Modifications in Glass Ionomer Cements: Nano-Sized Fillers and Bioactive Nanoceramics

“Key applications of nanotechnology in dentistry include implant surface modifications [62], production of reinforced polymeric composites by incorporation of nano-sized particles [60], and caries prevention [63].”

“A more critical problem associated with such aesthetic restorations is the absence of therapeutic remineralization of caries-affected dentin and the poor durability/integrity of the resin–dentin interface during aging [34].”

“In contrast to “bioinert” materials such as resin composites, dental silver amalgam, and porcelain, bioactive restorations have a more positive effect on remineralization and tissue regeneration [37].”

“At high concentrations, fluoride has been thought to reduce the rate of demineralization, enhance the remineralization process, inhibit the growth, and attachment of bacteria on tooth surfaces and impede the formation of a complex bacteria biofilm [117].”

“Generally, a smaller particle size and higher packing density of fillers improves compression strength and hardness of GICs, whereas larger particles can lead to a higher wear resistance [39].”

“The final “maturation” of t e cement may take several months while the aluminum ions may be released slowly and binding of water by the acid and glass takes place [18].”

“RMGICs micromechanically bond to dentine through infiltration of the collagen network previously exposed by using a 10% polyacrylic acid pre-treatment, in combination with chemical bonding obtained by ionic interaction of carboxyl groups from the acid with calcium ions of remaining HAP crystals within the partially de…”

“Due to their chemistry being similar to that of mineralized bone and dental tissues, hydroxypatite and fluorohydroxyapatite have been used in many fields of dentistry such as implant dentistry [71], and caries prevention [59,72].”

“Fourier transform infrared (FTIR) spectroscopy has been used to observe the effect of nano-modification of GICs via incorporation of apatite nano-crystals [44,45].”

“For instance, nano-hydroxyapatite (nHAp) crystals can favor remineralization of enamel [73,74].”

“Due to their high fluoride release and white color, dental applications of GICs include restoration of deciduous teeth [20], anterior class III and V restorations [21,22], cementation (luting) of crowns, bridges, and orthodontic appliances [23–25], restorations of non-carious teeth with minimal preparation [26,27], te…”

“When compared to resin composites, conventional RMGICs still possess reduced mechanical properties including brittleness and inferior strength along with aesthetics [2,3].”

“%) nano particles (nTiO2) to GIC powder has been shown to improve mechanical properties and anti-bacterial effects of the set material [69,70].”

“The key modifications include the combination of glass ionomer cements with auto-cured or photo-cured resin systems to produce resin-modified glass ionomer cements (RMGICs) [46,47].”

“For instance, nano-hydroxyapatite (nHAp) crystals can favor remineralization of enamel [73,74].”

“There are two approaches for the manufacture of nano-size particles: top-down and bottom-up [61].”

“Due to their high fluoride release and white color, dental applications of GICs include restoration of deciduous teeth [20], anterior class III and V restorations [21,22], cementation (luting) of crowns, bridges, and orthodontic appliances [23–25], restorations of non-carious teeth with minimal preparation [26,27], te…”

“It is a kind of film of tooth debris left behind on the tooth surface following tooth preparation [90].”

“RMGICs micromechanically bond to dentine through infiltration of the collagen network previously exposed by using a 10% polyacrylic acid pre-treatment, in combination with chemical bonding obtained by ionic interaction of carboxyl groups from the acid with calcium ions of remaining HAP crystals within the partially de…”

“It is well-documented that incorporation of nano-sized particles may improve the mechanical properties of polymeric dental materials [60,67].”

“Due to their high fluoride release and white color, dental applications of GICs include restoration of deciduous teeth [20], anterior class III and V restorations [21,22], cementation (luting) of crowns, bridges, and orthodontic appliances [23–25], restorations of non-carious teeth with minimal preparation [26,27], te…”

“However, the use of specific dentin pre-treatments with functional primers may prevent the collapse of dentinal collagen fibers and improve the bonding performance of resin adhesive as well as RMGICs [88,89].”

