Setting Reaction And Compressive Strength Of GlassPolyalkenoate Cements Based On Ca/Na Fluoro-

aluminosilicate Glasses

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INTRODUCTION

• Glass polyalkenoate cement (GPC) is also known as water based glass ionomercement (GIC)• Produced by the acid-base neutralization reaction of aqueous polyacrylic acid(PAA) with calcium fluoro-alumino silicate glass powder [1].

Figure 1: Reaction mechanism in GPC formation

• Uses: Dental restoration material, luting agent, cavity linings and bases [1].• Advantages: self-hardening, chemically bonded to dental tissues, non-toxicand good biocompatibility.

METHODOLOGY

GLASS COMPOSITION

Table 1: Glass composition in mole percentage

GPC PREPARATION

CONCLUSIONThe addition of MMT in LG3 and LG66 cementsincreased the compressive strength from 53 to74 MPa and from 10 MPa to 66 MPa at 14 and 28days aging time respectively.

OBJECTIVES

1. To follow the setting reaction of GPCs2. To study influence of MMT on compressive strength of GPC3. To investigate the influence of Na on the setting reaction of cement

Code SiO2 Al2O3 P2O5 CaO CaF2 Na2O

LG3 33.3 22.2 11.1 22.2 11.1 -

LG66 33.3 22.2 11.1 17.8 11.1 4.4

GPC with MMTGlass powder + PAA +

waterRatio : 2 : 1 : 1

GPC without MMTGlass powder + PAA + water

+ MMT clayRatio : 2 : 1 : 1 : 2.5wt%

Mixed homogenously and placed intotest mold

- test mold kept at 37°C for 1 hour.- quenched into liquid nitrogen ( for less 1 hour GPCs) anddehydrated with ethanol.- GPCs immersed and stored in water at 37 °C.-ageing time: 5 minutes, 10 minutes,30 minutes, 1 hour, 6 hours,1 day, 7days, 14 days and 28 days.

ANALYSIS

Setting reaction by Fourier Transform Infrared spectroscopy.Compressive strength by Instron compressive machine.

Figure 2: Compressive strength test

DISCUSSION

• Compressive strength for both cements increased with time.• Addition of MMT showed the significant increase of compressive strength for both cement. Theformation of hydrogen bonding between MMT and acid provides the great effect on thecompressive strength [2].• LG3 cement exhibited higher compressive strength than LG66 cement. However, the valuebecame slightly drop after 14 days .•The composition of the glasses has a substantial effect on the setting behaviour. Thus,compressive strength are different.•LG66 cement contain Na have a disproportionate influence on cement properties and affectcompressive strength [3].

• Absorption band between 1050 – 980 cm-1 is the asymmetric Si-O(Si) in original glasses.• As time elapsed, the shoulder peak at 1570 cm-1 and 1550 cm-1 became increase in intensity dueto formation COO-M+ as metal ions (Al3+ and Ca2+) crosslink with the carboxyl group in the acid [4].• In contrast, the intensity of shoulder peak at 1710 cm-1 became decrease in intensity due touptake of H+ from acid by silica network to form silica gel layer during the cross linking of metal ionsand COO- in cements formation.• Setting reaction of LG66 cement were slower than LG3 cement. Na+ in LG66 cement havetendency to compete with Al3+ and Ca2+ and delayed the crosslinking process [3].

0 5 1 0 1 5 2 0 2 5 3 030

40

50

60

70

80

0 5 10 15 2 0 25 300

10

20

30

40

50

60

70

80

WithMMT

WithoutMMT

COMPRESSIVE STRENGTH

Figure 3: Compressive strength of LG3cement

Figure 4: Compressive strength of LG66cement

Com

pres

sive S

tren

gth,

MPa

Com

pres

sive S

tren

gth,

MPa

Aging Time, day Aging Time, day

FTIR SPECTROSCOPY

4 000 3 500 3 000 2 500 20 00 15 00 10 00 50 00

20

40

60

80

100

% In

tens

ity

Wavenumber, cm-14 00 0 3 5 00 3 00 0 25 00 2 00 0 15 0 0 1 00 0 5 00

0

2 0

4 0

6 0

8 0

1 0 0

% In

tens

ity

Wavenumber, cm-1

Si-O (Si)Stretch

Si-O (Si)Stretch

Figure 5: FTIR spectrum for LG3 glass Figure 6: FTIR spectrum for LG66 glass

Figure 8: FTIR spectra for LG3 cement (5minutes-28days)

Figure 9: FTIR spectra for LG66 cement (5minutes-28days)

4 000 3 500 3 000 2 500 20 00 15 00 10 00 50 00

20

40

60

80

100

Figure 7: FTIR spectrum for PAA

O-Hstretch

COOH

CONCLUSION• FTIR spectroscopy can be used to follow the setting reaction of GPCs by assigning the conversionof COOH to COO- M+.• The compressive strength for both GPCs were increased with the addition of MMT.• The presence of Na influence the setting reaction and compressive strength of GPCs.

REFERENCES1. Nicholson J.W., Chemistry of glass-ionomer cements: a review. Biomaterials 1988, 19, 485-494.2. Dowling A.H., Stamboulis A., Fleming J.P., The influence of montmorillonite (MMT) clay reinforcement on the

performance of a glass ionomer restorative. Journal of dentistry 2006, 34, 802-810.3. De Barra, Hill R.G., Influence of alkali metal ions on the fracture properties of glass polyalkenoate (ionomer)

cements. Journal of Biomaterial 1998, 19, 495-502.4. Crisp S., Wilson A.D., Reaction in glass-ionomer cements . The precipitate reaction. J.Dent Res 1974, 53, 1420-

1424.

Wavenumber, cm-1

% In

tens

ity