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| IMC Wiki | Cement types for base fillings (2) - Glass ionomer cement

Cement types for base fillings (2) - Glass ionomer cement

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Glass ionomer cements (GIC)

#pic#

GICs can be considered a further development of carboxylate cements.

The powder consists primarily of:
  • calcium aluminium silicate glass (fluorite, corundum, quartz, aluminium phosphate, cryolite, aluminium fluoride)
The liquid consists of:
  • polyacrylic acid and
  • a solution of a copolymer made of acrylic and itaconic acid (poly (acrylic malein) acid).
The big advantages of GICs are:
  • the adhesion to dental hard substance (slightly better to enamel than to dentine) and
  • that the colour of the material is the same as that of the tooth.
Glass ionomer cements can be classified as follows:
Type I: Fixing material
Type II: Filling and restoration material
Type III: Quickly curing cavity base materials
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Working with glass ionomer cement

  • Drip the liquid onto the plate; reseal the bottle immediately!
  • Extract a more than sufficient amount of powder with the measuring spoon and keep it in small portions not too close to the liquid:
    • the powder to liquid ratio is approximately 3:1,
    • Immediately reseal the powder bottle.
  • Mix the powder little by little in small portions slowly into the liquid:
    • Regularly spread the mixed material out thinly to allow the reaction heat to dissipate.
    • Mixing time is approx. 1 minute.
    • Never mix in too much powder at any one time, as this will accelerate the curing time.
    • The material should never be mixed up too quickly, as this, too, will accelerate curing.
    • The powder should always be mixed into the liquid, never vice versa! Liquid should never be added to a cement mix that has become too stiff.
    • The desired consistency should never be achieved by waiting for a thin mixture to thicken.
  • Once the cement has been introduced into the cavity, it will cure quickly as a result of body temperature (which is actually to be desired) so that work can continue quickly.
The following characteristics indicate that the cement has the right consistency:
  • The glass ionomer cement is runny but still sticks to the spatula.
  • It can be lifted approximately 1 cm vertically off of the surface of the mixing plate with the spatula before the cement film separates.
  • If it is to be used as cavity base cement, the GIC should have the consistency of marzipan.

Capsule systems

GICs are sensitive as far as the mixing proportions of powder and liquid are concerned.
For this reason, GICs have been developed in the form of capsule systems, which can be mixed automatically using a special machine (product example: Ketac Fil).
The advantage lies is their ease of use and the constant mixing ratio, i.e. the cement invariably has the ideal consistency.
The higher costs represent the only disadvantage.

Other types of GICs

Water-curing GICs
In order to simplify the working process, polycarbonic acid which has been freeze-dried in a vacuum is mixed with the powder. Water or non-viscous tartaric acid is added as a liquid.
Product examples: Aqua Ionabond, Ketac Bond, Cembase

Light-curing GICs
To reduce the time that it takes for GICs to cure, light-curing materials have been developed. To a certain extent, curing occurs as with conventional GICs or by means of a light-induced polymerisation of the plastic components.
Some mixtures contain primarily plastics that are able to be polymerised but have been enriched with silicate glasses and an x-ray contrast material. Overall, GIC filled composites rather than light-curing GICs are more commonly used. Compomers represent a further development as a filling material.
Product examples: Ionoseal, Vitrebond, Vitremer, Photac Fil

Cermet GIC (Cermet = Ceramic Metall)
Metal particles (e.g. 40% silver) are added to the GIC. These cements were developed especially as cavity base cements and filling materials. However, the cement becomes brittle as a result of adding silver. It is suggested that cracks form adjacent to the silver particles. Adhesion to enamel and dentine is inferior to that of conventional GICs.
Product example: Ketac Silver

Placing of a temporary cement filling

Temporary fillings usually consist of phosphate or glass ionomer cement, or sometimes glass ionomer cements are used in the form of capsules (product example: Ketac Cem, Ketac Molar).

Material

  • 2 ml syringe with local anaesthetic, long injection cannula for regional block anaesthesia, short injection cannula for infiltration anaesthesia
  • red high-speed angle handpiece
  • rotary instruments:
    • pear-shaped diamond polishers, normal grain (without colour mark)
    • fine / finest grain (with red or yellow colour mark)),
    • hard metal instrument interlocking crosswise, if required (to remove old amalgam fillings)
  • green right angle
  • rose-head burs in different sizes (e.g. ISO 010 - 018)
  • multi-functional syringe (air/water)
  • large and small saliva ejector
  • cotton wool rolls (ca. 10 pieces)
  • cotton wool pellets (ca. 5 pieces)
  • Dappen glass with e.g. H2O2 (3%) or CHX (2%) or NaOCl (5%)
  • phosphate cement or glass ionomer cement (consisting of powder and liquid)
  • glass plate
  • cement spatula
  • cement condenser
  • matrix holder with suitable matrix band (e.g. Tofflemire's®)
  • suitable inter-dental wedge made of maple wood, colour-coded according to size
    (one inter-dental wedge is required for each proximal space to be filled)
  • 2 flag holders with occlusal foil in different colours, e.g. black and red
  • dental floss

Treatment overview

  • anaesthesia
  • removal of old fillings and/or primary preparation
  • caries excavation
  • cavity disinfection
  • insertion of matrix and inter-dental wedge
  • insertion of cement into the cavity
  • preparation of the temporary filling
  • occlusal control