Objectives . Shrinkage stress is still considered to be a major drawback of resin-based composite materials. It was claimed that resin systems based on the SDR™ technology (Stress Decreasing Resin) with a Polymerization Modulator being chemically embedded in the polymerizable resin backbone, are able to induce a lower shrinkage during polymerization in composite materials. The aim of this study was therefore to analyse the shrinkage behaviour of two experimental composites based on the SDR™ technology 1 in comparison to a low shrinkage silorane-based 2 and 4 regular methacryate-based composites 3 .
Materials and methods . The shrinkage behaviour during polymerization was measured with a Stress-Strain-Analyzer (SSA T80, Engineering Consultancy Peter Dullin Jr, Munich) with compensation of the compliance of the machine. The composite specimens ( n = 10) were placed between two aluminium attachments with a distance of 4 mm and a height of 2 mm, building a simulated cavity between the attachments (C-factor: 0.3) and were cured for 20 s (Freelight2, 1200 mW/cm 2 , 3M-ESPE). The shrinkage stress was recorded as a function of time for 300 s.
Results . The shrinkage stress, measured 300 s after photo-initiation, is presented in the table below:
| Composite | Stress [MPa] |
|---|---|
| P&P-Adaptable 1 (Dentsply) | 1.10 a (.09) |
| P&P-Universal 1 (Dentsply) | 1.10 a (.07) |
| Filtek Silorane 2 (3M-ESPE) | 3.57 b (.30) |
| EsthetX Plus 3 (Dentsply) | 4.44 c (.27) |
| Filtek Supreme Plus 3 (3M-ESPE) | 4.62 c (.31) |
| EsthetX Flow 3 (Dentsply) | 5.25 d (.25) |
| Filtek Supreme Plus Flow 3 (3M-ESPE) | 6.54 e (.27) |
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