R. Cavin

Osteoblast precursor cell activity on HA surfaces of different treatments

The clinical success of dental implants is governed by implant surfaces and bone cell responses that promote rapid osseointegration and long-term stability. The specific objective of this study was to investigate osteoblast precursor cell responses to hydroxyapatite (HA) surfaces of different treatments. Since the nature of bone cell responses in vitro is influenced by the properties of HA ceramics, this study was divided into two components: a chemical and crystallographic characterization of the HA ceramics and an in vitro cell culture study. The sintered HA samples were observed to have the highest crystallite size as compared to the as-received HA and calcined HA samples. No differences in the surface roughness and chemical composition were observed among the sintered, calcined, and as-received HA surfaces. In concurrence with the X-ray diffraction, high resolution XPS resolution of Ca 2p also indicated a higher crystallinity on sintered HA samples as compared to the calcined and as-received HA samples. As indicated by increased alkaline phosphatase-specific activity, increased cell-surface and matrix-associated protein, and 1.25 (OH2) vitamin D3-stimulated osteocalcin production, a more differentiated osteoblast-like phenotype was observed on the sintered HA surfaces compared to the as-received HA and calcined HA surfaces. An increased osteoblast-like cell activity on the sintered HA surfaces suggested that the crystallite size of HA surfaces may play an important role in governing cellular response.

Osteoblast Precursor Cell Attachment on Heat-treated Calcium Phosphate Coatings

The influence of properties of calcium phosphate (CaP) coatings on bone cell activity and bone-implant osseointegration is not well-established. This study investigated the effects of characterized CaP coatings of various heat treatments on osteoblast response. It was hypothesized that heat treatments of CaP coatings alter the initial osteoblast attachment. The 400°C heat-treated coatings were observed to exhibit poor crystallinity and significantly greater phosphate or apatite species compared with as-sputtered and 600°C heat-treated coatings. Similarly, human embryonic palatal mesenchyme (HEPM) cells, an osteoblast precursor cell line, seeded on 400°C heat-treated coatings, exhibited significantly greater cell attachment compared with Ti surfaces, as-sputtered coatings, and 600°C heat-treated coatings. The HEPM cells on Ti surfaces and heat-treated coatings were observed to attach through filopodia, and underwent cell division, whereas the cells on as-sputtered coatings displayed fewer filopodia extensions and cell damage. Analysis of the data suggested that heat treatment of CaP coatings affects cell attachment.

Surface roughness of titanium on bone morphogenetic protein-2 treated osteoblast cells in vitro.

Surface topography plays a critical role in the interaction of dental implants with adjacent tissues. No statistical differences in oxide composition and surface contamination were observed between 600 grit and polished titanium surfaces. The expression of osteoblast phenotype was enhanced when osteoblast progenitor cells (2T9) were stimulated with bone morphogenetic protein-2 on polished and 600 grit titanium surfaces. Bone morphogenetic protein-2 stimulated phenotypic expression on 600 grit titanium surfaces was marked by prolonged alkaline phosphatase specific activity and more rapid osteocalcin production as compared with the polished titanium surfaces. Because the surface area of the 600 grit titanium surface was shown to be 8 percent greater than that of the polished titanium surface, it is possible that increased surface area played a role in the enhanced expression of the osteoblast phenotype. (Implant Dent 1997;6:19–24)

Osteoblast responses to as-deposited and heat treated sputtered CaP surfaces

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.

Protein Adsorption and Osteoblast Responses to Heat-Treated Titanium Surfaces

The clinical success of dental implants is governed in part by surface properties of implants and their interactions with the surrounding tissues. The objective of this study was to investigate the effect of heat-treated titanium (Ti) surfaces on protein adsorption and osteoblast responses in vitro. The passivated Ti samples used in this study were either nonheat-treated or heat-treated at 750 degrees C for 90 minutes. Using x-ray diffraction analyses, no oxide peaks were observed on the nonheat-treated surfaces, suggesting an amorphous oxide. Crystalline rutile TiO2 peaks were observed on the heat-treated Ti surfaces. The contact angles of water on heat-treated Ti surfaces (32.0 +/- 2.5 degrees) were statistically lower compared with the nonheat-treated Ti surfaces (47.7 +/- 2.3 degrees). In addition, the mean albumin concentration on the nonheat-treated Ti surfaces (3.57 +/- 0.33 micrograms/mL) was observed to be significantly different from the mean albumin concentration on heat-treated Ti surfaces (2.25 +/- 0.26 micrograms/mL). In the presence of an osteoblast precursor cell line, significantly different hexosaminidase activity, protein production, and alkaline phosphatase activity were observed for cells grown on heat-treated Ti surfaces compared with nonheat-treated Ti surfaces.

Protein Adsorption And Osteoblast Responses To Heat Treated Titanium Surfaces

The clinical success of dental implants is governed in part by surface properties of implants and their interactions with the surrounding tissues. The objective of this study was to investigate the effect of heat-treated titanium (Ti) surfaces on protein adsorption and osteoblast responses in vitro. The passivated Ti samples used in this study were either nonheat-treated or heat-treated at 750 degrees C for 90 minutes. Using x-ray diffraction analyses, no oxide peaks were observed on the nonheat-treated surfaces, suggesting an amorphous oxide. Crystalline rutile TiO2 peaks were observed on the heat-treated Ti surfaces. The contact angles of water on heat-treated Ti surfaces (32.0 +/- 2.5 degrees) were statistically lower compared with the nonheat-treated Ti surfaces (47.7 +/- 2.3 degrees). In addition, the mean albumin concentration on the nonheat-treated Ti surfaces (3.57 +/- 0.33 micrograms/mL) was observed to be significantly different from the mean albumin concentration on heat-treated Ti surfaces (2.25 +/- 0.26 micrograms/mL). In the presence of an osteoblast precursor cell line, significantly different hexosaminidase activity, protein production, and alkaline phosphatase activity were observed for cells grown on heat-treated Ti surfaces compared with nonheat-treated Ti surfaces.