Author(s): Gu YW, Yap AU, Cheang P, Khor KA
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Abstract Glass ionomer cements (GICs) are a class of bioactive cements that bond directly to bone. In this paper, a new bioactive hydroxyapatite (HA)/zirconia (ZrO(2))-filled GIC composite was developed to improve the biocompatibility and bioactivity of the GICs with the surrounding bone and connective tissues. Nano-sized HA/30 wt\% ZrO(2) powders were heat treated at 700 degrees Celsius and 800 degrees Celsius for 3 h to elucidate the influence of the crystallinity of composite powders on the performance of HA/ZrO(2)-GICs. The effects of different volume percentages of HA/ZrO(2) powders (4, 12, 28 and 40 vol\%) substituted within GICs were investigated based on their microhardness, compressive strength and diametral tensile strength. The HA/ZrO(2)-GICs composite was soaked in distilled water for 1 day and 1 week before subjecting the samples to mechanical testing. Results showed that the glass and HA/ZrO(2) particles were distributed uniformly in the GIC matrix. The substitution of highly crystalline HA/ZrO(2) improved the mechanical properties of the HA/ZrO(2)-GICs due to the slow resorption rate for highly crystalline powders in distilled water. The mechanical properties of HA/ZrO(2)-GICs increased with increasing soak time due to the continuous formation of aluminium salt bridges, which improved the final strength of the cements. The compositions 4 and 12 vol\% HA/ZrO(2)-GICs exhibited superior mechanical properties than the original GICs. The mechanical properties of HA/ZrO(2)-GICs were found to be much better than those of HA-GICs because ZrO(2) has the attributes of high strength, high modulus, and is significantly harder than glass and HA particles. Furthermore, ZrO(2) does not dissolve with increasing soaking time.
This article was published in Biomaterials
and referenced in Bioceramics Development and Applications