I’ve had a crown on my first molar on the upper left for three years. After my yearly exam last month, the dentist said that my X-ray showed a cavity. She showed me the X-rays on the monitor in the treatment room. However, the dentist could not explain why I had a cavity. My dentist plans to remove the crown and decay and place a new crown. Dental insurance won’t provide any coverage for the crown. Why do I have a cavity in a tooth beneath a crown anyway? What caused it? Thanks. Marie from NJ

Marie,

Dental insurance companies will only pay for a replacement crown if your current one is at least five years old. However, a high-quality crown can last ten years or longer. Although decay will not affect your dental crown, bacteria can leak in, causing a cavity in the tooth beneath the crown.

What Causes a Cavity Beneath a Crown?

If a crown is damaged, loose, or has a gap between the tooth and crown, bacteria can enter the space and cause tooth decay.

• Damaged or loose crown – Trapped bacteria beneath a crown can lead to decay.
• Loose margin — If the crown and tooth do not fully meet, bacteria can leak, causing plaque and decay.

What Is the Treatment for a Cavity Beneath a Crown?

Treating a cavity beneath a crown includes removing the crown, cleaning the tooth, filling the cavity, and replacing the crown with a new one. Untreated decay can spread and increase the risk of tooth loss. Please do not ignore a cavity in a tooth beneath a crown.

Get a Second Opinion

If you are dissatisfied with your dentist’s diagnosis of a cavity beneath your crown or the treatment plan, you can get a second opinion from a skilled cosmetic dentist.

Metairie, Louisiana, dentist Dr. Duane Delaune sponsors this post.