Early Reaction Kinetics of Contemporary Glass-Ionomer Restorative Materials Howard W. Robertsa / David W. Berzinsb
Purpose: To investigate polyalkenoate reaction rates in conventional glass-ionomer cement (GIC) and resin-modified glass ionomer (RMGI) restorative materials using infrared spectroscopy. Materials and Methods: Nine conventional GIC and six RMGI restorative materials were prepared according to manufacturer’s directions and placed on a FTIR (Fourier transform infrared spectroscopy) diamond ATR (attenuated total reflectance) surface. FTIR spectra (700 to 1800 cm-1) were obtained each minute for 3 h. VLC specimens were light polymerized after 1 min; at 5 min, all samples were covered with gauze saturated with deionized water. Polyalkenoate reaction was determined by measuring area growth (Å/cm-1) between 1375 and 1500 cm-1. Mean peak areas were determined at 5, 15, 30, 90, and 180 min and compared using ANOVA (p = 0.05) Results: For all RMGI materials, VLC polymerization inhibited the polyalkenoate reaction rate. Compared to conventional GIC, RMGI materials demonstrated less polyalkenoate reaction. Compared to dark curing, RMGI light polymerization significantly inhibited the polyalkenoate reaction rate. Conclusions: The addition of resin components to glass-ionomer products significantly retards and impedes the polyalkenoate reaction. The polyalkenoate reaction rate of RMGI products was significantly lower than that of self-curing GIC restorative materials. Furthermore, light activation of RMGI products further retards the polyalkenoate rate. When clinicians require the therapeutic benefit of a polyalkenoate product, perhaps a conventional GIC restorative product should be the first material of choice. Keywords: polyalkenoate, polyalkenoate reaction, resin modified glass ionomer, glass-ionomer cement. J Adhes Dent 2015; 17: 67–75. doi: 10.3290/j.jad.a33526
G
lass-ionomer cements (GIC) were invented in 1969 and developed by Wilson and Kent in the early 1970s.44 They generally consist of a mixture of various polyacrylic acids and tartaric acid that react with a fluoroaluminosilcate glass in an acid-base reaction.30,45 Glassionomer cements have undergone incremental formulation changes in attempts to improve their physical properties and clinical handling characteristics that have included the use of alternative polyacids,30 water-activated dehydrated polyacid powders,30,35 cermets,28 metal additions,41,44 and smaller mean glass particle size.14 Resin-modified glass-ionomer (RMGI) materials were introduced in the late 1980s/early 1990s and consist of GIC components (water-soluble polymeric acids, ion-leachable glass, and water) combined with organic, photopolymerizable mono-
a
Director, Dental Graduate Research, Keesler Air Force Base, MS, USA. Experimental design, performed all experiments, wrote manuscript.
b
Director, Graduate Dental Biomaterials, Marquette University School of Dentistry, Milwaukee, WI, USA. Substantial review/revision and contribution to discussion and experimental design.
