Synthesis And Evaluation Of Silica Particles From Rice Husk For Fabrication Of Dental Nanohybrid Composites
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Date
2015-10
Authors
Noushad, Mohammed
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The objective of this study was to synthesize silica particles from rice husk with ideal characteristics, like spherical shape, low surface area and wide particle size distribution, for use as fillers in dental composites. The silica was leached in to a solution of NaOH to form sodium silicate. The silica was synthesized from sodium silicate solution using a simple acid precipitation technique. Several parameters were tested to obtain silica particles with ideal characteristics for use as fillers in dental composites. These included the effect of various precipitating acids and solvents, effect of dilution of sodium silicate solution, mixing speed, feed rate and various concentrations of solvents. It was possible to obtain spherical silica particles with a BET surface area of 30 m2/g and a mean diameter of 261nm. The silica particles were modified using a coupling agent, 3--(Trimethoxysilyl) propyl methacrylate. The silica surface was successfully modified using a very simple technique and was characterized using FTIR and NMR studies. Dental composites with two different filler/matrix ratios (EC1: 40/60 and EC2: 50/50) were fabricated from the surface modified nanohybrid silica, followed by mechanical properties testing, which included flexural strength, flexural modulus, compressive strength, Vickers’ hardness and surface roughness tests. Although both experimental dental composites showed promising results, EC2 exhibited better test values. EC2 showed a flexural strength of 106.6 MPa, flexural modulus of 6.2 GPA, compressive strength of 190.6 MPa, Vickers’ hardness of 38.66 HV1 and surface roughness of 0.057
Ra which are comparable with a commercial dental composite. Biocompatibility of the
silica particles and EC2 were tested using cytotoxicity studies on human periodontal
ligament fibroblast cells using the MTT assay. The silica particles were non-cytotoxic at
all the concentrations tested. The results for experimental dental composite showed that
it was moderately cytotoxic only at the highest tested concentrations, which is in
agreement with several other studies. The results indicate that rice husk, which is an
agricultural waste, is a good and inexpensive source of silica for potential use as fillers
in dental composites.
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Keywords
Synthesize silica particles , from rice husk.