# Antibacterial Ceramics for Dental Applications
## 1 Introduction  
Bioglases (BGs) have found wide applications as biomaterials for soft and hard tissue regeneration [1, 2, 3, 4, 5, 6]. BGs have the ability to bond with bone upon contact with physiological fluids, making them suitable as bone-replacement biomaterials in the form of implants, scaffolds, granules, powders, or coatings. They have excellent biocompatibility, bioactivity, conductivity, and osteoinductivity, a controllable degradation rate, and improved bone healing [1, 2, 7, 8]. These materials have been used to treat cancer since the beginning of the 21 st century [2]. However, the applications of BGs as bone and dental implants can induce an immune response even in the absence of immune-stimulatingsignals. New BGs are being developed that are immunologically inert and also have antibacterial properties [9; 10; 11]. Microleakages caused by a misfit between the margin of the crown restoration and the dental tissue or the dissolution of adhesive materials lead to plaque accumulation, which can cause secondary caries [12; 13]. All-ceramic crowns are an excellent choice for clinical crown restoration due to their good mechanical properties and biological stability, as well as their chemical and optical properties compatible with those of natural teeth, such as translucency, color, fluorescence, opalescence, and aesthetics [14; 15; 16]. However, due to the lack of antibacterial effect, secondary caries may still develop [17], which shortens the lifespan of dental restorations and leads to early replacement of the crown restoration. Therefore, the development of antibacterial dental ceramics for crown restorations that prevent secondary caries is one of the biggest challenges in prosthodontics. Another application area for antibacterial ceramics besides crown restorations is dental implants. They are used to replace teeth lost due to severe damage, large area cavities, or gum disease [18; 19; 20; 21; 22]. Infections at the implant site can hinder or even completely prevent osseointegration, potentially leading to implant failure or the need for surgical removal of the implant [23; 24; 25; 26]. Bacterial infections play a key role in the development of necrotic processes of the dental pulp and the formation of periapical lesions [27]. In periodontitis, the gums, periodontal ligaments, and supporting alveolar bone are gradually destroyed due to an inflammatory reaction triggered by subgingival pathogenic microorganisms [13; 18; 19; 20; 21; 22]. For example, chronic apical periodontitis is an inflammatory reaction caused by infection of the pulp. It induces bone resorption in the apical and periapical areas of the teeth [28; 29], originating from high bacterial contamination along the root canal system [27]. _Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterobacter cloaca_, and _Escherichia coli_ are the major bacteria that are responsible for implant infections. Gram-positive and Gram-negative bacteria have different cell shapes, biochemistry, and biomolecular mechanisms that allow them to survive and grow on the surface of dental implants. They are difficult to remove, resist the immune system, and frequently cause opportunistic infections [30]. The resistance of microorganisms to antibiotics has required the development of new materials with antibacterial properties to reduce or avoid excessive use of antibiotics [9; 24; 31; 32; 33; 34]. Most of the current dental materials exhibit no antibacterial functionality against Gram-positive and Gram-negative bacteria. To increase the success rate of dental treatments, dental materials need to be improved to effectively reduce colonization and microbial development [13; 35; 36; 37; 38; 39; 40; 41]. Materials with intrinsic antibacterial activity are also in high demand for various clinical applications, such as bone grafts. They are often required to treat open fractures with significant bone loss [24; 42].