Dark Lines on Porcelain Restorations

Dark Lines on Porcelain Restorations

Porcelain restorations are selected for their aesthetic appeal and natural appearance. The majority of porcelain restorations are dental crowns and veneers, however inlays and onlays can also be fabricated using porcelain. When you select porcelain restorations, you expect the result to be flawless. Which is why the emergence of dark lines around your restoration are a less than desirable complication to your perfect smile. 

PFM crown on mirrored background

However, there are some unfortunate cases where dark lines can appear on porcelain restorations. The most common example of this is with porcelain fused to metal (PFM) restorations. PFM restorations are a type of porcelain restoration that is composed of a porcelain shell that is fused over a metal core. The porcelain layer is the thickest around the visible portion of the tooth, but gets thinner the closer it gets to the gum line. 

When a PFM crown is first placed, the gums should cover up this thin part of the restoration. Over time, however, the gums may begin to recede, or pull away from the tooth. When this happens, the margin between the crown and the natural tooth can show. This unfortunately also means that the metal can usually be visible as well, making it look like there is a dark line at the base of the tooth. 

In some cases, certain types of metal may also bleed into the gums, giving them a tattooed appearance. This is more common in older restorations, since newer PFM crowns use metals that usually do not cause this problem. In other cases, people have been known to develop a metal allergy while wearing the crown, which can result in inflamed gum tissue. Generally speaking, dentists usually recommend replacing the PFM crown with an all-porcelain crown in cases where dark lines or metal allergies have appeared. 

While most cases of dark lines come from PFM restorations, all-porcelain restorations can have the same problem if they are not placed properly. In cases where an all-porcelain dental crown or veneer does not fit the tooth and seal it, staining often occurs along the edges of the restoration and the natural tooth. Not only does this form an unsightly dark line, but it can increase the risk of developing tooth decay underneath the restoration. 

For this reason, it is extremely important to choose the right cosmetic dentist to place a porcelain restoration. An experienced dentist will ensure that the restoration is the proper fit and that it seals the tooth in order to prevent future dark lines and decay. Unfortunately, once a restoration has a dark line, the only way to get rid of it is to remove and replace the restoration. Therefore, it is important that it is done right the first time. You can also help to maintain your restoration by brushing twice a day, flossing once a day, and visiting your dentist every six months for a dental checkup and cleaning. 

Overall, dark lines on porcelain restorations are a visually unappealing complication of PFM restorations or ill-fitted all-porcelain restorations. Once they appear, they cannot be removed unless the restoration is replaced. However, they can be prevented by switching to an experienced cosmetic dentist who can place a properly fitted all-porcelain restoration, and by practicing proper oral hygiene. 

Dr. Alina Huang has been practicing dentistry in Manhattan for the last eight years. She was born in New York City, and raised in California where she received her Bachelor’s degree at UCLA, and her D.D.S. at the University of the Pacific in San Francisco. She then made her return to NYC where she completed her General Practice Residency at Montefiore Medical Center and has been working in private practice ever since. She continues her learning by attending courses to stay current with the latest advancements in dentistry and refine her skills.