Luis Alberto dos Santos

α-Tricalcium phosphate cements modified with β-dicalcium silicate and tricalcium aluminate: Physicochemical characterization, in vitro bioactivity and cytotoxicity

Biocompatibility, injectability and in situ self-setting are characteristics of calcium phosphate cements which make them promising materials for a wide range of clinical applications in traumatology and maxillo-facial surgery. One of the main disadvantages is their relatively low strength which restricts their use to nonload-bearing applications. α-Tricalcium phosphate (α-C3P) cement sets into calcium-deficient hydroxyapatite (CDHA), which is biocompatible and plays an essential role in the formation, growth and maintenance of tissue-biomaterial interface. β-Dicalcium silicate (β-C2S) and tricalcium aluminate (C3A) are Portland cement components, these compounds react with water to form hydrated phases that enhance mechanical strength of the end products. In this study, setting time, compressive strength (CS) and in vitro bioactivity and biocompatibility were evaluated to determine the influence of addition of β-C2S and C3A to α-C3P-based cement. X-ray diffraction and scanning electron microscopy were used to investigate phase composition and morphological changes in cement samples. Addition of C3A resulted in cements having suitable setting times, but low CS, only partial conversion into CDHA and cytotoxicity. However, addition of β-C2S delayed the setting times but promoted total conversion into CDHA by soaking in simulated body fluid and strengthened the set cement over the limit strength of cancellous bone. The best properties were obtained for cement added with 10 wt % of β-C2S, which showed in vitro bioactivity and cytocompatibility, making it a suitable candidate as bone substitute.

β-Dicalcium silicate-based cement: Synthesis, characterization and in vitro bioactivity and biocompatibility studies

β-dicalcium silicate (β-Ca₂ SiO₄, β-C₂ S) is one of the main constituents in Portland cement clinker and many refractory materials, itself is a hydraulic cement that reacts with water or aqueous solution at room/body temperature to form a hydrated phase (C-S-H), which provides mechanical strength to the end product. In the present investigation, β-C₂ S was synthesized by sol-gel process and it was used as powder to cement preparation, named CSiC. In vitro bioactivity and biocompatibility studies were assessed by soaking the cement samples in simulated body fluid solutions and human osteoblast cell cultures for various time periods, respectively. The results showed that the sol-gel process is an available synthesis method in order to obtain a pure powder of β-C₂ S at relatively low temperatures without chemical stabilizers. A bone-like apatite layer covered the material surface after soaking in SBF and its compressive strength (CSiC cement) was comparable with that of the human trabecular bone. The extracts of this cement were not cytotoxic and the cell growth and relative cell viability were comparable to negative control.

Cementos Biomédicos de Fosfato Tricálcico Reforzados con Silicatos y Aluminatos de Calcio-Preparación, Caracterización y Estudios de biodegradación

The combination of in situ self-setting and biocompatibility makes calcium phosphate cements highly promising materials for a wide range of clinical applications. However, its low strength limits its use to only non-stress applications. α-Tricalcium phosphate (α-TCP) cement sets into calcium-deficient hydroxyapatite (CDHA), which is a biocompatible compound and can induce osteointegration. β-Dicalcium silicate (β-C2S) and tricalcium aluminate (C3A) are Portland cement components, these compounds react with water to form hydrated phases that enhance mechanical strength of the end products. In this investigation, were prepared α-TCP cements modified with β-C2S and C3A. α-TCP powder was prepared through acid-base method, β-C2S and C3A were synthesized by sol-gel method. Materials were characterized chemical and physically. Biodegradability was studied by soaking the materials in simulated body fluid (SBF) at 37°C for 7 days. All cements exhibited long setting times and excellent setting temperature. T (100% α-TCP) and TS10 (10%-β-C2S) were converted to CDHA after 7 days soaking in SBF and their compressive strength were comparable to that of trabecular bone. TA10 (10%-C3A) was only partly converted to CDHA and showed the lowest compressive strength.