# Propolis as Natural Product in the Oral Cavity Bacterial Infections Treatment: A Systematic Review
## 4 Results
### Antibacterial Activity of Propolis in Oral Cavity Bacterial Infections
#### 4.2.1 In Vitro Studies
Moreover, the adhesion study showed that 30 minutes and 2 hours of treatment with propolis significantly reduces the adherence of _S. gordonii_[36]. The effect of red propolisis hydro-alcoholic extract on _S. mutans_ biofilm formation was evaluated by [PERSON] et al. [85]. The obtained MBC value (1171.87 \(\mathrm{\SIUnitSymbolMicro}\)/mL) was about four times higher than the MIC value (292.97 \(\mathrm{\SIUnitSymbolMicro}\)/mL). Chlorhexidine showed bactericidal activity against _S. mutans_ in the concentration range from 0.15 to 300 \(\mathrm{\SIUnitSymbolMicro}\)/mL. Moreover, a bigger number of colony-forming units was detected in 3% propolisis extract in comparison to 0.12% chlorhexidine extract. The researchers did not record significant differences between the group that received inoculum (3% red propolisis extract, 0.85% NaCl, 0.05% NaF, and 0.12% chlorhexidine) and 0.12% chlorhexidine only as long as the forming of a mature biofilm on the surface of enamel blocks is concerned. Moreover, the insoluble extracellular polysaccharide (IEPS) that prevailed over soluble (SEPS) was significantly lower in the group that used red propolisis and chlorhexidine when compared with the negative control. The 3% propolisis extract effectively reduces _S. mutans_ colonization, impairing the production of soluble and insoluble extracellular polysaccharides, and it reduces dental enamel demineralization, which suggests that propolisis can be effective in anti-carious effect [85]. The effect of Korean propolis ethanol extract from six different regions against _S. mutans_ was analyzed by [PERSON] and [PERSON] [86]. All of the samples reduced microbial growth. The results showed that propolisis collected from the regions Uijengbu and Sangiu were the most effective against _S. mutans_. The authors analyzed two concentrations of propolisis extract (10 and 50 mg/mL). The obtained results of the inhibition zone were from 8.07 \(\pm\) 0.21 to 9.10 \(\pm\) 0.17 mm for propolisis (10 mg/mL) and from 9.33 \(\pm\) 0.38 to 10.88 \(\pm\) 0.39 mm for propolisis (50 mg/mL), dependently on the region of origin [86]. The antibacterial activity of propolisis mouthwash against _S. mutans_ was analyzed by [PERSON] et al. [87]. The determination of MIC was used to estimate the product's antibacterial properties and its effectiveness against _S. mutans in vitro_. The obtained MIC value for propolisis is presented in Table 3. The MIC value for chlorhexidine was 5 \(\mathrm{\SIUnitSymbolMicro}\)/mL. Ethanol as a solvent did not show any impact on the activity of propolisis extract. Moreover, the mixture of 1.3% propolisis with 0.06% chlorhexidine showed inhibitory activity against _S. mutans_ even with the use of a 64-fold dilution to the ultimate chlorhexidine concentration (9.5 \(\mathrm{\SIUnitSymbolMicro}\)/mL) [87]. The antibacterial activity of 6.5% Iranian propolisis ethanol extract against _S. mutans_ and _S. salivarius_ was analyzed by [PERSON] et al. [34]. They analyzed 57 _Streptococcus spp_. strains: _S. salivarius_ (n = 20), _S. mutans_ (n = 20), _S. oralis_ (n = 3), _S. mitis biovar 1_ (n = 4), _S. uberis_ (n = 5), _S. bovis_ (n = 3), _S. equinus_ (n = 1), and _S. parasanguinis_ (n = 1). The results indicate that Iranian propolisis inhibits variogenic bacteria and oral biofilm formation, and it is not cytotoxic for normal cells; thus, it can be a promising complementary medicine. In case of Iranian propolisis extract, the lowest MIC has _S. salivarius_. The obtained MIC values depend on the strain and were one to five times lower than the MBC values (Table 3). The sub-MIC concentrations significantly decreased the biofilm growth after 24 h treatment. The most effective were Iranian propolisis extract (6 \(\mathrm{\SIUnitSymbolMicro}\)/mL) and quercetin (20 \(\mathrm{\SIUnitSymbolMicro}\)/mL). The maximum biofilm reduction was 71 to 76% and 44 to 56%, respectively, for propolisisextract and quercetin, depending on the used method. The results indicated a much greater efficiency of the extract than the one of quercetin [34].