Why are my teeth sensitive to cold?

Cold sensitivity is one of those complaints people live with for years before they mention it. They learn to chew on one side, skip the ice, and breathe through their nose on a cold Hamilton morning. It becomes background noise. But sensitivity is information, and reading it correctly tells you whether you need a different toothpaste or a filling.

What is actually happening inside the tooth

A tooth has three layers. Enamel on the outside is the hardest substance in your body and has no nerves in it. Underneath sits dentine, which is softer and, under a microscope, looks like a bundle of thousands of tiny tubes. Those tubes run inward toward the pulp, where the nerve lives.

As long as enamel covers the dentine, cold never reaches those tubes and you feel nothing. When enamel wears thin, or when the gum pulls back and exposes the root, which never had enamel over it in the first place, the tubes are open for business. Cold makes the fluid inside them shift, the nerve registers that movement, and you get a sharp zing that disappears almost as fast as it arrived.

That quick in-and-out pattern is the signature of everyday sensitivity. Remember it, because it is the main thing separating a nuisance from a problem.

The usual causes

• Receding gums. The most common cause we see. The root surface gets uncovered, and root has no enamel to protect it. This is often tied to gum inflammation, which is why we wrote about gums that bleed when you brush.
• Brushing too hard. A firm brush and a heavy hand wear enamel at the gumline and push the gum back at the same time. It is a double hit, and it is entirely avoidable.
• Acid. Pop, sports drinks, citrus, wine and frequent snacking soften enamel. Reflux and frequent vomiting do the same from the inside.
• Grinding and clenching. Night-time grinding wears through enamel faster than eating ever will. More on that in our article on teeth grinding and night guards.
• Whitening. Temporary sensitivity is normal during and shortly after treatment, and it settles.
• A new filling. A tooth can be touchy for a few days to a couple of weeks afterwards while it calms down.

Your toothpaste choice matters more than most people think here, and we go through it in our guide to choosing the right toothpaste.

When a zing is more than sensitivity

This is the part worth reading twice. General sensitivity affects several teeth, reacts to cold, and stops within a few seconds. A specific problem behaves differently. Call us if you notice:

• One tooth, not several. Sensitivity that has narrowed down to a single tooth usually has a single cause, such as decay or a crack.
• Pain that lingers. If the ache hangs around for 30 seconds or more after the cold is gone, the nerve may be inflamed rather than simply exposed.
• Pain with heat. Reacting to hot drinks, especially with a throb, is a more serious sign than reacting to cold.
• Pain that wakes you up. Toothache at night should always be checked.
• Pain when you bite down. A sharp pain on release often points to a cracked tooth.

Depending on what we find, the fix might be a simple tooth-coloured filling, a crown to hold a cracked tooth together, or root canal therapy if the nerve is already inflamed. Catching it at the twinge stage usually means the smaller of those options. If the pain is severe or swelling has started, that is an emergency dental matter and you should call us the same day.

What actually helps at home

For ordinary sensitivity, these are the changes that make a difference:

• Use a soft-bristled brush and let the bristles do the work. Pressure does not clean better, it just wears things down.
• Use a sensitivity toothpaste as your everyday toothpaste, morning and night. Give it two to four weeks before judging it. Most people quit too early.
• Wait about an hour after anything acidic before you brush. Enamel is softened right after acid, and brushing straight away scrubs it while it is vulnerable.
• Drink pop and juice with a meal rather than sipping through the afternoon. Constant sipping keeps your mouth acidic for hours.
• If you suspect grinding, mention it. A night guard protects enamel that will not grow back.

Regular cleanings and check-ups matter here too. We can spot enamel wear, early recession and a small cavity long before any of them start hurting, and we can apply fluoride to strengthen the areas that are getting thin.

The short version

A quick zing across several teeth that vanishes in seconds is usually exposed dentine, and it responds well to a soft brush, a sensitivity toothpaste and a bit of patience. An ache in one tooth that lingers, throbs, or reacts to heat is a different story, and it will not fix itself. When in doubt, let us take a look. We see plenty of patients from across the Mountain who waited months on a twinge that turned out to be a five-minute conversation and a small filling.