Glass Ionomer Cement Filling

Introduction –Glass Ionomer Cement Filling

 A Glass Ionomer Cement (GIC) is a dental restorative material used in dentistry for the purpose of filling teeth and luting cements. These materials are based on the reaction of silicate glass powder and poly-alkenoic acid.

Minimal cavity preparation is required hence easy to use in children
This cement bonds chemically to dental hard tissues and releases fluoride for a long period, making it widely applicable in dental practice. The desirable properties of glass ionomer cements make them useful materials in the restoration of caries in low-stress areas like smoothand small anterior proximal cavities in primary teeth.

Chemical classification:

GICs are commonly classified into five principal types:

  1. Conventional- They are derived from aqueous polyalkenoic acid such as polyacrylic acid and a glass component that is usually a fluoroaluminosilicate.
  2. Resin Modified (Conventional GIC with addition of HEMA)
  3. Hybrid (Also known as Dual-cured Glass Ionomer Cements) – These combine an acid-base reaction of the traditional glass ionomer with an amine-peroxide polymerization reaction.
  4. Tri-cure – It has a chemical curing tertiary amine-peroxide reaction. Much lower release of fluoride than the conventional glass ionomer materials.
  5. Metal-reinforced Cements- a silver-amalgam alloy powder is added to conventional materials to increase the physical strength of the cement.

Composition – Glass Ionomer Cement Filling:

Application involves mixtures of a powder and a liquid. The type of application decides the viscosity of the cement, which is adjusted by varying the particle size distribution and the powder-to-liquid ratio.

Manipulations in GIC cement filling:

  1. Surface of the prepared tooth should be clean and dry
  2. The consistency of the mixed cement should be appropriate so that complete coating of the surface irregularities and complete seating of prostheses takes place.
  3. Excess cement should be removed at the appropriate time.
  4. Surface finishing should be done without excessive drying
  5. The restoration surface must be protected properly to prevent cracking or dissolution.

Properties:

  1. Setting Time- GlC sets in 6–8 minutes from the start of mixing. The setting time is lesser for type I materials than Type II materials. The setting can be slowed if the cement is mixed on a cold slab but this technique has negative effect on strength.
  2. Aesthetics- Conventional glass ionomer cements are of natural color and available in different shades. The addition of resin in the modified materials has improved the translucency, but they are still rather opaque and not as esthetic as composite-resins.
  3. Water Sensitivity, Solubility- The initial solubility is high (0.4 %) due to leaching of intermediate products. The complete setting reaction takes place in 24 hours. Therefore, the cement should be protected from saliva in mouth during this period.
  4. Adhesion- By bonding a restorative material to tooth structure, the cavity is becomes sealed. This protects the pulp, eliminates secondary caries and prevents leakage at the margins.
  5. Margin Adaptation and Leakage- Marginal adaptation is increased by applying pressure by a gloved finger or thumb after placing a bulk of material in the cavity walls. Care should be taken to avoid movement of the material during setting. Thepressure should be maintained till the material sets to the point where it does not get deformed on removal of pressure.
  6. Physical Strengths- The main limitation of the glass ionomer cements is a relative lack of strength and low tolerance to wear.They are very brittle and prone to bulk fracture.
  7. Biocompatibility- This is very important because the cement is in direct contact with enamel and dentin of natural teeth.
  8. Anti-cariogenic effect- Fluoride is released from the glass powder at the time of mixing and lies free within the matrix. Fluoride can also be taken up into the cement during topical fluoride treatment and is released thereafter. Thus, the cement acts as a fluoride reservoir over a long period. As a result, the glass ionomer cements are considered clinically anti-cariogenic.

Advantages of GIC cement:

  1. Inherent adhesive property for the teeth
  2. High retention rate
  3. Very little shrinkage and good marginal seal effect
  4. Causes Fluoride release and hence inhibits caries
  5. Biocompatible
  6. Minimal cavity preparation is required hence easy to use in children
  7. suitable for use even in absence of skilled dental manpower and facilities

Disadvantages of GIC cement:

  • Brittle
  • Soluble
  • Abrasive
  • Water sensitive during setting phase.
  • Some products release less fluoride than conventional GIC
  • Not inherently radiopaque though addition of radio-dense additives such as barium can alter radio density
  • Less aesthetic than composite

Uses:

The general use-based classification of GICs is as follows:

  • Type I – In luting cements
  • Type II – For restorations
  • Type III – In Liners and bases
  • Type IV – As Fissure sealants
  • Type V – In Orthodontic Cements
  • Type VI – For Core build up
  • Type VII- Fluoride release
  • Type VIII- ART (atraumatic restorative technique)
  • Type IX- InDeciduous teeth

- Link of interest: Twitter Glass Ionomer Cement Filling – Dental Treatment.

 

This article is not medical advice nor a substitute to professional health advice. Always consult a doctor.

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