title: CaO--P2O5--Na2O-based sintering additives for hydroxyapatite (HAp) ceramics.
abstract: We have assessed the effect of CaO--P2O5--Na2O-based sintering additives on mechanical and biological properties of hydroxyapatite (HAp) ceramics. Five different compositions of sintering additives were selected and prepared by mixing of CaO, P2O5, and Na2CO3 powders. 2.5 wt% of each additive was combined with commercial HAp powder, separately, followed by ball milling, and sintering at 1250 degrees C and 1300 degrees C in a muffle furnace. Green and sintered densities of the compacts were analyzed for the influence of additives on densification of HAp. Phase analyses were carried out using an X-ray diffractometer. Vickers microhardness testing was used to evaluate hardness of sintered compacts of different compositions. A maximum microhardness of 4.6 (+/- 0.28) GPa was attained for a composition with 2.5 wt% addition of CaO:P2O5:Na2O in the ratio of 3:3:4. Results from mechanical property evaluation showed that some of these sintering additives improved failure strength of HAp under compressive loading. Maximum compressive strength was observed for samples with 2.5 wt% addition of CaO. Average failure strength for this set of samples was calculated to be 220 (+/- 50) MPa. Cytotoxicity, and cell attachment studies were carried out using a modified human osteoblast cell line called OPC-1. In vitro results showed that these compositions were non-toxic. Some sintering aids enhanced cell attachment and proliferation, which was revealed from SEM examination of the scaffolds seeded with OPC-1 cells.
authors.affiliation: School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Kalita
authors.forename: S
authors.initials: S
authors.lastname: Bose
authors.forename: H L
authors.initials: HL
authors.lastname: Hosick
authors.forename: A
authors.initials: A
authors.lastname: Bandyopadhyay
mesh_terms: D018786:Bone Substitutes / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002448:Cell Adhesion; D002455:Cell Division; D002460:Cell Line; D048429:Cell Size; D002470:Cell Survival; D002516:Ceramics / Q000737:chemistry; D019245:Compressive Strength; D017886:Durapatite / Q000737:chemistry*; D006244:Hardness; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008968:Molecular Conformation; D008970:Molecular Weight; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology*; D010087:Oxides / Q000737:chemistry*; D017553:Phosphorus Compounds / Q000737:chemistry*; D019279:Resin Cements; D017670:Sodium Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D018786:Bone Substitutes; D017610:Calcium Compounds; D010087:Oxides; D017553:Phosphorus Compounds; D019279:Resin Cements; D017670:Sodium Compounds; C480091:compoconnect; C096707:sodium oxide; C012500:phosphorus pentoxide; D017886:Durapatite; C016538:lime