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The Effects of Metal Ceramic Restoration

While some celebrities enjoy having gold teeth, when it comes to dental work involving anterior, or front teeth seen in the smile, most people prefer to look as natural as possible. Gold crowns are commonly made for posterior, or back teeth, but for the front teeth, porcelain fused to metal, or PFM, restorations are more attractive. PFM restorations have many positive effects for a patient; however, there are some less-desirable effects, as well.

  1. PFM Crowns and Bridges

    • Crowns and bridges are routine, yet they are precise procedures performed in dental offices. Crowns are necessary especially when a tooth has had a root canal, has been broken or there is more decay than tooth structure. They are also made when someone has had an implant screw placed in the bone where a tooth is missing to replace the tooth. Bridges replace a missing tooth, or teeth, by making crowns for the teeth on either side of the gap and fusing an artificial tooth in between. PFM crowns and bridges are permanent restorations, as they are cemented in place, and only removed to repair or re-make. Preparation for a PFM is slightly different for a gold crown. The dentist reduces more tooth structure than for a gold crown to accommodate the layer of metal and the thickness of porcelain.

    Making a PFM Crown or Bridge

    • Preparation of the tooth is done by the dentist, and impressions taken of the preparation. Temporary crown or bridge fabrication protects the prep until the crown is completed at the dental laboratory. The patient returns for cementation at a later date. A dental technician at the lab starts making the crown by casting a metal coping for the crown or bridge. After the coping is made to the correct thickness needed to serve as the base of the PFM, porcelain is applied over the coping and fired in a kiln-like machine at a high temperature. The porcelain is fused to the metal and is what is seen in a patient's smile. The technician carves anatomy into the porcelain, making it look natural and then glazes it. It is returned to the dentist for cementation in the patient's mouth.

    Advantages

    • The advantages of a PFM crown or bridge are many. The PFM is quite normal looking. A trained laboratory technician can make a crown or bridge that to the casual observer appears as fake. It is practical and mouth-friendly due to the thick layer of glaze. It does not discolor over time and with proper dental care maintenance, it can last for many years, if not the lifetime of the person wearing it. PFM is optimal for restorations on anterior teeth, and can be shaded to blend in with the patient's natural dentition.

    Disadvantages

    • PFM crowns and bridges have drawbacks as restorations. Natural teeth have translucency, especially closer to the biting edges. A PFM is opaque and light is unable to pass through the metal under the porcelain. They can appear and feel bulkier to the patient. When a PFM wearer laughs or opens his mouth wide, the shiny metal is visible on the back of the crown because it is not covered by porcelain. The gum line recedes over time on a PFM tooth, exposing a black line that is the metal collar of the PFM. Porcelain is susceptible to breakage; the breakage exposes the metal under the PFM. In addition, broken porcelain is rough to the patient's tongue. If the glaze gets broken by either breakage or wear, it creates an annoying rough spot. The porcelain on a PFM can be hard on the opposing teeth, wearing them down faster than natural teeth. Finally, natural teeth stain or discolor over time. A PFM does not, and becomes more noticeable as being artificial.

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