage bridge and may come loose.