Register or Submit a manuscript.
Quick Link
Recent Progress in Materials

(ISSN 2689-5846)

Recent Progress in Materials  (ISSN 2689-5846) is an international peer-reviewed Open Access journal published quarterly online by LIDSEN Publishing Inc. This periodical is devoted to publishing high-quality papers that describe the most significant and cutting-edge research in all areas of Materials. Its aim is to provide timely, authoritative introductions to current thinking, developments and research in carefully selected topics. Also, it aims to enhance the international exchange of scientific activities in materials science and technology.
Recent Progress in Materials publishes original high quality experimental and theoretical papers and reviews on basic and applied research in the field of materials science and engineering, with focus on synthesis, processing, constitution, and properties of all classes of materials. Particular emphasis is placed on microstructural design, phase relations, computational thermodynamics, and kinetics at the nano to macro scale. Contributions may also focus on progress in advanced characterization techniques.          

Main research areas include (but are not limited to):
Characterization & evaluation of materials
Metallic materials 
Inorganic nonmetallic materials 
Composite materials
Polymer materials
Biomaterials
Sustainable materials and technologies
Special types of materials
Macro-, micro- and nano structure of materials
Environmental interactions, process modeling
Novel applications of materials

Publication Speed (median values for papers published in 2023): Submission to First Decision: 5.3 weeks; Submission to Acceptance: 12.6 weeks; Acceptance to Publication: 7.5 days (1-2 days of FREE language polishing included)

Current Issue: 2024  Archive: 2023 2022 2021 2020 2019
Open Access Review

Modifications of Glass Ionomer Cements Using Nanotechnology: Recent Advances

Dimitrios Dionysopoulos *, Olga Gerasimidou , Constantinos Papadopoulos 

Department of Operative Dentistry, Faculty of Dentistry, School of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece

* Correspondence: Dimitrios Dionysopoulos

Academic Editor: Eugeniusz Sajewicz

Special Issue: Advanced Dental Materials

Received: May 01, 2022 | Accepted: May 24, 2022 | Published: June 01, 2022

Recent Progress in Materials 2022, Volume 4, Issue 2, doi:10.21926/rpm.2202011

Recommended citation: Dionysopoulos D, Gerasimidou O, Papadopoulos C. Modifications of Glass Ionomer Cements Using Nanotechnology: Recent Advances. Recent Progress in Materials 2022; 4(2): 011; doi:10.21926/rpm.2202011.

© 2022 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.

Abstract

Glass ionomer cements (GICs) are dental materials that were invented by Wilson & Kent in 1972. They can chemically bond to enamel and dentin and can exhibit anti-cariogenic activity that allows the release and uptake of fluoride ions. They also possess the ability to render color. The setting reaction of GICs is a neutralization reaction that results in the formation of polycarboxylate salts. The most important GIC modification process involves the addition of resin components, resulting in the development of resin-modified glass ionomer cements (RMGICs), which contain self-and photo-curing systems. Modification of conventional GICs and RMGICs can be achieved by the incorporation of nano-sized fillers into the materials. Conventional GICs and RMGICs can also be modified by introducing nano-sized bioceramics to the glass powder. It has been previously reported that the incorporation of nano-sized particles helps improve the mechanical properties of conventional GICs. Conversely, the commercially available nano-filled RMGICs do not hold any significant advantage over conventional RMGICs as far as the mechanical and adhesive properties are concerned. Glass carbomer is a novel glass ionomer material, and the bioactivity of which is better than the bioactivity of the conventional GICs. However, it is more brittle and less strong than the modern conventional GICs. Additionally, clinical techniques that can be used to transfer external energy on the surface of a GIC have also been used for modification. These techniques can be used to reduce the duration of the initial setting stage and improve the rate of the setting reactions, resulting in faster development of the mechanical properties. Premature failure of the restorations can be avoided under these conditions. The lack of long-term clinical studies limits the use of nano-modified glass ionomers and glass carbomers in daily clinical practice. More randomized clinical trials are required to justify the use of these modern modified materials.

Keywords

Bioactive materials; glass ionomer cements; modifications; nanofillers; nanotechnology

1. Introduction

Glass ionomer cements (GICs) are dental materials that were invented by Wilson & Kent in 1972 [1]. They can chemically bond to enamel and dentin. The origin of the anti-cariogenic activity of the materials can be attributed to the release and uptake of fluoride ions. The materials can be used to render color effectively [2,3,4]. Glass ionomers exist in powder and liquid form. The powder consists of fluoro-alumino-calcium-sodium-silicate glass particles, usually in the form of SiO-AlO2-CaF2-AlPO4-Na3AlF6. Some formulations contain strontium (Sr) and barium (Ba) compounds that improve radiopacity and remineralization properties. The liquid is an aqueous solution of various polycarboxylic acids, which are primarily polyalkenoate acids. The low viscosity of the acids facilitates the handling of cements [5,6,7]. Tartaric acid is also added to the liquid to improve the ease of handling and increase working time [8].

The setting reaction associated with GICs is a neutralization reaction, resulting in the formation of polycarboxylate salts [9]. Initially, the hydrated protons (Η3Ο+) of the polyacid react with the basic particles in glass. This promotes the movement of Na+, Ca2+, and Sr2+ ions, and later Al3+ ions, from glass to the polyacid solution [10,11,12]. These ions react with the polyacid molecules and form ionic bonds. Thus, the formed insoluble polysalt network causes the cement to harden [10]. Water is an essential component of glass ionomers as it is the solvent of polymeric acid. It contributes to the release of protons. It functions as the matrix for the setting reaction and is also a structural component of cement [13]. The loss of water from freshly hardened cement creates an unsightly chalk surface due to the formation of microcracks (Figure 1). To prevent dehydration, it is important to coat the surface of the cement with a hydrophobic material such as Vaseline or a suitable resin varnish [14].

Click to view original image

Figure 1 Representative scanning electron microscopy (SEM) image of the surface of a high-viscosity glass ionomer cement Equia Fill after desiccation presents microcracks.

The setting reaction has been studied by various spectroscopic methods, and it has been observed that the reactions proceed over two phases [15]. Ionic bonds, which are responsible for the immediate hardening of the cement, are formed in the first phase. Ionic bonds involving Al3+ ions are formed in the second phase, and the formation of these bonds starts approximately 10 min after the initial setting. The process continues at a slow rate for approximately 24 h [11,12]. This is followed by the process of maturation, which takes several weeks or months. During this process, minor changes such as an increase in the compressive strength and degree of translucency occur. The process is accompanied by a decrease in toughness and degree of opacity. The content of bound water increases to a limiting value, and the extent of bonding (attributable to the process of continuous ion exchange) to the tooth surface increases [16].

