Contraction stress of low-shrinkage composite materials assessed with different testing systems

Marchesi, Giulio; Breschi, Lorenzo; Antoniolli, Francesca; Di Lenarda, Roberto; Ferracane, Jack; Cadenaro, Milena

doi:10.1016/j.dental.2010.05.007

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Volume 26, Issue 10 , Pages 947-953, October 2010

Contraction stress of low-shrinkage composite materials assessed with different testing systems

Giulio Marchesi
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy
Lorenzo Breschi
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy
- IGM-CNR, Unit of Bologna c/o IOR, Bologna, Italy
- Corresponding author at: Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Piazza Ospedale, 1, I-34129 Trieste, Italy. Tel.: +39 040 3992192; fax: +39 040 3992665.
Francesca Antoniolli
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy
Roberto Di Lenarda
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy
Jack Ferracane
- Department of Restorative Dentistry, Oregon Health & Science University, Portland, OR, USA
Milena Cadenaro
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy

Received 23 May 2010; accepted 25 May 2010.

Abstract

Objectives

The contraction stress of a silorane-based material and a new low-shrinkage nanohybrid composite were compared to three conventional dimethacrylate-based resin composites using two different measuring systems. It was hypothesized that the silorane-based material and the low-shrinkage nanohybrid composite would exhibit lower contraction stress than dimethacrylate-based composites irrespective of measuring system.

Methods

The materials tested were Filtek Silorane LS (3M ESPE), Venus Diamond (Heraeus Kulzer), Tetric EvoCeram (Ivoclar Vivadent), Quixfil (Dentsply DeTrey), and Filtek Z250 (3M ESPE). Shrinkage stress was assessed using a stress–strain analyzer consisting of two opposing attachments, one connected to a load sensor and the other fixed to the device, or a system fixed to a universal testing machine with an extensometer as a feedback system. All specimens were light-cured with 20J/cm²; the contraction force (N) generated during polymerization was continuously recorded for 300s. Contraction stress (MPa) was calculated at both 40s and 300s. Data were statistically analyzed by three-way ANOVA and Tukey's post hoc test (α=0.05).

Results

Venus Diamond exhibited the lowest stress under both experimental conditions. Stress values scored as follows: Venus Diamond<Tetric EvoCeram<Filtek Silorane LS<Quixfil<Filtek Z250 (p<0.05). Stress values measured with the stress–strain analyzer were significantly lower than those measured with the universal testing machine with feedback.

Significance

The hypothesis was partially rejected because only Venus Diamond exhibited the lowest stress values among the tested materials. Contraction stress was higher for all composites when measured in a test system with a feedback. This study confirms that simply reducing the shrinkage does not ensure reduced stress development in composites.

Keywords: Silorane, Resin composite, Stress, Contraction, Polymerization