## 7 Activity of Ceragenins in the Presence of Saliva and Dental Plaque  
To ensure the clinical applicability of ceragenins for the prevention and therapy of oral cavity disorders, it is pivotal to ensure that their killing activities are retained in the presence of fluids in oral environments, including saliva or dental plaque. Saliva, as is widely acknowledged, is an essential element of the oral environment. It not only ensures proper digestion, moisturizes the mouth, neutralizes toxic acids, and promotes the remineralization of teeth, but also maintains oral health through the presence of a variety of AMPs [152]. It is well recognized that although pathogens generate an extracellular matrix by utilizing endogenous constituents in saliva during the biofilm development process [153], the antimicrobial effects of AMPs restrict the excessive growth of microbial populations. Simultaneously, components of saliva such as mucin or proteases limit the effectiveness of some endogenous antimicrobials, such as human cathelicidin LL-37 [154] or exogenous disinfectants (e.g., chlorhexidine [155; 156]). Compelling evidence demonstrates that ceragenins, due to their non-peptide chemical structure, are resistant to proteases, which are present in the oral cavity, as well as retain their antimicrobial activity in the presence of human saliva. To date, a few studies demonstrated that ceragenins, both in free form and attached to the surface of metallic nanoparticles, display potent bactericidal and fungicidal activity in the presence of human saliva. [PERSON] et al. showed that, in contrast to human cathelicidin LL-37, which is partially inactivated by salivary mucins, ceragenin CSA-13 displays potent antimicrobial effects against _P. aeruginosa_ and _E.coli_ both in the presence of purified mucins or whole saliva, suggesting its possible application in the treatment of oral infection [154]. This effect was confirmed in two other experiments by [PERSON] et al. ; in one of the studies, CSA-13 demonstrated its activity against _P. aeruginosa_[157], while in the other one--against _S. salivarius_, _S. mutans_, _E. faecalis_, and _H. pylori_[143]. Notably, the maintenance of antimicrobial activity of ceragenins in the presence of saliva was also confirmed with _Candidia_ fungi. As demonstrated by [PERSON] et al. [137] as well as [PERSON] et al. [158], ceragenins CSA-13 and CSA-44 limit the viability and biofilm formation by yeast (or yeast in mixture culture with _E. faecalis_) upon the addition of saliva (50%). Likewise, the potent antimicrobial activity of ceragenins was also maintained in the presence of dental plaque, as a tooth-borne complex biofilm composed of a broad and varied microbial community (mostly bacteria, but also fungi). It accumulates on the hard tissues of teeth in the oral cavity mainly due to improper oral hygiene and diet. Notably, the imbalance between the tooth biofilm and host response leads to the most common oral diseases such as dental caries and periodontal disease [159], and for this reason, the elimination of dental plaque results in beneficial local and systemic effects. Although a limited number of studies have been performed using dental plaque, research performed by both [PERSON] et al. [143] and [PERSON] et al. [137] confirm that even in the presence of accumulated dental plaque, therapeutic activity persists. Considering the example of _Candidia_ yeast, it might be stated that although the concentrations of ceragenins required to limit the outgrowth of pathogens in dental plaque are higher than those measured in PBS or even in the presence of saliva, MIC values are still within non-toxic and relatively low levels, i.e., ranging from 8 to 16 \(\upmu\)g/mL. These results strongly suggest that an oral formulation containing ceragenin would be highly successful in eliminating harmful microorganisms from the mouth. Furthermore, this formulation would not be influenced by different body fluids, which would enhance its practicality in a clinical setting.