Depending on their clinical application, glass ionomers can be classified into four categories [10]: a) GICs for bonding bridges, crowns, inlays/onlays, posts, and orthodontic rings; b) GICs for fillings (these are further divided into two subcategories: the first includes aesthetic cements for anterior teeth, which have a variety of shades and translucencies [17,18] and the second includes reinforced glass ionomers which are used in posterior teeth); c) GICs for tooth cavity bases and liners [19,20]; and d) GICs for dental sealants [21].

There are several factors that limit the application of GICs under certain clinical conditions. The mechanical properties of the GICs are poorer than those of the resin-based materials [22]. The limiting factors also include low resistance to abrasion [23] and high sensitivity to moisture in the oral cavity [24]. Various modification methods have been used to tune the composition of the GICs to address the problem of reduced physical-mechanical properties. The most prominent modification method included the addition of resin components in the GICs. This resulted in the development of the resin-modified glass ionomer cements (RMGICs), which contain self-and photo-curing systems [25,26]. Zinc [27,28], stainless steel [29], strontium oxide [30], silicon particles [31], bioactive apatite [32], a mixture of bioactive apatite and strontium [33,34], synthetic fibers [35] polyacids containing N-vinylpyrrolidone [36], and amino acid monomers [37] have been used over the years as additives to improve the mechanical properties of the materials. In recent years nanotechnology has been used to produce new composite resins. It has been reported that the method can be used to effectively improve the mechanical properties of the materials [38,39]. Similar efforts have been made to improve the physical and mechanical properties of both conventional and resin-modified GICs. Glass Carbomer, a modified GIC,contains modified glass particles, nano-hydroxyapatite, and silicone oil [40,41].

Most recent versions of GICs typically consist of powders that contain some of the polymeric acids in dried form, resulting in the formation of a low-viscosity acid solution. The freshly mixed cement prepared under these conditions contains high amounts of acid that promote the rapid setting of the material. The process also imparts good strength. These types of materials are labeled as “high-viscosity” GICs, a term typically applied to materials characterized by high powder/liquid ratios of at least 3.6:1 [16]. In 2015, a novel GIC material known as the Equia Forte (GC Inc., Kyoto, Japan) was introduced for application in high-load-bearing areas in posterior teeth. It is a glass hybrid restorative material containing a multifunctional monomer and reinforced with ultrafine, highly reactive glass particles [42,43]. The time frame for the development of glass ionomer materials is presented chronologically in Table 1.

Table 1 Developments of glass ionomer materials.

Therefore, the purpose of this literature review is to present the current data for the latest modifications of GICs, emphasizing the modifications involving nanotechnology.

2. Resin-Modified Glass Ionomer Cements (RMGICs)

RMGICs were introduced in the field of dentistry in the late 1980s. These are hybrid materials with combined properties of conventional GICs and composite resins. The components present in the powder are almost the same as the components present in conventional GICs. The liquid methacrylate monomers and a photoinitiator system are also present in the system [44]. The monomer is typically 2-hydroxyethyl methacrylate (HEMA), and the photo initiator is usually camphorquinone (CQ)[45].

Two different chemical reactions occur during the process of setting of RMGICs. The acid-base reaction is initiated immediately after the process of powder/liquid mixing. The polymerization of the methacrylate monomers is stimulated using a dental light-curing unit such as light-emitting diode (LED) devices. The properties of the material can potentially degrade due to the simultaneous progress of the two antagonistic reactions [46]. The method of mixing and the light-curing should be conducted following the instructions provided by the manufacturer to avoid deleterious effects on the structure of the cement [46].

Post photopolymerization, the material is exposed to conditions of a fast initial hardening process to form the polymer network. However, the acid-base reaction continues after light-curing and is completed within 10-12 min of mixing [4]. Unlike conventional GICs, moisture-protecting substances need not be used immediately after application, and this can be attributed to the formation of the polymer network. They also show greater resistance to compression, diametrical tensile strength, degree of bending, and modulus of elasticity than the conventional GICs [22,47]. They present lower water sorption ability, a lesser degree of solubility, and higher translucency than conventional GICs. These improve the aesthetic performance of the materials. The process of polymerization shrinkage during setting limits the application of RMGICs. The extent of fluoride release recorded for the RMGICs is lower than that recorded for the conventional GICs. This can be attributed to the low solubility (attributable to the less hydrophilic nature) of the material and the release of unreacted monomers to the surrounding tissues. Fluoride is released in two phases in conventional GICs. A large amount of fluoride is released during the first phase (burst effect). This is followed by the steady release of a small amount of fluoride ions during the second phase. The second phase is longer than the first phase [48,49]. Small amounts of Na+, Al+3, PO4-3, and Ca+2 ions are also released during the process. They exhibit buffer properties and increase the pH of the oral fluids in an acidic environment [50,51].

In terms of biocompatibility, RMGICs lag behind conventional GICs because they release the monomer HEMA, especially during the first 24 h. It can penetrate dentinal tubules and is considered potentially cytotoxic to pulpal cells [52,53,54]. It has been previously reported that low cytotoxicity (determined by conducting MTT assays) values were recorded for all the tested materials (conventional GICs, RMGICs and resin composites) and low extraction times were involved, indicating minimal cytotoxicity of the materials (less than 30% inhibition). One RMGIC presented significantly higher cytotoxicity compared to the other materials [54]. RMGICs should always be light-cured for at least the manufacturers’ recommended time at thicknesses no greater than the maximum recommended value to minimize HEMA release [52]. Efforts have been made to modify RMGICs with nanoparticles and bioceramic particles to address the persisting issues [55,56].

3. Modifications of GICs using Nanotechnology

Nanotechnology involves the production of functional materials and structures whose dimensions are in the range of 1-100 nm. The materials are produced using various physical and chemical methods [57,58]. The introduction of nanotechnology in restorative dentistry led to the development of nano-filler particles. The physical, chemical, and biological properties of a particle in the nanoscale dimension are different from the properties of the particles at the atomic/molecular level. The properties of nanomaterials are also different from the properties of the bulk material [59]. Tooth tissues are composed of nanoscale structural units [60]. Hence, synthetic nanoparticles of similar nature are needed to mimic the properties of natural teeth. Two primary approaches in the field of nanotechnology are used for developing small or improved materials. These methods are also used to form complex assemblies from small components. The first approach involves the solid-state processing of materials. The processing methods include the processes such as milling, machining, and lithography. Approaches such as chemical vapor deposition, monolithic processing, wet etching, and plasma etching are used to fabricate functional structures at micro and nano levels [61]. The second approach includes the fabrication of materials via edifice-up particles by harvesting atomic elements [62]. The methodis based on highly organized chemical synthesis methods and the growth of materials [63].

