Biomedical Engineering Reference
In-Depth Information
(A)
(C)
1mm
(B)
1mm
1mm
FIGURE 3.3
Photographs of tooth slices coated with CNTs. (A) Nontreated tooth slice (control), (B) transverse view of
CNT-coated tooth slice, and (C) sagittal view of CNT-coated tooth slice.
From Ref.
[235]
.
CNT
[235]
. The presence of CNT at the interface of dentin and composite resin can reduce
the chance of secondary decay development in the long term by providing protection against decay
inducing bacteria and initiating HA nucleation on its surface. However, the gray discoloration
(
Figure 3.3
) at the dentin
composite resin interface due to CNT needs to be overcome to make
this application a reality.
One of the most common complications of denture prostheses is the cracking of denture base
from either accidental dropping or long-term fatigue failure. Denture base is usually made of
PMMA because of its excellent esthetics, low density, low cost, and ability to be repaired.
However, it has relatively low fracture strength which makes a denture base vulnerable to crack by
either impact or flexural fatigue under chewing
[237]
. Recently, MWNT (0.1
1.0 wt%) has been
incorporated into PMMA to increase flexural strength and fracture toughness of denture base mate-
rials
[238]
. A similar application of MWNT (0
10 wt%) to PMMA-based bone cement used in the
orthopedic area has shown to improve the fatigue performance of bone cement
[239]
. Authors of
both studies found that loading of MWNT in PMMA improved flexural strength and fatigue
performances of polymers in a dose-dependent manner. It was speculated that well-dispersed
MWNT was able to reinforce PMMA matrix prior to crack initiation and to arrest/retard early
phase of crack propagation. Even with the significant improvement in mechanical properties, resul-
tant black color of the denture base remains as a disadvantage of CNT application.
