Dental caries
How bacteria in dental plaque turn dietary sugar into acid, how repeated acid attacks dissolve enamel faster than saliva and fluoride can repair it, and how decay spreads through dentine to inflame the pulp and cause abscesses.
By the end, you can
- Describe the structure of enamel, dentine and pulp, and the protective role of saliva.
- Explain how plaque bacteria ferment sugars to acid and why the frequency of sugar matters.
- Explain the balance between demineralisation and remineralisation, and the role of fluoride.
- Explain how caries progresses through dentine to cause pulpitis and an abscess.
- Relate sensitivity, toothache and swelling to the stage of caries.
- Recognise the zones of a carious lesion, how caries is classified and detected, and explain how fluoride, sealants, restorations and root canal treatment act on the process.
What it is
Dental caries is the localised destruction of tooth tissue by acid produced when bacteria in dental plaque ferment dietary sugars. It is a dynamic process of mineral loss and gain: early lesions can be reversed, while cavities that reach the dentine and pulp cause pain and infection. It is the most common non-communicable disease worldwide.
3 types to tell apart
- Enamel caries
- Begins as a white spot of subsurface demineralisation, which can remineralise.
- Dentine caries
- Spreads faster through softer dentine towards the pulp; usually forms a cavity.
- Root caries
- On exposed root surfaces after gum recession, more common in older adults.
Normal function
Enamel, dentine, pulp and saliva
, the hardest tissue in the body, is about 96% mineral, mostly crystals of hydroxyapatite. It has no cells and cannot regrow, but its surface constantly exchanges minerals with saliva.
Beneath it, is softer and less mineralised, and is crossed by microscopic tubules containing extensions of cells that line the . The pulp, entering through the , contains nerves and blood vessels and can lay down new dentine in response to irritation.
Saliva washes away food, buffers acid with bicarbonate and phosphate, and is supersaturated with calcium and phosphate, which replace mineral lost from enamel. A thin protein film (the pellicle) coats the tooth, and bacteria attach to it to form dental plaque.
Underlying change · Step 1 of 4
Plaque bacteria make acid from sugar
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 2 of 4
Enamel loses mineral faster than it regains it
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 4
Decay reaches dentine and pulp
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 4 of 4
Infection beyond the tooth
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .