## 1 Introduction  
One of the major challenges in modern regenerative medicine is to develop biomaterials that are both mechanically strong and bioactive. The mechanical properties are necessary to prevent any structural failure during normal activity of the patient or during handling the implant in the operation. Bioactivity is desirable for the bone repair process to dominate fibrous repair. Usually, in the field of bioceramics, these properties are antagonist [1]. Eutectic ceramics grown from the melt have a great potential as structural and functional materials due to their high resistance, low density, and synergic combination of phases. At present, the ceramic materials used in bone implants are polycrystalline and usually fabricated by conventional sintering method, requiring high temperatures to achieve high densification. The presence of pores and defects at grain boundaries reduce the mechanical behavior of these materials. Directionally solidified eutectrics have excellent mechanical properties inherent to the full density, homogeneous microstructure, reduced interphase spacing, and large surface area of clean, strong interfaces. From the biological point of view, among the eutectic ceramics we can find some that have a bioactive behavior and others are bioinert. [PERSON] et al. [2] have shown that glasses and ceramics in the systems containing CaO-P\({}_{2}\)O\({}_{5}\)-SiO\({}_{2}\) can be designed to optimize biological and mechanical response. They have reported in the phase diagram of the system wollastonite (CaO-SiO\({}_{2}\))-tricalcium phosphate (3 CaO-P\({}_{2}\)O\({}_{5}\)) an invariant point at 1402 \({}^{\circ}\)C and a eutectic composition of 80%mol of wollastonite (W) and 20%mol of tricalcium phosphate (TCP). Further studies concluded that ceramics and glasses with this composition can be used in bone repair applications. Such ceramics, known as Bioeutectic, have the property of developing a porous hydroxyapatite-like structure in simulated biological conditions by the dissolution of the wollastonite phase and transformation of the tricalcium phosphate phase [3]. The role of Si ions on the biomineralization process has been widely reported. Si ions substitution in CaP ceramics and glasses has effects on the differentiation, proliferation, and collagen synthesis of osteoblasts and facilitates precipitation of hydroxyapatite (HAp) on the bioceramic surface by increasing the solubility of the material through the creation of crystalline defects with substitution for PO\({}_{4}\)\({}^{3-}\) for SiO\({}_{4}\)\({}^{4-}\) generating a more electronegative surface [4]. Alumina and zirconia-based eutectics have high strength, wear resistance, and fracture toughness but poor bioactivity [5]. Zirconia-based materials are especially interesting in orthopaedics (bone screws, knee implants) and maxillofacial applications and also as dental material because of their aesthetics characteristics (translucency and colour). For example, tetragonal zirconia polycrystal with three percent of yttria (3Y-TZP) has been widely used in dental applications. However, hydrothermal degradation leads to microcracking, grain pull-out, and finally surface roughening [6]. More stable zirconia can be achieved in 3Y-TZP by adding a small amount of alumina, which is homogeneously distributed in the zirconia matrix [7]. It is considered that the use of yttria as a dopant is the cause of ageing of zirconia because of the creation of oxygen vacancies by yttrium ions, thus inducing the diffusion of hydroxyl groups in the lattice and consequently giving rise to stress corrosion type mechanism. Coatings to be used for thermal barriers based on ZrO\({}_{2}\) stabilized by CaO and MgO have been the purpose of intensive research aiming at producing protective layers and to be applied to promote the adhesion in Ti-ceramic dental restoration as reported by [PERSON] et al. [8]. Magnesia- and calcia-doped zirconia ceramics have been object of little consideration in bone restoration because of their lower toughness.