Discovering a dark or black discoloration under a dental crown is a common concern. Understanding its potential causes and appropriate solutions is important for maintaining oral health.
Common Reasons for Discoloration
Recurrent Decay
Recurrent decay is a frequent cause of black discoloration under a crown. Bacteria can infiltrate the small gap between the crown and the natural tooth, leading to new cavities. This process often occurs silently but can darken the underlying tooth structure.
Crown Leakage or Marginal Gap
An imperfect seal between the crown and tooth allows bacteria, food particles, and fluids to seep underneath. This accumulation can lead to decay or staining of the underlying tooth structure.
External Staining
Pigments from foods, drinks like coffee and tea, or tobacco can penetrate small crevices around the crown, staining the tooth structure visible at the margin or seeping underneath.
Crown Material
The dark appearance can also be due to the crown material itself, especially with older porcelain-fused-to-metal (PFM) crowns. These have a metal base, and if gums recede, the dark metal margin can become visible. The metal may also show through if the porcelain chips or wears away.
Internal Tooth Discoloration
Internal tooth discoloration can become noticeable under a translucent crown. This can result from past tooth trauma or a root canal procedure, which may darken the internal tooth structure over time. Remnants of old filling materials under the crown can also contribute to a dark appearance.
What to Do Next
Professional Consultation
Discovering black discoloration under a dental crown requires a professional dental consultation. Self-diagnosis is unreliable; a dentist can accurately determine the cause through a comprehensive examination.
Examination and Diagnosis
During a dental visit, the dentist will conduct a visual examination of the crown and surrounding gum tissue. They may use a dental probe to check for gaps around the crown’s margin. X-rays are routinely taken to detect underlying decay, infection, or structural issues not visible to the naked eye.
Treatment Options
Treatment options vary depending on the diagnosis:
If recurrent decay is present, the old crown is typically removed, the decay treated, and a new crown or filling placed.
For crown leakage or marginal gaps, replacing the crown is often necessary to establish a proper seal.
Surface staining might be addressed with professional cleaning and polishing.
If discoloration is due to metal showing through from a PFM crown or internal tooth discoloration, aesthetic replacement with an all-ceramic crown might be an option.
In cases of extensive decay reaching the tooth’s pulp, a root canal treatment may be required before a new crown can be placed.
Preventing Future Issues
Oral Hygiene
Maintaining consistent oral hygiene is fundamental to preventing future issues with dental crowns. Brushing twice daily with fluoride toothpaste and flossing once a day, paying close attention to the area around the crown margin, helps remove plaque and food debris. This practice minimizes the risk of bacterial accumulation and decay.
Regular Dental Check-ups
Regular dental check-ups are also important for early detection of any potential problems. These routine visits allow the dentist to monitor the condition of the crown and the underlying tooth, and professional cleanings can remove hardened plaque and surface stains. Early intervention can prevent minor issues from becoming more complex.
Dietary Habits and Crown Material
Dietary habits also play a role in maintaining crown health. Limiting the consumption of sugary foods and acidic drinks can reduce the risk of tooth decay around the crown. When considering future crown placements, discussing material options, such as all-ceramic crowns, with the dentist can help achieve desired aesthetic outcomes and potentially reduce visible discoloration.