Biomedical Engineering Reference
In-Depth Information
Sun et al.
[28]
showed that TiO
2
nanoparticles in adhesives could improve DC and mechanical
properties expecting better bond strength and durability.
7.9.3
Antibacterial orthodontic adhesives containing nanosilver
Enamel demineralization is a commonly recognized complication of orthodontic treatment with
fixed appliance. Preventing these lesions is an important concern for orthodontists because the
lesions are unesthetic, unhealthy, and potentially irreversible. The introduction of antibacterial
adhesives would improve the outcome of orthodontic treatment due to less bacterial adhesion to the
orthodontic appliance. Ahn et al.
[77]
suggested an orthodontic adhesive containing nanosilver par-
ticles as antimicrobial agent. The adhesive showed less bacterial adhesion and less bacterial growth
without affecting bond strength.
7.9.4
Radiopaque dental adhesives
Secondary caries may be detected visually by the discolorations at the tooth/restoration interface,
though X-ray photographs are often required to safely discriminate such lesions from stained mar-
gins. Radiographs rely on the difference in radiopacity between healthy dental tissue, cariogenic
hard tissue, and restorative material. Modern composite-filling materials commonly contain radi-
opaque components, such as Sr- or Ba-glass fillers, making them easily distinguishable by X-ray
from the tooth. Dental adhesives, however, do not contain such radiopaque materials today making
them hard to distinguish from caries. Schulz et al.
[23]
focused on the development of radiopaque
adhesives by incorporating flame-made Ta
2
O
5
/SiO
2
nanoparticles in methacrylic matrices. The
nanofilled adhesive had radiopacity better than enamel and dentin without adverse effect on bond-
ing to hard dental tissues.
7.9.5
Self-adhesive composites
The introduction of self-adhesive composites will offer clinicians the simple approach toward the
restorative procedure by eliminating the number of steps associated with bonding procedure. The
latest trend has been toward the development of flowable composites containing adhesive mono-
mers such as Vertise Flow (Kerr) and Fusio Liquid Dentin (Pentron Clinical). These formulations
are based on traditional methacrylate systems, but incorporating acidic monomers typically found
in dentin bonding agents such as glycerol phosphate dimethacrylate in Vertise Flow may be capable
of generating adhesion through mechanical and possibly chemical interactions with tooth structure.
These materials are currently recommended for liners and small restorations and are serving as the
entry point for universal self-adhesive composites
[78]
.
7.9.6
Self-healing adhesives
The concept of self-healing polymers relies on encapsulation of monomers and catalyst and incor-
porating these encapsulated healing precursors into the polymer. When cracks are initiated in the
polymer, the capsules rupture and healing monomers fill the crack and polymerize there allowing
healing of the crack. In the field of dental adhesion, self-healing bonding resins may provide a new
