Glass ionomer cements
- Dental material
Glass ionomer sticks to the tooth by itself and releases fluoride. Weaker than composite but forgiving: good for children, root caries and community care.
What it is
Glass ionomer cement sets by an acid–base reaction between a fluoride-containing glass powder and a polyacrylic acid liquid. It bonds chemically to enamel and dentine by exchanging ions with the tooth's calcium, so it needs no separate adhesive. It releases fluoride and can take it up again from toothpaste and varnish. Resin-modified versions add light-cured resin for faster setting and better strength.
Composition and properties
- Chemical adhesion to tooth; expands with heat much like the tooth itself, so margins stay sealed.
- Fluoride release helps protect the tooth around the filling.
- Lower strength and wear resistance than composite: not for large load-bearing fillings in adults.
- Sensitive to moisture and drying in the first minutes: it is protected with a coating after placement.
- Uses: ART, primary teeth, root and cervical caries, liners and bases, luting crowns, and sealants where isolation is poor.
Uses, limits and safety
- In patients who cannot keep a dry field (young children, older adults, special needs) it often outlasts composite.
- Not a good choice for the edges of front teeth or large cusp replacements because it chips and wears.
- Its fluoride release is a bonus, not a substitute for diet and hygiene changes.
Next step / Initial management
- High-caries child or older adult with many lesions: glass ionomer restorations or ART as part of a caries-control plan.
- Root caries in a patient with dry mouth: glass ionomer plus fluoride and saliva advice.
- Repeated loss or fracture of glass ionomer fillings in load-bearing areas: refer to the dentist to review the material.
Test yourself
Think of the answer, then tap the question to see it.
How does glass ionomer bond to tooth?
Chemically, by ion exchange between its polyacrylic acid and the calcium of enamel and dentine.
In which two clinical situations is glass ionomer a good choice?
Any two of: ART, primary teeth, root or cervical caries, a liner or base, luting, sealants where isolation is poor.
What is its main limitation compared with composite?
Lower strength and wear resistance, so it is not used for large load-bearing restorations in adults.
Connections
In Pharmacology1
Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.
Sources: Glass Ionomer Cement (StatPearls Publishing (NCBI Bookshelf), 2024); Twenty-five-year atraumatic restorative treatment (ART) approach: a comprehensive overview (Clinical Oral Investigations (PMC open access), 2012); Failure Risk of Composite Resin and Amalgam Restorations: A Systematic Review and Meta-Analysis (International Dental Journal (PMC open access), 2025).
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Representative model, for educational purposes only.