Current Trends on Glass and Ceramic Materials

In the recent past advanced materials with innovative processing techniques are being developed for applications starting from day to day home appliances to space shuttle. One of the most important and direct usage of advanced materials is for solving problems in human health care, particularly in replacement of the damaged or lost bone tissues. In this direction, the development of synthetic materials known as biomaterials, fabrication of their structures for bone implants and for tissue engineering (Scaffolds) followed by their implantation in human body is a highly interdisciplinary subject and is addressed jointly by material scientists, engineers as well as by the surgeons.

This chapter gives an introduction about the advanced materials that are used as biomaterial, their requirements and materials-tissue interactions. This is followed by the discussion on bioceramic materials and their classification as nearly inert, bioactive and resorbable materials with examples. Among the number of materials developed for bioapplications, those showing higher compatibility with the tissues and which proliferate the growth of tissues play a prominent role. Among these, some of the ceramics like hydroxyapatite and tricalcium phosphate are widely used due to their chemical similarity to bone and good biocompatibility. In this context, a review on preparation methods, processing and forming, thermal stability and densification and some of the characteristic properties of hydroxyapatite ceramics has been presented.

The chapter also deals with the processing and shaping aspects of bioceramic materials including basic principles, experimental result and discussions. Colloidal processing, slip casting, gel casting and mouldless casting methods are discussed as applied to Al₂O₃, hydroxyapatite and tricalcium phosphate as specific examples of bioceramic materials to fabricate differently shaped dense and porous samples intended for implant and scaffold applications.

Dental ceramic restorations are essentially oxide based glass-ceramic systems. Glass-ceramics are employed in medicine and dentistry because they are relatively easy to process and have impressive mechanical properties. In addition, allceramic dental restorations are attractive for both dentists and patients because they have excellent aesthetics and their low thermal conductivity makes them comfortable in the mouth. In addition, the material is extremely durable and relatively easy to manufacture into customised units. The first ceramic to be used in dental restoration was dental porcelain. Introduced in the 1960s, this material has shown excellent aesthetics and biocompatibility, but its strength is only adequate for a limited range of applications. The development of advanced dental material technologies has recently led to the introduction of a range of all-ceramic restorations in dentistry. In this chapter, the authors have summarised the fundamental principles of glass-ceramic technology particularly it’s use in dentistry and also give general information about current commercial materials and those currently under development. Detailing their properties, processing methods and how they may affect the future of dentistry.

Microwave heating technique has attracted considerable attention for the processing of various materials such as ceramics, glasses, polymers, composites and even metals. Researchers are trying to apply this technology to new areas. The present review presents a short overview of some recent applications of conventional and/ or microwave processing for the synthesis of novel ceramics and glass-ceramics.

This work reports the preparation and characterization of newly developed 10CaF₂-10Na₂CO₃-15CaO-59P₂0₅-5Si0₂ glasses, doped with lanthanides, in this case cerium and lanthanum oxide (10CaF₂-10Na₂CO₃-15CaO-59P₂0₅-1CeO₂-5SiO₂ and 10CaF₂-10Na₂CO₃-15CaO-59P₂0₅-1La₂O₃-5SiO₂, respectively). The structure and morphology of the developed glasses have been investigated by Raman and FTIR spectroscopy. Scanning electron microscopy with an energy dispersive analyzer and X-ray mapping was used to assess the morphological properties of the glasses. Glass-ceramic composites, for bone tissue applications, were obtained by the mixture of 2.5wt% of each glass with 97.5wt% of hydroxyapatite. These were also analyzed by means of XRD and SEM. Composites were biologically evaluated with human osteoblastic-like cells. Lanthanide doped-hydroxyapatite composites revealed an improved biological behaviour, regarding cell adhesion and proliferation, compared to hydroxyapatite and undoped glasshydroxyapatite composites. Lanthanide doped composites reported an adequate biocompatibility, further enhancing the cell adhesion and proliferation, behaviour that indicates a prospective application in bone tissue engineering.

Regenerative periodontal therapy aims to predictably restore the tooth's supporting periodontal tissues and should result in the formation of a new connective tissue attachment (i.e. new cementum with inserting periodontal ligament fibres) and new alveolar bone. This chapter aims to address the clinical application of bone grafts on periodontal regenerative approaches, with given relevance to the use of calcium phosphate ceramics. Furthermore, a clinical case is presented in which the regenerative capability of a glass-reinforced hydroxyapatite (Bonelike^®) is thoroughly evaluated by clinical and tomographic measurements in the healing of a periodontal intrabony defect.

Glasses with compositions 20MO·xBi₂O₃·(79.5-x)B₂O₃ (15 ≤ x ≤ 35, x in mol%,) and 20MO·xSiO₂·(79.5-x)Bi₂O₃ (10 ≤ x ≤ 50, x in mol%, M = Zn and Cd) containing 0.5 mol% Er³⁺ ions were prepared by normal melt-quench technique (1150°C in air). The effect of host glass composition on the optical absorption and fluorescence spectra of Er³⁺ ions have been observed with varying contents of Bi₂O₃. Judd-Ofelt approach has been applied for f-f transition of Er³⁺ ions to evaluate various intensity parameters viz. Ω_λ (λ = 2, 4, 6). The variation of Ω₂ with Bi₂O₃ content has been attributed to change in the asymmetry of ligand field at the rare earth ion site. The Judd-Ofelt intensity parameters were determined from intensities of absorption bands in order to calculate the radiative properties viz. transition probability (A_rad), and radiative life-time of the excited states (τ_r). From the emission spectra, full width at half maxima (FWHM), stimulated emission crosssection (σ) and figure of merit were evaluated and compared with other hosts. The observed NIR emission (⁴I_13/2→⁴I_15/2 at 1.5μm) in Er³⁺-doped zinc/cadmium bismuth borate/ silicate glasses may be useful in optical communication.