ABSTRACT
Statement of Problem: Mechanical strength and durability of dental composites are the main topics studied in this field of science today. This study examined fumed silica-based composite as a strong and durable restorative material through flexural and cycling test methods
Objective: The purpose of this study was to evaluate the effect of silanization, ageing, cycling and hybridizing on mechanical properties of fumed silica-based resin composite
Materials and Methods: Composites were made of light-cured copolymer based on Bisphenol A glycolmethacrylate [Bis-GMA] and Triethylene glycoldimethacrylate [TEGDMA] at proportion of 50:50 which reinforced by fumed silica filler. For each composite sample, 5 specimen bars were made using Teflon mould [2 x 2 x 25 mm3]. The samples with 12 wt% fumed silica [FS] were considered as a base line group. The samples were exposed to cyclic cold water [FS-CCW] and hot water [FS-CHW]. The effect of silanization and adding more filler was studied together with samples containing 12 wt% [FS-S [12], 16 wt% [FS-S [16] and 20 wt% [FS-S [20] fumed silica filler. The filler was silanized with [?-MPS]. The degree of conversion was assessed with Fourier Transform Infra-Red spectroscopy. Flexural properties were evaluated with the Three-Point Bending test. Flexural data were analyzed with Excel software. Hardness was measured with an Atomic Force Microscope [AFM]
Results: The degree of conversion of the resin reached 74% within 24 hrs. Salinization allowed more filler to be wetted by resin. Addition of silanized particles from sample FS-S [12] to sample FS-S [20] improved the mechanical strength. Hybridizing fumed silica with nano-silica [FS-N] had no significant effect on the strength, but nano-hardness improved greatly. Ageing and cycling had adverse effects on the strength of the sample FS. The flexural strength of FS-CHW was 72% less than FS sample
Conclusion: Sample FS-N with low diluent and filler percentage complied with the requirements of flexural strength was established by ISO 4049/2009 and may be cost benefit to be used as a dental composite for clinical application