Correspondence: Dr. H.W. Roberts, 81 DS/SGD, 606 Fisher Street, Keesler Air Force Base, MS, 39531 USA. Tel: +1-228-376-5190. e-mail: [email protected]
Vol 17, No 1, 2015
Submitted for publication: 03.02.14; accepted for publication: 10.12.14
mers with an initiation system.29 Although a given RMGI’s exact composition is proprietary, the resin component in the set material of RMGIs available in the mid-1990s was estimated to be approximately 4.5 to 6 percent.15,40 RMGI materials were developed with the intent to improve the mechanical properties and early moisture sensitivity observed with the conventional GIC materials,8,46 and basically exist in two forms: one in which part of the water is replaced by water-soluble, photopolymerizable 2-hydroxyethylmethacrylate monomer (HEMA), and one in which methacrylate groups are predominately grafted onto the polyacrylic molecules.9,15 Although HEMA is the predominant methacrylate used in RMGI materials, newer product formulations may use a combination of HEMA and diurethane dimethacrylate, bisphenol A diglycidyl ether dimethacrylate (bis-GMA), polyethylene glycol dimethacrylate (PEG-DMA), triethylene glycol dimethacrylate (TEG-DMA), or other dimethacrylate monomers.7,10,24,34,36,37,42 The RMGI setting reaction is more complex than that of conventional GIC materials, especially in terms of HEMA interactions with the other constituents.30 HEMA lengthens both the working and setting times of a GIC material, and decreases the compressive strength as well.1,31 HEMA is thought to compress the polyacrylic acid configu67
Roberts and Berzins
Table 1
Products used
Product
Type
Components
Manufacturer
Chemfil Rock
Self-curing smallparticle condensable GIC
Liquid: polycarboxylic acid 10%–25% Powder: zinc-modified fluoroaluminosilicate glass3
Dentsply Caulk; Milford, DE, USA
Fuji II LC
RMGI
Liquid: polyacrylic acid 20%–22%, 2,2,4 trimethylhexamethylene dicarbonate 5%–7%, triethylene glycol dimethacrlyate 4%–6%10 Powder: aluminofluorosilicate glass11
GC America; Alsip, IL, USA
Fuji IX GP
Self-curing smallparticle condensable GIC
Liquid: polyacrylic acid 30%–40%12 Powder: polyacrylic acid 5%–10%, fluoroaluminate glass 90%–100%13
GC America
Fuji IX GP EXTRA
Self-curing smallparticle condensable GIC
Liquid: polyacrylic acid 30%–40%12 Powder: polyacrylic acid 5%–10%, fluoroaluminate glass 90%–100%13
GC America
Ketac Fil Aplicap
Self-curing largeparticle GIC
Liquid: copolymer of acrylic acid-maleic acid 35%–55%, water 40%–55%, tartaric acid 5%–10%18 Powder: glass powder >99%19
3M ESPE; St Paul, MN, USA
Ketac Molar
Self-curing smallparticle condensable GIC
Liquid: copolymer of acrylic acid-maleic acid 35%–55%, water 40%–55%, tartaric acid 5%–10%20 Powder: glass powder 80%–90%, copolymer of acrylic acid-maleic acid 1%–6% 23
3M ESPE
Ketac Molar Quick
Self-curing smallparticle condensable GIC
Liquid: copolymer of acrylic acid-maleic acid 35%–55%, water 40%–55%, tartaric acid 5%–10%21 Powder: glass powder 93%–98%, copolymer of acrylic acid-maleic acid 1%–5%, dichlorodimethylsilane reaction product with silica22
3M ESPE
Ketac Nano Light Cure Glass Ionomer Restorative
RMGI
Paste A: silane-treated glass 40%–55%, silane-treated zirconia 20%–30%, polyethylene glycol dimethacrylate 5%–15%, silane-treated silica 5%– 15%, HEMA 1%–15%, glass powder < 5%, bis-GMA < 5%, triethylene glycol dimethacrylate 99%, N,N-dimethylbenzocaine < 0.5%33
3M ESPE
Riva LC
RMGI
Liquid: polyacrylic acid 20%–40%, tartaric acid 5%–10%, HEMA 20%–25%, dimethacrylate cross linker 10%–25%, acid monomer 10%–20% Powder: fluoroaluminosilicate powder 95%–100%37
