chemistry

Glass ionomer cement

Glass ionomer cement is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Glass ionomer cement rather than just read about it. In short: A glass ionomer cement (GIC) is a dental restorative material used in dentistry as a filling material and luting cement, including for orthodontic bracket attachment. Glass-ionomer cements are based on the reaction of silicate glass-powder (calciumaluminofluorosilicate glass) and polyacrylic acid, an ionomer.

Key takeaways

Glass ionomer cement belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Glass ionomer cement to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Glass ionomer cement from memory before moving on to harder problems.

Reference excerpt

A glass ionomer cement (GIC) is a dental restorative material used in dentistry as a filling material and luting cement, including for orthodontic bracket attachment. Glass-ionomer cements are based on the reaction of silicate glass-powder (calciumaluminofluorosilicate glass) and polyacrylic acid, an ionomer. Occasionally water is used instead of an acid, altering the properties of the material and its uses. This reaction produces a powdered cement of glass particles surrounded by matrix of fluoride elements and is known chemically as glass polyalkenoate. There are other forms of similar reactions which can take place, for example, when using an aqueous solution of acrylic/itaconic copolymer with tartaric acid, this results in a glass-ionomer in liquid form. An aqueous solution of maleic acid polymer or maleic/acrylic copolymer with tartaric acid can also be used to form a glass-ionomer in liquid form. Tartaric acid plays a significant part in controlling the setting characteristics of the material. Glass-ionomer based hybrids incorporate another dental material, for example resin-modified glass ionomer cements (RMGIC) and compomers (or modified composites). Non-destructive neutron scattering has evidenced GIC setting reactions to be non-monotonic, with eventual fracture toughness dictated by changing atomic cohesion, fluctuating interfacial configurations and interfacial terahertz (THz) dynamics. It is on the World Health Organization's List of Essential Medicines.

Background Glass ionomer cement is primarily used in the prevention of dental caries. This dental material has good adhesive bond properties to tooth structure, allowing it to form a tight seal between the internal structures of the tooth and the surrounding environment. Dental caries is caused by acid, a byproduct of bacterial metabolism of dietary sugars for use as energy. The acid produced from this metabolism results in the breakdown of tooth enamel and subsequent inner structures of the tooth, if the disease is not intervened by a dental professional, or if the carious lesion does not arrest and/or the enamel re-mineralises by itself. Glass ionomer cements act as sealants when pits and fissures in the tooth occur and release fluoride to prevent further enamel demineralisation and promote remineralisation. Fluoride can also hinder bacterial growth, by inhibiting their metabolism of ingested sugars in the diet. It does this by inhibiting various metabolic enzymes within the bacteria. This leads to a reduction in the acid produced during the bacteria's metabolism of fermentable carbohydrates, preventing a further drop in pH and therefore preventing caries. There is evidence that when using sealants, only 6% of people develop tooth decay over a 2-year period, in comparison to 40% of people when not using a sealant. However, it is recommended that the use of fluoride varnish alongside glass ionomer sealants should be applied in practice to further reduce the risk of secondary dental caries.

Resin-modified glass ionomers The addition of resin to glass ionomers improves them significantly, allowing them to be more easily mixed and placed. Resin-modified glass ionomers allow equal or higher fluoride release and there is evidence of higher retention, higher strength and lower solubility. Resin-based glass ionomers have two setting reactions: an acid-base setting and a free-radical polymerisation. The free-radical polymerisation is the predominant mode of setting, as it occurs more rapidly than the acid-base mode. Only the material properly activated by light will be optimally cured. The presence of resin protects the cement from water contamination. Due to the shortened working time, it is recommended that placement and shaping of the material occurs as soon as possible after mixing.

History Dental sealants were first introduced as part of the preventative programme, in the late 1960s, in response to increasing cases of pits and fissures on occlusal surfaces due to caries. This led to glass ionomer cements to be introduced in 1972 by Wilson and Kent as derivative of the silicate cements and the polycarboxylate cements. The glass ionomer cements incorporated the fluoride releasing properties of the silicate cements with the adhesive qualities of polycarboxylate cements. This incorporation allowed the material to be stronger, less soluble and more translucent (and therefore more aesthetic) than its predecessors. Glass ionomer cements were initially intended to be used for the aesthetic restoration of anterior teeth and were recommended for restoring Class III and Class V cavity preparations. There have now been further developments in the material's composition to improve properties. For example, the addition of metal or resin particles into the sealant is favoured due to the longer working time and the material being less sensitive to moisture during setting. When glass ionomer cements were first used, they were mainly used for the restoration of abrasion/erosion lesions and as a luting agent for crown and bridge reconstructions. However, this has now been extended to occlusal restorations in deciduous dentition, restoration of proximal lesions and cavity bases and liners. This is made possible by the ever-increasing new formulations of glass ionomer cements. One of the early commercially successful GICs, employing G338 glass and developed by Wilson and Kent, served purpose as non-load bearing restorative materials. However, this glass resulted in a cement too brittle for use in load-bearing applications such as in molar teeth. The properties of G338 being shown to be related to its phase-composition, specifically the interplay between its three amorphous phases Ca/Na-Al-Si-O, Ca-Al-F and Ca-P-O-F, as characterised by mechanical testing, differential scanning calorimetry (DSC) and X-ray diffraction (XRD), as well as quantum chemical modelling and ab initio molecular dynamics simulations.

Glass ionomer versus resin-based sealants When the two dental sealants are compared, there has always been a contradiction as to which materials is more effective in caries reduction. Therefore, there are claims against replacing resin-based sealants, the current gold standard, with glass ionomer.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Glass ionomer cement

Start with the simplest possible case. Write down what Glass ionomer cement claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Glass ionomer cement before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Glass ionomer cement ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Glass ionomer cement

In research: Glass ionomer cement appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Glass ionomer cement in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Glass ionomer cement is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dental materials, Glass chemistry, World Health Organization essential medicines, so understanding it makes those chapters shorter.
In everyday life: Look for Glass ionomer cement outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Glass ionomer cement in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Glass ionomer cement means in your own words.
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Frequently asked questions

What is Glass ionomer cement in simple terms?

Why does Glass ionomer cement matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Glass ionomer cement?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Glass ionomer cement.