In the field of dentistry, nanotechnology has been used to modify the surface of bone implants [64], improve the mechanical properties of resin composites [38,65,66], and prevent caries [67]. Efforts have also been made to improve the mechanical properties of both conventional and resin-modified GICs. The aim is also to significantly improve physical properties and address issues associated with wear resistance, hardness, and elasticity. Researchers have also aimed to achieve patient satisfaction in terms of aesthetic appearance. They have attempted to improve the translucency and polishing ability by incorporating nanoparticles into GICs [68].

3.1 Modifications of Conventional GICs with Nanoparticles

Hydroxyapatite and fluorapatite exhibit significantly high chemical affinity toward bone and dental tissues and for this reason they have been used in the field of implantology [69] and prevention of caries [57,67]. Nano-hydroxyapatite crystals have been found to contribute significantly to the remineralization of enamel [70,71]. It has been reported that the addition of nano-hydroxyapatite to resin composites significantly improves their mechanical properties [72]. Nano-hydroxyapatite or nano-fluorapatite, when used as additives in conventional GIC powder, significantly improves the compressive strength, tensile strength, and flexural strength of the materials [73]. Glass ionomers containing nano-fluorapatite have better mechanical and adhesive properties than those containing nano-hydroxyapatite. This can be potentially attributed to the low solubility of nano-fluorapatite [36,73]. The improved mechanical properties of GICs that contain nano-apatite are apparent due to the formation of ionic bonds between polyacrylic acid and apatite crystals [36]. It has been claimed that when GIC powder containing nano-hydroxyapatite is used with a liquid containing a mixture of polyacrylic acid, itaconic acid, and polymers of N-vinylpyrrolidone (instead of the commonly used polyacrylic copolymer), the mechanical properties of GICs are further improved. This may be explained by the formation of strong chemical bonds between N-vinylpyrrolidone and apatite crystals [36]. Nano-apatite-containing GICs exhibit a better degree of adhesion (with dental tissues) than the other materials. This can be attributed to the ability of apatite crystals to form strong ionic bonds with Ca ions in dental tissues [74]. The small nano-apatite particles significantly increase the surface area of the particles and improve the ability of the particles to penetrate demineralized enamel and dentin. This results in an increased adhesion to the tooth surface [75].

Apart from nano-apatite, other types of nanoparticles have also been used to improve the mechanical properties of GICs. More specifically, in some GIC products, nanoparticles (3-5 wt %) of titanium dioxide (TiO2) have been added to the powder to improve the mechanical properties and increase the antimicrobial activity of the cement [76,77]. Although TiO2 is considered to exhibit toxic effects, results from in vitro studies did not reveal that the toxicity of the nano-TiO2-containing GIC was higher than the toxicity of the conventional ones [78,79]. GICs can also be modified by adding a mixture (4 vol %) of nano-hydroxyapatite and zirconia (ZrO2) particles to the powdered samples. This also results in improved mechanical behavior. This improvement may be attributed to the uniform distribution of the glass and the mixture of nano-apatite and zirconia particles within the matrix of the cement [33]. Fractures in the cement structure were also observed. The origin of the fractures was attributed to the weak bond between the glass and the zirconia. Therefore, the content of the mixture of hydroxyapatite and zirconia should not exceed 4 vol% [33].

3.2 Modifications of RMGICs with Nanoparticles

The property of chemical adhesion is considered to be the most important property of GICs. GICs can effectively adhere to dental tissues. RMGICs bond to dentin both micromechanically (the resin penetrates the collagen network) and chemically (by forming a chemical bond between the carboxylic acid groups and the Ca ions of the crystals of hydroxyapatite of partially demineralized enamel and dentin through ionic reactions) [9,80]. Nano-RMGICs show a similar bonding mechanism. It has been observed that minimal penetration of the resin into the dentin occurs in these cases, indicating that the strength and efficiency of bonding depend more on the ionic bond than on the micromechanical retention. This is similar to the case of conventional GICs [55]. The commercially available RMGIC Ketac N100/Ketac Nano (3M ESPE) contains nano-agglomerated silicon particles and is accompanied by a primer (Ketac Nano Primer), which is applied to the tooth surface before placement of the cement. However, relevant studies have shown that there is no significant difference in bond strength to dentin between nano-reinforced and conventional RMGICs [55].

It has been demonstrated that the use of 37% orthophosphoric acid before the application of the cement can increase the shear bond strength of nano-RMGICs due to the removal of the smear layer and increase in the surface energy [56,81,82]. However, high molecular-weight carboxylic polymers (MW = 8000-15000) present in RMGICs cannot penetrate demineralized dentin. This leaves the dentin collagen network unprotected and exposed to the risk of hydrolytic degradation [83,84]. Thus, excessive demineralization of dentin should be avoided when RMGICs are used [74,85] as the polyalkenoic polymers cannot penetrate the collagen of the dentin [86]. Therefore, it is suggested that weak acidic primer or aqueous solutions of polyacrylic acid (usually 25%) should be used for pretreatment of the tooth surface to improve the adhesion ability of nano-RMGICs. A recent clinical study has compared a nano-RMGIC with a conventional RMGIC and a composite resin. It was found that after 1 year there were no differences among the materials in terms of retention of the restorations. However, the nano-RMGICs exhibited higher discoloration and lower marginal integrity than the conventional ones [87]. In another in vitro study, it was reported that the marginal integrity of nano-RMGIC restorations was lower than that of the conventional ones. This presumably is explained by the lower bond strength that present the nano-RMGIC especially to and enamel [88].

Modifications in the shape and size of the fillers can affect the mechanical properties of a glass ionomer material in the same way as happens in resin composites [22,89]. RMGICs are more resistant to bending, changes in tensile bond strength, and solubility compared to conventional GICs. This can be primarily attributed to the formation of chemical bonds between the glass particles and the organic matrix [22,47]. Traditional RMGICs have been found to be more resilient to bending and fatigue than commercially available nano-RMGICs [89,90]. Additionally, nano-RMGICs exhibit inferior mechanical behavior under acidic conditions [89] than conventional GICs.This can potentially influence the longevity of the nano-RMGIC restorations in the oral cavity.

As mentioned before, the addition of nano-hydroxyapatite, nano-fluorapatite, and nano-fluorohydroxyapatite particles can improve the surface properties of the RMCIGs. The improvement can be attributed to the increase in the content of the inorganic phase at the surface [91]. On the other hand, the use of nano-hydroxyapatite particles significantly extends the setting time of the material up to 800 s. This is significantly higher than the time range outlined in the ISO specifications (90-480 s) [92]. Although the exact mechanism of this increase in setting time is yet to be well understood, it appears as if the nanoparticles interfere with the process of polymerization of the monomers [93]. The abrasion caused by toothbrushing on the surface of nano-RMGICs has been found to induce less surface loss compared to conventional RMGICs. Nevertheless, under clinical conditions where microbial and chemical activities are observed, no statistically significant differences were found between the two types of RMGICs in terms of surface roughness and hardness [94]. Hence, despite the modifications brought about by the addition of nanoparticles, the surface roughness and hardness of the RMGICs were poorer than those of the composite resins, due to their lower abrasion resistance and their higher solubility [94,95,96].

