ABSTRACT
The clinical success of dental implants is governed by implant surfaces and bone cell responses that promote rapid osseointegration. The objective of this study was to evaluate the in vitro osteoblast cell response to heat treated and non-heat treated CaP coatings. In this study, the heat treated surfaces exhibited a poorly crystallized HA-type structure whereas the non-heat treated surface exhibited an amorphous structure. The heat treated CaP surfaces were observed to have a mean contact angle measurement of 57.95+/-0.95 degrees, whereas the non-heat treated CaP surfaces were observed to have a mean contact angle measurement of 44.6+/-0.3 degrees. From the in vitro cell culture study, the ATTC CRL 1486 human embryonic palatal mesenchyme (HEPM) cells displayed a similar protein production and hexosaminidase activity on the heat treated and non-heat treated CaP surfaces throughout the nine day experiment. However, the HEPM cells cultured on non-heat treated CaP surfaces were observed to have higher specific ALP activity after nine days' incubation compared to cells cultured on heat treated CaP surfaces. The higher specific ALP activity by cells on non-heat treated surfaces were suggested to be attributed to the lower degree of crystallinity and the lower contact angles observed in this study.
ABSTRACT
The purpose of this study was to investigate the effect of sintering different calcium phosphate (CaP) surfaces on protein adsorption and osteoblast cell response. As-received and sintered hydroxyapatite (HA) and brushite were used in this study. X-ray diffraction revealed a poorly crystallized HA structure for the unsintered HA and a highly crystallized HA for the sintered HA surfaces. A brushite-type structure was indicated on the unsintered brushite surfaces, whereas sintered brushite surfaces contained mixtures of different CaP phases. Using 1 mg/mL albumin solution, protein was suggested to selectively adsorb on the CaP surfaces. A statistically higher albumin adsorption was observed on unsintered HA (9.5 micrograms/mL) and unsintered brushite (50.1 micrograms/mL) surfaces compared to sintered HA (3.2 micrograms/mL) and sintered brushite (3.4 micrograms/mL) surfaces. In the in vitro study using osteoblast cells, no statistical responses were observed between cells cultured on sintered HA and sintered brushite after 8 days of incubation. However, statistical differences in osteocalcin and protein production were observed between the unsintered HA and unsintered brushite. In addition, statistical differences in protein production, alkaline phosphatase activity, and osteocalcin production were observed between sintered CaP and unsintered CaP surfaces. From the protein adsorption and cell responses observed in this study, it was concluded that CaP surfaces need to be fully characterized prior to implantation.
