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Dent Mater. 2018 Oct;34(10):1459-1465. doi: 10.1016/j.dental.2018.06.013. Epub 2018 Aug 1.

Development of an oxirane/acrylate interpenetrating polymer network (IPN) resin system.

Author information

1
Department of Comprehensive Dentistry, the University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.
2
Department of Periodontics, JBSA-Randolph, San Antonio, TX 78150, United States.
3
DM Healthcare Products, Inc., San Diego, CA, United States.
4
Department of Comprehensive Dentistry, the University of Texas Health Science Center at San Antonio, San Antonio, TX, United States. Electronic address: rawls@uthscsa.edu.

Abstract

OBJECTIVE:

Develop a hydrophobic, degradation-resistant dental restorative based on an Oxirane-Acrylate IPN System (OASys) with low shrinkage-stress to substantially extend clinical lifetime.

METHODS:

Unfilled OASys blends were prepared using dipenta-erythritol-hexaacrylate (DPHA) and p-cycloaliphatic-diepoxide (EP5000). Varying proportions of camphorquinone/iodonium photoinitiator, with a co-reactant oligomeric-diol, served as the experimental curing system. The effects of oxirane-acrylate ratio on the degree-of-cure (Durometer-D hardness), hydrophobicity (contact angle), mechanical properties (3-point bending), near-infrared FTIR degree-of-conversion (DoC), polymerization shrinkage, and shrinkage stress were determined. 70:30 BisGMA:TEGDMA resin served as control.

RESULTS:

Oxirane tended to decrease hardness and increase hydrophobicity. 0:100, 25:75, 50:50 EP5000:DPHA are harder after 24h than control. 75:25 and 100:0 EP5000:DPHA increased in hardness over 24h, but were softer than control. All groups increased in contact angle over 24h. After 24h, 50:50, 75:25 and 0:100 EP5000:DPHA were more hydrophobic (∼75-84°) than the control (∼65°). Acrylate DoC was ∼60% across all experimental groups. Initial oxirane conversion varied from ∼42% in 100:0 EP5000:DPHA to ∼82% 75:25 EP5000:DPHA. However, oxirane DoC increased for 100:0 EP5000:DPHA to ∼73° over 24h, demonstrating dark cure. Moduli and ultimate transverse strengths of OASys groups were higher than for 0:100 EP5000:DPHA, with 50:50 EP5000:DPHA having higher modulus than other experimental groups. However, the control had higher modulus and UTS than all experimental groups. Volumetric shrinkage averaged 7% for experimental groups, but stress decreased dramatically with increasing oxirane content.

SIGNIFICANCE:

Hydrophobic, low shrinkage-stress OASys resins are promising for development of composites that improve longevity and reduce the cost of dental care.

KEYWORDS:

Acrylate; Cationic photoinitiation; Degree of conversion; Hydrophobicity; Interpenetrating network; Oxirane; Restorative resin; Shrinkage stress; Volumetric shrinkage

PMID:
29929846
PMCID:
PMC6311097
DOI:
10.1016/j.dental.2018.06.013
[Indexed for MEDLINE]
Free PMC Article

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