The release of fluoride ions from GICs and RMGICs is one of their major advantages, as fluoride is well documented to reduce demineralization, increase remineralization, inhibit the growth of bacterial and inhibit their adhesion to tooth surfaces [97]. Because fluoride is not involved in the setting process of GIC, it can be released in large amounts by an ion exchange mechanism without affecting the structure of the cement. GICs also have the ability to uptake fluoride from the oral fluids that function as fluoride storage, which can be re-released preventing demineralization of the tooth tissues [98]. However, it has not been clinically confirmed whether the amount of fluoride released by GICs is sufficient to prevent the formation of caries [99,100]. It has been reported that the amount of fluoride release achieved using nano-RMGIC is similar to the amount of fluoride release achieved using conventional RMGICs. However, the amount is lower than that released by conventional GICs [49,89]. Notwithstanding nano-RMGICs release more fluoride in an acidic environment (pH = 4), the total amount of fluoride they released after 84 days was comparable to the total amount of fluoride released by conventional RMGICs [89]. Results from in vitro studies revealed that nano-RMGICs significantly reduce the development of secondary caries. Unfortunately, there are no long-term clinical trials to confirm these results in vivo.

4. Glass Carbomer

Glass ionomer cements are considered to be bioactive materials as they release biologically active ions (F, Na, Si, and P) in the oral environment, which can beneficially interact with dental tissues. They also present buffer properties under acidic conditions and reduce the pH of the environment. The glass carbomer is a novel glass ionomer cement, which was claimed to be more bioactive than conventional GICs [10]. Despite the fact that the name “glass carbomer” is the brand name of a product of the GCP Dental company, it has been accepted to be used in literature [10,40,41]. Its setting reaction is an acid-base reaction that occurs between the aqueous solution of the polymeric acid and the basic glass containing certain components which are not usually present in other GICs [10]. In particular, these components are (a) glass beads of cement powder that have been treated with strong acids (HCl), (b) silicone oil containing polydimethylsiloxane, and (c) nano-hydroxyapatite and nano-fluorapatite fillers.

The treatment of glass carbomer particles with strong acids results in a significant reduction in the calcium content on the surface of the particles, which is confined to the interior of the particles [101]. The glass used in the glass carbomer contains strontium, large amounts of silicon, and a small amount of calcium. Compared to the other GICs, it contains a relatively larger amount of silicon but a similar amount of aluminum, phosphorus, and fluoride [102]. The treatment of the powder particles with the strong acids results in a reduction in the rate of the reaction between the polyacrylic acid and the copolymer of acrylic-maleic acid. The silicone oil which is added to the powder is absorbed on the surface of the glass particles, preventing their direct reaction with the polymeric acids. Thus, the glass carbomer can be easily mixed in a large powder-liquid ratio, and the high rates of the setting reaction (initiated by the contact between the two components) can be avoided. The rate of the setting reaction lowers following the mixing of the materials. However, it can be accelerated by irradiating the system with a light-curing unit (LCU) for at least 60 s following the manufacturer’s recommendation [40]. The LCU emits heat resulting in an increase in the temperature of the cement. This catalyzes the setting reactions and accelerates the process of hardening of the cement. This method has been proposed in various previous studies conducted on conventional GICs [103,104,105].

As noted previously, the amount of silica in the glass carbomer is higher than the amount of silica present in other GICs and hydroxyapatite fillers. This results in the production of a brittle cement [10]. To address this problem, the manufacturer added silicone oil that bonded with the structure of the material via hydrogen bonds. Under these conditions, the cement becomes more resilient.

Two parallel chemical reactions take place during the setting of the glass carbomer. The first reaction occurs between glass and polyacid, while the second reaction occurs between nano-hydroxyapatite particles and polyacid. Both are acid-base reactions and occur following the process of hardening the cement. Then a polysalt matrix is formed, which encompasses glass particles and hydroxyapatite. The polysalt matrix is similar to the matrix of other GICs except for the fact that it contains polydimethylsiloxane oil [102]. To date, few long-term clinical studies on glass carbomer restorations have been published [106,107,108]. Therefore, there is no evidence of the effectiveness of the material in oral environment.

5. Thermocuring of Glass Ionomer Cements

As mentioned previously, the mechanical and physical properties of GICs, such as sensitivity to moisture, initial fracture toughness, and resistance to wear, are poorer than those of the resin-based restorative materials, which can be primarily attributed to the slow progress of their setting reaction [109,110]. Due to these drawbacks of the conventional GICs, it has been suggested to accelerate their initial setting reaction providing external energy, such as radiant heat, by utilizing dental light-curing units (LED or diode lasers) usually for 60-120 s [104,111,112] or kinetic energy by using dental ultrasonic scalers, usually for 55 s [113,114,115]. The delivery of external energy on the surface of a GIC reduces the duration of the initial stage of the setting process. This also improves the rate of the setting reactions leading to a faster development of the mechanical properties avoiding premature failure of their restorations [116]. More specifically, heat transfer from the light sources to the GIC surface increases ion mobility at the initial stage of the setting process and reduces the viscosity of the material resulting in the enhanced reactivity of the calcium ions in the glass and carboxylate groups of the polyalkenoic acids. This process also helps to improve and accelerate the setting reaction [112].

Various studies have reported that the transfer of external energy to the surface of GICs can increase surface microhardness [117], resistance to abrasion [118], adhesion to tooth tissues [119], and compressive strength [111], while it can reduce water sorption and solubility [120]. On the other hand, it decreases fluoride release from the surface of the material [103,104,105]. This method in combination with the development of GICs with novel composition is very promising for the improvement of the clinical behavior of the tooth restorations of GICs, especially in areas characterized by high mastication forces, such as the occlusal surfaces of the posterior teeth.

6. Conclusions

In conclusion, modification of conventional GICs with nanoparticles improves their mechanical properties as the structure of the material is reinforced. Under these conditions, these materials become more stable and insoluble and the bond strength with the dental tissues improves. Commercially available RMGICs modified with nanoparticles do not show any significant benefit over conventional RMGICs in terms of mechanical properties and bond strength to tooth tissues. Glass carbomer is considered more bioactive than conventional GICs. The former, is apparently more fragile and less resilient than the latter. These new modified GICs require clinical documentation for their effectiveness, which can be achieved through conduction of more long-term clinical trials.

