Flowability of composites is no guarantee for contraction stress reduction

Cadenaro, Milena; Marchesi, Giulio; Antoniolli, Francesca; Davidson, Carel; De Stefano Dorigo, Elettra; Breschi, Lorenzo

doi:10.1016/j.dental.2008.11.010

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Volume 25, Issue 5 , Pages 649-654, May 2009

Flowability of composites is no guarantee for contraction stress reduction

Milena Cadenaro
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Via Stuparich, 1, I-34125 Trieste, Italy
- Corresponding author. Tel.: +39 040 3992803; fax: +39 040 3992665.
Giulio Marchesi
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Via Stuparich, 1, I-34125 Trieste, Italy
Francesca Antoniolli
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Via Stuparich, 1, I-34125 Trieste, Italy
Carel Davidson
- Department of Dental Materials Science, University of Amsterdam, Louwesweg 1 1066EA Amsterdam, The Netherlands
Elettra De Stefano Dorigo
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Via Stuparich, 1, I-34125 Trieste, Italy
Lorenzo Breschi
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Via Stuparich, 1, I-34125 Trieste, Italy
- IGM-CNR, Unit of Bologna c/o IOR, Bologna, Italy

Received 6 March 2008; accepted 25 November 2008.

Abstract

Objectives

The purpose of this study was to measure the contraction stress development of three flowable resin-composite materials (Grandio Flow, VOCO GmbH, Cuxhaven, Germany; Tetric Flow, Ivoclar Vivadent, Schaan, Liechtenstein; Filtek Supreme XT Flowable Restorative, 3M ESPE, ST. Paul, MN, USA) and an universal micro-hybrid composite resin (Filtek Z250, 3M ESPE, St. Paul, MN, USA) during photopolymerization with a halogen curing light, using a novel stress-measuring gauge.

Methods

Curing shrinkage stress was measured using a stress-analyzer. Composites were polymerized with a halogen curing unit (VIP, Bisco Inc., Schaumburg, IL, USA) for 40s. The contraction force (N) generated during polymerization was continuously recorded for 180s after photo-initiation. Contraction stress (MPa) was calculated at 20s, 40s, 60s, 120s and 180s. Data were statistically analyzed.

Results

Filtek Supreme XT Flowable Restorative exhibited the highest stress values compared to other materials (p<0.05), while the lowest values were recorded with Tetric Flow (p<0.05). Tetric Flow was also the only flowable composite showing stress values lower than the conventional composite Filtek Z250 (p<0.05).

Significance

Flowable composites investigated with this experimental setup showed shrinkage stress comparable to conventional resin restorative materials, thus supporting the hypothesis that the use of flowable materials do not lead to marked stress reduction and the risk of debonding at the adhesive interface as a result of polymerization contraction is similar for both type of materials.

Keywords: Flowable, Resin-composite, Stress, Contraction, Polymerization