Tooth decay is the gradual destruction of the tooth by acids produced when bacteria in plaque feed on sugar. It starts as a white spot on the enamel, which can still be reversed with fluoride, and progresses to a cavity, then to the nerve. Early decay needs a small filling; late decay may need root canal treatment or extraction, so regular check-ups matter.
What causes tooth decay?
Decay needs four things at the same time: a tooth surface, bacteria, sugar and time.
- Bacteria living in dental plaque, the sticky film that forms on teeth every day, digest sugars and starches from food and drinks.
- They produce acids that dissolve minerals from the enamel, the outer layer of the tooth.
- Saliva neutralises those acids and helps repair the enamel, but only if it gets enough time between sugar intakes.
- When acid attacks are too frequent, mineral loss wins and the tooth slowly breaks down.
How often you eat or drink sugar matters more than how much. Sipping sweet tea, juice or soft drinks throughout the day, or snacking constantly, keeps teeth in an acid bath for hours.
Who is most at risk?
- People who snack or drink sugary drinks often
- People who brush irregularly or without fluoride toothpaste
- People with a dry mouth, caused by some medicines, smoking, mouth breathing or certain medical conditions
- Teeth with deep grooves, crowded teeth and old fillings with gaps, where plaque hides
- Children and teenagers, whose enamel is younger and whose diets are often sweeter
- Older adults with receding gums, as exposed roots decay faster than enamel
Decay in children has its own particularities; our guide to preventing tooth decay in children covers them in detail.
The stages of tooth decay
| Stage | What happens | Symptoms | Usual treatment |
|---|---|---|---|
| 1. White spot | Enamel loses minerals but the surface is intact | None | Fluoride, better cleaning, less sugar: can be reversed |
| 2. Enamel decay | A small hole forms in the enamel | Usually none | Small filling |
| 3. Dentine decay | Decay spreads faster in the softer dentine | Sensitivity to sweet, cold or hot | Filling, sometimes inlay or crown |
| 4. Nerve involvement | Bacteria reach the pulp | Lingering or throbbing pain | Root canal treatment or extraction |
| 5. Abscess | Infection spreads beyond the root | Pain on biting, swelling | Root canal treatment or extraction, drainage |
The key message: decay is silent for a long time. By the time it hurts, it is usually in the dentine or deeper. This is why check-ups every six months are so effective, because the dentist finds decay at stages 1 to 3, when treatment is simpler.
Signs of tooth decay you may notice
- A white, brown or black spot or a visible hole in a tooth
- Food getting stuck in the same place
- Sensitivity to sweet, cold or hot
- A sharp pain when biting
- Bad breath or a bad taste
- A rough edge felt with the tongue
Dark lines in the grooves of back teeth are not always decay; they can be stains. Only an examination, sometimes with an X-ray, can tell the difference. Decay between teeth is often invisible without an X-ray.
How tooth decay is treated
Reversing early decay
At the white-spot stage, the enamel can rebuild minerals. Fluoride toothpaste, sometimes a stronger fluoride varnish applied by the dentist, better cleaning and fewer sugar intakes can stop the lesion.
Fillings
Once there is a cavity, the decayed tissue is removed under local anaesthesia if needed, and the tooth is rebuilt with a tooth-coloured composite filling. Our article on composite fillings explains the procedure.
Inlays, onlays and crowns
When decay has destroyed a large part of the tooth, a laboratory-made inlay, onlay or crown may be stronger and longer-lasting than a very large filling.
Root canal treatment or extraction
When decay reaches the nerve, the pulp becomes inflamed or dies. Root canal treatment allows the tooth to be kept; extraction is the alternative when the tooth cannot be restored.
How to prevent tooth decay
- Brush twice a day for two minutes with a fluoride toothpaste, spit but do not rinse afterwards. See our guide to brushing your teeth correctly.
- Clean between your teeth daily with floss or small interdental brushes.
- Limit how often you have sugar: keep sweets and sweet drinks to mealtimes rather than spreading them through the day.
- Drink water between meals, and avoid sweet drinks at bedtime.
- Chewing sugar-free gum after meals stimulates saliva.
- Have check-ups and professional cleaning at the interval your dentist recommends.
- Ask about fissure sealants for children’s back teeth.
What does decay treatment cost?
The cost depends on the stage at which decay is found. A small filling is quick and inexpensive; a root canal treatment followed by a crown involves several visits and costs considerably more. The most economical approach is almost always early detection. The exact cost of your treatment depends on the tooth, the extent of the decay and the material chosen, and is explained after an examination.
Treating and preventing decay at Ajam Dental Clinic, Tripoli
At Ajam Dental Clinic, Fouad Chehab Boulevard, Al-Makateb Building, 1st floor, Tripoli, we check for decay, explain what we find and what can wait, and treat cavities with tooth-coloured fillings, inlays, onlays or crowns as needed. Children’s care is provided by Dr. Soumaya Ajam, who holds a university diploma in paediatric dentistry. Learn about our preventive care and contact us by WhatsApp or phone to book a check-up.
Frequently asked questions
Can tooth decay be reversed?
Only at the very earliest stage, the white spot, when the enamel surface is still intact. Fluoride, better cleaning and fewer sugar intakes allow the enamel to rebuild minerals and the lesion can stop. Once a real hole has formed, the tooth cannot grow back: the decayed part has to be removed and replaced with a filling or another restoration.
How fast does tooth decay progress?
It varies a lot. Decay in enamel can take months or even years to progress, while decay in the softer dentine, or in children's teeth, can advance much faster. Diet, cleaning, saliva and fluoride all influence speed. Regular check-ups catch most lesions while they are still small.
Why does a decayed tooth suddenly stop hurting?
Sometimes the nerve dies after a period of inflammation, and the pain stops. This is not good news: the dead nerve can become infected and lead to an abscess, sometimes with swelling. A tooth that hurt and then suddenly became painless should still be examined.
Is tooth decay contagious?
The bacteria involved in decay can be passed from person to person, for example from parent to child through shared spoons. But decay itself only develops when those bacteria have frequent access to sugar on poorly cleaned teeth. Good habits in the family matter more than avoiding every contact.
Are dark lines on my back teeth always decay?
No. The grooves of back teeth often pick up stains from tea, coffee or food, which are harmless. Decay may look similar, though, and decay under the surface can be larger than it appears. A dentist can distinguish the two with a careful examination and, if needed, an X-ray.
Does sugar-free mean safe for teeth?
Sugar-free products do not feed decay bacteria the way sugar does, so sugar-free gum and drinks are better choices. However, many sugar-free soft drinks and juices are still acidic and can erode enamel. Water remains the best drink between meals.
Have a question about your teeth?
Send a WhatsApp message to Dr. Abdel Rahman Ajam or Dr. Soumaya Ajam, or call the clinic to book a consultation.
This article provides general information for patients. It does not replace an examination by a dentist, who can advise you on your own situation.
