IADR Abstract Archives
Influence of Loading force on the Micro Hardness of Composites
Objective: Hardness of composites will be estimated directly under load to eliminate the influence of elastic resilience. Aim of this work was to assess the influence of different loading forces on the hardness values of different composites measured by different investigators. Methods: 5 different composite materials, VITA LC, Voco Admira and Voco Grandio as light curing composites, with different filler content and Voco Structur and Ivoclar Systemp as temporary C&B materials were chosen. All measurements were realised with the same device “Optidur”, Vickers indentation under load, by three different investigators. 20 Specimens with a dimension of 15x10x2mm were produced from each material for each of the investigators. 10 specimens were storage 1h at RT and 10 in water at 37°C over 24 hours. The data would be analysed by ANOVA. Results: For all investigated composites an increase of the hardness values depend on the loading force and the filler content would be observed. The deviation is higher in case of temporary materials and under lower indentation load.
Tab.1: HV after storage 24h, 37°C in water
|
F[N] |
VITA |
Admira |
Grandio |
Structur |
Systemp |
|
11,3 |
570,9±66,5 |
917,7±230,4 |
2006,4±291,3 |
148,5±41,3 |
224,9±26,2 |
|
6,4 |
481,9±47,4 |
1025,5±200 |
1629,5±301,2 |
114,8±38,1 |
206,2±30,7 |
|
3,4 |
421,5±76,8 |
791,6±148 |
1332±274,8 |
79,1±40,7 |
168,7±37,4 |
|
1,5 |
335,6±74,1 |
610±145,6 |
1023,9±198,5 |
73,6±59,2 |
180,7±52,8 |
|
0,49 |
155,6±26,9 |
155,6±26,9 |
525,9±139,7 |
37,3±21,2 |
66,0±46,5 |
Conclusions: Direct comparisons of hardness values of composites can be made only under consideration of the applied load because the kind of polymerisation and the filler content influence significant the shape of hardness vs. indentation force curves. For hardness measurements of composites will recommended to measure with three different indentation loads to improve the accuracy.