ISSN 2321-807X New Glass Compositions Based on Calcium-Fluoroaluminosilicate for dental composite Rafed. M Al-Bader* , Kareema M.Ziadan** and M. S Al-Ajely*** * College of Dentistry, University of Basrah, Basrah, Iraq
[email protected] ** Department of Physics, college of science, University of Basrah, Basrah ,Iraq
[email protected] *** Department of Chemistry, college of education, University of Mosul, Mosul ,Iraq
[email protected] ABSTRACT The new inorganic Calcium fluoroaluminosilicate samples M1-M10 were prepared and their physical properties such as Xray, FTIR, BET and SEM were studied and were successfully used in dental filling of light cured composite type. The optimum ratio of the new filler components was also studied to match the comparable properties of the commercial composite filling, the successful application of the prepared fillers together with high tensile strength, high compressive strength and other properties indicate the useful use of this powder mixture in light cured type composite.
Indexing terms/Keywords Glass; Calcium Aluminosilicate; composite filling.
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Journal: Journal of Advances in Chemistry Vol. 10, No. 5
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ISSN 2321-807X INTRODUCTION Modern dental composite materials are a blend of glass or ceramic particles dispersed in a photo-polymer sable synthetic organic resin matrix. The polymer materials usually blended together with the finely divided inorganic material such as a Calcium Fluoroaluminosilicate glass (Ca-FAlSi) or other glass compositions having an effective amount of radiopaque oxide that renders the resultant glass radiopaque to X-rays. Calcium Fluoroaluminosilicate glasses (Ca-FAlSi) are the basis of degradable characteristics glass used in Dentistry as filler for cement or light curing, self curing composites.[1] Calcium Fluoroaluminosilicate glasses (Ca-FAlSi) are contained Fluoride ions , Fluoride is well known to prevent dental decay by inhibiting enamel and dentine demineralisation, The incorporation of filler particles into a resin matrix and filler characteristics (i.e., radiopacity, filler distribution, shape and size) changes the physical properties, such as elastic modulus, compressive and tensile strength [2-5]. The alumina to silica ratio of the glass plays a critical role in determining the glass and composite properties, However, in more complex glasses containing fluorine and phosphate the alumina: alumina ratio is much less important.[6] The three main parts of applicable glass ionomer cements in dentistry include silica (SiO 2), alumina (Al2O3), and calcium fluoride (CaF2) have certain properties of this type of cement, which make them highly suitable for application in dentistry, when bound together by fusion ,they create an appropriate glassy structure forming the filler material. The composition of the glass determines properties like translucency. If the silica content exceeds 40% the glass will be transparent whereas glasses high in calcium fluoride or alumina are opaque Glasses, because it has a beneficial effect on the preparation and on the cement forming properties of the glass as well as on the caries preventing potential of resulting GIC through the fluoride release. Calcium fluoroaluminosilicate glasses (Ca-FAlSi) were synthesized by many different method such as non-Hydrolytic sol-gel [7], polymeric precursor method [8], and fusion method[9],The fusion method has been widely used for the preparation of these vitreous systems. In terms of temperature, dental glasses can be classified as ‘high’ and ‘low’ fusing glass. The high-fusing( above 950°C ) have been found to be more resistant to thermal and mechanical shock as well as to erosion by mouth fluids. Low-fusing porcelains (650°C-950°C) are less desirable but are preferred in dentistry because of their working up ability.[10] In this work the calcium-fluoroaluminosilicate glass (Ca-FAlSi) is prepared by fusion the mixture of oxides and fluorides (SiO2 , Al2O3,AlF3, CaF2, NaF, and AlPO4) within a temperature range from 1200 - 1500ºC. [1, 11] The synthesis and structure of the gasses were characterized using X- ray diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) Surface Area Analysis, Fourier Transform Infrared Spectroscopy (FTIR), energy dispersive X-ray analysis (EDX), and thermal analysis (TG/DTA). These types of powder samples were studied in preparing light cured composite filling successfully and will be published in next work.
EXPERMANTAL METHOD Material The raw reagents used to prepare the powders were SiO2 (99%, Sigma), Al2O3 (99%, Merck) CaF2 (99%, UNIChem), AlF3 (99%, LOBA Chemie), NaF (99%, MERCK) and AlPO4 (MERCK).
Preparation of glasses The glass components were silica (SiO2,), Alumina (Al2O3), Calcium Fluoride (CaF2) ,Aluminum Phosphate Al2PO4, Aluminum Florid AlF3 and Sodium Florid NaF .They were weighed in the appropriate ratios as show in Table 1. and mixed for 2 h in a ball mill. the powders were then sieved to a particle size of < 75 μm. The resulting mixture was heated in an electric furnace (MIHM- VOGT P6/B GERMANY at temperature range of about 1200ºC),Starting from room temperature to 950 - 1200°C (5°C min intervals , 50 to 500°C , 10°C min intervals and 500 to 1200°C) for 2 hours to obtain the required glass. The glass was then grounded in a ball-mill (RETSCH PM 100 Germany) for 2h and then passed through a sieve , mesh opening of < 25µm. The produced powder were used for subsequent analysis and then for dental filling.
