Vol 21 No. 1

J Bagh College Dentistry Vol. 21(1), 2009 The effect of amalgam…
mechanism for such adhesive to amalgam is
micro-mechanical type that depends on the film
thickness of the adhesive. Hand condensation
effect may be more obvious than the mechanical
condensation under these circumstances.
Similarly, for the control groups, there was no
bonding mechanism between the amalgam and
dentin just the micro-mechanical adaptation
enhanced by heavy hand condensation. This
attribution is supported by the classic studies and
recent reports about the hand condensation
effects and the bonding mechanism of recent
dentin bonding agents to amalgam (14).
Sweeney (15) , Jorgensen (16) , and Mjor (17)
contributed to such researches. Some of them
found that the hand condensation performed
better in reducing porosities at amalgam / dentin
interface and it had better adaptability. Others
reported that there were some kinds of
mechanical interlocking between amalgam
particles and dentin irregularities even that the
self-sealing criteria of amalgam was not started
yet .
The Syntac adhesive / primer has 4-META
and HEMA co-monomers that may bond the
amalgam chemically and micro-mechanically.
This “real” bonding may show the obvious effect
of mechanical condensation to enhance the
bonding of amalgam to dentin. This explanation
is supported by the findings of Chapman &
Crim (12) , which had already mentioned.
The Use of Dentin Bonding Agents. For both
types of condensation techniques and under the
conditions of this study, there was highly
significant difference between the different types
of adhesives used on the one hand, and between
the groups with the bonding treatment and that
without bonding treatment (controls) on the
other. These results are in agreement with several
studies. Zardiackas & Stoner (2) , Shimizu et a1 (3) ,
and Varga et a1 (4) showed that the bonding of
amalgam to tooth structure was possible under
laboratory conditions with higher over the
unbonded one .
In addition, numerous clinical studies had
reported favorable results, which were obtained
when using amalgam bonding approach. Those
studies were done by Summitt et a1 (18) , Setcos et
a1 (19) , and Belcher & Stewart (35) . These results
support the finding obtained by this about the
bonding of amalgam to dentin by using dentin
adhesive systems and with higher TBS than that
of the controls.
The differences in the bond strengths different
generations of dentin binding agents have been
shown in various studies.
Under the circumstances of this study, the
Syntac adhesive showed higher TBS to dentin than
the Scotchbond Multi-Purpose. This finding is in
agreement with that of Retief et a1 (14) , although the
TBS values were higher than those of this study.
However, Chappell & Eick (22) and Holtan et a1 (23)
found that the Scotchbond Multi-Purpose had
significantly better bond strength between the
amalgam and dentin than the Syntac and
Scotchbond Multi-Purpose may be due to the
different chemistries of these bonding systems ,
although some similarities do exist. The similarity
found in the pretreatment procedure in using the
same chemical composition etchants 9355
phosphoric acid). The Scotchbond Multi-Purpose
primer contains HEMA and polyalkenoata copolymer
and the adhesive contains BIS-GMA and
HEMA (14) . The Syntac-one bottle-contains 4-
META and HEMA (24) . Examinations with an
electron microscope have shown that the
hydrophilic monomers connect with both organic
dental hard tissue by forming ion complexes with
calcium ions of enamel and dentin and hydrogen
bridges with collagen fibers of dentin (25) . This
complicated connection may be the reason for such
higher TBS values obtained in this study over the
Scotchbond Multi-Purpose.
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Restorative Dentistry 36