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Short answer: glass ionomer cement is a dental material that sets by an acid-base reaction between a basic glass powder and a water-soluble polymeric acid. It is used as a restorative, a lining or base, and a luting cement. The standard ISO name is “glass polyalkenoate cement,” and the resin-modified versions add a light-cured resin component (Sidhu and Nicholson, 2016).
This page gives general product and materials information for laboratory, clinic and supply staff. It is not clinical or purchasing advice; follow the manufacturer’s instructions for use for any specific product.
Definition and composition
Glass ionomer cements (GICs) are acid-base cements. A review in the Journal of Functional Biomaterials describes three essential ingredients: a water-soluble polymeric acid, an ion-leachable basic glass, and water. The acid is usually poly(acrylic acid) or a copolymer of acrylic and maleic acid (2:1). The glasses are alumino-silicates containing fluoride and phosphate, typically calcium-based and sometimes strontium-based. Tartaric acid is added as a modifier of the setting rate (Sidhu and Nicholson, 2016).
The same review notes that the formal ISO name is “glass polyalkenoate cements,” and that “glass-ionomer” is an accepted trivial name.
How it sets
When powder and liquid are combined, the acid attacks the glass and releases ions, which cross-link the polymer chains. According to the review, the main acid-base reaction happens soon after mixing. A slower cross-linking driven by aluminium continues for about a day, and a longer “maturation” over weeks increases strength and translucency. Properties therefore depend on mixing, the powder-to-liquid ratio and maturation time (Sidhu and Nicholson, 2016).
Water is part of the cement’s chemistry, which is why the manufacturer’s instructions for use address moisture handling for each product.
Types and classification
Two different classification schemes are in use, and they answer different questions. One groups cements by what they are used for. The other groups them by chemistry.
Glass ionomer cement types by use (conventional cements)
- Type I: luting and bonding, for example crowns, bridges and orthodontic appliances.
- Type II: restorative. Materials are grouped as aesthetic anterior or fast-setting posterior products.
- Type III: lining and base.
Glass ionomer cement classification by chemistry
| Name | What distinguishes it | Source |
|---|---|---|
| Conventional GIC | Sets by the acid-base reaction alone; no resin. | Sidhu and Nicholson, 2016 |
| Resin-modified GIC (RMGIC) | Adds a resin component (HEMA) and a photo-initiator (camphorquinone); sets by the acid-base reaction and by light-activated polymerization. Introduced in the early 1990s. | Sidhu and Nicholson, 2016 |
| Glass carbomer | A product from GCP Dental; the review reports limited long-term data and that it appears more brittle and less strong than the best conventional GICs. Its claimed bioactivity is unconfirmed. | Sidhu and Nicholson, 2016 |
| “Glass polyalkenoate cement” | The ISO name for the conventional class, not a separate material. | Sidhu and Nicholson, 2016 |
Type I, II and III describe use; conventional, resin-modified and glass carbomer describe chemistry. A product label can combine them, for example a resin-modified luting cement, so the two schemes should not be treated as one list.
Glass ionomer cement vs resin cement
The distinction comes down to how the material sets. A conventional GIC contains no resin and sets by acid-base chemistry. An RMGIC sits between the two classes: it keeps the glass and polyacid but adds resin that is light-cured. A product sold as a resin cement belongs to a different material class from a conventional glass ionomer, so the setting chemistry printed in the manufacturer’s instructions for use is the reliable way to tell which one a product is.
A comparison of fluoride release in Restorative Dentistry and Endodontics (Cabral et al., 2015) states that materials with less resin content, such as glass ionomers and resin-modified glass ionomers, have higher porosity than compomers and composites. The resin-modified version also carries a trade-off: the review reports that its biocompatibility is markedly worse than conventional GIC because of HEMA, which is cytotoxic to pulp cells and a contact allergen (Sidhu and Nicholson, 2016).
Where it matters for clinics and supply decisions
Regulatory class. Under 21 CFR 872.3275, zinc oxide-eugenol cement is Class I and exempt from premarket notification, while dental cement other than zinc oxide-eugenol is Class II. Glass ionomer is not a zinc oxide-eugenol cement, so it falls under the second paragraph; each product’s own FDA clearance record gives its actual classification (eCFR, checked 2026-10-30).
Standard minimums. The review cites ISO 9917-1 minimum compressive strengths of 70 MPa for luting cements and 100 MPa for restorative cements; these are the least acceptable values for market entry, not typical performance. A product data sheet that quotes conformity to this standard can be checked against those numbers.
Handling and storage reading of the IFU. Because the properties depend on mixing, powder-to-liquid ratio, maturation and moisture control, these are the items to read in each product’s instructions for use. Related CASRAI pages cover ISO 4049 for polymer-based restoratives, the dental office supply checklist and the wider lab equipment hub; the dental research overview gives the research context.
Common misunderstandings
- “Fluoride release proves protection.” The review states that there is not yet convincing evidence of a clinical benefit from fluoride release, that release shows an early burst followed by lower sustained release, and that release into saliva is much lower than laboratory water data.
- “It bonds like a resin.” GIC bonds chemically to enamel and dentine, but the reported tensile bond strengths are about 2.6 to 9.6 MPa on enamel and 1.1 to 4.1 MPa on dentine, and failures are usually cohesive, which reflects the strength of the cement itself.
- “Resin-modified and conventional are interchangeable.” They differ in setting mechanism and, per the review, in biocompatibility.
- “Glass carbomer is just another GIC.” The review reports limited long-term data for it.
FAQ
What are the types of glass ionomer cement?
By use, conventional cements are Type I (luting and bonding), Type II (restorative) and Type III (lining and base). By chemistry, the main groups are conventional, resin-modified and glass carbomer.
How is glass ionomer cement classified?
Two ways: by intended use (Types I to III) and by chemistry (conventional, resin-modified, glass carbomer). Regulators group it under dental cement; in the United States dental cement other than zinc oxide-eugenol is Class II under 21 CFR 872.3275.
Is glass ionomer cement the same as resin cement?
No. Conventional glass ionomer sets by an acid-base reaction without resin; resin-modified versions add light-cured resin to that reaction. Check the setting chemistry stated in the manufacturer’s instructions for use.
What is glass ionomer cement made of?
A basic fluoro-alumino-silicate glass powder, a water-soluble polymeric acid such as poly(acrylic acid), and water, with tartaric acid as a setting modifier.
Sources
- Sidhu SK, Nicholson JW. A Review of Glass-Ionomer Cements for Clinical Dentistry. J Funct Biomater 2016;7(3):16. PMC5040989, checked 2026-10-30.
- Cabral MFC et al. Do conventional glass ionomer cements release more fluoride than resin-modified glass ionomer cements? Restor Dent Endod 2015;40(3):209-215. PMC4534725, checked 2026-10-30.
- U.S. Food and Drug Administration, 21 CFR 872.3275 Dental cement, eCFR, checked 2026-10-30.
