Commenced in January 2007
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The Effect of TiO₂ and SiO₂ Nanoparticles Addition to Conventional Glass Ionomer Cement on Compressive Strength, Microhardness, Setting Time and Color change

Authors: Amal Magdi El Shahawi, Mai Mahmoud Elbatanony


Glass ionomer cements (GICs) with their low wear, low mechanical strength properties, extended setting rate, and high initial moisture sensitivity; represent major obstacles for their extensive clinical use. Such deficiencies limit their use in stressbearing areas and contribute to restoration failure. Hence, various alterations have been introduced to enhance the physicomechanical properties of GICs. Aim: This study aimed to investigate the effect of adding TiO₂ and SiO₂ nanoparticles on compressive strength (CS), surface microhardness, setting time and color change of conventional glass ionomer cement. Materials and Methods: Conventional glass ionomer (GC Gold Label Luting& Lining Cement. Tokyo, Japan), TiO₂ powder (32 nm in size)( Alfa Aesar, Germany), and SiO₂ nanofillers ( Sigma Aldrich, USA) were used. TiO₂ (2.5 wt%) and SiO2 (2.5 wt%) were added to the conventional glass ionomer and samples were prepared according to the manufacturer’s instructions. The tested properties of the experimental group were compared with that of the conventional GIC. Surface microhardness was tested using Vicker’s Hardness tester (NEXUS 4000 TM, INNOVATEST, model no.4503, Netherlands), while compressive strength was tested using universal testing machine (Shimadzu 5KN Autograph AG-Xplus, Japan). The effect on setting time was evaluated according to ASTM C266, using Gillmore Needle Apparatus, while color change was evaluated by using spectrophotometer( Cary 5000 UV-VIS-NIR, USA ). Results: A higher statistically significant mean Hardness value was revealed by the experimental group (95.368±17.84), in comparison to control group (35.922±1.64) (p=0.00). Regarding the compressive strength a higher statistically significant mean value was revealed by the control group (115.936±9.61), in comparison to experimental group (35.922±)(p=0.00). Longer setting time was recorded for the experimental group, meanwhile there was no change in color for experimental group (E= 2.13). Conclusions: addition of 2.5 wt% TiO₂ and 2.5 wt% SiO₂ to the conventional glass ionomer increased surface microhardness, increased setting time and decreased the compressive strength. The additives used has no effect on color of the tested GIC. Conventional glass ionomer loaded with TiO₂ and SiO₂ nanofillers showed higher surface hardness results compared to the conventional glass ionomer while regarding compressive strength, the conventional type showed higher compressive results, there was no change in colour but the experimental samples recorded longer setting time compared to the conventional glass ionomer.

Keywords: glass ionomer, hardness, compressive strength, setting time

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