I had my six-month dental exam and cleaning last week, and it was time for X-rays. The dentist told me that my upper left lateral incisor has decay inside it and needs a root canal. I’m struggling to understand this because the tooth has never been filled, crowned, or otherwise treated. It doesn’t hurt, and I can’t see any signs of a cavity or external damage.

Also, my X-rays from last year showed no issues, at least according to my previous dentist. The tooth protrudes slightly and doesn’t contact my lower teeth when I chew. Interestingly, my dentist referred me to an endodontist who shares the same uncommon last name as my dentist. I’m suspicious. Can I have a decayed tooth without any visible signs on the outside of the tooth? Thanks. Hannah

Hannah,

Decay doesn’t originate inside a tooth. It always starts on the outer surface and progresses inward. Once bacteria reach the pulp, infection follows, often requiring root canal treatment.

If your dentist mentioned damage that appears to start internally, they may be describing something other than decay.

Understanding Internal Resorption

Internal resorption is an uncommon inflammatory condition in which the pulp begins to dissolve the tooth structure from the inside. Dentists don’t fully understand why it occurs, but irritation to the pulp seems to be a contributing factor.

In the absence of decay, trauma sometimes explains that irritation. A tooth that protrudes slightly may absorb more force over time. Even so, this diagnosis is rare, which makes confirmation essential.

How to Confirm the Diagnosis

Before moving forward with treatment, consider a second opinion from an endodontist. This step helps remove bias and increases diagnostic accuracy.

To do that effectively:

• Obtain copies of your X-rays.
• Avoid sharing prior diagnoses or dentist names.
• Let the specialist interpret the images independently.

The Importance of X-Ray Angles

External root resorption can look very similar to internal resorption on a single X-ray. Taking images from significantly different angles often reveals whether the defect lies inside the root or on the outer surface.

Plano, Texas, female dentist Dr. Miranda Lacy sponsors this post.