  rime
& Bond ŽNT is the successor to Prime & Bond
2.1 and is the best 5th generation bonding
agent. It is truly a one coat technique
and this is accomplished by several mechanisms:
1.
The overall resin concentration has been
raised
2. A small resin (D-resin) has been added
3. A crosslinking agent (T-Resin) has
been added
4. A nanofiller has been added
 The
nanofiller is extremely small, and is only
about 7nm in diameter and hence it reaches
all the places the liquid components of
Prime & Bond ŽNT reaches. Figure 4 shows
the comparative sizes of the Nanofiller
to the size of a Dyract ŽAP particle of
about 0.8ľm. It is evenly distributed in
the resin matrix when cured and serves as
an additional crosslinker and adds to the
strength of the adhesive layer and the hybrid
layer. The average dentinal tubule is about
0.8ľm and the channels between the collagen
fibrils in acid conditioned dentine is about
20nm wide with a diameter of 5-10nm. The
nanofiller has therefore the perfect size
to penetrate these channels to provide added
"Nano-retention". The filled adhesive is
stronger than unfilled adhesive and when
infiltrated into conditioned dentine, it
provides the polymeric toughness as well
as strength.
The
higher bond strengths of Prime & Bond ŽNT
to enamel and dentine using both the Spectrum
TPH and Dyract ŽAP have been extensively
demonstrated by several of the world's leading
authorities. When the adhesion of five of
the current leading "5th generation" bonding
agents to enamel and dentine were compared,
Prime & Bond ŽNT recorded the highest bond
strength by a good margin.
Prime
& Bond ŽNT also improved the fluoride release
mechanism from an initial burst of fluoride
release to a more gradual, but higher level
of fluoride release over a longer time period.
Dr.
J Perdigao (Univ. of N. Carolina) concluded
that "Prime & Bond ŽNT consistently formed
fully-penetrated, "filled" hybrid layers,
filled resin tags and penetrated laterally
into secondary canals."
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