Bonding effectiveness and interfacial characterization of a nano-filled resin-modified glass-ionomer.
Glass-ionomers (GIs) exhibit excellent clinical bonding effectiveness, but still have shortcomings such as polishability and general aesthetics. The aims of this study were (1) to determine the micro-tensile bond strength (microTBS) to enamel and dentin of a nano-filled resin-modified GI (nano-RMGI; Ketac N100, 3M-ESPE), and (2) to characterize its interfacial interaction with enamel and dentin using transmission electron microscopy (TEM).


METHODS
The nano-RMGI was used both with and without its primer, while a conventional RMGI restorative material (conv-RMGI; Fuji II LC, GC) and a packable conventional GI cement (conv-GI; Fuji IX GP, GC) were used as controls. After bonding to freshly extracted human third molars, microspecimens of the interfaces were machined into a cylindrical hourglass shape and tested to failure in tension. Non-demineralized TEM sections were prepared and examined from additional teeth.


RESULTS
The microTBS to both enamel and dentin of nano-RMGI and conv-GI were not statistically different; the microTBS of non-primed nano-RMGI was significantly lower, while that of conv-RMGI was significantly higher than that of all other groups. TEM of nano-RMGI disclosed a tight interface at enamel and dentin without surface demineralization and hybrid-layer formation. A thin filler-free zone (<1 microm) was formed at dentin. A high filler loading and effective filler distribution were also evident, with localized areas exhibiting nano-filler clustering.


CONCLUSIONS
The nano-RMGI bonded as effectively to enamel and dentin as conv-GI, but bonded less effectively than conv-RMGI. Its bonding mechanism should be attributed to micro-mechanical interlocking provided by the surface roughness, most likely combined with chemical interaction through its acrylic/itaconic acid copolymers.
Coutinho
E
E
Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium.
Cardoso
M V
MV
De Munck
J
J
Neves
A A
AA
Van Landuyt
K L
KL
Poitevin
A
A
Peumans
M
M
Lambrechts
P
P
Van Meerbeek
B
B
D000268:Adhesiveness; D055598:Chemical Phenomena; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure; D003799:Dental Stress Analysis; D003804:Dentin / Q000648:ultrastructure; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength
C079765:Fuji II LC cement; C439808:Fuji IX GP Fast; D005899:Glass Ionomer Cements; D019279:Resin Cements; D012117:Resins, Synthetic