The purpose of this study was to estimate the changes of marginal adaptation to the
cavity floor of light-cured glass ionomer cement base after application of a composite
restoration. Eighty non-carious extracted human molars were used in the present study.
Circular cavities were prepared on the center of the exposed dentin surface to 0.5mm,
1.0m, 1.5mm, 2.0mm in depth and the prepared cavities were pretreated with Dentin
conditioner and filled with Fuji II LC(GC Int. Co., Japan). They randomly assigned into
3 groups according to the difference in application of a composite restoration; Group
1(control group) : only glass ionomer base, Group 2: The application of a composite
restoration surrounded by dentin with class I cavity over glass ionomer base after
conventional dentin bonding to the exposed dentin and glass ionomer base, Group 3: The
application of composite restoration not-surrounded by dentin over glass ionomer base
after conventional dentin bonding to the exposed dentin and glass ionomer base.
To examine the interface between cavity floor and light-cured glass ionomer cement
base, each groups were sectioned vertically through the center of restorations with
diamond saw and the gap size(㎛) of interface measured by SEM. The results were
analyzed by using One Way ANOVA.
The results were as follows: 1. Good adaptation between glass ionomer cement base
and cavity floor was showed in specimens with 0.5mm, 1.0mm depth base of control
group. But in specimens with 1.5mm, 2.0mm depth base of control group, the gap was
measured about 15㎛, 40㎛ respectively.
2. Gap size in group 2 was significantly higher than that in control group(P<0.05).
3. Gap size in group 3 was significantly higher than that in control group and group
2(P<0.05).
4. It was possible to observe the good adaptation between glass ionomer cement base
and dentin which was intermediated with 4-10㎛ hybrid layer in specimens with 0.5mm,
1.0mm depth base of control group. Cohesive fracture within cement base was observed
in all specimens which had the gap between glass ionomer cement base & dentin.
5. It was possible to observe the gap formation between cement base and bonding agent
and between composite resin and dentin in all specimens of group 2.
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