Bioactive glasses (BAGs) have been studied for decades for clinical use, and they have found many dental and orthopedic applications. BAGs have also been shown to have an antibacterial effect e.g., on some oral microorganisms. In this extensive work we show that six powdered BAGs and two sol-gel derived materials have a clear antibacterial effect on 29 clinically important bacterial species. We also incorporated a rapid and accurate flow cytometric (FCM) method to calculate and standardize the numbers of viable bacteria inoculated in the suspensions used in the tests for antibacterial activity. In all materials tested growth inhibition could be demonstrated, although the concentration and time needed for the effect varied depending on the BAG. The most effective glass was S53P4, which had a clear growth-inhibitory effect on all pathogens tested. The sol-gel derived materials CaPSiO and CaPSiO II also showed a strong antibacterial effect. In summary, BAGs were found to clearly inhibit the growth of a wide selection of bacterial species causing e.g., infections on the surfaces of prostheses in the body after implantation.

Bioactive glasses (BAGs) of different compositions have been studied for decades for clinical use and they have found many dental and orthopaedic applications. Particulate BAGs have also been shown to have antibacterial properties. This large-scale study shows that two bioactive glass powders (S53P4 and 13-93) and a sol-gel derived material (CaPSiO II) have an antibacterial effect on 17 clinically important anaerobic bacterial species. All the materials tested demonstrated growth inhibition, although the concentration and time needed for the effect varied depending on the BAG. Glass S53P4 had a strong growth-inhibitory effect on all pathogens tested. Glass 13-93 and sol-gel derived material CaPSiO II showed moderate antibacterial properties.

Sol-gel-derived SiO2 and CaO-P2O5-SiO2 have been shown to be bioactive and bone bonding. In this study bioactive sol-gel-derived SiO2 and CaO-P2O5-SiO2 systems were tested for in in vitro bioactivity. The calcined ceramic monoliths were immersed in a simulated body fluid and analyzed to follow the hydroxyapatite formation on the ceramic surface. Apatite-forming ability was investigated in terms of structural changes by changing the composition and the preparation method. The role of Ca and P dopants in the substrate structure is complicated, and careful characterization is needed. The composition and structure together determine the in vitro bioactivity. The pore structure was analyzed using N2-adsorption/desorption isotherms. The results indicate that a great mesopore volume and a wide mesopore size distribution favor hydroxycarbonate apatite nucleation and a great surface area is not needed. The performed preparation process for silica in a basic environment provides a convenient way to prepare a mesoporous material.

A firm bond between an implant and the surrounding soft tissue is important for the performance of many medical devices (e.g., stents, canyls, and dental implants). In this study, the performance of nonresorbable and reactive sol-gel-derived nano-porous titania (TiO(2)) coatings in a soft tissue environment was investigated. A direct attachment between the soft tissue and the sol-gel-derived titania coatings was found in vivo after 2 days of implantation, whereas the titanium control implants showed no evidence of soft tissue attachment. The coated implants were in immediate contact with the connective tissue, whereas the titanium controls formed a gap and a fibrous capsule on the implant-tissue interface. The good soft tissue attachment of titania coatings may result from their ability to initiate calcium phosphate nucleation and growth on their surfaces (although the formation of poorly crystalline bonelike apatite does not occur). Thus, the formation of a bonelike CaP layer is not crucial for their integration in soft tissue. The formation of bonelike apatite was hindered by the adsorption of proteins onto the initially formed amorphous calcium phosphate growth centers, thus preventing the dissolution/reprecipitation processes required for the formation of poorly crystalline bonelike apatite. These findings might open novel application areas for sol-gel-derived titania-based coatings.

Titanium and its alloys are used widely in the manufacture of orthopedic and dental implants. Sol-gelprepared titania is able to stimulate bone-like apatite formation in in vitro and in vivo cultures. These materials can be used, for example, as coatings on dental and orthopedic implants. However, the processes that lead to apatite formation are not fully understood. In this study different kinds of titania coatings on commercially pure titanium (c.p. Ti) were tested for apatite-forming ability. The rate of apatite formation is considered to be descriptive of a material's bioactive (bone-bonding) potential. Apatite-forming tests were done in simulated body fluid (SBF). Apatite-forming ability was highest with the addition of valeric acid to sol (600°C) or with sintering sol-gel coatings at 450°-550°C. At that temperature range calcium phosphate forms on the coatings in 1 week. Calcium phosphate forming is observed in 1 day on standard coatings sintered at 500°C.

Different sol-gel-derived titania and titania-silica films were prepared and their properties related to in vitro bioactivity. The films were prepared by depositing the sols on the substrate surface using a dip-coating method. The sols were monitored carefully as a function of time, using rheological techniques and dynamic light scattering. The topography of the films was characterized using atomic force microscopy, and thicknesses and refractive indexes of the films were evaluated by fitting transmittance spectra measured in a wave length region of 370-1100 nm with a spectrophotometer. The in vitro bioactivity tests were performed in simulated body fluid. Surface topography was found to be of great importance with respect to the bioactivity of the studied films.

Thus, no evidence of enhanced bone formation to nano-HA-modified implants was observed compared to nano-titania-modified implants. The presence of specific nanostructures dependent on the surface modification exhibiting different size and distribution did modulate in vivo bone response.

The sol-gel technique provides a method to produce porous titania (TiO 2 ) coatings, which are known to induce bone-like hydroxyapatite formation on their surface in vitro. In this study, the calcium phosphate formation (in vitro bioactivity) on a sol-gel-derived titania coating was investigated in vitro in a simulated body fluid in the presence and absence of albumin (BSA) and fibrinogen (Fib) in solution as well as the effect of surface immobilized proteins on the biomineralization process. The effect of proteins on calcium phosphate (CP) formation was followed by ion concentration analysis, XRD, SEM-EDX, and XPS. When BSA and Fib were present in solution, the CP layer growth kinetics were strongly retarded. It is suggested that the bone-like apatite formation on sol-gel-derived titania coatings occurs via continuous dissolution/reprecipitation processes, where the initially formed CP phase(s) recrystallizes into a more thermodynamically stable phase(s), as previously observed for other biomaterials. Inhomogeneous charging was observed in the XPS experiments, which could be used to distinguish between an amorphous CP layer and poorly crystalline CP regions.