REVIEW ARTICLE

Year : 2019  |  Volume : 7  |  Issue : 1  |  Page : 21-23

Recent advancements in glass ionomer materials with introduction of nanotechnology: A review

Ghada AlOtaibi
Restorative Department, Riyadh Elm University, Riyadh, Kingdom of Saudi Arabia

Correspondence Address:
Dr. Ghada AlOtaibi
Lecturer, Restorative Department, Riyadh Elm University, Riyadh
Kingdom of Saudi Arabia

Source of Support: None, Conflict of Interest: None

2

DOI: 10.4103/INJO.INJO_17_19

In dentistry, there is a continuous need of change in techniques and materials, according to the change in demand from patients’ professional perceptions and with advancement in technology. Both components of glass ionomer cements (GICs) inhibit wide chemical diversity, which provide potential of progress in GICs. Therefore, the main aim of this article was to study the various advancements in GICs with the introduction of nanotechnology in GIC. Various modifications in GICs were carried out. This article is an attempt to overview different advances in glass ionomer such as compomers, condensable/self-hardening GIC, low viscosity/flowable GIC, fiber-reinforced GIC, chlorhexidine-impregnated GIC, proline-containing GIC, nano-bioceramic-modified GIC, and calcium aluminate GIC. Nanotechnology is introduced in conventional GIC and resin-modified GIC to improve the mechanical properties of GIC. It has been concluded that large number of modifications were carried out with GIC, and the introduction of nanotechnology had improved the general properties of GIC. Nano-resin-modified GICs (nano-RMGICs) do not possess any substantial advantage or disadvantage, in terms of surface mechanical properties, compared to conventional restorative materials.

Keywords: Glass ionomer, introduction, materials, nanotechnology

Introduction

1. Compomer: It is a combination of the word “comp” for composite and “omer” for ionomer. Though introduced as a type of GIC, it became apparent that in terms of clinical use and performance, it is best considered as a composite.



2. Condensable/self-hardening GIC: These are basically, purely chemically activated resin-modified glass ionomer cements (RMGICs) with no light activation at all. It is used mainly in pediatric dentistry for cementation of stainless steel crowns, space maintainers, bands, and brackets.



3. Low viscosity/flowable GIC: It is mainly used as lining, pit and fissure sealing, endodontic sealers, sealing of hypersensitive cervical areas, and it has increased flow.



4. Bioactive glass: Developed by Hench and colleagues in 1973, this material considers the fact that on acid dissolution of glass, there is formation of a layer rich in calcium and phosphate around the glass, such a glass can form intimate bioactive bonds with bone cells and get fully integrated with the bone. It is used in retrograde filling material, for perforation repair, augmentation of alveolar ridges in edentulous ridges, implant cementation, and infra-bony pocket correction.



5. Fiber-reinforced GIC: To improve the depth of cure, reduced polymerization shrinkage, improved wear resistance, and increase in flexural strength of GIC, alumina fibers are mixed with glass powder. This technology is called the polymeric rigid inorganic matrix material, which involves incorporation of a continuous network/scaffold of alumina and silicon di oxide ceramic fibers.



6. Proline-containing GIC: It is an amino acid–containing GIC, which has better surface hardness properties. This formulation of fast-set glass ionomer showed increased water sorption without adversely affecting the amount of fluoride release. Considering its biocompatibility, this material shows promise not only as a dental restorative material but also as a bone cement with low cytotoxicity.



7. Calcium aluminate GIC: A hybrid product with a composition between that of calcium aluminate and GIC, it is designed for luting fixed prosthesis. The calcium aluminate contributes to a basic pH during curing, reduction in microleakage, excellent biocompatibility, and long-term stability and strength.

