IADR Abstract Archives
Composite wear testing with simulated chewing of food particles.
Objectives: Two body wear simulations suffer from artifacts like tribofilm formation and/or increased surface fatigue due to direct contact of the sample and the antagonist. The main aim of this study was to compare the amount of wear and wear pattern of a traditions two-body wear simulator with a newly developed chewing simulator, which allows a more clinically relevant type of wear testing by chewing of food particles.
Methods: Composites (n=13) with very different composition were tested in the same chewing-simulation device (CSD) with two different experimental conditions: direct contact wear (2BW) and chewing of a food slurry (3BW). Currently, millet seed suspension, which is already a defacto standard in the ACTA wear simulator, was used as slurry. The samples were tested in a CSD against ceramic antagonists (load: 50N, 50000 cycles, lateral excursion: 0.5mm). 2BW used water as lubrication, 3BW, a millet seed-water mixture instead. All samples were cleaned, taken impressions of (polyether), plaster models made, scanned (SEM) and statistically analysed (tukey post hoc and two-factor-variance).
Results: The two-factor variance analysis calculated with the mean maximum wear after 50.000 cycles showed for both factors, material and method (2BW vs. 3BW) highly siginificant differences(p<2,2e-16). The results of the tukey post hoc-test revealed in the 3BW more similar wear values for most composites, in the 2BW-setup the values were more scattered. Micro-filler-composites showed the lowest wear in 2BW but higher in 3BW(50/230μm), in 3BW however hybrid-composites showed similar wear results(130/150μm). All mean wear results are in table 1. The qualitative analysis of the SEM pictures revealed the development of a tribofilm in the 2BW, that was no longer present in the 3BW-pictures.
Conclusions: Within the limitations of an in-vitro-study it may be concluded that the simulation of wear in most 2BW-simulation does not provide us with accurate results on the wear performance of composites. In the 3BW-simulation the millet seed inhibts the manifestation of a tribofilm hence allowing the antagonist to abrade the specimen. Therefore composites with different composition seem to perform similar in 3BW. Testing in a 3BW-environment could provide more accurate predictions of the clinical wear resistance of dental materials.
Methods: Composites (n=13) with very different composition were tested in the same chewing-simulation device (CSD) with two different experimental conditions: direct contact wear (2BW) and chewing of a food slurry (3BW). Currently, millet seed suspension, which is already a defacto standard in the ACTA wear simulator, was used as slurry. The samples were tested in a CSD against ceramic antagonists (load: 50N, 50000 cycles, lateral excursion: 0.5mm). 2BW used water as lubrication, 3BW, a millet seed-water mixture instead. All samples were cleaned, taken impressions of (polyether), plaster models made, scanned (SEM) and statistically analysed (tukey post hoc and two-factor-variance).
Results: The two-factor variance analysis calculated with the mean maximum wear after 50.000 cycles showed for both factors, material and method (2BW vs. 3BW) highly siginificant differences(p<2,2e-16). The results of the tukey post hoc-test revealed in the 3BW more similar wear values for most composites, in the 2BW-setup the values were more scattered. Micro-filler-composites showed the lowest wear in 2BW but higher in 3BW(50/230μm), in 3BW however hybrid-composites showed similar wear results(130/150μm). All mean wear results are in table 1. The qualitative analysis of the SEM pictures revealed the development of a tribofilm in the 2BW, that was no longer present in the 3BW-pictures.
Conclusions: Within the limitations of an in-vitro-study it may be concluded that the simulation of wear in most 2BW-simulation does not provide us with accurate results on the wear performance of composites. In the 3BW-simulation the millet seed inhibts the manifestation of a tribofilm hence allowing the antagonist to abrade the specimen. Therefore composites with different composition seem to perform similar in 3BW. Testing in a 3BW-environment could provide more accurate predictions of the clinical wear resistance of dental materials.