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Friday, September 07, 2012
A novel dentin bonding system containing poly(methacrylic acid) grafted nanoclay: Synthesis, characterization and properties
Dental Materials Pages 1041-1050, October 2012
Developing a novel dentin
bonding system containing poly(methacrylic acid)-grafted-nanoclay
(PMAA-g-nanoclay) as reinforcing filler, with high stability of
nanoparticle dispersion and improved bond strength and mechanical
properties were the main objectives of this study.
Materials and methods
acid) (PMAA) was grafted onto the pristine sodium montmorrillonite
(Na-MMT) nanoclay surface and characterized using FTIR, TGA, and X-ray
diffraction (XRD). The PMAA-g-nanoclay was incorporated into an
experimental dentin bonding system as filler in different concentrations
and stability of nanoclay dispersion in the dilute adhesive, morphology
of nanoclay layers in the photocured adhesive matrix, shear bond
strength to caries-free extracted human premolar teeth, and mode of
failure were studied. The mechanical properties including diametral
tensile strength (DTS), flexural strength (FS), and flexural modulus
(FM) were also investigated. The measured FM was also compared to
theoretical prediction models.
The grafting of
PMAA onto the nanoclay surface was confirmed and the results revealed a
partially exfoliated structure for PMAA-g-nanoclay. The dispersion
stability of the modified nanoparticles in the dilute adhesive increased
more than 45 times in comparison with the pristine nanoclay. The
incorporation of 0.5wt.%
PMAA-g-nanoclay to the adhesive resulted in a significant increase in
microshear bond strength, DTS, and FS. Higher PMAA-g-nanoclay contents
resulted in increased flexural modulus. The experimental flexural
modulus was in good agreement with the Halpin–Tsai theoretical model.
of PMAA-g-nanoclay particles as novel functional fillers into dental
adhesive could result in the development of bonding systems with
improved physical, mechanical, and adhesion properties.