Southern Dental Industries (SDI); Bayswater, Victoria, Australia
Riva LC HV
RMGI
Liquid: polyacrylic acid 20%–40%, tartaric acid 5%–10%, HEMA 15%–25%, dimethacrylate cross linker 10%–25%, acid monomer 10%–20% Powder: fluoroaluminosilicate powder 95%–100%37
SDI
Riva Self Cure Fast
Self-curing smallparticle condensable GIC
Liquid: polyacrylic acid 20%–30%, tartaric acid 10%–15%, remainder water Powder: fluoroaluminosilicate glass 90%–95%, polyacrylic acid 5%– 10%38
SDI
Riva Silver
Self-curing cermet
Liquid: polyacrylic acid 30%, tartaric acid 10%, remainder water Powder: fluoroaluminosilicate glass 40%–70%, polyacrylic acid
Purpose: To investigate polyalkenoate reaction rates in conventional glass-ionomer cement (GIC) and resin-modified glass ionomer (RMGI) restorative materials using infrared spectroscopy. Materials and Methods: Nine conventional GIC and six RMGI restorative materials were prepared according to manufacturer’s directions and placed on a FTIR (Fourier transform infrared spectroscopy) diamond ATR (attenuated total reflectance) surface. FTIR spectra (700 to 1800 cm-1) were obtained each minute for 3 h. VLC specimens were light polymerized after 1 min; at 5 min, all samples were covered with gauze saturated with deionized water. Polyalkenoate reaction was determined by measuring area growth (Å/cm-1) between 1375 and 1500 cm-1. Mean peak areas were determined at 5, 15, 30, 90, and 180 min and compared using ANOVA (p = 0.05) Results: For all RMGI materials, VLC polymerization inhibited the polyalkenoate reaction rate. Compared to conventional GIC, RMGI materials demonstrated less polyalkenoate reaction. Compared to dark curing, RMGI light polymerization significantly inhibited the polyalkenoate reaction rate. Conclusions: The addition of resin components to glass-ionomer products significantly retards and impedes the polyalkenoate reaction. The polyalkenoate reaction rate of RMGI products was significantly lower than that of self-curing GIC restorative materials. Furthermore, light activation of RMGI products further retards the polyalkenoate rate. When clinicians require the therapeutic benefit of a polyalkenoate product, perhaps a conventional GIC restorative product should be the first material of choice. Keywords: polyalkenoate, polyalkenoate reaction, resin modified glass ionomer, glass-ionomer cement. J Adhes Dent 2015; 17: 67–75. doi: 10.3290/j.jad.a33526
G
lass-ionomer cements (GIC) were invented in 1969 and developed by Wilson and Kent in the early 1970s.44 They generally consist of a mixture of various polyacrylic acids and tartaric acid that react with a fluoroaluminosilcate glass in an acid-base reaction.30,45 Glassionomer cements have undergone incremental formulation changes in attempts to improve their physical properties and clinical handling characteristics that have included the use of alternative polyacids,30 water-activated dehydrated polyacid powders,30,35 cermets,28 metal additions,41,44 and smaller mean glass particle size.14 Resin-modified glass-ionomer (RMGI) materials were introduced in the late 1980s/early 1990s and consist of GIC components (water-soluble polymeric acids, ion-leachable glass, and water) combined with organic, photopolymerizable mono-
a
Director, Dental Graduate Research, Keesler Air Force Base, MS, USA. Experimental design, performed all experiments, wrote manuscript.
b
Director, Graduate Dental Biomaterials, Marquette University School of Dentistry, Milwaukee, WI, USA. Substantial review/revision and contribution to discussion and experimental design.