Author Contributions

Dimitrios Dionysopoulos: Conceptualization, collection of the data, writing the manuscript; Olga Gerasimidou: Data curation, writing the manuscript; Constantinos Papadopoulos: writing-review and editing the manuscript.

Competing Interests

The authors have declared that no competing interests exist.

References

  1. Wilson AD, Kent BE. The glass-ionomer cement, a new translucent dental filling material. J Appl Chem Biotechnol. 1971; 21: 313. [CrossRef]
  2. Tyas MJ, Burrow MF. Adhesive restorative materials: A review. Aust Dent J. 2004; 49: 112-121. [CrossRef]
  3. Dionysopoulos D. The effect of fluoride-releasing restorative materials on inhibition of secondary caries formation. Fluoride. 2014; 47: 258-265.
  4. Forss H, Jokinen J, Spets-Happonen S, SeppäL, Luoma H. Fluoride and mutans streptococci in plaque grown on glass ionomer and composite. Caries Res. 1991; 25:454-458. [CrossRef]
  5. Prosser HJ, Powis DR, Wilson AD. Glass-ionomer cements of improved flexural strength. J Dent Res. 1986; 65: 146-148. [CrossRef]
  6. Smith DC. Development of glass-ionomer cement systems. Biomaterials. 1998; 19: 467-478. [CrossRef]
  7. Guggenberger R, May R, Stefan KP. New trends in glass-ionomer chemistry. Biomaterials. 1998; 19: 479-483. [CrossRef]
  8. Mccabe JF, Walls A. Applied dental materials. Hoboken: John Wiley & Sons; 2013.
  9. Anusavice KJ, Shen C, Rawls HR. Phillips' science of dental materials. St Louis: Elsevier Health Sciences; 2012.
  10. Sidhu SK, Nicholson JW. A review of glass-ionomer cement for clinical dentistry. J FunctBiomater. 2016; 7: 16. [CrossRef]
  11. Pires R, Nunes TG, Abrahams I, Hawkes GE, Morais CM, Fernandez C. Stray-field imaging and multinuclear magnetic resonance spectroscopy studies on the setting of a commercial glass-ionomer cement. J Mater Sci Mater Med. 2004; 15: 201-208. [CrossRef]
  12. Zainuddin N, Karpukhina N, Hill RG, Law RV. A long-term study on the setting reaction of glass ionomer cements by 27Al MAS-NMR spectroscopy. Dent Mater. 2009; 25: 290-295. [CrossRef]
  13. Nicholson JW. Chemistry of glass-ionomer cements: A review. Biomaterials. 1998; 6: 485-494. [CrossRef]
  14. Earl MSA, Mount GJ, Hume WR. The effect of varnishes and other surface treatments on water movement across the glass-ionomer cement surface. II. Aust Dent J. 1989; 34: 326-329. [CrossRef]
  15. Crisp S, Pringuer MA, Wardleworth D, Wilson AD. Reactions in glass-ionomer cements: II. An infrared spectroscopic study. J Dent Res. 1974; 53: 1414-1419. [CrossRef]
  16. Nicholson JW. Maturation processes in glass-ionomer dental cements. Acta BiomaterOdontol Scand. 2018; 4: 63-71. [CrossRef]
  17. Van Dijken JW. 3-Year clinical evaluation of a compomer, a resin-modified glass ionomer and a resin composite in class III restorations. Am J Dent. 1996; 9: 195-198.
  18. Abdalla AI, Alhadainy HA, García-Godoy F. Clinical evaluation of glass ionomers and compomers in Class V carious lesions. Am J Dent. 1997; 10: 18-20.
  19. McLean JW, Powis DR, Prosser HJ, Wilson AD. The use of glass-ionomer cements in bonding composite resins to dentine. Br Dent J. 1985; 158: 410-414. [CrossRef]
  20. Andersson-Wenckert IE, Van Dijken JW, Kieri C. Durability of extensive Class II open-sandwich restorations with a resin-modified glass ionomer cement after 6 years. Am J Dent. 2004; 17: 43-50.
  21. Dionysopoulos D, Sfeikos T, Tolidis K. Fluoride release and recharging ability of new dental sealants. Eur Arch Paediatr Dent. 2016; 17: 45-51. [CrossRef]
  22. Xie D, Brantley WA, Culbertson BM, Wang G. Mechanical properties and microstructures of glass-ionomer cements. Dent Mater. 2000; 16: 129-138. [CrossRef]
  23. Peutzfeldt A, García-Godoy F, Asmussen E. Surface hardness and wear of glass ionomers and compomers. Am J Dent. 1997; 10: 15-17.
  24. Um CM, Øilo G. The effect of early water contact on glass-ionomer cements. Quintessence Int. 1992; 23: 209-214.
  25. Wilson AD. Resin-modified glass-ionomer cements. Int J Prosthodont. 1990; 3: 425-429.
  26. Soncini JA, Maserejian NN, Trachtenberg F, Tavares M, Hayes C. The longevity of amalgam versus compomer/composite restorations in posterior primary and permanent teeth: Findings from the New England children's amalgam trial. J Am Dent Assoc. 2007; 138: 763-772. [CrossRef]
  27. Zoergiebel J, Ilie N. Evaluation of a conventional glass ionomer cement with new zinc, formulation: Effect of coating, aging and storage agents. Clin Oral Investig. 2013; 17: 619-626. [CrossRef]
  28. Boyd D, Towler MR. The processing, mechanical properties and bioactivity of zinc based glass ionomer cements. J Mater Sci Mater Med. 2005; 16: 843-850. [CrossRef]
  29. Kerby RE, Bleiholder RF. Physical properties of stainless-steel and silver-reinforced glass-ionomer cements. J Dent Res. 1991; 70: 1358-1361. [CrossRef]
  30. Deb S, Nicholson JW. The effect of strontium oxide in glass-ionomer cements. J Mater Sci Mater Med. 1999; 10: 471-474. [CrossRef]
  31. Tjandrawinata R, Irie M, Yoshida Y, Suzuki K. Effect of adding spherical silica filler on physico-mechanical properties of resin modified glass-ionomer cement. Dent Mater J. 2004; 23: 146-154. [CrossRef]
  32. Moshaverinia A, Roohpour N, Chee WWL, Schricker SR. A review of powder modifications in conventional glass-ionomer dental cements. J Mater Chem. 2011; 21: 1319-1328. [CrossRef]
  33. Gu YW, Yap AU, Cheang P, Khor KA. Zirconia-glass ionomer cement—A potential substitute for miracle mix. Scr Mater. 2005; 52: 113-116. [CrossRef]
