Innovative Composites for Dental Restoration
H. WOLTERa, W. STORCHa, S. NIQUEa, R. MALETZb, T. NEUMANNb, M. DANEBROCKb, aFraunhofer-ISC, Würzburg, Germany; bVOCO GmbH, Cuxhaven, Germany
Objectives: For a longevity restoration, dental composites with low polymerization shrinkage and tooth-like thermo-mechanical properties are desirable. Taking these requirements into account, the objective of this investigation was to compare dental filling materials based on the nano-hybrid technology (ORMOCER®-based matrices) with the Silorane technology (epoxy-based matrix).
Methods: The composites characterized were FiltekTM Silorane (I, 3M-Espe) with an epoxy-based ring-opening polymerizable matrix and four experimental nanohybrid composites with different monomer-free ORMOCER®-matrices (IIa – IId, Fraunhofer ISC/VOCO). The materialxs polymerization shrinkage and their Youngs modulus were determined according to DIN 13907 and ISO 4049, respectively. The coefficient of thermal expansion α was measured in the temperature range of 5 – 50 °C.
Results:
| Composites | ||||
I | IIa | IIb | IIc | IId
| |
Filler content [wt.-%/vol.-%] | 76*/n. a. | 84.0/70.8 | 86,0/73,8 | 86.5/74.5 | 85.0/70.0 |
Volume shrinkage [%] | 1.2 (± 0.1) | 1.7 (± 0.1) | 1.3 (± 0.2) | 1.6 (± 0.1) | 1.4 (± 0.0) |
Youngs modulus [GPa] | 9.8 (± 0.3) | 12.8 (± 0.4) | 12.3 (± 0.4) | 15.2 (± 0.4) | 11.9 (± 0.4) |
α [10-1K-1] 5 – 50 °C | 30.4 (± 0.1) | 22.8 (± 0.1) | n. d. | 20.8 (± 0.1) | 24.8 (± 0.4) |
*3M-ESPE product brochure
The Youngs modulus of composite I is comparably low, while the α-value is comparably high. Due to the polymerization by a ring-opening mechanism a very low shrinkage is observed in spite of the low filler content. In comparison, the experimental composites IIa – IId show higher Youngs moduli (11.9 – 15.2 GPa), lower α-values (20.8 – 24.8·10-1K-1) and only slightly higher shrinkage values (1.3 – 1.7 %) caused by functionalized structure of oligomers within the ORMOCER®-resins and high filler contents.
Conclusion:
Taking the low shrinkage and the more tooth-like Youngs moduli and α-values into account, the monomer-free ORMOCER®-based nano-hybrid composites are examples of a promising alternative class of dental material.
This work was supported by the BMBF under the contract 03N400bA3.