## 4 Discussion
This acidity is low enough to inhibit the growth of most microorganisms of the ones tested here [26; 27; 38; 70; 71; 72]. Although statistically significant differences were observed among the pH values off the different honey types, it was not possible to conclude any positive (or negative) statistically significant effect of these differences on the antimicrobial action either in well diffusion experiments or in MIC estimates. Furthermore, hydrogen peroxide produced by the glucose oxidase is one of the most important antibacterial components of honey, although some authors believe the non-peroxide activity is equally or even more important. Glucose oxidase is incorporated into honey during the foraging of the bees and oxidizes glucose to glucolactone [40; 41]. This oxidation results in the production of gluconic acid and in the reduction of molecular oxygen to hydrogen peroxide [73]. The latter substance however can also be produced by polyphenol autoxidation [74]. In the present study, the hydrogen peroxide's antibacterial activity was assessed by the addition of catalase (Figures 2 and 3). Catalase can be found naturally in honey and is of pollen origin [75]. The results show (Figures 2 and 3) that for all types of honey and for all pathogens, MIC increases after the addition of catalase. This increase in MIC implies an increased susceptibility of the dental pathogens due to the hydrogen peroxide content of honey. However, hydrogen peroxide, although a significant bactericidal ingredient, is not the sole or the most potent cause of the antibacterial activity of unprocessed honey. In our study, citrus honey contains 3.35 and 4.67 more hydrogen peroxide than oregano honey and _Satureja_ spp. honey, respectively (Table 8), yet 5 out of 7 pathogens and reference strains showed a smaller inhibition zone in comparison to the other honey (Table 9). On the other hand, the bacterial susceptibility can perhaps be attributed to the strain or even species-specific factors. Furthermore, several phytochemical factors with antibacterial activity have been identified in honey [76; 77]. All these substances have been described as non-peroxide antibacterial factors [78]. In most of the MIC experiments with artificial saliva as the diluent, no statistically significant differences were observed. A significant increase of MIC was observed in citrus and oregano and sage honeys against _F. nucleatum_ and in all honeys against _S. aureus_ A, _S. aureus_ B, and _S. aureus_ ATCC 12600. Artificial saliva alters the viscosity of honey as well as its colloid structure. These physicochemical changes reduce the susceptibility of certain bacteria and thus the increase in MIC values in our study. However, this effect must have a species-specific element since only the _S. aureus_ strains were found most susceptible to all honeys. In addition to the previous information, volatiles, organic acids, lysozyme, beeswax, nectar, pollen and propolis are important chemical factors that provide antibacterial properties to honey [78; 79; 80]. Propolis, a natural resinous mixture produced by honeybees, which exhibits anti-microbial, anti-inflammatory, cytostatic, and cariostatic properties. has been used already for cosmetic cremes for the skin and oral hygiene sources such as denitfrices. Propolis, as it is known, influences the cytoplasmic membrane and has an inhibitory effect on the bacterial motility and enzymatic activity. It has bacteriostatic activity at low concentrations and can be bactericidal at high concentrations [81]. It breaks down bacterial cell wall, cytoplasm and prevents bacterial cell division. There are reports on the effectiveness of propolis-containing denitfrices for the control of caries in young adults [82]. In addition, in the study of [PERSON] et al. (2010) [83], it was also established that propolis and especially the ethanol extract of propolisols (EEP) exerted bacteriostatic and bactericidal effects against _S. mutans_, respectively, at concentrations of 1.875 and 3.75 \(\upmu\)g/mL or more.