Yusoff, Mohd Nazrulhuzaimi Md
(2021)
Fabrication and characterisation of flowable composite incorporated with nanohybrid silica extracted from rice husk.
Masters thesis, Universiti Sains Malaysia.
Abstract
This study was aimed to fabricate a local, low-cost and eco-friendly flowable composite in the application of tooth filling by using nanohybrid silica filler derived from rice husk. Several experimental flowable composites were made by diluting the Bis-GMA with TEGDMA at different proportions. Only 50:50, 45:55 and 40:60 ratio of Bis-GMA:TEGDMA coded as EF50B, EF45B and EF40B respectively were selected due to their desirable consistency. The flow, physical and mechanical properties of the experimental flowable composites were compared with three commercial flowable composites (Revolution Formula 2, Tetric N-Flow and G-aenial Universal Flo) as the benchmarks. Data was statistically analysed by one-way ANOVA (p=0.05) followed by Scheffe or Dunnett T3 post-hoc test. No significant differences were observed between the flowability of experimental flowable composites (EF50B and EF45B) and the commercial counterparts (Tetric N-Flow and G-aenial Universal Flo). Furthermore, there was also no significant difference between EF40B and Revolution Formula 2. The drip distance of EF50B and EF45B showed no significant differences when compared to Tetric N-Flow. Generally, surface roughness of all the experimental flowable composites showed no statistically significant differences to all the commercial flowable composites except G-aenial Universal Flo. They had a comparable smooth surface under scanning electron microscope (SEM). No significant differences were detected between the Vickers hardness of all the experimental flowable composites with Revolution Formula 2 and also between
EF50B and Tetric N-Flow. Flexural strength of EF50B and EF45B had no significant difference in comparison to Revolution Formula 2. All the tested flowable composite had passes the minimum requirement (50 MPa) for restorative material that are not intended to be used involving occlusal surfaces. Compressive strength of all the experimental flowable composites were significantly lower than that of commercial flowable composites. Flexural modulus of all the experimental flowable composites had no significant difference with Revolution Formula 2. No significant differences were found between the compressive modulus of all the experimental flowable composites with Tetric N-Flow and also between EF45B and EF40B with Revolution Formula 2. Among the experimental flowable composite, the dilution of Bis-GMA showed an increasing trend on the flowability, drip distance and compressive strength while decreasing trend on the Vickers hardness, flexural strength, flexural modulus and compressive modulus. However no trend were observed for their surface roughness due to the dilution. Overall, the experimental flowable composites had an acceptable flow, physical and mechanical properties and can be a potential green based dental filling.
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