MECHANICAL PROPERTIES OF DENTAL NANOHYBRID COMPOSITE CONTAINING PREPOLIMERIZED FILLERS Tijana
1 Lainović , Aljoša
2 Ivanišević ,
Marko
2 Vilotić ,
Tatjana
1 Vukadinov ,
Larisa
3 Blažić
1 Faculty
of Medicine, School of Dentistry, University of Novi Sad, Novi Sad, Serbia 2 Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia 3 Faculty of Medicine, School of Dentistry, University of Novi Sad, Clinic of Dentistry of Vojvodina, Novi Sad, Serbia Nanopaprika-profile page url: http://www.nanopaprika.eu/profile/TijanaLainovic Dental resin-based composite restoratives are filled with inorganic filler particles of different sizes, added into polymer in order to improve their physical, mechanical and surface properties. Composites for tooth restoration purposes are usually divided according to their filler particle sizes, as: microhybrid, microfilled, nanohybrid and nanofilled materials. The nanosized fillers are expected to improve the mechanical strength of nanocomposites, in comparison with the microfills and the universal microhybrid ones. The aim of this study was to compare the compressive and diametral tensile strength of dental nanohybrid (Tetric EvoCeram, Ivoclar Vivadent – TEC), nanofilled (Filtek Ultimate Body, 3M ESPE – FUB) and mycrohybrid (Filtek Z250, 3M ESPE – FZ250) composite, available at the market. Cylindrical specimens’ polymerization was light-activated by dental LED light-curing unit (Bluephase C8). The compressive and diametral tensile strength test were then conducted at Universal testing machine. The results were analysed by using ANOVA statistic test and the measurements were compared by means of the Tukey test. Scanning electron microscope was used to analyse materials’ structure. Preparation of specimens
TEC’s composition with PPF
The nanohybrid TEC showed statistically lower values of both compressive and diametral tensile strength. The nanofilled FUB and microhybrid FZ250 did not differ significantly regarding the tested properties. The reason for this mechanical differences of TEC can be explained by its composition. Material
Compressive strength (MPa) ± 51,16 SD
Diametral tensile strength (MPa) ± 9,65 SD
FUB FZ250 TEC
325,34 320,55 210,23
47,50 45,24 28,16
This material possess prepolymerized fillers (PPF), which are added in it in order to achieve the high filler volume fraction. The contact zone of prepolymerized fillers with matrix polymer is a weak point of this material which is shown by the SEM images, where the propagation of fracture has been clearly shown in the mentioned zone.
SEM image of FUB’s surface
SEM image of TEC’s surface
The presence of prepolymerized filler in dental resin-based composites, classified in any of the classification groups, can be considered as a weakening factor regarding the composites’ mechanical strength. Acknowledgments Supported by: Project TR-035020 and III-45016 of the Ministry of Education, Science and Technological Development, Republic of Serbia ; and 3M (East) AG company, Ivoclar Vivadent distributers for Serbia, and Mikodental – Shofu, Japan for Serbia.