## 2 Nanomaterials in Endodontics
### Bioglass  
Bioglass (BG) was first developed by [PERSON] and his colleagues in 1960. It is a material consisting mainly of silicon dioxide (SiO\({}_{2}\)), sodium oxide (Na\({}_{2}\)O), calcium oxide (CaO) and phosphorus pentoxide (P\({}_{2}\)O\({}_{5}\)) [76]. One of the characteristic features of bioglass is its ability to create a layer similar to hydroxyapatite in contact with living tissue and the unique ability to bond to both hard tissues such as bone and soft tissues [77]. That versatility gives it an advantage over synthetic hydroxyapatite and make bioglass an attractive material for biomedical applications such as dental fillings, bone implants and tissue regeneration materials [78]. Bioglass has the ability to release various ions such as sodium, phosphates, calcium and silicon into the environment. The release of silicon ions plays a particularly important role. Once released, silicon ions react to form silanols, which spontaneously polymerize to form a layer of silica gel. This layer acts as a seed for the formation of new bone tissue. Additionally, when bioglass is exposed to an aqueous environment, a layer of hydroxyapatite forms on its surface [79]. This phenomenon makes bioglass even more bioactive, which means it promotes the regeneration and integration of bone tissues [80]. Bioglass allows the formation of hydroxyapatite layers on its surface, which provide a physical connection with the bone. The process of dissolving bioglass causes the release of silica, the activation of genes that control osteogenesis, i.e., the process of forming new bone tissue, and the production of growth factors; bioglass thus stimulates osteoblasts to produce new bone through various mechanisms [81]. Equally important is that the osteoblasts can interact with collagen, which is the main component of bone tissue. This allows for a more comprehensive bonding of bioglass with bone tissue, which is very similar in structure to natural tissue [82]. Bioglass not only stimulates the regeneration of bone tissue, but also accelerates the bone healing process. Some scientists report that bioglass can also be used to stimulate the healing of soft tissue wounds and the regeneration of peripheral nerves. It is used to remineralize early cautious lesions and to treat the excessive sensitivity of dentin, so it can help maintain oral health [83; 84; 85; 86; 87]. Additionally, products based on bioactive glass have the ability to stimulate angiogenesis, i.e., the process of creating new blood vessels [88; 89; 90; 91]. This property can be beneficial in therapy where increased blood flow to damaged tissue is needed to speed up the healing process. These applications demonstrate the versatility and potential of bioglass as a medical material. Direct pulp capping is an important procedure to preserve the vitality of the tooth pulp. The pulp covering preparation must be biocompatible and have the ability to induce the formation of a dentine bridge protecting the pulp [92]. In this treatment, bioactive glass works better than most traditional dental materials. At the same time, the material used for this purpose should ensure a tight closure of the root canals to prevent re-infection of the pulp, should not cause negative immunological reactions, and should have antibacterial properties and be easy to use, which will facilitate the root canal treatment process and ensure a precise application [93; 94]. The ideal material should also support the process of creating a dentin bridge, which protects the pulp against bacteria and other external factors, while supporting the process of the regeneration of tooth tissues. In experimental studies, the formation of dentin-like tissue was observed after bioglass was placed on the pulp stumps of mouse teeth. In subsequent studies carried out on the first molars of rats, after mechanical exposure of the pulp, bioglass material was used to directly cover the pulp.