610 the journal of prosthetic dentistry volume 81 number 5

CLINICAL IMPLICATIONS
The findings of this in vitro study suggest that Fuji II LC glass ionomer cement pro-
vided a better marginal adaptation than Dyract composite in Class V restorations,
and the amount of resin content and filler particles of the materials may influence the
degree of microleakage.

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tive materials to composites for the conservative
restoration of these lesions because of their adhesion to
tooth structure, fluoride release, biocompatibility,
lower shrinkage values, reduced microleakage, and
acceptable esthetics.
7-11
Light-cured resin-modified
glass ionomer cements were developed to improve the
handling and working characteristics of the original
glass ionomer formulation.
12,13
Improved adhesion to
dentin is probably caused by both a chemical bond
from the polyacrylic acid component and formation of
a hybrid layer from the hydrophilic HEMA.
14-21
Favorable adhesive and fluoride-releasing properties
of glass ionomer cements have lead to their widespread
use as restorative, lining, and luting materials. To over-
come the problems of moisture sensitivity and low early
mechanical strengths associated with the conventional
glass ionomer cements (GICs) and at the same time
maintain their clinical advantages, some hybrid versions
of GIC were introduced that are light-cured, because
of their small quantity of resin components such as
HEMA or BIS-GMA. In some situations, the polyacid
also has been modified with side chains that can be
polymerized by light-curing mechanisms. The actual
formulations vary between manufacturers, but the
amount of resin in the final set restoration is between
4.5% to 6%, such as for Fuji II LC and Vitremer glass
ionomer cements. The addition of a resin component
to GIC and its effects on the development of the ionic
crosslink and the subsequent marginal seal against the
tooth structure needs further evaluation.
To overcome technique-sensitive mixing and han-
dling properties of the resin-modified glass ionomer
cements, new materials containing acid-decomposable
glass and acidic polymerizable monomers substituting
the polyalkenoic acid polymer were developed. These
materials were termed polyacid-modified resin compos-
ites
,
22-26
commonly called compomers. Dyract poly-
acid-modified resin composite belongs to the new
materials that have either been marketed as multipur-
pose materials, or contain both of the essential compo-
nents of a glass-ionomer cement but at levels that are
insufficient to produce an acid-base reaction.
13
With
this material, the resin content is approximately 28%.
The purpose of this study was to compare the
microleakage of Class V restorations produced with the
3 materials, which differ in their resin content, to test
the hypothesis that resin content affects microleakage.