Determination of Polymerization Stress in Low Shrinkage Resin Composites

Objective: Low shrinkage resin composites are in the focus of research in posterior resin composite restoratives. The aim of this study was to examine the polymerization shrinkage stress of low shrinkage resin composites (Exp. Composite/DENTSPLY, Exp. Flowable/DENTSPLY, ELS/Saremco, Exp.Ormocer/VOCO) and a control (Filtek Silorane/3 M ESPE).

Method: Cylindrical cavities (Ø 5mm) in Araldit B epoxide resin plates (40x40x2mm) were pre-treated with the Rocatec system to ensure a bonding of the resin composites. The resin composite specimens (n = 10) were exposed for 60s with a QTH curing device (Translux Energy, Heraeus Kulzer, Germany). The samples were stored dark and dry (23 °C). Polymerization shrinkage stress data [MPa] 4 min and 24 h post exposure were calculated based on the diameter of the isochromatic curves of first order, obtained from the Araldit-plates.

Results: After 24 h the following mean stress values were obtained: 4,6 ± 1,3 MPa for Filtek Supreme XT, 2,8 ± 0,1 MPa for Exp. Composite, 2,7 ± 0,1 MPa for Exp. Flowable, 2,5 ± 0,04 MPa for Filtek Silorane, 2,8 ± 0,2 MPa for ELS. After 24 h, Filtek Supreme XT showed significantly higher polymerization shrinkage stress values compared to all other materials.

Conclusion: The new and experimental materials (DENTSPLY) showed shrinkage stress development comparable to Filtek Silorane and ELS. The shrinkage stress developed by Filtek Supreme XT was significantly higher than the shrinkage stress developed by the other composites.

This study was supported by DENTSPLY, Konstanz, and VOCO, Cuxhaven, Germany.