Mechanical properties of newly developed flowable composite derived from rice husk at different monomer ratios / Nor Ain Fatihah Azlisham ... [et al.]

An ideal flowable composite (FC) requires good mechanical properties to fulfill its role as a dental restorative material and ensure durability and clinical efficacy, with these properties being influenced by different monomer ratios. The study aimed to evaluate the mechanical properties of the newly developed FC on Vickers hardness, flexural strength, and flexural modulus at different monomer ratios. The newly developed FC employed nanohybrid silica from rice husk and zirconia as fillers, and the ratio of urethane dimethacrylate to triethylene glycol dimethacrylate (UDMA:TEGDMA) at 20:80, 30:70, 50:50, 60:40, 80:20 and 90:10 as monomers. Filtek Supreme Ultra Flowable Restorative, Revolution Formula 2, and G-aenial Universal Flo served as control groups. The data were statistically analyzed using oneway ANOVA with post-hoc Bonferroni test. Generally, the higher UDMA ratio in the newly developed FCs exhibited higher mechanical properties. All newly developed FCs demonstrated a significant decrease in Vickers hardness than control groups. The flexural strength values at ratios of 50:50, 60:40, 80:20, and 90:10 were comparable with control groups and passed the International Organization for Standardization 4049 requirement. Meanwhile, the flexural modulus of the newly developed FC at the ratio of 90:10 was comparable to Revolution Formula 2. In summary, the differences in monomer ratios affect the mechanical properties of the newly developed FCs. The improved mechanical properties at ratios of 80:20 and 90:10 could potentially substitute sustainable dental restorative materials, subjected to further investigations.