Elsevier

Journal of Dentistry

Volume 43, Issue 8, August 2015, Pages 897-912
Journal of Dentistry

Review
Conventional glass-ionomer materials: A review of the developments in glass powder, polyacid liquid and the strategies of reinforcement

https://doi.org/10.1016/j.jdent.2015.04.004Get rights and content

Abstract

Objectives

The development of glass-ionomers (GIs) from the earliest experimental GI formulations to the modern day commercially available GIs was reviewed. The aim of the review was to identify the developments in the glass powder and polyacid liquid constituents of GIs since their inception in the late 1960s.

Data

The glass powder has undergone major changes from the earliest GI powder formulation (G200) in an effort to enhance the reactivity with the polyacid liquid. The GI liquids have also been optimised by the manufacturers in terms of polyacid composition, molecular weight and concentration to improve the handling characteristics. Despite these developments in the glass powder and polyacid liquid constituents, GIs cannot ‘truly’ be advocated for the restoration of posterior dentition due to the poor mechanical properties when compared with dental amalgam and resin-based composites (RBCs).

Sources

Various attempts to improve the mechanical properties of GIs through substitution of reinforcing fillers to the GI powder or modification of the GI liquid were identified in the dental literature. Despite the claimed improvements in mechanical properties of the modified GIs, a wide variation in mixing and testing conditions was identified which prevented a valid assessment of the reported reinforcement strategies. When investigating a GI reinforcement strategy it is crucial that the mixing and testing conditions are standardised to allow a valid comparison between studies.

Study selection

The dental literature reporting the earliest experimental GIs to modern day commercially available GIs (1969–2015) was reviewed. In addition, full-text publications and abstracts published in English reporting various GI reinforcement strategies were included.

Conclusion

Nevertheless, major improvements in GI formulations through a reinforcement strategy have yet to be made to enable clinical usage of GIs for the restoration of posterior dentition.

Clinical Significance

GIs chemically are inherently weak but bond to sound tooth structure without the need for preconditioning or removal of sound tooth structure such that improvements in the mechanical properties of GIs would be desirable. Although advances have been made through different GI glass powder and polyacid liquid formulations over the past 40 years, further improvements in the mechanical properties of the current GIs are required to be indicated for the restoration of posterior dentition. The literature is replete with reports on GI reinforcement, however, improved reporting and control of mixing and testing conditions are required for a valid assessment of the reinforcement strategies.

Section snippets

Historical development of glass-ionomers

Glass-ionomers (GIs) were developed and patented1 in the late 1960s by Alan Wilson and co-workers at the Laboratory of the Government Chemist (LGC) in London to replace dental silicate cements. Dental silicate cements – then the primary material of choice for the restoration of anterior dentition – were inherently brittle, susceptible to acid erosion, failed to adhesively bond to sound tooth structure and raised concerns owing to increased pulpal sensitivity.2 A major impediment to the

Developments in GI powder

GIs are composed of an ion leachable glass powder and a polyacid liquid which are mixed together using a predetermined power:liquid mixing ratio to form a solid mass on setting. The GI powder is prepared from an aluminosilicate glass which serves as a source of ions for the cement forming reaction.24, 25 The glass composition controls the setting rate of the cement forming reaction26, 27 and the refractive index match to the polysalt matrix dictates the translucency of the set GI.28 The glass

Developments in GI liquid

The liquid component of the earliest experimental GI (ASPA-I) was composed of an acrylic acid homopolymer solution (50% by mass)16 which had poor working and setting characteristics and was susceptible to gelation due to formation of intermolecular hydrogen bonds between the polymer chains.16 To improve the handling characteristics, tartaric acid (5% by mass) was added to the acrylic acid homopolymer (47.5% by mass) to form ASPA-II51 which improved the working and setting characteristics.

Strategies of reinforcement

Since the introduction of ASPA to the dental market in the early 1970s, the GI powder and liquid constituents have undergone significant changes in chemical make-up. As a result, the range of clinical applications has expanded from luting cements to cavity liners or bases and restorative materials. The major advantage of GIs over dental amalgam and resin-based composites (RBCs) for the restoration of natural dentition is the ability of GIs to chemically bond to sound tooth structure.77, 78 In

Conclusion

In conclusion, the extensive literature available on GIs extending from the earliest to modern day commercially available materials was reviewed with the aim of highlighting the major developments in the GI powder and liquid components. The GI glass powder has undergone significant changes from the earliest formulation (G-200) in an effort to enhance the reactivity with the GI liquid. The GI liquids have also been optimised by the manufacturers in terms of polyacid composition, molecular weight

References (147)

  • G. Mayanagi et al.

    Effect of fluoride-releasing restorative materials on bacteria-induced pH fall at the bacteria–material interface: an in vitro model study

    Journal of Dentistry

    (2014)
  • A.D. Neve et al.

    Development of novel dental cements I. Formulation of aluminoborate glasses

    Clinical Materials

    (1992)
  • A.D. Neve et al.

    Development of novel dental cements II. Cement properties

    Clinical Materials

    (1992)
  • M. Darling et al.

    Novel polyalkenoate (glass-ionomer) dental cements based on zinc silicate glasses

    Biomaterials

    (1994)
  • S.G. Griffin et al.

    Influence of glass composition on the properties of glass polyalknoate cements. Part I. Influence of aluminium to silicon ratio

    Biomaterials

    (1999)
  • D.C. Smith

    Development of glass-ionomer cement systems

    Biomaterials

    (1998)
  • S.G. Griffin et al.

    Influence of glass composition on the properties of glass polyalknoate cements. Part II. Influence of phosphate content

    Biomaterials

    (2000)
  • S. Crisp et al.

