THE JOURNAL OF - Dentsply

Blunck/Zaslansky
[% MQ1]
100
95
a.
90
85
Optibond FL
80
75
T1 T2 T3 T4 T5 T6
[% MQ1]
100
95
b.
90
85
Syntac
80
75
T1 T2 T3 T4 T5 T6
c.
[% MQ1]
100
95
90
85
80
75
Clearfil SE Bond
T1 T2 T3 T4 T5 T6
Fig 3 Median MQ1 values in % of entire margin length
in dentin with error bars indicating the standard error of
the mean for the multi-bottle reference materials (a) Opti
Bond FL, (b) Syntac and (c) Clearfil SE Bond at the six
evaluation stages T1 (after 21 days’ water storage), T2
(after 1st TC), T3 (after 1 year of water storage), T4 (after
2nd TC), T5 (after 3 years of water storage) and T6 (after
3rd TC). Black lines: regression lines weighted by the corresponding
standard error; dotted lines: 95% confidence
intervals.
study, but overall the scores are quite high, perhaps due to
the fact that the deterioration is generally quite minimal.
Further examination of the present data allows creating a
quasi-dynamic perspective of the deterioration rate of the
restorations (Fig 3 and Table 3). Thus it is seen that there is
a general negative trend in the MQ1 values, when these are
determined after water storage and/or thermocycling (TC).
Clearly, the specific state of the bond between each
restorative and the tooth is not easily determined by any surface-evaluation
method, particularly following long-term water
storage. The decision was thus made to use TC to induce
mild stress to every tooth-restoration interface in order to better
reveal its state as determined by the marginal quality evaluation.
As can be seen in Table 3, the effect of TC is not constant
during early vs late (> 1 year) water storage, and this is
attributed to the differences in the adhesive stability in water.
A number of publications have dealt with the effects of
similar long-term water storage beyond 2 years. 2,3,7,16,22,
23,27 To the best of our knowledge, however, none have managed
to produce high-resolution long-term data mapping the
marginal quality deterioration on the same samples.
Despite the fact that the cavity dimensions were standardized,
the amount of stress induced to the interface of
each restoration probably varied considerably. This might
be due to the large variations in the coefficients of thermal
expansion of each restorative 28,29 or possibly due to tooth
variability. Be that as it may, because the manufacturer-recommended
composites were used, it was assumed that the
conditions were optimal for each adhesive, and that the
best performance was obtained. It remains to be seen if other
combinations of composite/adhesive deliver improved
long-term results. Possibly, a standard composite restorative
should be used for such tests in the future in order to
better compare the effectiveness of the investigated adhesives.
The importance of the effect of the composite resins
can clearly be seen in the groups of Adper Prompt L-Pop and
Xeno III, where large differences in MQ1 values and slopes
are seen for the same adhesive. Note however, that while
Adper Prompt L-Pop in combination with Tetric Ceram
showed a statistically significant decrease in MQ1 compared
to the results obtained with Filtek Z250, all three
combinations with Xeno III (Dyract XP, Quixfil, and Tetric Ceram)
revealed no statistically significant differences in marginal
integrity. We therefore conclude that these adhesives
react differently to composite resins with higher polymerization
shrinkage stress values.
Both in vitro 6,7,10,11 and in vivo studies 8,12,13,35,37 have
shown that multi-bottle multi-step adhesive systems such as
236 The Journal of Adhesive Dentistry