An in vitro biological and anti-bacterial study on a sol-gel derived silver-incorporated bioglass system.

OBJECTIVES: The purpose of this study was to evaluate the in vitro antibacterial and biological activity of silver-incorporated bioactive glass system SiO2-CaO-P2O5-Ag2O (AgBG). The bacteriostatic and bactericidal properties of this new quaternary glass system along with the ternary sol-gel glass system SiO2-CaO-P2O5 (BG) have been studied using Escherichia coli as a test micro-organism. The AGBG system thus appears to be a promising material for dental applications, since similar effects might be produced on a film of bacteria and mucous that grows on the teeth. METHODS: The SiO2-CaO-P2O5-Ag2O and SiO2-CaO-P2O5 glass systems were synthesized by the sol-gel technique and characterized for their physicho-chemical properties. The antibacterial activity and biological properties were evaluated by determining the minimum inhibitory concentrations (MICs). Release of Ag+ into the culture medium was measured by inductively coupled plasma (ICP) analysis. RESULTS: The in vitro antibacterial action of the SiO2-CaO-P2O5-Ag2O was compared with that of its ternary counterpart glass system. The concentrations of Ag-bioglass, in the range of 0.02-0.20 mg of Ag-bioglass per millilitre of culture medium, were found to inhibit the growth of these bacteria. The Ag-bioglass not only acts bacteriostatically but it also elicited a rapid bactericidal action. A complete bactericidal effect was elicited in the early stages of the incubation at Ag-bioglass concentration of 20 mg/ml and the ternary glass system had no effect on bacterial growth or viability. The antibacterial action of Ag-bioglass was exclusively attributed to the leaching of Ag+ ions from the glass matrix. SIGNIFICANCE: One of the major advantages of incorporating silver ions into a gel glass system is that the porous glass matrix can allow for controlled sustained delivery of the antibacterial agent to dental material, used even under anaerobic conditions such as deep in the periodontal pocket. This glass system also provides long-term action required for systems which are constantly at risk of microbial contamination.

Suitability evaluation of sol-gel derived Si-substituted hydroxyapatite for dental and maxillofacial applications through in vitro osteoblasts response.

UNLABELLED: Si-hydroxyapatite (Si-HAP) has been used in orthopedic, dental, and maxillofacial surgery as a bone substitute. OBJECTIVE: The aim of this investigation was to study the effect of Si substitution into the hydroxyapatite matrices and evaluate the biocompatibility effects of Si-HAP material in vitro with human osteoblasts. METHODS: Silicon-substituted hydroxyapatite (Si-HAP) bioceramic materials were prepared by incorporating small amounts of silicon into the structure of hydroxyapatite [Ca10(PO4)6(OH)2, HAP] through a sol-gel method. A series of silicon substitutions ranging from 0, 1, 3 and 5 mol%, which are comparable to the measured silicon contents in natural bone, were performed. RESULTS: Single-phase Si-HAP was obtained upon calcining the as-prepared powders up to 800 degrees C since no secondary phases, such as tricalcium phosphate (TCP), tetracalcium phosphate (TeCP) or calcium oxide (CaO), were identified by X-ray diffraction analysis. The effects of silicon-substituted hydroxyapatite (Si-HAP) materials towards the responses of human osteoblast-like (HOB) cells were investigated and compared with pure hydroxyapatite. SIGNIFICANCE: The Si-HAP indicated a significant increase in cell growth density with culture time irrespective of the amount of Si substituted in HAP. A high Si content (5 mol%) appears to promote rapid bone mineralization, since large amount of calcium phosphate minerals started to develop across the ECM by day 31 for a sample containing 5 mol% Si. On the other hand, a high Si content may result in fast dissolution of the material, owing to a decrease of HAP crystallite size, which might not be ideal for cell attachment for prolonged time periods. An optimum level of Si appears to exist at 3 mol%, which balances these effects.

Sol gel derived SiO(2)-CaO-MgO-P(2)O(5) bioglass system--preparation and in vitro characterization.

The synthesis of SiO(2)-CaO-MgO-P(2)O(5) bioactive glass was carried out by the sol-gel method. Sol-gel derived bioglass material was crushed into powder to produce pellet disks by uniaxial pressing, followed by sintering at 900 degrees C. The biocompatibility evaluation of the formed glass was assessed through in vitro cell culture experiments and immersion studies in simulated body fluid (SBF) for different time intervals while monitoring the pH changes and the concentration of calcium and magnesium in the SBF medium. Scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray diffraction analysis, and FT-IR spectroscopy studies were conducted before and after contact of the material with SBF. At first, an amorphous calcium phosphate was formed; after 21 days this surface consisted of deposited crystalline spheres of apatite. The present investigation also revealed that the sol-gel derived quaternary bioglass system has the ability to support the growth of osteoblast-like cells in vitro and to promote osteoblast differentiation by stimulating the expression of major phenotypic markers.

Rietveld structure and in vitro analysis on the influence of magnesium in biphasic (hydroxyapatite and beta-tricalcium phosphate) mixtures.

The structure of two different Mg-substituted biphasic (HAP and beta-TCP) mixtures along with the biphasic mixtures without substituted Mg(2+) was investigated using Rietveld refinement technique. The substituted Mg(2+) was found in the beta-TCP phase and its influence on the composition has led to an increase in HAP content of Mg-containing biphasic mixtures when compared with the HAP content detected in pure biphasic mixtures. The refined structural parameters of Ca(10)(PO(4))(6)(OH)(2) and beta-Ca(3)(PO(4))(2) confirmed that all the investigated compositions have crystallized in the corresponding hexagonal (space group P6(3)/m) and rhombohedral (space group R3c) structures. The substitution of lower sized magnesium was found preferentially incorporated at the sixfold-coordinated Ca (5) site of beta-TCP, which is due to the strong Ca (5).O interaction among all the five different Ca sites of beta-Ca(3)(PO(4))(2). The in vitro tests using primary culture of osteoblasts showed that all the tested samples are biocompatible and promising materials for in vivo studies.