Biomedical Engineering Reference
In-Depth Information
150 nm) in resin-modified glass
ionomer and observed the bond strength with tooth structure, and it was found that lowest
bonding strength was observed in the resin-modified glass ionomer (0.75 MPa), followed by
micro-HA-added GIC group (1.02 MPa), and nano-HA-added GIC group presented highest bond-
ing strength (1.91 MPa). The reason for the increased bonding strength of GIC with the addition
of HA is that calcium ions from HA may participate in chemical ionic bonding between the tooth
and the material as shown in
Figure 5.3
. Bonding strength was greater in the nano-HA-added
GIC group compared to micro-HA added GIC group, which can be attributed to smaller particle
size of nano-HA; smaller particles have increased surface area, which contributes to enhanced
solubility and infiltration capacity to enamel surface, thereby reinforcing the bonding strength.
The demineralized enamel surface study showed that the resin-modified GIC exhibited increased
irregularities, and microporosities arise from the loss of inorganic materials from the inter-rod
space in enamel. Whereas, samples with nano-HA showed smoother enamel surface with
increased regularity compared to the micro-HA. Increased resistance to demineralization with
nano-HA samples can be explained by smaller particle size of nano-HA compared to micro-HA;
the smaller particle size enhanced its deposition into micropores in demineralized enamel. The
high solubility of nano-HA leads to effective release of calcium and phosphate ions, which fills
the demineralized micropores. HA particles and inorganic ions infiltrate into the demineralized
Lee et al.
[55]
added micro-HA (5
10
μ
m) and nano-HA (100
(A)
(B)
(C)
µ
µ
µ
µ
FIGURE 5.3
Fractured surface observed under SEM after bonding strength test (SEM
3
5000). (A) GIC only,
(B) GIC
nano-HA. Spherical apatite particle was not observed in the control group
(A). Decreased diameter of dentinal tubules and deposition of spherical apatite particle were observed in
experimental groups (B and C). Increased spherical apatite particle deposition was observed in nano-HA-
added GIC group (C) compared to micro-HA-added GIC group (B)
[55]
.
micro-HA, (C) GIC
1
1
