Abstract: Several hydroxyapatite (HAp) synthesis routes, such as solid state reactions, hydrothermal methods, wet procedures have been widely investigated. At the same time, in the last years many alternative methods to produce HAp, exploiting fish, bovine or pig bones, have been developed; among them the most used are thermal processes as well as subcritical water or alkaline hydrothermal routes.
This paper deals with a natural HAp nanopowder extracted from pig bones by a treatment with hot NaOH solution. It was demonstrated that the decomposition phenomena were avoided when the extracted HAp powder was calcined in CO2 atmosphere or by inducing the formation of CaO at 700 °C and then eliminating it through a washing procedure.
The washed HAp was then exploited for producing macroporous components having controlled porosity features in terms of pore shape, size and volume percentage. For this aim, a combination of gelcasting and sacrificial template methods was applied as forming procedure, using agar as natural gelling agent and polyethylene (PE) spheres as pore former.
Abstract: In the last years, bioactive glasses and glass-ceramics drew the attention for their application in the production of implants. Among them, Bioglass® 45S5 is the most commonly used in terms of bioactivity, but its sintering behavior and the related glass-ceramics strongly depend on the followed synthesis process. For these reasons, this paper reports a comparison of the properties and the thermal behavior of bioactive 45S5 glasses produced by a conventional melting process starting from suitable solid precursors or an innovative sol-gel procedure.
Abstract: Highly porous 45S5 Bioglass® scaffolds were fabricated by the foam replica method and successfully coated with a well attached gelatin layer by dipping and pipetting methods. Depending on macropore size of the scaffold and gelatin concentration, mechanically enhanced scaffolds with improved compressive strength in comparison to uncoated scaffolds could be obtained while preserving the high and interconnected porosity that is required for bone in-growth. Moreover, the scaffolds bioactivity by immersion in simulated body fluid (SBF) was investigated showing that gelatin coating preserves the intrinsic bioactivity of the Bioglass® scaffold. It was also shown that the gelatin layer can be loaded with tetracycline hydrochloride for developing scaffolds with drug delivery capability.
Abstract: In this work, the sol-gel synthesis of AP40 bioactive glass system was reported. The obtained powder was fully characterised in terms of microstructure, composition and thermal behaviour by X-ray diffraction (XRD) measurements, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry and differential thermal analysis (TG-DTA). In vitro dissolution tests were performed in order to assess the degradation behaviour of sol-gel derived AP40 samples thermally treated at different temperatures. Finally, preliminary results on cytocompatibility are reported, based on bioresorption activity of human peripheral blood monocytes differentiated into osteoclasts on sintered disks.
Abstract: Scientists have recently focused their attention on adult stem cells as new and more effective treatments for different diseases and disabilities. In fact, it is known that stem cells are capable of renewing themselves and that they can generate multiple cell types. Today, there is new evidence that stem cells are present in far more tissues and organs than once thought and that these cells are capable of developing into more kinds of cells than previously imagined. In this chapter, we focus the attention on teeth as source of stem cells. In particular, we describe the characteristic of the different types of dental stem cells and their use in tissue engineering.
Abstract: This work describes the anelastic behaviour of human dentin in the temperature range from 100 K to 673 K. Human molars, extracted from individuals (males 55-70 years old) as part of their dental treatment, were cut to obtain bar-shaped samples for mechanical spectroscopy (MS) experiments. The results are presented and discussed in two parts referring to experiments above and below room temperature.
Abstract: In the last years, several experimental techniques have been improved to measure mechanical properties of human dentin. Dentin exhibits a behavior like a functionally graded material with properties dependent on tubule density and orientation. This work describes and critically analyzes the elastic, anelastic and plastic characteristics of dentin on the basis of scientific literature, in particular data of Youngs modulus, shear modulus, Poissons ratio, yield and ultimate stress, hardness, fatigue, fracture toughness, creep, stress relaxation and damping have been considered. Finally, a new indentation technique (FIMEC test) is proposed to characterize the mechanical properties of dentin on a local scale.
Abstract: After a short introduction to bone substitute biomaterials and X-ray microtomography, this article describes a research work carried out for in-vitro characterization of bone substitute biomaterials as well as for in-vivo investigation of human bone grafted with biomaterials. Three different bone substitute biomaterials have been analyzed in-vitro by means of 3D microtomographic technique, while human bone samples grafted with bone substitute biomaterials are investigated by 3D microtomography and histological techniques. 3D images of bone substitutes and human bone samples with biomaterials have been obtained, together with morphometric parameters, by microtomography . 2D histological images have also been obtained by traditional technique only for human bone samples with biomaterials. Compared to traditional histological analysis, 3D microtomography shows better results for investigating bone tissue and bone substitute biomaterial, and in a short time. Nevertheless, histological analysis remains the best technique for the observation of soft tissue and blood vessels.
Abstract: In situ monitoring of structural changes, taking place upon calcium phosphate bone cements hardening process was carried out by means of the Energy Dispersive X-Ray Diffraction method. Two different cement systems were studied, one of them based on the octacalcium phosphate and another - on the dicalcium phosphate dehydrate. Both systems contained natural biopolymer chitosan and were soaked in Simulated Body Fluid. The obtained experimental results evidence that during the hardening of the cement containing octacalcium phosphate its partial transformation into hydroxyapatite takes place, whereas no significant changes were detected during the hardening process of cement containing the dicalcium phosphate dehydrate.