  34. Gu YW, Yap AU, Cheang P, Khor KA. Effects of incorporation of HA/ZrO2 into glass ionomer cement (GIC). Biomaterials. 2005; 26: 713-720. [CrossRef]
  35. Lohbauer U, Walker J, Nikolaenko S, Werner J, Clare A, Petschelt A, et al. Reactive fibre reinforced glass ionomer cements. Biomaterials. 2003; 24: 2901-2907. [CrossRef]
  36. Moshaverinia A, Ansari S, Movasaghi Z, Billington RW, Darr JA, Rehman IU. Modification of conventional glass-ionomer cements with N-vinylpyrrolidone containing polyacids, nano-hydroxy and fluoroapatite to improve mechanical properties. Dent Mater. 2008; 24:1381-1390. [CrossRef]
  37. Kao EC, Culbertson BM, Xie D. Preparation of glass ionomer cement using N-acryloyl-substituted amino acid monomers—Evaluation of physical properties. Dent Mater. 1996; 12: 44-51. [CrossRef]
  38. Curtis AR, Palin WM, Fleming GJP, Shortall ACC, 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: 188-197. [CrossRef]
  39. Xia Y, Zhang F, Xie H, Gu N. Nanoparticle-reinforced resin-based dental composites. J Dent. 2008; 36: 450-455. [CrossRef]
  40. Zainuddin N, Karpukhina N, Hill RG, Law RV. Characterisation of remineralising Glass Carbomer®, ionomer cement by MAS-NMR spectroscopy. Dent Mater. 2012; 28: 1051-1058. [CrossRef]
  41. Cehreli SB, Tirali RE, Yalcinkava Z, Cehreli ZC. Microleakage of newly developed glass carbomer cement in primary teeth. Eur J Dent. 2013; 7: 15-21.
  42. Ong JEX, Yap AU, Hong JY, Eweis AH, Yahya NA. Viscoelastic properties of contemporary bulk-fill restoratives: A dynamic-mechanical analysis. Oper Dent. 2018; 43: 307-314. [CrossRef]
  43. Furhmann D, Murchison D. Whipple S, Vandewalle K. Properties of new glass ionomer restorative systems marketed for stress-bearing areas. Oper Dent. 2020; 45: 104-110. [CrossRef]
  44. Dionysopoulos D, Gerasimidou O. Wear of contemporary dental composite resin restorations: A literature review. Restor Dent Endod. 2021; 46: e18. [CrossRef]
  45. Mitra SB. Adhesion to dentin and physical properties of a light-cured glass-ionomer liner/base. J Dent Res. 1991; 70: 72-74. [CrossRef]
  46. Yelamanchili A, Darvell BW. Network competition in a resin-modified glass-ionomer cement. Dent Mater. 2008; 24: 1065-1069. [CrossRef]
  47. Mathis RS, Ferracane JL. Properties of a glass-ionomer/resin-composite hybrid material. Dent Mater. 1989; 5: 355-358. [CrossRef]
  48. De Witte AM, De Maeyer EA, Verbeeck RM, Martens LC. Fluoride release profiles of mature restorative glass ionomer cements after fluoride application. Biomaterials. 2000; 21: 475-482. [CrossRef]
  49. Dionysopoulos D, Koliniotou-Koumpia E, Helvatzoglou-Antoniades M, Kotsanos N. Fluoride release and recharge ability of contemporary fluoride-containing restorative materials and dental adhesives. Dent Mater J. 2013; 3: 296-304. [CrossRef]
  50. Forss H. Release of fluoride and other elements from light-cured glass ionomers in neutral and acidic conditions. J Dent Res. 1993; 72: 1257-1262. [CrossRef]
  51. Czarnecka B, Nicholson JW. Ion release by resin-modified glass-ionomer cements into water and lactic acid solutions. J Dent. 2006; 34: 539-543. [CrossRef]
  52. Palmer G, Anstice HM, Pearson GJ. The effect of curing regime on the release of hydroxethylmethacylate (HEMA) from resin-modified glass-ionomer cements. J Dent. 1999; 27: 303-311. [CrossRef]
  53. Hamid A, Hume WR. Diffusion of resin monomers through human carious dentin in vitro. Endod Dent Traumatol. 1997; 13: 1-5. DOI: 10.1111/j.1600-9657.1997.tb00001.x. [CrossRef]
  54. Kan KC, Messer LB, Messer HH. Variability in cytotoxicity and fluoride release of resin-modified glass-ionomer cements. J Dent Res. 1997; 76: 1502-1507. [CrossRef]
  55. 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 Matter. 2009; 25: 1347-1357. [CrossRef]
  56. El-Askary F, Nassif M. Bonding nano-filled resin-modified glass ionomer to dentin using different self-etch adhesives. Oper Dent. 2011; 36: 413-421. [CrossRef]
  57. Hannig M, Hannig C. Nanomaterials in preventive dentistry. Nat Nanotechnol. 2010; 5: 565-569. [CrossRef]
  58. Najeeb S, Khurshid Z, Matinlirtna JP, Siddiqui F, Nassani MZ, Baroudi K. Nanomodified peek dental implants: Bioactive composites and surface modification—A review. Int J Dent. 2015; 2015: 381759. [CrossRef]
  59. Roco MC. Nanotechnology: Convergence with modern biology and medicine. CurrOpinBiotechnol. 2003; 14: 337-346. [CrossRef]
  60. Zafar MS, Ahmed N. Nano-mechanical evaluation of dental hard tissues using indentation technique. World Appl Sci J. 2013; 28: 1393-1399.
  61. Zhang L, Webster TJ. Nanotechnology and nanomaterials: Promises for improved tissue regeneration. Nano Today. 2009; 4: 66-80. [CrossRef]
  62. Baker Jr JR. Nanotechnology and medicine. J Oral Maxillofac Surg. 2007; 65: 27. [CrossRef]
  63. Wickson F. Narratives of nature and nanotechnology. Nat Nanotechnol. 2008; 3: 313-315. [CrossRef]
  64. Le Guéhennec L, Soueidan A, Layrolle P, Amouriq Y. Surface treatments of titanium dental implants for rapid osseointegration. Dent Mater. 2007; 23: 844-854. [CrossRef]
  65. Terry DA. Direct applications of a nanocomposite resin system: Part 1—The evolution of contemporary composite materials. PractProcedAesthet Dent. 2004; 16: 417-432.
  66. Chen MH. Update on dental nanocomposites. J Dent Res. 2010; 89: 549-560. [CrossRef]
  67. Hannig M, Hannig C. Nanotechnology and its role in caries therapy. Adv Dent Res. 2012; 24: 53-57. [CrossRef]
  68. Khurshid Z, Zafar M, Qasim S, Shahab S, Nassem M, Abureqaiba A. Advances in nanotechnology for restorative dentistry. Materials. 2015; 8: 717-731. [CrossRef]
