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Lone Oak Dental

Why do my crowns show a black line near the gums?

Many crowns done in the past and today have a black line where the crown meets the tooth.  The black line seen is the metal underlying the white porcelain in the restoration.  While the black line may look bad and be distracting in a smile, it is expected with porcelain fused to metal crowns or PFMs. Occasionally, the metal in the crown may be seen through the gum tissues creating a blue hue.  


Most of the crowns done at our Brookings dental office are metal free.  The materials used for crowns today such as e.max, zirconia and zirconia fused to porcelain are very strong and cosmetic.  In fact, the technology of these materials is so advanced that these crowns look better than PFMs and mimic natural teeth. Since these materials are tooth colored when manufactured, they require less of the tooth to be removed which decrease the chance of sensitivity and root canals.  

Another disadvantage of conventional porcelain fused to metal crowns is that the porcelain can break away from the metal.  When this happens, the gray and black metal will be very visible. If food traps in the broken area, it can lead to decay and gum disease.  Please see examples of the metal free crowns and veneers done by Dr. Jordan in our Smile Gallery section.  

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