Measurements: X-ray Powder Diffraction XRD patterns were recorded with a vertically mounted diffractometer system (XRD, SIEMENS , D5000 GERMANY) using Fe radiation. The scanning range (2θ) was from 10° to 70° at a scan speed of 2°/min and a step size of 0.02° in continuous mode. The crystal size (D) of the glass samples was determined by the Scherrer equation.
Fourier Transform Infrared Spectroscopy (FTIR) Fourier transformed infrared analysis (FTIR; 8300, Shimadzu Co., Kyoto, Japan) was performed to identify the functional group and the chemical bonds between atoms. The samples were obtained as KBr discs.
Brunauer, Emmett and Teller (BET) sample is degassed under heat and vacuum, after which it is cooled to liquid N2 temperatures and an inert gas is added in controlled amounts. The gas adsorbs on the surface to form one monolayer as pressure builds up in the sample chamber. The monolayer of gases forms a dipole and allows for a second layer to build up on it. Brunauer-Emmett Teller
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ISSN 2321-807X (BET) method using a CHEMBET 3000 QUANTACHROME, using nitrogen As the adsorption/desorption gas. The mean diameter obtained by applying the BET method
Scanning electron microscopy SEM The morphology and glass size particles were characterized by SEM (VEGA TESCAN - Czech ). The Energy dispersive X-ray analysis (EDX) was used to identify the chemical composition of the different phases in the samples. Specimens were identified by using a SEM operating with a Vantage System (VEGA TESCAN - Czech). The spectra for EDX measurements were obtained for 100 s live time (voltage: 15 kV; dead time 20–25%; working distance: 20 mm).
RESuLT AND DISCUSSION To confirm the amorphous state and the glass formation, the prepared samples were analyzed by (XRD) and differential thermal analysis (DTA). Fourier transform infrared spectroscopy (FTIR) . Scanning electron microscopy (SEM) also used to study the morphology of the prepared glass
Table 1. Batch composition (W%) of Calcium-Fluoroaluminosilicate Glass after fusion Sample
SiO2
Al2O3
M1
22
18
M2
22
19
M3
29
M4
CaF2
Al2PO4
AlF3
NaF
SiO2/Al2O3
22
15
23
0.8181
10W%
39
13
7
0.8636
16.6
34.2
9.9
5.3
5
0.5742
35
25
20
8
6
6
0.7142
M5
39.52
23.6
13.65
3.62
9.7
9.91
0.5971
M6
24.3
27.5
14.0
19.1
15.1
M7
33.9
17.5
8
15
10
M8
56.5
33.5
M9
48.9
29.1
15
M10
36.3
22
12
9
14.3
1.1361 15.6
0.5162
10
0.592
7
0.5905
6.4
0.59
X-ray diffraction patterns obtained from each Ca-FAlSi glass sample using Scherrer equation[12]
(1) where λ is the wavelength of the incident X-ray (0.193604 nm), β Scherrer constant between 0.85 -0.99 depending on the particle morphology (β = 0.89 for spherical crystals with cubic symmetry), θ is the diffraction angle, and W is the full width at half maximum (FWHM in radian). The results is shown in Fig. 1 indicate that glasses were amorphous. M4, M5, M8 and M10 glasses showed no peaks in the pattern. It also shows some additional peaks of low intensity which were not assigned, the main peak for glass M3 at about 34° 2θ appears as the typical split peak for higher concentrations of CaF 2. The crystal size of the glasses calculated from (equation 1) were found within a of 20–25 nm.
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Fig 1: XRD patterns of Calcium Fluoroaluminosilicate glasses
Figure 2 below shows the SEM images of Ca-FAlSi glasses of the ten studied sample compositions. The particles were sharp-edged, polygonal, and ranged from 1 to 15 µm in diameter. particle analysis using the NIH ImageJ program[13] that the mean size of glasses was 1.1 to 1.5 µm, reflecting a wide range of distribution of spherical powders around 20-25 µm. Other synthesized glass powders were also investigated for the morphology and particle size after spray drying. The results were summarized in the following images
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Fig 2: SEM of Calcium Fluoroaluminosilicate glasses. The specific surface area of the particles was performed using BET analyses , dBET is represented by[14]
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2
Where As is the specific surface area (m /g) and ρ is the theoretical density of the phase, Pycnometry was used to determine the density of all the filler materials by using a 10 mL Gay-Lussac type pycnomter, with an uncertainty of ± 0.02 3 g/cm .
2
The result was obtained within a range between 3.06 to 2.16 m /g for studied glasses a mean particle size was calculated and results are shown in Table2. Pycnometry was used to determine the density of all the filler materials. The precision of the density measurement was validated by the relatively small standard deviation (~0.02) of four measurements.