  69. Javed F, Vohra F, Zafar S, Almas K. Significance of osteogenic surface coatings on implants to enhance osseointegration under osteoporotic-like conditions. Implant Dent. 2014; 23: 679-686. [CrossRef]
  70. Huang SB, Gao SS, Yu HY. Effect of nano-hydroxyapatite concentration on remineralization of initial enamel lesion in vitro. Biomed Mater. 2009; 4: 034104. [CrossRef]
  71. Huang S, Gao S, Cheng L, Yu H. Remineralization potential of nano-hydroxyapatite on initial enamel lesions: An in vitro study. Caries Res. 2011; 45: 460-468. [CrossRef]
  72. Zakir M, Al Kheraif AAA, Asif M, Wong FSL, Rehman IU. A comparison of the mechanical properties of a modified silorane based dental composite with those of commercially available composite material. Dent Mater. 2013; 29: e53-e59. [CrossRef]
  73. Moshaverinia A, Ansari S, Moshaverinia M, Roohpour N, Darr JA, Rehman L. Effects of incorporation of hydroxyapatite and fluoroapatitenanobioceramics into conventional glass ionomer cements (GIC). Acta Biomater. 2008; 4: 432-440. [CrossRef]
  74. Lucas ME, Arita K, Nishino M. Toughness, bonding and fluoride-release properties of hydroxyapatite-added glass ionomer cement. Biomaterials. 2003; 24: 3787-3794. [CrossRef]
  75. Lee JJ, Lee YK, Choi BJ, Lee JH, Choi HJ, Son HK, et al. Physical properties of resin-reinforced glass ionomer cement modified with micro and nano-hydroxyapatite. J NanosciNanotechnol. 2010; 10: 5270-5276. [CrossRef]
  76. Elsaka SE, Hamouda IM, Swain MV. Titanium dioxide nanoparticles addition to a conventional glass-ionomer restorative: Influence on physical and antibacterial properties. J Dent. 2011; 39: 589-598. [CrossRef]
  77. Garcia-Contreras R, Scougall-Vilchis RJ, Contreras-Bulnes R, Sakagami H, Morales-Luckie RA, Nakajima H. Mechanical, antibacterial and bond strength properties of nano-titanium-enriched glass ionomer cement. J Appl Oral Sci. 2015; 23: 321-328. [CrossRef]
  78. Garcia-Contreras R, ScougauVilchis RJ, Contreras-Bulnes R, Kanda Y, Nakajima H, Sakagami H. Effects of TiO2nanoglass ionomer cements against normal and cancer oral cells. In Vivo. 2014; 28: 895-907.
  79. Hall S, Bradley T, Moore JT, Kuykindall T, Minella L. Acute and chronic toxicity of nano-scale TiO2 particles to freshwater fish, cladocerans, and green algae, and effects of organic and inorganic substrate on TiO2 toxicity. Nanotoxicology. 2009; 3: 91-97. [CrossRef]
  80. Lin A, McIntyre NS, Davidson RD. Studies on the adhesion of glass-ionomer cements to dentin. J Dent Res. 1992; 71: 1836-1841. [CrossRef]
  81. Imbery TA, Namboodiri A, Duncan A, Amos R, Best AM, Moon PC. Evaluating dentin surface treatments for resin-modified glass ionomer restorative materials. Oper Dent. 2013; 38: 429-438. [CrossRef]
  82. Hamama HH, Burrow MF, Yiu C. Effect of dentine conditioning on adhesion of resin-modified glass ionomer adhesives. Aust Dent J. 2014; 59: 193-200. [CrossRef]
  83. Sauro S, Watson TF, Thompson L, Toledano M, Nucci C, Banerjee A. Influence of air-abrasion executed with polyacrylic acid-Bioglass 45S5 on the bonding performance of a resin-modified glass ionomer cement. Eur J Oral Sci. 2012; 120: 168-177. [CrossRef]
  84. Sidhu SK, Schmalz G. The biocompatibility of glass-ionomer cement materials. A status report for the American Journal of Dentistry. Am J Dent. 2001; 24: 387-396.
  85. Hoshika S, DeMunck J, Sano H, Sidhu SK, Van Meerbeek B. Effect of conditioning and aging on the bond strength and interfacial morphology of glass-ionomer cement bonded to dentin. J Adhes Dent. 2015; 17: 141-146.
  86. Takahashi M, Nakajima M, Tagami J, Scheffel DL, Carvalho RM, Mazzoni A, et al. The importance of size-exclusion characteristics of type I collagen in bonding to dentin matrices. Acta Biomater. 2013; 9: 9522-9528. [CrossRef]
  87. Perdigão J, Dutra-Corrêa M, Saraceni SH, Ciaramicoli MT, Kiyan VH. Randomized clinical trial of two resin-modified glass ionomer materials: 1-year results. Oper Dent. 2012; 37: 591-601. [CrossRef]
  88. El Wakeel AM, Elkassas DW, Yousry MM. Bonding of contemporary glass ionomer cements to different tooth substrates; microshear bond strength and scanning electron microscope study. Eur J Dent. 2015; 9: 176-182. [CrossRef]
  89. Moreau JL, Xu HH. Fluoride releasing restorative materials: Effects of pH on mechanical properties and ion release. Dent Mater. 2010; 26: e227-e235. [CrossRef]
  90. Pameijer CH, García-Godoy F, Morrow BR, Jefferies SR. Flexural strength and flexural fatigue properties of resin-modified glass ionomers. J Clin Dent. 2015; 26: 23-27.
  91. Lin J, Zhu J, Gu X, Wen W, Li Q, Fischer-Brandies H, et al. Effects of incorporation of nano-fluorapatite or nano-fluorohydroxyapatite on a resin-modified glass ionomer cement. Acta Biomater. 2011; 7: 1346-1353. [CrossRef]
  92. Moraes RR, Gonçalves LS, Lancellotti AC, Consani S, Correr-Sobrinho L, Sinhoreti MA. Nanohybrid resin composites: Nanofiller loaded materials or traditional microhybrid resins? Oper Dent. 2009; 34: 551-557. [CrossRef]
  93. Najeeb S, Khurshid Z, Zafar MS, Khan AS, Zohaib S, Martí JM, et al. Modifications in glass ionomer cements: Nano-sized filler and bioactivity nanoceramics. Int J Mol Sci. 2016; 17: 1134. [CrossRef]
  94. De Paula AB, Fucio SB, Ambrosano GM, Alonso RC, Sardi JC, Puppin-Rontani RM. Biodegradation and abrasive wear of nano restorative materials. Oper Dent. 2011; 36: 670-677. [CrossRef]
