Effect of Heat-Treated Titanium Surfaces on Protein Adsorption and Osteoblast Precursor Cell Initial Attachment

Effect of Heat-Treated Titanium Surfaces on Protein Adsorption and Osteoblast Precursor Cell Initial Attachment
March 2005
Kern, Travis BS*; Yang, Yunzhi PhDÇƒÜ; Glover, Renee MSÇƒ?; Ong, Joo L. PhD¨?
Implant Dentistry: Volume 14
Abstract TOP
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 surfaces on protein adsorption and osteoblast precursor cell attachment in vitro. Passivated titanium samples used in this study were either non heat treated or heat treated at 750¨?C for 90 minutes. It was observed that the contact angle on heat-treated titanium surfaces was statistically lower compared with the non-heat-treated titanium surfaces. The non-heat-treated titanium surface was also observed to be amorphous oxide, whereas heat treatment of titanium resulted in the conversion of amorphous oxide to crystalline anatase oxide. No significant difference in albumin and fibronectin adsorption was observed between the heat-treated and non-heat-treated titanium surfaces. In addition, no significant difference in initial cell attachment was observed between the two groups. It was concluded that heat treatment of titanium resulted in significantly more hydrophilic surfaces compared to non-heat-treated titanium surfaces. However, differences in oxide crystallinity and wettability were not observed to affect protein adsorption and initial osteoblast precursor cell attachment.
Titanium (Ti), used as a material for dental implants, has excellent corrosion resistance and biocompatibility with the ability to establish close bony apposition. 1-5 Studies on surface properties of Ti have indicated the presence of an amorphous TiO2.6 Depending on the sterilization technique and surface treatments, oxide thickness in the range of 30 to 100 ?÷ have been reported.7-9 Increased oxide thickness and crystallinity were reported with anodization treatments.7,10 With other surface treatment, such as radio frequency glow discharge, an increase in surface energy was observed.11 Heat sterilization either through autoclaving or dry heat have also been reported to cause changes in the surface properties of the implant surface.12
Upon implantation, surfaces of Ti implants invariably first become coated with a thin proteinaceous film. The adsorbed protein layer depends on the implant surface and may consequently influence biologic activities in relation to cell attachment. As such, the investigation of protein adsorption on implant surfaces needs to be evaluated critically to determine some of the factors governing implant success.13,14 It is known that serum albumin occupies a special position among the plasma proteins. This accounts for approximately one half of the plasma protein.13,14 Fibronectin is one of the first extracellular matrix proteins produced by odontoblasts and osteoblasts.15-17 These proteins may play an important role in the interaction of the implant surface and surrounding matrix.
In addition, by altering the surface properties of Ti, different cellular responses have been observed. 17-27 In the previous study, it was observed that in the presence of an osteoblast precursor cell line, significant differences in hexosaminidase activity, protein production, and alkaline phosphatase activity were observed for cells grown on heat-treated Ti surfaces compared with non-heat-treated Ti surfaces.27 It was thus hypothesized that early osteoblast attachment may be affected by the heat-treated Ti surfaces. To determine whether changes in the properties of the Ti surfaces play a role in protein adsorption and initial osteoblast precursor cell attachment, the present study examined the protein adsorption and in vitro initial osteoblast precursor cell attachment on non-heat-treated and heat-treated Ti surfaces.
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