Why Cold Air Makes Some Teeth Hurt (and What Helps)

What's happening inside a sensitive tooth

Underneath the hard outer enamel, teeth are made of a softer layer called dentin, riddled with microscopic channels, dentinal tubules, that run toward the nerve. The leading explanation for tooth sensitivity, the hydrodynamic theory, holds that fluid inside those tubules shifts in response to temperature or pressure changes. Cold pulls that fluid outward, and the shift itself, not the cold directly, triggers the nerve and produces that sharp, brief jolt. Sensitive teeth have been found to have dramatically more of these tubules open and exposed, on the order of eight times as many, and wider, than teeth that aren't sensitive.

Why cold weather specifically brings it out

Breathing cold air through your mouth exposes teeth to a sharper, faster temperature change than most food or drink does, which is why winter often seems to be when sensitivity shows up or gets worse. Teeth with thinning enamel, gum recession that's exposed root surface, or a small crack are the most likely to already have those tubules exposed and ready to react.

What helps

• Breathing through your nose instead of your mouth in cold air cuts down direct exposure.
• A toothpaste made for sensitive teeth works by blocking the tubules (some contain stannous fluoride or similar compounds) or interrupting the nerve signal itself (potassium nitrate is the common ingredient for this). It typically takes a couple of weeks of regular use to notice a difference.
• Going easy on acidic foods and drinks limits further enamel softening in already-sensitive areas.
• A soft-bristled brush and a gentler technique protect against a common cause of gum recession in the first place: overly aggressive brushing.

When it's more than a winter annoyance

An occasional twinge from cold air is common and usually not a sign of anything serious. Sensitivity that's sharp, lingers well after the trigger is gone, or is limited to just one tooth is different. That pattern can point to a cavity, a cracked tooth, or a more significant area of enamel loss, and it's the kind of thing to have looked at instead of switching toothpaste and hoping.