Journal of Dental Research, Vol 77, 603-608, Copyright © 1998 by International & American Associations for Dental Research Online Journals
Elements of light-cured epoxy-based dental polymer systems
F. Millich, L. Jeang, J. D. Eick, C. C. Chappelow and C. S. Pinzino
Department of Chemistry, University of Missouri-Kansas City, 64110, USA.
The greatest problem with current dental composite systems is their
polymerization shrinkage. Extensive work is being done by many
investigators to alleviate this problem. Our approach has been to examine
epoxy- and spiro-orthocarbonate (SOC)-based resins. The hypothesis to be
tested in this study was that the cure characteristics of experimental
visible-light-cured epoxy resin systems are governed by the types and
concentrations of co-reactants and activators. Resin samples containing
onium salt initiators and a thiozanthone sensitizer were successfully cured
by means of either an experimental visible-light irradiation system or a
commercially available dental lamp. Test resins consisted of di-epoxies
alone or in combination, epoxy mixtures in combination with an SOC, or an
epoxy in combination with a caprolactone-derived polyol. Significant
findings were as follows: (a) Resins containing the SOC had longer cure
times than their counterparts; (b) the optimum ratios of epoxy to polyol
for most rapid cure were 50:50 or 60:40 under conditions tested; (c) resins
containing TONE 305 polyol generally were faster to cure than those
containing no polyol, or TONES 201 or 310; and (d) a resin mixture was
found that had a cure time of 1 to 3 min when irradiated with a commercial
dental lamp. Based on this exploratory study, it should be possible for
clinically relevant cure times to be achieved for visible-light-cured
epoxy-based resins by careful manipulation and optimization of key
elements.