Table 2. Results of crystal size and particles size for Calcium Fluoroaluminosilicate 3
(nm)
2
(µm)
(µm)
2.5654
0.944976
1.426867
37.30931
3.0614
0.770699
1.17024
29.68613
2.2673
1.052633
1.52816
2.444
2.4813
0.989397
1.4356
M5
2.4027
2.2706
1.122069
1.57356
M6
2.781
38.1681
2.6892
0.802282
1.151792
M7
2.4625
35.45395
2.1657
1.125291
1.152735
M8
2.438
20.08523
2.1888
1.124376
1.472481
M9
2.4018
30.12337
2.6042
0.959188
1.172233
M10
2.5080
36.2856
2.5644
0.966431
1.341481
Glass
Density (g/Cm )
M1
2.4930
32.29712
M2
2.543
M3
2.5143
M4
BET (m /g)
The FTIR spectra are presented in Fig. 3. The topology of glasses can be described in terms of finite component units, which are specific arrays of TO4 (T: Al, Si) tetrahedral[15], The values are in good agreement with those reported -1 earlier[8, 16]. Bands at 1100 cm are assigned to the asymmetric stretching vibration of Si–O bonds in a tetrahedral -1 network. Bands at 720cm are due symmetric stretching of Si–O–Si (bridging oxygen atoms between the tetrahedra). The -1 vibrations of the Si–O–Si, Al–O–Al, or Al–O– Si bonds are located at 460cm . The assignments of the bands are listed in Table 3. Using these assignations, it can be seen that the structure of fluorine free glass is built up of SiO 4 and AlO4 entities linked together as in the Ca-FAlSi glass, similar to the analysis of Khaghani et al[17].
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Fig 3: The FTIR spectra of Calcium Fluoroaluminosilicate glasses
Table 3. Assignments of the bands observed in FTIR spectra for Calcium Fluoroaluminosilicate glasses
Glass
460 Cm
-1
530-620 Cm-1
-1
730 Cm
1000-1100Cm
-1
Si–O–Si, Al–O–Al and Al–O–Si
SiO2 none bonded
symmetric stretching of Si–O–Si
asymmetric stretching vibrations of Si–O–Si
M1
445.56
617
711.73
1033.85
M2
457.13
729.09
1074.35
M3
459.06
609
713.66
1043.49
M4
449.41
612
713.73
1078.21
M5
451.34
614
717.52
1051.20
M6
447.49
602
659.66
1058.92
M7
460.99
612
717.52
1056.99
M8
447.49
615
773.46
1055.06
M9
449.41
713.66
1056.99
M10
445.56
617
1041.56
Energy dispersive X-ray analysis (EDX) used to elemental analysis of Ca-FAlSi glasses was performed for the following elements: Al, Si, O, P, Na, Ca and F. The results are listed in Table 4. It should be noted that a high amount of fluorine was incorporated in Ca-FAlSi.
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ISSN 2321-807X Table 4. Result of EDX : Elemental composition (mass %) of Ca-FAlSi glasses. Glass
O
F
P
Al
Si
Na
Ca
M1
33.29
25.79
2.78
15.4
11.59
10.5
0.66
M2
38.77
17.68
5.63
16.00
12.51
4.29
5.13
M3
32.65
25.73
1.23
10.04
12.21
2.23
15.90
M4
37.24
19.70
1.18
13.93
15.20
2.78
9.95
M5
38.1
20.91
0.55
12.97
15.59
4.44
7.54
M6
38.81
20.57
5.22
16.43
10.50
3.61
4.87
M7
46.36
11.44
0.47
12.85
22.16
5.19
1.53
M8
39.16
18.78
1.45
13.23
16.95
7.27
3.16
M9
42.84
15.08
0.57
12.78
16.01
2.49
10.20
M10
38.3
20.28
1.31
14.62
15.90
3.00
6.6
the DTA curves of the glasses prepared in this work were shown in fig. 4. These curves reveal the presence of an exothermic peak at 400-1000ºC temperature , which referred to the temperature of glass transition. Tg and crystallization TC, of glasses were recorded and summarized in Table 5. In sample M3 With the increase of CaF2 content, crystallization temperature of the glasses and intensity of the crystallization peak decrease significantly. For sample M8and M9 there is no peak
Fig 4: The DTA curve of Calcium Fluoroaluminosilicate glasses
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ISSN 2321-807X Table 5. The crystallization peak (Tc) and glass transition temperature (Tg) of glasses Glass
Tc
Tg
M1
851
553.9
M2
908
627.4
M3
780
696.4
M6
930
702
M8
1000
500
M9
1000
520
Conclusions SEM observation revealed the irregular nature of the powder particles. XRD analysis showed crystallites size in nano rang. From DTA curves, Tg of the respective glass compositions was measured. After analysis the FTIR spectra obtained for glasses it is possible to infer that these glasses can be used as filler for dental composites resin.
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ISSN 2321-807X [16] Stamboulis, A., Hill, R. G. and Law, R. V. Characterization of the structure of calcium alumino-silicate and calcium fluoro-alumino-silicate glasses by magic angle spinning nuclear magnetic resonance (MAS-NMR). Journal of noncrystalline solids, 333, 1 2004), 101-107. [17] Zhao, J., Platt, J. A. and Xie, D. Characterization of a novel light‐cured star‐shape poly (acrylic acid)‐composed glass‐ionomer cement: fluoride release, water sorption, shrinkage, and hygroscopic expansion. European Journal of Oral Sciences, 117, 6 2009), 755-765.
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