“Due to their high fluoride release and white color, dental applications of GICs include restoration of deciduous teeth [20], anterior class III and V restorations [21,22], cementation (luting) of crowns, bridges, and orthodontic appliances [23–25], restorations of non-carious teeth with minimal preparation [26,27], te…”

“Several key benefits characterize IC, such as its ability to bind che ically ith tooth structures via chelation of carboxyl group of acid polymeric chains and calcium ions (Ca2+) in the apatite of enamel and dentine [5].”

“3% expansion due to water sorption after 24 h of placement [83].”

“RMGICs have higher flexural strength, tensile strength, and resistance to solubility compared to conventional GICs which could be due to the chemical bonding between glass particles and the resin phase [39,101].”

“Fourier transform infrared (FTIR) spectroscopy has been used to observe the effect of nano-modification of GICs via incorporation of apatite nano-crystals [44,45].”

“Indeed, it has been observed that RMGICs not only release fluoride but they also have flexural strength superior to those of conventional GICs, as well as lower solubility [82].”

“%) nano particles (nTiO2) to GIC powder has been shown to improve mechanical properties and anti-bacterial effects of the set material [69,70].”

“Glass ionomer cements are being used for a wide range of applications in dentistry [14].”

“It is well-documented that incorporation of nano-sized particles may improve the mechanical properties of polymeric dental materials [60,67].”

“Moreover, nano-apatite containing glass ionomers are expected to have superior bonding to the tooth surface due to the possibility of the formation of the strong ionic linkages between the apatite crystals/particles in the cement and Ca-ions in the tooth structure [77].”

“Due to their high fluoride release and white color, dental applications of GICs include restoration of deciduous teeth [20], anterior class III and V restorations [21,22], cementation (luting) of crowns, bridges, and orthodontic appliances [23–25], restorations of non-carious teeth with minimal preparation [26,27], te…”

“However, more extensive studies are needed to ascertain the safety of nTiO2-containing GICs because free nTiO2 have been strongly suggested to be cytotoxic [81].”

“% to the GIC powder can improve the mechanical properties of the set GIC [52].”

“Similar approaches have been attempted to improve the physical and mechanical characteristics of GIC using nanotechnology [43,44].”

“Key applications of nanotechnology in dentistry include implant surface modifications [62], production of reinforced polymeric composites by incorporation of nano-sized particles [60], and caries prevention [63].”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“Recently, resin composites modified by the addition of nHAp have been observed to have superior mechanical properties than unmodified resin composites [75,76].”

“Indeed, minimally invasive dentistry can also be applied for the treatment of deeper carious lesions by adopting the atraumatic restorative treatment approach with the scope to selectively remove infected carious tissue leaving as much caries-affected dentin as possible for therapeutic remineralization [32,33].”

“The initial setting reaction is a gelation reaction between the components [12], followed by binding of the”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“However, recent studies have shown that in terms of micro-tensile bond strength (μTBS), there is no significant difference between nano-filled RMGIC and conventional RMGICs [84].”

“Indeed, several studies have suggested that the cumulative fluoride release from nano-RMGICs and conventional RMGICs are comparable with each other but still significantly lesser than conventional GICs [79,119,120].”

“In addition, due to their high bioactivity, GICs may also be used as bone cements [36].”

“However, the use of specific dentin pre-treatments with functional primers may prevent the collapse of dentinal collagen fibers and improve the bonding performance of resin adhesive as well as RMGICs [88,89].”

“However, even if using smaller particles (>5 μm) has revealed to improve mechanical properties remarkably [102], the challenge that remains prevalent even in RMGICs is the poor surface properties compared to resin composite restorations [3,101].”

“Due to their chemistry being similar to that of mineralized bone and dental tissues, hydroxypatite and fluorohydroxyapatite have been used in many fields of dentistry such as implant dentistry [71], and caries prevention [59,72].”

