Biomedical Engineering Reference
In-Depth Information
7.9.4 Radiopaque dental adhesives .................................................................................. 156
7.9.5 Self-adhesive composites ........................................................................................ 156
7.9.6 Self-healing adhesives ............................................................................................ 156
7.9.7 High-speed AFM..................................................................................................... 157
7.10 Conclusions and future directions ............................................................................................... 159
References ......................................................................................................................................... 160
7.1
Introduction
The field of adhesion to dental substrates has gained a lot of interest with massive research work
aiming at improving bond strength and increasing bond durability. Nanoscience and nanotechnol-
ogy are expected to play a major role in understanding and improving the outcome of adhesion and
dental restorative procedures. These improvements are expected to yield adhesives with antibacte-
rial capacities through the incorporation of antimicrobial nanoparticles. Self-healing adhesives will
be available for the dental profession through nanoencapsulation of monomers and incorporation of
these nanocapsules in the adhesives. Adhesives incorporating nanoparticles or nanorods will show
improved physicomechanical properties and catalytic activity with better polymerization and
conversion of adhesive monomers.
7.2
Brief history of dental adhesives
In the dental research area, Kramer and McLean in 1952
[1]
were the first to make an experimental
study in the field of adhesion to tooth substrate, but this was poorly unnoticeable until the
Buonocore's attempt in 1955
[2]
. Nowadays, the concept of “minimum interventions” or “mini-
mally invasive cavity preparations” has been widely accepted
[3]
which means that the diseased
dental tissues is only removed and replaced with adhesive restorations.
Previously, van Meerbeek et al.
[4]
classified the dental adhesives according to their actions on
the smear layer. One-step or two-step adhesives that modify the smear layer were the first category
in this classification. Another approach was the total removal of the smear layer, which involved
two-step or three-step adhesives. The last approach was the adhesive that dissolved the smear layer
rather than remove it. These adhesives utilize acidic “self-etching primers” that dissolve the smear
layer making it a part of the hybrid layer (
Figure 7.1
).
With the introduction of one-step self-etching adhesives, several brands were being available in
the market, which made wide varieties of such adhesives
[5]
. Dental adhesives were categorized
into (i) etch-and-rinse, either three-step or two-step, (ii) self-etching adhesives, either two-step or
one-step, and (iii) the glass ionomer adhesive which is considered a two-step etch-and-rinse adhe-
sive based on resin-modified glass ionomer (RMGI) formulation. Among all adhesive categories,
three-step etch-and-rinse adhesive is considered the “gold standard” regarding its clinical durability
(
Figure 7.2
).
