Daily Care
What causes cavities in adults?
21 July 2026 · The Dentist, Al Qusais, Dubai
The short answer
Cavities form when bacteria in plaque feed on sugars and starches and produce acid that dissolves tooth enamel and, over time, the softer dentine underneath. Adults get extra risk factors on top of this: receding gums that expose unprotected root surfaces, drier mouths from medication or age, and old fillings or crown edges that start leaking. A dentist needs to look at any tooth that's sensitive, discoloured, or aches when you bite, since cavities don't reverse on their own.
The basic mechanism: bacteria, acid, enamel
Every mouth has bacteria living in a sticky film called plaque. When you eat or drink anything with sugar or refined starch, those bacteria break it down and release acid as a by-product. That acid strips minerals out of your enamel in a process called demineralisation. Saliva normally fights back by neutralising the acid and redepositing minerals, but if the attacks come faster than saliva can repair, the enamel weakens and eventually a hole forms. Once the acid reaches the dentine beneath the enamel, decay spreads faster because dentine is softer and full of tiny channels leading straight to the nerve.
This is why frequency of sugar exposure matters more than total amount. Sipping a sweet drink over two hours does more damage than eating a dessert in ten minutes, because it keeps the mouth in an acidic state for longer.
Why adults face extra risk that teenagers don't
Gum recession is a big one. As gums pull back with age or due to gum disease, they expose the tooth root, which has no enamel covering it at all. Root surfaces decay faster and the resulting cavities are often felt as sharp sensitivity to cold or sweet foods before they're visible.
Dry mouth is another major factor. Many common medications, blood pressure tablets, antihistamines, antidepressants, reduce saliva flow. Since saliva is the main defence against acid, less of it means faster decay, particularly overnight when flow is naturally lowest anyway.
Old dental work also becomes a weak point. Fillings and crown margins don't last forever. The seal between filling and tooth can shrink or crack after years of chewing forces and temperature changes, letting bacteria sneak underneath where you can't see or clean them. Decay under an old filling can grow for a long time before it causes pain, because the nerve is somewhat insulated by the restoration above it.
Finally, adults tend to snack more than they think, coffee with sugar, fruit, crackers between meals, and often skip the twice-yearly checkups that catch small cavities before they need a root canal.
What actually lowers the risk, and when to get checked
Brushing twice daily with fluoride toothpaste, cleaning between teeth once a day, and cutting down how often (not just how much) sugar you eat all make a real difference. If your mouth feels dry often, chewing sugar-free gum or sipping water through the day helps keep saliva doing its job. If you have receding gums, ask about a fluoride varnish or toothpaste designed for root sensitivity.
The honest reality is that early decay often has no symptoms at all. Pain usually means the cavity has already reached the dentine or nerve. That's why routine checkups and X-rays matter more than waiting for a toothache.
If you're in Al Qusais and it's been a while since your last checkup, or you've noticed a twinge with cold drinks, book the free checkup at The Dentist. Dr. Faris Alkhanafseh or Dr. Mohammad Nour can tell you within one visit whether it's early decay that needs simple monitoring, a small filling, or something that's progressed further, and give you a written plan before any treatment starts.
This article is general information, not a diagnosis. If you are in Dubai, the free first checkup at our Al Qusais clinic is the fastest way to get an answer about your own teeth.