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Silanation of Compliant Aggregates Improves Mechanical Properties of Composite Resin
S.N. PERCY, H.L. CARDENAS, H.R. RAWLS, and V.A. LEE, University of Texas - San Antonio / Health Science Ctr, USA | Commercially available dental composite resins undergo
polymerization shrinkage during curing, setting up internal stress that can
result in debonding at the tooth-composite interface, tooth fracture and
composite failure. These materials also suffer from low toughness. We
previously showed that compliant aggregates composed of polybutadiene and
silica reduced contraction stress and increased modulus, flexural strength and
energy to break of an experimental composite resin. Objective: This
study was intended to determine if silanation of compliant aggregates further
improves mechanical properties of the composite resin. Methods: A
series of aggregate fillers were formed by adsorption of polybutadiene of MW
2-3 million onto fumed silica (300m2/g) from dichloromethane and
subsequently dried and sieved to particle size <25 micrometers. Aggregates were silanated using a 2% solution of
3-methacryloxypropyltrimethoxysilane in ethanol. Fillers with
polybutadiene:silica ratios ranging from 0.00005:1 to 0.5:1 were added to a bis-GMA/bis-EMA/TEGDMA
resin system at 9 volume % and light cured in bar form. Bars were tested in an
Instron Universal Testing machine in 3-point bend test mode. Results: Results
indicate that silanation of aggregates significantly increases flexural modulus
and flexural strength when compared to unsilanated aggregates (P<0.05). No significant
increase in energy to break was found. Conclusions: Silanation is an
effective method for increasing modulus and strength in this monomer/initiator/filler
system. Supported by NIDCR T32 Grant #DE14318 and NIDCR Grant #R21DE018353.
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Seq #160 - Properties of Polymers 10:45 AM-12:00 PM, Saturday, April 5, 2008 Hilton Anatole Hotel Trinity I - Exhibit Hall |
Back to the Dental Materials 5: Polymer-based Materials - Chemistry and Composition Program
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