When clients come to see us for a consult, one of their biggest concerns is the dark line around the edge of their existing porcelain crowns. They are also concerned that, if they receive more porcelain crowns and veneers, eventually they will see the same dark, ugly line around them. This is something that should not happen, or even be anticipated, when considering any type of cosmetic dentistry that involves porcelain crowns or veneers. So, let’s go over the reasons why these dark lines appear, and what we do at Dental Arts Hawaii to avoid them:
- 1) Metal-based porcelain crowns
Traditionally, porcelain crowns are made with a silver-colored metal base. This base is used because, when cemented to the tooth, it gives strength to the porcelain and helps prevent fractures. Unfortunately, as it reaches the gumline, the porcelain gets thinner and thinner; eventually, the metal base will reflect through. The crown may look good initially. But as the gum recedes throughout the years it exposes the thinner section of the porcelain, and the dark lines appear again after years of use.
- 2) Cheaper non-precious metals used
Many times these traditional crowns have a metal base made of cheaper, non-precious metals, such as tin. These metals can eventually leach out and tattoo the gum edges – and, once again, a dark line will appear. Worse yet, many people develop are allergy to these metals over time, and the gums become inflamed and bluish in appearance at the edges.
- 3) Ill-fitting Porcelain crown
If the porcelain crowns do not completely fit the tooth or seal it well, staining will eventually accumulate at the tooth’s edges. This is not just a dark-line-issue at this point; it can eventually damage the the underlying tooth by allowing bacteria and plaque to start the process of decay.