“Such aggressive dentine pre-treatments should not be adopted when using GIC-based materials [32,34,77,95], because their polyalkeonic polymers are excluded from permeating into dentine collagen [96].”

“Additionally, decreasing the particle size of apatites from micrometer scale to nanometer scale increases the surface area remarkably, and infiltration of the crystals into demineralised dentine as well as enamel pores; this may enhance bonding at the tooth-ionomer interface [78].”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“showed that doping conventional GICs with nano-sized glass particles can decrease the setting time and enhance the compression strength and elastic modulus [68].”

“A randomized clinical trial investigating the performance of nano-RMGIC compared to conventional GIC and resin composites showed that there is no difference in one year survival of either type of restoration [98].”

“The concept of using synthetic biomaterials to replace lost or damaged tissue is not new [1,2].”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“Indeed, several studies have suggested that the cumulative fluoride release from nano-RMGICs and conventional RMGICs are comparable with each other but still significantly lesser than conventional GICs [79,119,120].”

“It requires removal of the caries-infected dental tissues in order to arrest caries and induces dental remineralization while utilizing the healing potential of glass ionomer cements [26,35].”

“Due to their chemistry being similar to that of mineralized bone and dental tissues, hydroxypatite and fluorohydroxyapatite have been used in many fields of dentistry such as implant dentistry [71], and caries prevention [59,72].”

“suggests that aluminum may remain in the cement structure for up to one year [19].”

“Although purely mechanical degradation (abrasion) produced by tooth brushing simulates surface wear of nano-RMGCs to a significantly lesser degree compared to conventional RMGICs, in vitro studies suggest that there is no statistical difference between the surface roughness and hardness of nano-RMGICs and conventional…”

“Furthermore, addition of nHAp, nFAp and nanofluorohydroxyapatite to RMGICs can lead to an increased surface area, due to an increased filler-loading that may lead to improvements in the mechanical properties and bonding strength to the tooth [105].”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“% have a detrimental effect on the properties of the GIC [51].”

“On the other hand, the pH of functional primers is low enough to remove most of the smear layer and improve the chemical bond to dentin and enamel [85,91].”

“Similarly, it has been demonstrated that acid etching (37% phosphoric acid) can improve the shear bond strength of nano-filled RMGIC by removing the smear layer and increasing the surface energy [85,92,93].”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“Similarly, it has been demonstrated that acid etching (37% phosphoric acid) can improve the shear bond strength of nano-filled RMGIC by removing the smear layer and increasing the surface energy [85,92,93].”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“However, no significant improvement has been observed in bond strength when compared to conventional methods [97].”

“This may be due to the inferior bonding performance of nano-RMGIC when applied onto enamel rather than dentine [99].”

“Similar to all other composite restorative materials, modification of the size and shape of filler particles in a GIC can influence its mechanical properties [39,100].”

“Recently, resin composites modified by the addition of nHAp have been observed to have superior mechanical properties than unmodified resin composites [75,76].”

“Such aggressive dentine pre-treatments should not be adopted when using GIC-based materials [32,34,77,95], because their polyalkeonic polymers are excluded from permeating into dentine collagen [96].”

“Additionally, modification of GICs by incorporation polyvinyl phosphonic acid [48,49], fiber-reinforcement [50], bioactive apatite without [43] or with zirconia [51,52], zinc [53,54], strontium oxide [55], stainless steel [56], silica particles [57], amino acids [58], and N-vinylpyrrolidone [45] have all aimed at impr…”

“On the other hand, the pH of functional primers is low enough to remove most of the smear layer and improve the chemical bond to dentin and enamel [85,91].”

“Glass ionomer cements (GICs) have been presented with various modifications such as with resin or nano-additives [146–148] and are commonly used for applications such as cementation of prosthesis and restorations.”

“However, this name is simplistic because, depending on the composition chosen by the manufacturer, other elements may be incorporated, such as strontium, phosphate, zinc, calcium, or sodium [11,15,16].”