Dark Lines on Porcelain Restorations

Dark Lines on Porcelain Restorations

After having cosmetic dental treatment, you may be expecting your smile to look perfect forever. While cosmetic dental treatments do have varying lifespans that are generally about a decade, it is important to realize that the aesthetics of these treatments will diminish over time, meaning that they will eventually need to be replaced. One common indication that you may need to have your cosmetic restoration replaced is a dark line that appears near the gums. 

porcelain fused to metal crown on mirrored background

Dark lines are often associated with porcelain restorations, specifically those that include metal. Porcelain fused to metal (PFM) restorations have a metal interior with porcelain fused over the top, while all-porcelain restorations are composed entirely of porcelain. PFM is commonly used to fabricate dental crowns or bridges, while all-porcelain is often used for dental veneers. Nevertheless, both of these restorative materials can be susceptible to dark lines. 

Generally speaking, the vast majority of dark lines can be attributed to PFM restorations. This is because the dark lines are actually the metal showing. Even though PFM restorations have a porcelain exterior, this exterior becomes thinner the closer it gets to the gum line. This ultimately means that the metal is easily visible towards the bottom of the restoration. Although this is not noticeable when the crown is first placed, as the years pass and gum recession occurs, the metal will slowly be exposed and form a dark line along the gums. 

In addition to simply being visible, certain types of metals can “bleed” into the gums and give them a tattooed appearance. Depending on the individual, metal coming in contact with the gums may also cause inflammation, as well as an allergic reaction. Not only do inflamed gums pose a threat to your oral health, but they are also not visually appealing. 

all porcelain crowns

The simple solution to the problem of dark lines caused by PFM crowns is to simply have them removed and replaced with all-porcelain crowns. Since all-porcelain crowns do not use metal, they are unable to produce the same staining, will not inflame the gums, and will maintain an overall more aesthetic appearance for a longer period of time. 

However, there are some rare cases where all-porcelain restorations can also develop dark lines. In these cases, the dark lines are not caused by metal exposure, rather they occur as a result of poor-fitting restorations that allow pigments to accumulate around the edges. Not only does this look bad, but it can damage the underlying tooth. 

For this reason, it is highly recommended to do your research when choosing a cosmetic dentist. You will want to find a cosmetic dentist who is experienced in placing all-porcelain restorations, so that they can provide you with the correct type of restoration, dental materials, and fit. 

Overall, dark lines should not be a part of your cosmetic dental treatment. To minimize their appearance, you will want to avoid PFM restorations, as well as inexperienced cosmetic dentists that are unable to correctly place an all-porcelain restoration. 

Photo of Dr. Admar

Dr. Admar holds dual certificates — a Bachelor of Dental Surgery (BDS) in 2010 from India and a Doctor of Dental Surgery (DDS) in 2014 from Canada. He is now a full time practicing dentist in Kamloops where he provides a variety of services. Dr. Admar spends hundreds of hours in continued dental education to stay up to date in cosmetic and implant dentistry and he has achieved several advanced qualifications.

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