# Antibacterial Ceramics for Dental Applications
## 3 Results and Discussion
### Antibacterial Properties of Silver and Silver Ions
The investigation of the release kinetics of Ag\({}^{+}\), V4\({}^{+}\), and V5\({}^{+}\) and their influence on peri-implantitis in recent implants needs to be studied. Furthermore, the leucite phase must be stabilized because the microcline phase has a significantly higher solubility than the leucite phase. [PERSON] et al. [73] used IPS InLine and Noritake Cerabien ZR Line for their study to investigate the effect of \(\beta\)-AgVO\({}_{3}\) on the bacteria _S. mutans_, _S. sobrinus_, _P. aeruginosa_, and _Aggregatibacter actinomycetemcomitants_ (_A.a._). The concentrations of nano-\(\beta\)-AgVO\({}_{3}\) were 0.5%, 1%, 2.5%, and 5%. Brain Heart Infusion Agar was used for _S. mutans_ and _S. sobrinus_, cetrimide agar for _P. aeruginosa_, and blood agar for the preparation of _A.a._  
As shown in Figure 4A, nano-\(\beta\)-AgVO\({}_{3}\) in IPS InLine at a concentration of 5% had high antibacterial activity against _S. mutans_ and _S. sobrinus_ bacteria, but it was not effective against other bacteria [73]. Nano-\(\beta\)-AgVO\({}_{3}\) at a concentration of 5% was found to have antibacterial activity against _S. mutant_ bacteria in Noritake Cerabian ZR porcelain (Figure 4B) [73]. From these results, it can be concluded that the chemical composition of glass or glass ceramics can also play a significant role in the antibacterial effectiveness of the antibacterial additive used for functionalization. In addition, the antibacterial active ingredients can show pronounced bacterial dependence with regard to their antibacterial effect in ceramics. Further studies are needed to explain the cytotoxicity of these glasses. [PERSON] et al. used Vita VM9 as a leucite glass-ceramic (LGC) and silver nanoflakes (AgNF: thickness: \(\sim\)50 nm, width: \(\sim\)2 \(\upmu\)m) to prepare LGC-AgNF and AgNO\({}_{3}\)[74]. The concentrations of AgNF and AgNO\({}_{3}\) were 2, 5, 10, and 15 wt.%. The addition of Ag to LGC was found to affect the microhardness of LGC-Ag materials, resulting in a decrease from 6.5 GPa for pure LGC to almost 4.6 GPa for LGC + 15 wt.% AgNF and 4.5 GPa for LGC + 15 wt.% AgNO\({}_{3}\). When using LGC + Ag in layered dental crowns, the reduction in hardness has a positive effect on preventing wear of the opposing tooth. The addition of Ag to the ceramic as AgNO\({}_{3}\) and AgNPs imparts strong antibacterial properties to LGC and prevents the growth of Gram-positive (_S. aureus_) and Gram-negative (_E. coli_) bacteria on its surface (Figure 5) [74]. Figure 4: (**A**) CFU median for IPS InLine porcelain, (**B**) CFU median for Noritake Cerabien ZR porcelain. Data are from [PERSON] et al. [73]. Reprinted with permission from Elsevier. Samples with AgNO\({}_{3}\) showed slightly higher antibacterial activity compared to those with added AgNF. The authors explain this difference by the amount of silver ions released, which is higher for samples with added AgNO\({}_{3}\). Poor results were obtained for samples with 2 and 5 wt.% additives. The best antibacterial results were achieved with a concentration of 15 wt.% [74]. This means that the concentration of antibacterial ions plays a crucial role in the antibacterial effect of the bioglass. The results of this study provide a promising method for developing durable prostheses for dental restoration and body implants with antibacterial activity against Gram-positive as well as Gram-negative bacteria. The low release of Ag+ ions between 1 and 2 \(\mu\)g/cm\({}^{2}\) in 10 and 15 wt.% LGC + AgNO\({}_{3}\) samples and between 3.5 and 4 \(\mu\)g/cm\({}^{2}\) in LGC + AgNF is an important result regarding the cytotoxicity of Ag\({}^{+}\) ions. It meets the ISO 6872:2024 requirements for dental ceramics. Both doped LGC glasses also show low cytotoxicity on L929 and AW8507 cell lines [74]. The cellular response to glass-ceramics depends on the ionic dissolution of the residual glass phase of LGC.