# Antibacterial Ceramics for Dental Applications
## 1 Introduction
Contamination of the wound, e.g., from a contaminated implant surface, can cause soft tissue infections and osteomyelitisitis, which slows down the healing process and hinders bone formation [22]. The growth behavior of bacterial infections is largely controlled by the composition of the biomaterials and their surface properties [25; 41; 43]. Many attempts have been made to solve these major problems. The antibacterial effect of the materials used is based on three strategies: (a) local release, (b) contact-killing, and (c) the generation of synergetic properties [44; 45; 46]. However, each method has advantages and disadvantages, such as slow efficacy, toxicity, or the alteration of the physical properties of the sealer. Inorganic antimicrobial materials are typically more stable and exhibit long-term antibacterial properties. New filler additives made of glass and glass-ceramic are being developed to prevent bacterial reinfection of the root canal [27]. The development of bioceramics with good mechanical, bioactive, and antimicrobial properties is a major challenge for medicine [25; 47; 48; 49; 50; 51; 52; 53]. Zirconia ceramics, a typical dental ceramic material, have excellent biocompatibility, optical properties, and chemical stability [54]. They are often used for tooth repairs, dental implants, and orthopedic artificial joints, but their surface is hydrophilic, which allows for the adhesion of bacteria and the formation of biofilms on the surface when implanted into the body [54; 55]. Superhydrophobic surfaces usually exhibit self-cleaning behavior, corrosion, and antibacterial resistance [56; 57; 58; 59; 54]. By treating the zirconia surface using femtosecond laser ablation, new surface micro-textures are created, turning it into a hydrophobic surface. Such a treated zirconia surface can enhance biological responses and reduce the bacterial behavior of the interface [58]. The hydrophobic surface created by the laser treatment can be attributed to the topographical modifications of zirconia surfaces at the micro and nano scale. The hydrophobic surface can especially influence the initial stages of biofilm formation. This is very important because early-stage biofilm formation plays a crucial role in bacterial colonization and subsequent infection [60]. Bioceramics for dental applications should not only promote osteocyte formation and osteogenic differentiation but also be able to inhibit bacterial growth. The development of bioceramic materials with inherent antimicrobial properties, such as the incorporation of antimicrobial ions (silver, copper, zinc, cerium, strontium, etc. ), is the focus of researchers [38; 44; 61; 62]. Strontium (Sr\({}^{2+}\)), which is present in bone, muscle, liver, and body fluid offers antibacterial activity, improves osseointegration, and stimulates osteoblastic proliferation. Bioactive glasses doped with strontium have a positive effect on antibacterial efficiency and stimulate bone formation [61]. Zinc (Zn\({}^{2+}\)) can promote bone growth, proliferation, and the differentiation of bone cells, as well as DNA replication and protein and enzyme production [63]. Zinc ions are used to impact the antibacterial activity of bioactive glass due to their antibacterial and angiogenic properties [63]. Cerium is the only element in the lanthanide group that is stable in the tetravalent state. The easy exchange between the oxidation states Ce\({}^{3+}\) and Ce\({}^{4+}\) is the foundation for its catalytic activity as a scavenger of reactive oxygen species (ROS) and its antioxidative properties that protect osteoblasts from oxidative stress. Ce-BGs are nontoxic to cells and promote osteoblastic differentiation. Mineralization of primary osteoblasts increases collagen production. Cerium ions play a fundamental and effective role in preventing bacterial adhesion and proliferation on the implant surface. Cerium ions rapidly bind to _E. coli_ and disrupt respiration and other metabolic functions, leading to bacterial death [64; 65].