Caries, gingivitis and periodontitis: the lesion view
- Lesion
Plaque bacteria make acid that dissolves enamel (caries) and inflame the gums (gingivitis); unchecked, this destroys the tooth's support (periodontitis).
What it is
The mouth holds a complex microbiome; when its balance shifts, plaque biofilm causes the two commonest oral diseases. Caries is focal demineralisation of enamel and dentin by acids from bacterial fermentation of sugars; it is the main cause of tooth loss in young people. Gingivitis is reversible inflammation of the gums from plaque and calculus; periodontitis destroys the periodontal ligament, cementum and alveolar bone.
Structure
- Caries: chalky white spot in enamel that becomes a brown cavity; dentin softens as tubules fill with bacteria.
- Gingivitis: hyperemic, edematous gingiva with a dense infiltrate of neutrophils, lymphocytes and plasma cells.
- Periodontitis: deepened pockets, apical migration of the junctional epithelium, chronic inflammation, osteoclastic resorption of alveolar bone.
- Periapical lesion: granulation tissue or an epithelium-lined radicular cyst at the root apex.
Step by step
- Bacteria form a sticky biofilm (plaque) on the teeth when hygiene is poor.
- Frequent dietary sugar is fermented into organic acids that drop the pH at the tooth surface.
- Acid dissolves hydroxyapatite: demineralisation outpaces remineralisation and a cavity forms.
- At the gum margin, plaque toxins trigger inflammation (gingivitis).
- If dysbiosis persists, host neutrophils, cytokines and RANKL-driven osteoclasts destroy ligament and bone (periodontitis).
- The tooth loosens and is lost; bacteria can enter the blood during chewing or procedures.
Gingivitis vs periodontitis
| Feature | Gingivitis | Periodontitis |
|---|---|---|
| Tissue involved | Gingiva only | Ligament, cementum, alveolar bone |
| Bone loss | None | Yes, radiographic |
| Pockets | None or false pockets | True pockets with attachment loss |
| Reversibility | Reversible | Irreversible damage |
| Outcome | Bleeding gums | Tooth mobility and loss |
Clinical notes
- Caries and periodontitis are largely preventable with fluoride, sugar reduction and daily hygiene.
- Periodontitis is linked with poorly controlled diabetes in both directions.
- Dental caries remains very common in Colombia, including in pregnant women and children.
Test yourself
Think of the answer, then tap the question to see it.
What causes dental caries?
Focal demineralisation of enamel and dentin by acids produced when plaque bacteria such as Streptococcus mutans ferment dietary sugars.
What separates periodontitis from gingivitis?
Periodontitis destroys the supporting structures (periodontal ligament, cementum, alveolar bone) with attachment loss; gingivitis is limited to the gums and reversible.
How does fluoride protect teeth?
It is incorporated into enamel as fluoroapatite, which resists acid dissolution better than hydroxyapatite.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Dental Caries (StatPearls (NCBI Bookshelf), 2025); Periodontitis (StatPearls (NCBI Bookshelf), 2025); Gum Disease (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.