*Review* **Toughening of Bioceramic Composites for Bone Regeneration**

**Zahid Abbas †, Massimiliano Dapporto \*,†, Anna Tampieri and Simone Sprio \***

Institute of Science and Technology for Ceramics-National Research Council of Italy (ISTEC-CNR), 48018 Faenza, Italy; zahid.abbas@istec.cnr.it (Z.A.); anna.tampieri@istec.cnr.it (A.T.)

**\*** Correspondence: massimiliano.dapporto@istec.cnr.it (M.D.); simone.sprio@istec.cnr.it (S.S.); Tel.: +39-054-669-9760 (M.D.)

† Co-first author, these authors contributed equally to this work.

**Abstract:** Bioceramics are widely considered as elective materials for the regeneration of bone tissue, due to their compositional mimicry with bone inorganic components. However, they are intrinsically brittle, which limits their capability to sustain multiple biomechanical loads, especially in the case of load-bearing bone districts. In the last decades, intense research has been dedicated to combining processes to enhance both the strength and toughness of bioceramics, leading to bioceramic composite scaffolds. This review summarizes the recent approaches to this purpose, particularly those addressed to limiting the propagation of cracks to prevent the sudden mechanical failure of bioceramic composites.

**Keywords:** bioceramics; mechanical properties; calcium phosphate; carbon fibers; mineralization
