Tooth decay

Decay is not a hole that simply turns up one day. It is a slow process that runs for months and years, starts long before anything hurts, and at its earliest stage can still be reversed. After that comes a point beyond which enamel no longer repairs itself and the damage only goes deeper: decay is not something you get over, and waiting does not settle it. What stands out is that almost everything deciding the outcome is done at home by the person themselves, and there the key is not how much sugar they have in a day but how often.

What is actually happening to the tooth

Teeth are covered by plaque, a thin film made of bacteria. Those bacteria feed on the sugars in food and drink and produce acid in return. The acid draws calcium out of the enamel and the surface of the tooth weakens. Between meals saliva dilutes the acid and puts the minerals back. Decay begins wherever the losses outweigh the repairs.

The first stage looks like a small chalky white patch, usually right at the gum line or in the grooves of the back teeth. The enamel is still intact, there is no hole, and at this point the process can be turned round with fluoride and a change in the pattern of eating. If nothing changes, the weakened surface eventually caves in and a cavity forms. That one does not close up again: enamel cannot rebuild tissue it has lost.

Underneath the enamel lies dentine, which is softer, and decay moves through it noticeably faster, so a small opening on the outside often hides a large cavity inside. Deeper still sits the pulp, the nerve and blood vessels of the tooth; once bacteria reach it, real toothache appears, and after that an abscess at the root.

The signs people notice

The awkward thing about decay is that at the start it does not hurt at all. What should draw attention:

• chalky white patches that turn brown or black over time;
• a short sharp reaction to cold, hot or sweet things — a twinge that passes straight away;
• food starting to pack between two teeth where it never used to, or floss tearing and shredding at the same spot every time;
• roughness, a chipped edge or a pit you can feel with your tongue;
• a bad taste or bad smell that persists after brushing;
• pain on biting down on one particular tooth;
• a dull ache with no trigger, especially at night — that already means a deep cavity.

Something else worth knowing: decay between the teeth and decay under old fillings cannot be seen from outside at all. It is picked up at a check-up and on targeted X-rays, often by chance when someone came in about something else entirely. So "nothing hurts" does not mean "all is well", and pain that has gone away on its own usually signals not recovery but a nerve that has died.

Frequency matters more than quantity

Every time something sweet reaches the mouth, the plaque answers with a burst of acid, and the teeth sit in an acid environment for roughly half an hour until saliva restores the balance. That leads to a conclusion which upsets the usual view of sugar: six sweets eaten in one go after a meal do less harm than the same six spread one at a time through the day. The thing to count is not grams but episodes.

• Sweet and acidic things are better taken at the end of a proper meal than between meals.
• The worst offenders are drinks sipped slowly over a long time: sweetened tea and coffee, juice, fizzy drinks, sports and energy drinks. Between meals, water or unsweetened tea.
• Acidic drinks wear enamel down without any help from bacteria, so sugar-free versions are not harmless either. Better through a straw and not held in the mouth.
• At night there is almost no saliva, and whatever is eaten after the evening brush stays on the teeth until morning.
• Cough syrups, lozenges, chewable vitamins and some antacids contain sugar. For anything taken over a long period, ask for the sugar-free form.
• Sugar-free chewing gum after eating genuinely helps: it drives saliva flow.
• A dry mouth — from medication, mouth breathing or after radiotherapy — speeds decay up sharply. Tell the dentist about it.

Brushing that earns its keep

Technique counts for more than effort here, and a handful of habits that are rarely explained make more difference than the choice of toothpaste.

• Brush twice a day with fluoride toothpaste, and the evening brush is not the one to skip: it should be the last thing that happens in the mouth before sleep.
• Spit the paste out and do not rinse with water. Rinsing washes away the fluoride, which needs to stay on the enamel and keep working. For the same reason, mouthwash goes at another time of day rather than straight after brushing.
• Two minutes, a soft brush, light pressure. Pressing hard with stiff bristles wears the enamel away at the gum line and exposes the root, and it does not clean any better.
• Clean between the teeth once a day with interdental brushes of the right size, or with floss. A toothbrush does not reach in there, and that is where decay most often starts.
• Do not brush immediately after vomiting, reflux or an acidic drink: acid-softened enamel simply gets scraped off. Rinse with water and wait about an hour.
• Whitening pastes and abrasive powders offer no protection against decay. If decay keeps coming back, a dentist can prescribe high-fluoride toothpaste, a gel or a varnish, and those do work.

