It’s a common question we hear at dental clinics across Canada: “If I already have a filling, can I still get a cavity in that tooth?”
The short answer is: yes — cavities can form under or around existing fillings.
Here’s why it happens, how to spot the signs, and what you can do to prevent it.
🦷 First, What’s a Filling Supposed to Do?
A dental filling is used to restore a tooth that has been damaged by decay. Your dentist removes the decayed part of the tooth and fills the space with a material like composite resin, amalgam, or ceramic. This protects the tooth from further damage and helps it function like normal again.
But like anything else in your mouth — fillings aren’t permanent. Over time, wear and tear, bacteria, or even your daily habits can affect how well they hold up.
🕳️ Yes, Cavities Can Form Under Fillings — Here’s How:
- Leaky Fillings: Over time, a filling can begin to separate slightly from the tooth, creating tiny gaps. Bacteria can sneak into these spaces and cause decay beneath the surface.
- Worn or Cracked Fillings: Just like natural teeth, fillings can wear down, crack, or chip. These changes create opportunities for bacteria to get in.
- Poor Oral Hygiene: If plaque and food particles aren’t properly cleaned away, even teeth with fillings are at risk of decay — especially around the edges of the restoration.
- Secondary Decay (Recurrent Caries): This is the term dentists use when new decay forms around or under an existing filling. It’s one of the most common reasons fillings need to be replaced.
🚨 Signs You Might Have a Cavity Under a Filling
- Tooth sensitivity (especially to hot, cold, or sweets)
- A persistent toothache or dull pain
- Feeling like the filling is “loose” or doesn’t fit right
- Discolouration around the edge of the filling
- Food constantly getting stuck in the same spot
Note: Sometimes, you might not feel anything at all — which is why regular dental checkups are so important.
🦷 How Dentists Detect Cavities Under Fillings
During your routine exam, your dentist may use:
- X-rays to check beneath the filling
- Visual and tactile exams to spot cracks, gaps, or wear
- Special tools or lights to detect decay around the edges
If decay is found, the old filling may need to be removed and replaced — sometimes with a larger filling, or even a crown, depending on the damage.
🛡️ How to Prevent Cavities Under Fillings
- Brush twice daily with fluoride toothpaste
- Floss every day to clean between teeth and along the gumline
- Limit sugary snacks and drinks, especially between meals
- Visit your dentist regularly for cleanings and exams
- Replace worn fillings as recommended by your dental team
🇨🇦 A Canadian Note
In Canada, most dental insurance plans cover regular checkups and X-rays — and early detection can save you the cost and discomfort of more complex treatment down the road.
Need a Filling Checked?
If you’re concerned about an old filling or think you might have a cavity forming underneath, don’t wait. At [Clinic Name], our experienced team in [City, Province] can assess the health of your fillings and provide fast, gentle care if treatment is needed.
👉 Book your appointment today — your smile deserves regular maintenance, too!