Introduction of Nanotechnology in GICs

1. Powder-modified nano glass ionomers: Described for the first time by De Caluwé et al.,^[11] it involves doping conventional GICs with nano-sized glass particles, which can decrease the setting time and enhance the compression strength and elastic modulus. The main advantages of decreasing setting times of direct restorative materials are enhanced ease of handling and manipulation.
   1. Modification using nano-apatite: Addition of nano-apatite or nano-fluoroapatite to the powder component of conventional GIC has a positive impact on the compressive, tensile, and flexural strengths of the set cement after being stored in distilled water for 7 days.^[5]
   2. Modification with nano-sized hydroxyapatite, calcium fluoride, and titanium dioxide particles: It has been recently reported by Gu et al.^[12] that the combined incorporation of HAp and zirconia (HAp/ZrO₂) at concentrations of 4% volume to the GIC powder can improve the mechanical properties of the set GIC.^[5]
2. Nano-filled resin-modified GICs: Resin-modified GICs also have a polymer resin component, which usually sets by a self-activated (chemically cured) or light-activated polymerization reaction. To develop the mechanical properties of a resin composite with the anticaries potential of GICs, these were developed. However, compared to composites, resin-modified GICs have reduced mechanical properties, including brittleness and inferior strength along with aesthetics.^[5] To overcome these drawbacks, there have been attempts to incorporate nano-sized fillers and bioceramic particles to RMGICs.^[13],[14] Properties of nano-RMGICs are as follows:
   1. Bonding of nano-RMGIC with tooth structure: More ionic bonding with tooth rather than micromechanical retention, much akin to conventional GICs.^[5]
   2. Mechanical and physical properties of nano-RMGICs: Poor flexural strength and fatigue limit in commercially available nano-RMGICs.^[5] Perform the worst when mechanically tested on acid challenge.^[5] Acidic environment may jeopardize the long-term survival rate of nano-RMGICs.
   3. Surface mechanical properties of RMGICs: The aesthetic properties of dental resin composite materials have been radically improved.^[5]
   4. Fluoride release from nano-ionomers: Slightly increased fluoride release from nano-RMGICs at a pH of 4.^[5]

Conclusion

References

1.	Mount GJ. A new paradigm for operative dentistry. J Conserv Dent 2008;11:3-10.   [PUBMED]  [Full text]
2.	Hendricson WD, Cohen PA. Oral health care in the 21st century: Implications for dental and medical education. Acad Med 2001;76:1181-206.
3.	Sidhu SK, Nicholson JW. A review of glass-ionomer cements for clinical dentistry. J Funct Biomater 2016;7:E16.
4.	Khoroushi M, Keshani F. A review of glass-ionomers: From conventional glass-ionomer to bioactive glass-ionomer. Dent Res J (Isfahan) 2013;10:411-20.
5.	Najeeb S, Khurshid Z, Zafar MS, Khan AS, Zohaib S, Martí JM, et al. Modifications in glass ionomer cements: Nano-sized fillers and bioactive nanoceramics. Int J Mol Sci 2016;17:1134.
6.	Hannig M, Hannig C. Nanomaterials in preventive dentistry. Nat Nanotechnol 2010;5:565-9.
7.	Najeeb S, Khurshid Z, Matinlinna JP, Siddiqui F, Nassani MZ, Baroudi K. Nanomodified peek dental implants: Bioactive composites and surface modification—A review. Int J Dent 2015;2015:381759.
8.	Le Guéhennec L, Soueidan A, Layrolle P, Amouriq Y. Surface treatments of titanium dental implants for rapid osseointegration. Dent Mater 2007;23:844-54.
9.	Curtis AR, Palin WM, Fleming GJ, Shortall AC, Marquis PM. The mechanical properties of nanofilled resin-based composites: The impact of dry and wet cyclic pre-loading on bi-axial flexure strength. Dent Mater 2009;25:188-97.
10.	Terry DA. Direct applications of a nanocomposite resin system: Part 1—The evolution of contemporary composite materials. Pract Proced Aesthet Dent 2004;16:417-22.
11.	De Caluwé T, Vercruysse CW, Fraeyman S, Verbeeck RM. The influence of particle size and fluorine content of aluminosilicate glass on the glass ionomer cement properties. Dent Mater 2014;30:1029-38.
12.	Gu YW, Yap AU, Cheang P, Khor KA. Effects of incorporation of HA/ZrO(2) into glass ionomer cement (GIC). Biomaterials. 2005 Mar;26:713-20.
13.	Coutinho E, Cardoso MV, De Munck J, Neves AA, Van Landuyt KL, Poitevin A, et al. Bonding effectiveness and interfacial characterization of a nano-filled resin-modified glass-ionomer. Dent Mater 2009;25:1347-57.
14.	El-Askary F, Nassif M. Bonding nano-filled resin-modified glass ionomer to dentin using different self-etch adhesives. Oper Dent 2011;36:413-21.

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