Warning signs
Sensitivity to sweet, cold or hot, a brown or black spot, a hole where food gets stuck, pain when chewing. Many cavities cause no symptoms at all: they are found at a check-up or on an X-ray, between two teeth.
The treatment
Under local anaesthetic, the decayed part of the tooth is removed, and the cavity cleaned and disinfected. It is then filled with composite, a resin whose shade is chosen to blend with the tooth. It usually takes 20 to 45 minutes depending on the size of the cavity.
When decay is very extensive, a stronger laboratory-made restoration (inlay, onlay or crown) may be better to protect the tooth.
Afterwards
Avoid eating while your lip and cheek are still numb, so you don't bite yourself. Slight sensitivity to cold can last a few days. If the tooth feels "too high" when you close, come back: a few seconds' adjustment fixes it.
Stopping it coming back
Brush twice a day with fluoride toothpaste, floss or use interdental brushes every evening, snack and sip sugary drinks less between meals, and have a yearly check-up. Cavities form mostly when you eat or drink sugar often during the day, more than from the total amount of sugar.
Frequently asked questions
Does treating a cavity hurt?
No: the tooth is numbed. You only feel vibration and pressure.
Are grey amalgam fillings still used?
At the practice, cavities are treated with tooth-coloured composites. An old amalgam in good condition doesn't need replacing; it's changed if it cracks or decay starts again underneath.
Can a cavity heal on its own?
No. Very early decay limited to the enamel surface can sometimes be stopped with fluoride, but once there's a hole, it needs treating.