Biomedical Engineering Reference
In-Depth Information
21.1
Introduction
Root canal treatment is a highly predictable procedure with success rates of up to 96%
[1,2]
. The
success of the treatment primarily depends on proper cleaning and shaping to disrupt the microbial
ecology, disinfecting the root canal system, and finally sealing it to prevent microleakage.
Although the treatment has a high success rate, failure still occurs due to inadequate cleaning and
shaping in anatomically complex root canal systems and/or continued microbial leakage due to lack
of adequate sealing material characteristics
[3
5]
. Current materials possess certain limitations
such as shrinkage, solubility in oral environment, and moisture intolerance. Therefore, development
of proper material for cleaning and shaping as well as sealing the root canal system are essential
for long-term root canal treatment success.
Newer advances, including developments in armamentarium such as the use of the dental oper-
ating microscope and improved materials, have influenced the outcome of periradicular surgery,
according to some studies
[6
10]
. Although success rates have increased incrementally, the option
to extract teeth and replace them with dental implants has grown in popularity. Outcomes of pri-
mary endodontic treatment, which have the highest success rate of endodontics procedures, have
been compared to implants
[11
13]
. Because of the “predictable” option to replace a tooth with a
dental implant when endodontic treatment has failed, the perceived benefit of endodontic treatment
depends on the continued improvement and refinement in the physical characteristics of materials,
techniques, and armamentarium.
One such focus in both the medical and dental fields is the clinical applications of nanotechnol-
ogy. Nanomaterial research has initiated a new era in material development for improved clinical
outcomes. Nanotechnology is defined as the creation of functional materials with structures sized
100 nm or smaller
[14]
. In the field of endodontics, a fair amount of research is underway in an
attempt to enhance every step in clinical procedures from files to filling materials. The smaller
sized nanomaterials, more resistant to wear and fatigue, are being suggested for surface modifica-
tions of currently used rotary nickel
titanium files for root canal treatment to help reduce the inci-
dence of instrument failure. The antimicrobial properties of some nanoparticles may be able to
enhance the efficacy of irrigants and intracanal medicaments due to their size and possible disper-
sion in complex root canal anatomies.
Apart from these, a more concentrated effort has been ongoing to develop “nanomodified” mate-
rials. Dispersion of these particles into current and novel materials could fortify the sealing ability of
obturating and sealer materials, as well as root-repair/root-end filling materials. For example, nano-
composites constitute a relatively new class of materials with the dispersed phase having at least one
ultrafine dimension, typically a few nanometers as demonstrated in
Figure 21.1
. They include poly-
meric materials composed of nanoparticles like carbon nanotubes (CNTs), organically-modified clays
(organoclays), or other nanoscale materials. Because of the nanoscale structure and huge interfacial
area between polymer and organoclay, polymer
clay nanocomposites exhibit enhanced mechanical
and thermal properties. Polymer
clay nanocomposites are particularly attractive for potential appli-
cations where enhanced barrier properties as well as physical properties are desired.
CNTs are predicted to have unique mechanical properties including high stiffness and axial
strength as a result of their cylindrical graphitic structure. Experimental studies have shown that
isolated CNTs possess exceptionally high Young's moduli in the terapascal range which are
much higher than those typically found in stainless steel and carbon fibers
[15]
. Carbon fibers