    Properties of improved glass-ionomer cement formulations

    Journal of Dentistry

    (1975)
  • J.W. Nicholson et al.

    Changes in compressive strength on ageing in glass polyalkenoate (glass-ionomer) cements prepared from acrylic/maleic acid copolymers

    Biomaterials

    (1997)
  • G.J. Pearson et al.

    Long-term flexural strength of glass-ionomer cements

    Biomaterials

    (1991)
  • V.H.W. Khouw-Liu et al.

    An in vitro investigation of polyvinylphosphonic acid based cement with four conventional glass-ionomer cements. Part 2: maturation in relation to surface hardness

    Journal of Dentistry

    (1999)
  • V.H.W. Khouw-Liu et al.

    An in vitro investigation of polyvinylphosphonic acid based cement with four conventional glass-ionomer cements. Part 1: flexural strength and fluoride release

    Journal of Dentistry

    (1999)
  • A.E. Gonzalez

    Viscoelasticity of ionomer gels. 2. The elastic moduli

    Polymer

    (1984)
  • S. Crisp et al.

    Characterisation of glass-ionomer cements 3. Effect of polyacid concentration on the physical properties

    Journal of Dentistry

    (1977)
  • A.H. Dowling et al.

    The influence of polyacrylic acid number average molecular weight and concentration in solution on the compressive fracture strength and modulus of a glass-ionomer restorative

    Dental Materials

    (2011)
  • A.D. Wilson et al.

    Characterisation of glass-ionomer cements 4. Effect of molecular weight on physical properties

    Journal of Dentistry

    (1977)
  • A.H. Dowling et al.

    Can polyacrylic acid molecular weight mixtures improve the compressive fracture strength and elastic modulus of a glass-ionomer restorative?

    Dental Materials

    (2011)
  • C.W.B. Oldfield et al.

    Fibrous reinforcement of glass-ionomer cements

    Clinical Materials

    (1991)
  • M. Kobayashi et al.

    Strengthening of glass-ionomer cement by compounding short fibres with CaO–P2O5–SiO2–Al2O3 glass

    Biomaterials

    (2000)
  • U. Lohbauer et al.

    Reactive fibre reinforced glass-ionomer cements

    Biomaterials

    (2003)
  • J.W. McLean

    Cermet cements

    Journal of the American Dental Association

    (1990)
  • A.W.G. Walls et al.

    The properties of glass polyalkenoate (ionomer) cement incorporating sintered metallic particles

    Dental Materials

    (1987)
  • S.E. Elsaka et al.

    Titanium dioxide nanoparticles addition to a conventional glass-ionomer restorative: Influence on physical and antibacterial properties

    Journal of Dentistry

    (2011)
  • A.H. Dowling et al.

    Modification of titanium dioxide particles to reinforce glass-ionomer restoratives

    Dental Materials

    (2014)
  • A.U.J. Yap et al.

    Experimental studies on a new bioactive material: HAIonomer cements

    Biomaterials

    (2002)
  • Y. Gu et al.

    Effects of incorporation of HA/ZrO2 into glass-ionomer cement (GIC)

    Biomaterials

    (2005)
  • M.E. Lucas et al.

    Toughness, bonding and fluoride-release properties of hydroxyapatite-added glass ionomer cement

    Biomaterials

    (2003)
  • A. Moshaverinia et al.

    Effects of incorporation of hydroxyapatite and fluoroapatite nanobioceramics into conventional glass-ionomer cements (GIC)

    Acta Biomaterialia

    (2008)
  • Wilson AD, Kent BE. Surgical cement. British Patent...
  • A.D. Wilson et al.

    Dental silicate cements I. The chemistry of erosion

    Journal of Dental Research

    (1967)
  • A.D. Wilson

    A hard decade's work: steps in the invention of the glass-ionomer cement

    Journal of Dental Research

    (1996)
  • A.D. Wilson et al.

    Dental silicate cements II. Preparation and durability

    Journal of Dental Research

    (1967)
  • A.D. Wilson et al.

    Dental silicate cements III. Environment and durability

    Journal of Dental Research

    (1968)
  • A.D. Wilson

    Dental silicate cements IV. Alternative liquid cement formers

    Journal of Dental Research

    (1968)
  • A.D. Wilson et al.

    A new translucent cement for dentistry. The glass ionomer cement

    British Dental Journal

    (1972)
  • A.D. Wilson et al.

    Scientific and clinical development

  • A.D. Wilson

    Developments in glass-ionomer cements

    International Journal of Prosthodontics

    (1989)
  • M.S.A. Earl et al.

    The effect of varnishes and other surface treatments on water movement across the glass-ionomer cement surface

    Australian Dental Journal

    (1989)
  • A.D. Wilson et al.

    Reactions in glass-ionomer cements IV. Effect of chelating comonomers on setting behaviour

    Journal of Dental Research

    (1976)
  • S. Crisp et al.

    Reactions in glass ionomer cements V. Effect of incorporating tartaric acid in the cement liquid

    Journal of Dental Research

    (1976)
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      Citation Excerpt :

      The glass component is prepared by sintering mixtures of powdered silica (SiO2), alumina (Al2O3), cryolite (Na3AlF6), aluminium trifluoride (AlF3), fluorite (CaF2) and aluminium phosphate (AlPO4) at 1100–1500 °C. Nowadays, some commercial brands include Zinc, Lanthanum, Strontium, or Calcium fluoroaluminosilicate [40]. Polyacrylic acid is the main content of the aqueous solution although tartaric and maleic acid as well as homo- or co-polymer of acrylic acid can be found [8].

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