Dental crowns are designed to protect damaged or weakened teeth — but what happens if you get a cavity under the crown?
While it may sound surprising, decay can still form underneath a dental crown, especially if the tooth isn’t properly cleaned or sealed over time. Left untreated, it can compromise both the crown and the natural tooth underneath.
Here’s what a cavity under a crown is, how to spot the signs, and what your dentist can do to treat it.
🦷 What Is a Cavity Under a Crown?
A cavity under a crown occurs when tooth decay forms beneath the crown, in the natural tooth structure that supports it. This type of decay is also called recurrent decay or secondary caries.
Because the crown covers the tooth, cavities in this area are not always visible — and they often go unnoticed until you experience pain, sensitivity, or the crown becomes loose.
🔍 What Causes a Cavity Under a Crown?
Even with a crown in place, the tooth underneath is still vulnerable to decay — especially if bacteria are able to sneak in at the margins (where the crown meets the natural tooth).
Common causes include:
- Poor oral hygiene around the crown
- Gum recession, which exposes the crown’s edges
- Microleakage due to old or worn-out cement
- Loose or cracked crowns allowing bacteria in
- High sugar intake and acid exposure
- Lack of regular dental check-ups to monitor crown integrity
Over time, bacteria and plaque can build up at the margin of the crown, eventually leading to decay underneath.
⚠️ Signs of a Cavity Under a Crown
It’s not always easy to detect a cavity under a crown — but keep an eye out for these symptoms:
- Tooth pain or sensitivity (especially to hot, cold, or sweets)
- A persistent dull ache or sharp pain when biting down
- Inflamed or receding gums near the crown
- A dark line or shadow around the crown’s edge
- A loose crown or one that feels “off” when chewing
- Bad breath or bad taste, especially near the crown
- Food consistently getting stuck near the crown
If you notice any of these symptoms, don’t wait — catching the problem early can save your tooth and crown.
🛠 How Is a Cavity Under a Crown Treated?
Treatment depends on how severe the decay is and how much of the natural tooth is affected.
🪥 Mild or moderate decay:
- The crown is carefully removed
- Decay is cleaned out and treated
- A new crown is placed to seal the area and restore strength
🦷 Advanced decay:
If the decay has reached the tooth’s nerve, you may need:
- A root canal
- Possibly a post and core build-up
- A new custom crown after healing
❌ In severe cases:
If the tooth is too damaged to restore, extraction may be necessary — followed by a dental implant or bridge to replace it.
🧼 How to Prevent Cavities Under Crowns
- Brush twice daily with fluoride toothpaste
- Floss gently but thoroughly around the crown (use floss threaders or a water flosser)
- Avoid sticky, sugary foods that cling to crown edges
- Visit your dentist regularly for check-ups and X-rays
- Ask about fluoride treatments or sealants if you’re prone to decay
Routine dental exams allow your dentist to monitor crown margins and catch early signs of leakage or decay.
Final Thoughts
A cavity under a crown might not be visible — but it can cause serious damage if left untreated. With regular dental care and attention to changes in your mouth, you can catch issues early and keep your crown — and your tooth — in good shape.
Noticing discomfort or changes around your crown? We’re here to help. Our team offers gentle, thorough evaluations and advanced treatment options to restore and protect your smile. Book an appointment today and let us take a closer look.