  95. de Fúcio SB, de Paula AB, de Carvalho FG, Feitosa VP, Ambrosano GM, Puppin-Rontani RM. Biomechanical degradation of the nano-filled resin-modified glass-ionomer surface. Am J Dent. 2012; 25:315-320.
  96. de Paula AB, de Fúcio SB, Alonso RC, Ambrosano GM, Puppin-Rontani RM. Influence of chemical degradation on the surface properties of nano restorative materials. Oper Dent. 2014; 39: e109-e117. [CrossRef]
  97. Wiegand A, Buchalla W, Attin T. Review on fluoride-releasing restorative materials—Fluoride release and uptake characteristics, antibacterial activity and influence on caries formation. Dent Mater. 2007; 23: 343-362. [CrossRef]
  98. Dionysopoulos D, Koliniotou-Koumpia E, Kotsanos N. The effect of low-concentration fluoride solutions on fluoride recharge ability of contemporary dental restoratives and adhesives. Fluoride. 2015; 48: 351-363.
  99. Ullah R, Zafar MS. Oral and dental delivery of fluoride: A review. Fluoride. 2015; 48: 195-204.
  100. Zafar MS, Ahmed N. Therapeutic roles of fluoride released from restorative dental materials. Fluoride. 2015; 8: 184-194.
  101. Dionysopoulos D, Kotiniotou-Koumpia E, Heivatzoglou-Antoniades M, Kotsanos N. In vitro inhibition of enamel demineralization by fluoride-releasing restorative materials and dental adhesives. Oral Health Prev Dent. 2016; 14: 371-380.
  102. Van Den Bosch W, Van Duinen RN. Self hardening glass carbomer composition. 2004;US20060217455A1. Available from: https://patents.google.com/patent/US20060217455A1/en.
  103. Tolidis K, Dionysopoulos D, Gerasimou P, Sfeikos T. Effect of radiant heat and ultrasound on fluoride release and surface hardness of glass ionomer cements. J Appl BiomaterFunct Mater. 2016; 14: 463-469. [CrossRef]
  104. Dionysopoulos D, Tolidis K, Strakas D, Gerasimou P, Sfeikos T, Gutknecht N. Effect of radiant heat on conventional glass ionomer cements during setting by using a blue light diode laser system (445 nm). Lasers Med Sci. 2017; 32: 703-709. [CrossRef]
  105. Dionysopoulos D, Tolidis K, Gerasimou P, Sfeikos T. Effect of three clinical curing treatments on fluoride release and surface hardness of glass-ionomer cements. Int J Periodontics Restorative Dent. 2017; 37: e197-e203. [CrossRef]
  106. Gorseta K, Glavina D, Borzabadi-Farahani A, Van Duinen RN, Skrinjaric I, Hill RG, et al. One-year clinical evaluation of a Glass Carbomer fissure sealant, a preliminary study. Eur J ProsthodontRestor Dent. 2014; 22: 67-71.
  107. Chen X, Du MQ, Fan MW, Mulder J, Huysrnans MC, Frencken JE. Caries-preventive effect of sealants produced with altered glass-ionomer materials, after 2 years. Dent Mater. 2012; 28: 554-560. [CrossRef]
  108. Hu X, Zhang W, Fan M, Mulder J, Frencken JE. Frequency of remnants of sealants left behind in pit and fissures of occlusal surfaces after 2 and 3 years. Clin Oral Investig. 2017; 21: 143-149. [CrossRef]
  109. De Gee AJ, Van Duinen RN, Werner A, Davidson CL. Early and long-term wear of conventional and resin-modified glass ionomers. J Dent Res. 1996; 75: 1613-1619. [CrossRef]
  110. Yap AU, Cheang PH, Chay PL. Mechanical properties of two restorative reinforced glass-ionomer cements. J Oral Rehabil. 2002; 29:682-688. [CrossRef]
  111. Kleverlaan CJ, Van Duinen RNB, Feilzer AJ. Mechanical properties of glass ionomer cements affected by curing methods. Dent Mater. 2004; 20: 45-50. [CrossRef]
  112. Gavic L, Gorseta K, Glavina D, Czarnecka B, Nicholson JW. Heat transfer properties and thermal cure of glass-ionomer dental cements. J Mater Sci Mater Med. 2015; 26: 249. [CrossRef]
  113. Talal A, Tanner KE, Billington R, Pearson GJ. Effect of ultrasound on the setting characteristics of glass ionomer cements studied by Fourier transform infrared spectroscopy. J Mater Sci Mater Med. 2009; 20: 405-411. [CrossRef]
  114. Dehurtevent M, Deveaux E, Hornez JC, Robberecht L, Tabary N, Chai F. Influence of heat and ultrasonic treatments on the setting and maturation of a glass-ionomer cement. Am J Dent. 2015; 28: 105-110.
  115. Thanjal NK, Billington RW, Shahid S, Luo J, Hill RG, Pearson GJ. Kinetics of fluoride ion release from dental restorative glass ionomer cements: The influence of ultrasound, radiant heat and glass composition. J Mater Sci Mater Med. 2010; 21: 589-595. [CrossRef]
  116. Towler MR, Bushby AJ, Billington RW, Hill RG. A preliminary comparison of the mechanical properties of chemically cured and ultrasonically cured glass ionomer cements, using nano-indentation techniques. Biomaterials. 2001; 22: 1401-1406. [CrossRef]
  117. O’Brien T, Shoja-Assadi F, Lea SC, Burke FJ, Palin WM. Extrinsic energy sources affect hardness through depth during set of a glass-ionomer cement. J Dent. 2010; 38: 490-495. [CrossRef]
  118. Dionysopoulos D, Tolidis K, Sfeikos T, Karanasiou C, Parisi X. Evaluation of the surface microhardness and abrasion resistance of two dental glass-ionomer cement materials after radiant heat treatment. AdvMaterSciEng. 2017. DOI: 10.1155/2017/5824562. [CrossRef]
  119. Algera TJ, Kleverlaan CJ, De Gee AJ, Prahl-Andersen B, Feilzer AJ. The influence of accelerating the setting rate by ultrasound or heat on the bond strength of glass ionomers used as orthodontic bracket cements. Eur J Orthod. 2005; 27: 472-476. [CrossRef]
  120. Dionysopoulos D, Tolidis K, Strakas D, Gerasimou P, Sfeikos T, Gutknecht N. Effects of blue diode laser (445 nm) and LED (430-480 nm) radiant heat treatments on dental glass ionomer restoratives. Opt Laser Tech. 2018; 99: 249-255. [CrossRef]
Newsletter
Download PDF Download Citation
0 0
Newsletter  

TOP