Glass ionomer cement
Glass ionomer cement (GIZ) is a filling material used in dentistry . It consists of pure polyacrylic acid or copolymers of acrylic acid , itaconic acid or maleic acid and of calcium - aluminum - silicate - glass and distilled water .
Setting reaction
The acids dissolve the calcium and aluminum from the silicate glass. Thereby diffuses the calcium faster than the aluminum and therefore reacts first with the acid. The calcium crosslinks the acid and calcium polycarboxylate gel is formed within 5 to 10 minutes. After about 24 hours, the aluminum is also stored in the calcium polycarboxylate gel matrix and stabilizes it so significantly that the water-insoluble calcium aluminum carboxylate gel is formed, which is the actual filling material. The setting reaction follows an acid-base reaction. Plastics can also be added instead of metals. These plastic-modified glass ionomer cements are cured by light (e.g. halogen or LED polymerisation lamps ).
Adhesion to the tooth
Glass ionomer cements adhere chemically to the hard tooth substance via the carboxy group of the acid (enamel 5 MPa, dentine 3 MPa). An adhesive technique as with plastics ( composite or compomer ) is not required. In addition, glass ionomer cements show no polymerization shrinkage . Their disadvantages compared to plastic fillings are the significantly lower breaking strength and flexural strength as well as the low abrasion resistance .
indication
Depending on the viscosity, glass ionomer cements are indicated for cementation of crowns and bridges, as a lining material (sandwich technique), as well as for milk tooth fillings and semi-permanent fillings of class I, II and V cavities .
It can be used for smaller caries defects on the neck of the tooth, but it must then be checked regularly by the dentist for durability.
As part of the project funded by the WHO ART-supply ( A traumatic R estoration T reatment = filling treatment without drill) glass ionomer cements are used as definitive restorative in developing countries. In areas that are not supplied with electricity and no treatment units are available, carious teeth are treated painlessly using hand instruments and therefore do not require local anesthesia.
particularities
Due to the large particle size of the silicate particles, GIZ is difficult to polish.
Fluoride release
By releasing fluoride ions, it prevents secondary caries .
Pulp tolerance
The pulp tolerance has not yet been clearly established. Areas close to the pulp must therefore be covered with underfills made of calcium hydroxide . The cavities or the crown stumps must be disinfected because, in contrast to phosphate cement, glass ionomer cement lacks the bactericidal effect.
Individual evidence
- ^ Willamowski, Matthias, Spitta-Verlag (Balingen): Dental materials science . 1st edition. Spitta Verlags GmbH, Balingen 2018, ISBN 978-3-946761-65-5 , p. 326 .
- ↑ a b glass ionomer cement. Website of the Dental Health Working Group .
- ↑ a b R. Frankenberger, N. Krä ?? mer, Glasionomerzemente (PDF; 940 kB).
- ↑ Chadwick B, Dummer P, Dunstan F, et al. The Longevity of Dental Restorations. A Systematic Review (PDF; 90 kB), Evidence-Based Dentistry, 3/2002, pp. 96-99 ISBN 1-4622-0490-2 .
- ^ Tooth fillings: the standards, KZBV .