There are several studies that describe the
addition of antibacterial components in adhesive
resins18). In most cases, soluble antimicrobials were
incorporated to show antibacterial activity dependent
upon their release. The disadvantage of these
approaches is harmful effects on the production and
maintenance of integral adhesive interfaces.
Deterioration of adhesive interface is inevitable by
the release of the agents from cured resin, and this
results in low durability of restoration. In addition,
disturbance of resin polymerization sometimes occurs
by inclusion of the additives, leading to reduction in
mechanical properties of the interface and
enhancement of interfacial deterioration as ageing.
In the case of incorporation of MDPB, the
antibacterial component is immobilized at the
bonding interface after setting of restorations. The immobilized component of MDPB is not released
from the interface, contributing to the durability of
restorations. By agar-disc diffusion tests using an
intervening dentin disc, Schmalz et al.14) examined
the production of inhibitory zones by Clearfil Protect
Bond applied onto dentin. They found that no
inhibition zones were produced under the dentin disc
when the adhesive applied was light-cured, indicating
sufficient curing of MDPB in the primer. By in vivo
tests, Clearfil Protect Bond proved to produce more
durable interface than the conventional adhesives in
the oral environment in terms of bond strength to
dentin23). No reduction in dentin bond strength for
the restorations using Clearfil Protect Bond was
demonstrated even after function for 1 year in
human mouth. In addition to its excellent bonding
ability to sound or caries-affected dentin and
enamel24-28), many other in vitro tests also supported
the prominent bonding durability of this
adhesive29-31). These findings appear to reflect the
advantages of incorporation of the antibacterial
monomer.