8 Warning Signs You Might Have a Cavity Under Your Filling

A cavity under an old filling may start small but can lead to bigger problems if left untreated. The challenging part is that it often hides in plain sight. Recognising the early signs can help you act quickly and protect your smile.

1. Sensitivity to Hot, Cold, or Sweet Foods

If a once-comfortable tooth suddenly twinges when you sip something cold or bite into a sweet treat, it could be more than just a one-off. Temperature or sugar sensitivity is a common sign of decay beneath a filling.

2. Persistent or Throbbing Tooth Pain

Ongoing discomfort—especially a dull ache or pulsing pain—may suggest a cavity is forming under your restoration. Don’t ignore pain that lingers for more than a day or two.

3. Visible Dark Spots or Staining Around the Filling

Discolouration near or around a dental filling could mean bacteria are making their way in. Even a small spot might point to a deeper problem beneath the surface.

4. Cracks or Damage in the Filling

While today’s fillings are highly durable, they don’t last forever. A tiny crack can create the perfect entry point for bacteria, leading to tooth decay below.

5. Bad Breath or Unpleasant Taste

If brushing and flossing aren’t addressing your bad breath, or you’ve noticed a strange taste that won’t go away, decay under a filling could be the culprit.

6. Swelling or Tenderness Around the Gum

Gums that feel sore, look swollen, or bleed near a filled tooth may be reacting to deeper decay. It’s your body’s way of signalling that something isn’t right.

7. Changes in Bite or Tooth Shape

If your bite suddenly feels “off” or a filled tooth appears slightly misshapen, it may be a sign that decay is weakening the tooth’s structure.

8. Loosening of the Filling

Does your filling feel like it’s shifting or not sitting quite right? That’s a definite red flag. A loose filling can let bacteria in and accelerate tooth damage.