Children's teeth: where it goes wrong most

Brushing starts when the first tooth appears, and up to school age an adult either does it or goes over it afterwards: until then children do it badly, however confident they look.

• Fluoride toothpaste is needed from the very beginning, in an amount matched to age: a smear the size of a grain of rice for the youngest, a pea-sized amount at nursery age. Teach them to spit and not to rinse.
• No bottle of sweet drink at bedtime. Juice, squash, sweetened milk or tea sucked in the cot is the commonest cause of early destruction of the front teeth. At night and for settling, the bottle holds water only, and the bottle itself is gradually swapped for a cup around the first birthday.
• Do not suck the dummy clean or taste food off the child's spoon: bacteria pass from adult to infant. It is worth the adults in the household having their own teeth sorted out.
• Honey, jam or syrup on a dummy is a direct route to decay.
• Baby teeth get treated. "They will fall out anyway" is an expensive mistake: it ends in pain, in an abscess, in the loss of the space held for the adult tooth, and in years of fear of the dentist.
• At the practice, children have fluoride varnish applied and the grooves of the adult back teeth sealed soon after they come through. The first visit belongs in the first or second year of life, and after that at the intervals the dentist sets.

When help is needed, and how fast

See a dentist the same day if:

• the pain is constant and throbbing, wakes you at night, or does not settle with an ordinary painkiller;
• pain triggered by something hot lasts more than a minute after the stimulus is taken away;
• the gum is swollen, a tender lump has appeared on it, or pus is discharging;
• the cheek has swollen, there is a taste of pus and a temperature has come up — that is how an abscess presents.

Call an ambulance straight away (across Europe the emergency number is 112) if the swelling spreads under the jaw, into the neck or towards the eye, if swallowing, opening the mouth, speaking or breathing becomes difficult, if the voice changes, or if there are shivers, confusion or severe weakness. Swelling like that presses on the airway and is treated in hospital, not in a dental chair. It does not wait until morning.

A few more things that come up constantly. Painkillers and antibiotics do not cure an abscess, they only buy time: the pus has to be let out. A painful cheek is not warmed, because heat drives the infection along. Nor is a tablet placed against the tooth or gum — aspirin burns the lining that way. And an adult tooth knocked out whole is a separate emergency: the attempt to put it back in its socket belongs in the first hour.

What the dentist can do

Treatment depends on how far things have gone, and the range is wide.

• An early white patch does not need a drill yet: it is covered with fluoride varnish, a high-concentration paste is prescribed, and it is kept under review.
• A cavity that has formed is closed with a filling.
• If decay has reached the pulp, the tooth is treated through the root canals and then usually covered with a crown, because the walls are left brittle.
• A tooth beyond saving is taken out, and how the gap will be filled is discussed in advance.

The gap between check-ups is set by the dentist and differs from person to person: one may only need a visit once a year, while someone at high risk goes every three or four months. X-rays showing the spaces between teeth are taken when indicated, not at every appointment. No home remedy stops decay, and the most expensive treatment almost always ends up with the person who kept putting off the appointment while they put up with it.

Online consultation

A filling cannot be placed remotely, and no one can examine a tooth with instruments over video: decay itself is only treated in person. What an online appointment does settle is the question that worries people most — what kind of pain this is and how urgent it is, whether it is safe to wait for an appointment or whether today is the day to go in. The doctor goes through the signs of an abscess and of the swelling that needs an ambulance, helps rebuild the routine of cleaning and eating when decay keeps returning, and talks through dry mouth from medication, children's teeth and fear of treatment. The urgent signs listed above are not assessed remotely — with those you seek help immediately.

This material is for information only and does not replace medical advice.