Effect of photoinitiators on the in vitro performance of a dentin adhesive exposed to simulated oral environment

Ye, Qiang; Park, Jonggu; Topp, Elizabeth; Spencer, Paulette

doi:10.1016/j.dental.2008.09.011

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Volume 25, Issue 4 , Pages 452-458, April 2009

Effect of photoinitiators on the in vitro performance of a dentin adhesive exposed to simulated oral environment

Qiang Ye
- Bioengineering Research Center, The University of Kansas School of Engineering, Lawrence, KS, USA
- Department of Mechanical Engineering, The University of Kansas, Lawrence, KS, USA
Jonggu Park
- Bioengineering Research Center, The University of Kansas School of Engineering, Lawrence, KS, USA
- Department of Mechanical Engineering, The University of Kansas, Lawrence, KS, USA
Elizabeth Topp
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, KS, USA
Paulette Spencer
- Bioengineering Research Center, The University of Kansas School of Engineering, Lawrence, KS, USA
- Department of Mechanical Engineering, The University of Kansas, Lawrence, KS, USA
- Corresponding author at: Bioengineering Research Center, University of Kansas School of Engineering, Learned Hall, 1530 W. 15th Street, Room 3111, Lawrence, KS 66045-7609, United States. Tel.: +1 785 864 8140; fax: +1 785 864 1742.

Received 24 April 2008; received in revised form 20 August 2008; accepted 29 September 2008.

Abstract

Objectives

Our previous study showed poor mechanical durability and nano-sized heterogeneities in cross-linked dentin adhesives cured in the presence of water. To further explore the relationship between nano-scale heterogeneities and the long-term mechanical properties of dentin adhesives, the properties of model dentin adhesives polymerized using hydrophilic photoinitiators were compared with those of adhesives polymerized using hydrophobic camphorquinone-based photoinitiators.

Methods

The model adhesives consisted of HEMA and bisGMA with a mass ratio of 45/55 and were photopolymerized in the presence of 8.3mass% water. The photo-polymerization of the model adhesives during irradiation was monitored in situ using a Perkin-Elmer Spectrum One FTIR in the ATR sampling mode. The tensile properties were determined for all samples after dry storage at room temperature, or after aqueous storage in distilled deionized water.

Results

There was a continuous decline of mechanical properties for the specimens cured in the presence of water during 3 months aqueous storage, especially for the specimens that contained hydrophobic photoinitiators. The multi-component systems containing hydrophilic photoinitiators were shown to produce superior model dental adhesives when these materials are cured in the presence of water.

Significance

Designing initiator systems to perform in this heterogeneous environment may improve the mechanical performance of dentin adhesives, as the results presented here indicate.

Keywords: Hydrophilic/hydrophobic photoinitiator, Dentin adhesive, Durability, Mechanical property, Nanoheterogeneity