Journal of Dental Research, Vol 71, 434-437, Copyright © 1992 by International & American Associations for Dental Research Online Journals
Synthesis and evaluation of novel multifunctional oligomers for dentistry
J. W. Stansbury
Dental and Medical Materials Group, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
A new type of multifunctional oligomer was synthesized, and its potential
as a base monomer in dental composite formulations was evaluated. The
oligomer of ethoxylated bis-phenol A diacrylate (OEBPA) was prepared in
good yield by a formaldehyde insertion/condensation reaction. Although
double bonds along the oligomer backbone are arranged in pairs such that
cyclopolymerization is possible, it is not presently known whether this
process plays a significant role in the polymerization. Indirect evidence
supporting efficient cyclopolymerization involves the reduced
polymerization shrinkage observed for polymerized OEBPA relative to
polymers of other monomers used as base resins. Photo-cured composites
containing either OEBPA, BIS-GMA, or ethoxylated bis-phenol A
dimethacrylate (EBPADM) as base resin and TEGDMA as diluent were compared.
While the resulting diametral tensile and transverse strengths did not
differ significantly, the values for the energy absorbed to failure
indicated that the OEBPA- and EBPADM-based formulations yielded composites
with somewhat greater toughness than that of the BIS-GMA material. This
multifunctional oligomer offers mechanical strength and conversion values
that are comparable with those of existing base resin monomers while
providing an approximate 30% reduction in polymerization shrinkage.
