title: Zinc-based glass polyalkenoate cements with improved setting times and mechanical properties.
abstract: The suitability of glass polyalkenoate cements (GPCs) for skeletal applications is limited by the presence, in the glass phase, of the aluminium ion (Al3+), a neurotoxin. The zinc ion (Zn2+), a bacteriocide, has been incorporated into aluminium-free GPCs based on zinc silicate glasses. However, these GPCs have considerably shorter working times and poorer mechanical properties than their Al3+-containing counterparts. Based on results for calcium phosphate cements, there is an indication that mixing a GPC with an organic compound, tricalcium citrate (TSC), may lead to cements with improved rheological and mechanical properties. We developed a range of Zn-based GPCs and determined their working times (Tw), setting times (Ts), compressive strength (CS) and biaxial flexural strengths (BFS). A GPC composed of 1g of a calcium-zinc silicate glass (BT100) mixed with a 50wt.% aqueous solution on polyacrylic acid (coded E9, Mw 80,800) at a powder liquid ratio of 2:1.5 exhibited the best combination of Tw, Ts, CS and BFS. We also found that the addition of TSC (over the range 5-15wt.%) to a GPC led to significant increases in both Tw (from 40+/-3 to 100+/-4s) and Ts (from 70+/-2 to 3000+/-4s) accompanied by changes in both CS and BFS that were affected by the duration of the aging time of the specimens in distilled water (for example, after aging for 7 days CS dropped from 62+/-2 to 17+/-1MPa, while after aging for 30 days, BFS increased 27+/-6 to 31+/-7MPa and then dropped to 17+/-1MPa). Future modification and characterization of the examined GPCs are needed before they may be considered as candidates for orthopaedic applications.
authors.affiliation: Materials and Surface Science Institute, National Technological Park, University of Limerick, Limerick, Ireland. Daniel.Boyd@ul.ie
authors.forename: D
authors.initials: D
authors.lastname: Boyd
authors.forename: O M
authors.initials: OM
authors.lastname: Clarkin
authors.forename: A W
authors.initials: AW
authors.lastname: Wren
authors.forename: M R
authors.initials: MR
authors.lastname: Towler
mesh_terms: D001696:Biomechanical Phenomena; D001843:Bone Cements; D002951:Citrates; D019245:Compressive Strength; D005899:Glass Ionomer Cements; D008422:Materials Testing; D012212:Rheology; D013324:Strontium; D015032:Zinc
chemical_list: D001843:Bone Cements; D002951:Citrates; D005899:Glass Ionomer Cements; C514290:trisodium citrate; D015032:Zinc; D013324:Strontium