Biomedical Engineering Reference
In-Depth Information
Table 4.1
Descriptive Table of Components (wt%) Recorded from Nanofilled Composites
Submitted to EDS
Composite Resins
Ba
Al
O
Si
Esthet-X Enamel
37.56
6.15
23.37
32.92
Esthet-X Dentin
37.00
6.05
17.42
39.53
Filtek Supreme XT Enamel
40.79
59.26
Filtek Supreme XT Dentin
37.38
62.62
Grandio Enamel
10.38
36.93
52.70
Grandio Dentin
5.18
10.12
33.27
51.42
, not recorded.
When fillers were analyzed with energy dispersive spectroscopy (EDS), the following components
were observed: aluminum (Al), barium (Ba), silicates (Si), and other heavy metals used to increase
the radio opacity (
Table 4.1
). For clinical inference, the composites with Ba and Al (Esthet-X) shall
be more evident in X-ray and for clinical longevity of the filling. For Grandio, the dentin shade must
be inserted in deeper increments which is more radiopaque when compared to the enamel shade (as
seen in the X-ray in
Figure 4.26B
).
4.6
FILLER WEIGHT CONTENT (WT%)
Thermogravimetric analysis is used to evaluate filler concentration in percentage by weight. The
specimens of composite were inserted in a platinum container and subjected to 20°C/min tempera-
ture increase until 700°C (TGA 2050, TA Instruments, New Castle, DW, USA) in a nitrogen satu-
rated atmosphere. The temperature of organic matrix degradation and filler weight percent (wt%) were
recorded. The amount of inorganic residues was established by stabilization of the weight of the sam-
ple. The determination of the inorganic content was performed by weighing the mass of the composite
specimen before and after the entire elimination of the organic phase
[10]
. The filler weight content of
common nanofilled composites ranged from 75.75 to 87 wt% (see
Figure 4.4
and
Table 4.2
).
In the relevant literature, it can be seen that there is a strong positive correlation between filler
content and mechanical properties. Xu
[9]
concluded that there was a uniform improvement of elas-
tic modulus and hardness when filler load was enhanced. Similarly, Sabbagh et al.
[11]
recorded a
strong correlation (
r
0.82) between the filler weight content and elastic modulus of composite res-
ins. Thus, the following section will describe the mechanical properties of nanofilled composites.
4.7
WATER SORPTION
Water absorption by composite materials is a diffusion-controlled process, and the uptake of water
occurs largely in the resin matrix
[12]
. The water sorbed by the polymer matrix can cause filler/
matrix debonding (
Figure 4.4
, or even hydrolytic degradation of the fillers
[13]
and may reduce the
