In professional cosmetic dentistry practices, this black line should never occur in patients that have porcelain crowns or veneers. However, a common apprehension amongst new patients that I meet is concern surrounding the emergence of a dark line around their current porcelain crowns. This black line is often the source of their fear of getting more porcelain veneers and crowns, as they are sceptical of additional black lines developing.
The reasons for the emergence of black lines and what is done to avoid getting them is outlined below.
- Metal-based porcelain crowns In older practices, porcelain crowns are created using a metal foundation that is silver coloured. This base was used because it provides durability to the porcelain and aids in the avoidance of fractures when attached to the tooth. However, eventually the porcelain wears and becomes thinner, enabling the metal colour to reflect through the teeth. Although the crown was visually appealing to start with, over years, the dark line emerges, coinciding with the gum’s recession.
- Cheaper non-precious metals used. It is common that these more traditionally made crowns comprise of a metal base that is formed from inexpensive, non-precious metals, such as tin. However, these metals have an increased likeliness of spreading out and staining the edges of your gum (the black line). In some cases, people have also been known to have allergic reactions to the metals over time, causing the gums to become swollen and irritated, with a bluish tinge.
- Ill-fitting Porcelain crown
If the porcelain crown was not fitted or sealed correctly, it is inevitable that staining will form at the edges of the teeth. This can ultimately harm the tooth below the crown by enabling plaque and bacteria to form, initiating deterioration. At our practice, we ensure that all dentists are extremely precautious and perform their tasks meticulously to prevent these situations. We also avoid using metal-based crowns to ensure that black lines will never appear. At our practice, we use more modern porcelains that are resilient and are bonded to the teeth, rather than cemented. This ensures that the porcelain is more sturdy and hard-wearing and lessens the possibility of fractures. When we bond the porcelain crowns or veneers, we are also extremely careful in generating a glass-like appearance against the tooth, which lessens tooth staining and avoids leakages under the teeth.
More contemporary porcelains are extremely durable & bonded to teeth, rather than cemented, which gives strength to porcelain and avoids the possibility of fractures
When bonding porcelain crowns or veneers, we are meticulous & fastidious in creating a glass-like finish against the tooth which both minimises staining at tooth edges & prevents seepages under the teeth.