title: Effects of incorporation of HA/ZrO(2) into glass ionomer cement (GIC).
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.
authors.affiliation: School of Materials Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Y W
authors.initials: YW
authors.lastname: Gu
authors.forename: A U J
authors.initials: AU
authors.lastname: Yap
authors.forename: P
authors.initials: P
authors.lastname: Cheang
authors.forename: K A
authors.initials: KA
authors.lastname: Khor
mesh_terms: D001843:Bone Cements / Q000138:chemical synthesis / Q000737:chemistry*; D019245:Compressive Strength; D017886:Durapatite / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006244:Hardness; D008422:Materials Testing; D010316:Particle Size; D011208:Powders; D013499:Surface Properties; D013718:Tensile Strength; D015040:Zirconium / Q000737:chemistry*
chemical_list: D001843:Bone Cements; D005899:Glass Ionomer Cements; D011208:Powders; D017886:Durapatite; D015040:Zirconium; C028541:zirconium oxide