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Investigations on a methacrylate-based flowable composite based on the SDR™ technology
Nicoleta Ilie1, Reinhard Hickel
1Department of Restorative Dentistry, Dental School of the Ludwig-Maximilians-University, Goethestr 70, 80336 Munich, Germany. nicoleta.ilie@dent.med.uni-muenchen.de
This study introduces a novel composite material for dental restorations that significantly reduces polymerization shrinkage stress and rate compared to conventional methacrylate-based materials. While exhibiting intermediate mechanical properties, its unique characteristics require further investigation for predicting interfacial stress.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Minimizing polymerization shrinkage in dental composite materials is a critical challenge in restorative dentistry.
- Conventional methacrylate-based resins often exhibit significant shrinkage, leading to stress at the tooth-restoration interface.
- Controlling polymerization kinetics through innovative resin systems is a key area of research.
Purpose of the Study:
- To evaluate the shrinkage behavior of an experimental flowable composite material designed for reduced shrinkage.
- To compare the shrinkage stress, gel point, and micro-mechanical properties of the experimental material against commercial composites.
- To assess the influence of a novel photoactive group on polymerization kinetics and material performance.
Main Methods:
- Shrinkage stress, gel point, and micro-mechanical properties (Vickers hardness, modulus of elasticity, creep) were measured for 10 samples per group.
- The experimental flowable resin-based composite (RBC) was compared with methacrylate-based micro- and nano-hybrid flowable RBCs, their high-viscosity counterparts, and a silorane-based composite.
- Photoinitiation was performed using an LED unit (Freelight2) for 20 seconds at 1226 mW/cm(2).
Main Results:
- The experimental material exhibited significantly lower contraction stress (1.1 MPa) and shrinkage rate compared to conventional methacrylate composites.
- It achieved the earliest gel point alongside the silorane-based composite, indicating controlled polymerization kinetics.
- Flowable materials, including the experimental one, showed inferior micro-mechanical properties (lower hardness and modulus, higher creep) compared to hybrid composites.
Conclusions:
- The experimental flowable composite demonstrates a significant reduction in shrinkage stress and rate, offering a potential advantage over traditional materials.
- Its micro-mechanical properties are intermediate, with increased rigidity and plasticity compared to other flowable resins.
- The complex interplay of reduced shrinkage and altered mechanical properties necessitates further study to predict its effect on interfacial stress.