Correspondence: Dr. H.W. Roberts, 81 DS/SGD, 606 Fisher Street, Keesler Air Force Base, MS, 39531 USA. Tel: +1-228-376-5190. e-mail: [email protected]
Vol 17, No 1, 2015
Submitted for publication: 03.02.14; accepted for publication: 10.12.14
mers with an initiation system.29 Although a given RMGI’s exact composition is proprietary, the resin component in the set material of RMGIs available in the mid-1990s was estimated to be approximately 4.5 to 6 percent.15,40 RMGI materials were developed with the intent to improve the mechanical properties and early moisture sensitivity observed with the conventional GIC materials,8,46 and basically exist in two forms: one in which part of the water is replaced by water-soluble, photopolymerizable 2-hydroxyethylmethacrylate monomer (HEMA), and one in which methacrylate groups are predominately grafted onto the polyacrylic molecules.9,15 Although HEMA is the predominant methacrylate used in RMGI materials, newer product formulations may use a combination of HEMA and diurethane dimethacrylate, bisphenol A diglycidyl ether dimethacrylate (bis-GMA), polyethylene glycol dimethacrylate (PEG-DMA), triethylene glycol dimethacrylate (TEG-DMA), or other dimethacrylate monomers.7,10,24,34,36,37,42 The RMGI setting reaction is more complex than that of conventional GIC materials, especially in terms of HEMA interactions with the other constituents.30 HEMA lengthens both the working and setting times of a GIC material, and decreases the compressive strength as well.1,31 HEMA is thought to compress the polyacrylic acid configu67
Roberts and Berzins
Table 1
Products used
Product
Type
Components
Manufacturer
Chemfil Rock
Self-curing smallparticle condensable GIC
Liquid: polycarboxylic acid 10%–25% Powder: zinc-modified fluoroaluminosilicate glass3
Dentsply Caulk; Milford, DE, USA
Fuji II LC
RMGI
Liquid: polyacrylic acid 20%–22%, 2,2,4 trimethylhexamethylene dicarbonate 5%–7%, triethylene glycol dimethacrlyate 4%–6%10 Powder: aluminofluorosilicate glass11
GC America; Alsip, IL, USA
Fuji IX GP
Self-curing smallparticle condensable GIC
Liquid: polyacrylic acid 30%–40%12 Powder: polyacrylic acid 5%–10%, fluoroaluminate glass 90%–100%13
GC America
Fuji IX GP EXTRA
Self-curing smallparticle condensable GIC
Liquid: polyacrylic acid 30%–40%12 Powder: polyacrylic acid 5%–10%, fluoroaluminate glass 90%–100%13
GC America
Ketac Fil Aplicap
Self-curing largeparticle GIC
Liquid: copolymer of acrylic acid-maleic acid 35%–55%, water 40%–55%, tartaric acid 5%–10%18 Powder: glass powder >99%19
3M ESPE; St Paul, MN, USA
Ketac Molar
Self-curing smallparticle condensable GIC
Liquid: copolymer of acrylic acid-maleic acid 35%–55%, water 40%–55%, tartaric acid 5%–10%20 Powder: glass powder 80%–90%, copolymer of acrylic acid-maleic acid 1%–6% 23
3M ESPE
Ketac Molar Quick
Self-curing smallparticle condensable GIC
Liquid: copolymer of acrylic acid-maleic acid 35%–55%, water 40%–55%, tartaric acid 5%–10%21 Powder: glass powder 93%–98%, copolymer of acrylic acid-maleic acid 1%–5%, dichlorodimethylsilane reaction product with silica22
3M ESPE
Ketac Nano Light Cure Glass Ionomer Restorative
RMGI
Paste A: silane-treated glass 40%–55%, silane-treated zirconia 20%–30%, polyethylene glycol dimethacrylate 5%–15%, silane-treated silica 5%– 15%, HEMA 1%–15%, glass powder < 5%, bis-GMA < 5%, triethylene glycol dimethacrylate 99%, N,N-dimethylbenzocaine < 0.5%33
3M ESPE
Riva LC
RMGI
Liquid: polyacrylic acid 20%–40%, tartaric acid 5%–10%, HEMA 20%–25%, dimethacrylate cross linker 10%–25%, acid monomer 10%–20% Powder: fluoroaluminosilicate powder 95%–100%37
Southern Dental Industries (SDI); Bayswater, Victoria, Australia
Riva LC HV
RMGI
Liquid: polyacrylic acid 20%–40%, tartaric acid 5%–10%, HEMA 15%–25%, dimethacrylate cross linker 10%–25%, acid monomer 10%–20% Powder: fluoroaluminosilicate powder 95%–100%37
SDI
Riva Self Cure Fast
Self-curing smallparticle condensable GIC
Liquid: polyacrylic acid 20%–30%, tartaric acid 10%–15%, remainder water Powder: fluoroaluminosilicate glass 90%–95%, polyacrylic acid 5%– 10%38
SDI
Riva Silver
Self-curing cermet
Liquid: polyacrylic acid 30%, tartaric acid 10%, remainder water Powder: fluoroaluminosilicate glass 40%–70%, polyacrylic acid
