# 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
sanguins_, a significant decrease was observed after treatment with Brazilian propolisis (50 ug/mL), while the complete growth inhibition was in the concentration of 200 ug/mL. Unfortunately, Brazilian propolisis was less effective against _A. actinomycetemcomitants_, since in the concentration of 2000 ug/mL, the growth was still observed. In case of _P. gingivalis_, the propolisis effect depended on the species (W83 and ATCC33277). The obtained results showed that in case of W83, a substantial reduction in growth was recorded for the propolisis concentration of 50 ug/mL, and the total growth inhibition was observed in the propolisis concentration of 200 ug/mL, while for ATCC33277, it was 100 and 400 ug/mL, respectively [80]. The antimicrobial effect of 10% (_w/v_) ethanol extract of Indian propolisis against _S. pyogenes_ was analyzed by [PERSON] et al. [81]. The inhibition zone of the extract for _S. pyogenes_ was 16 \(\pm\) 2 mm [81]. The antimicrobial activity seven different types of South Brazilian organic propolisis samples (OP1-OP7) against _S. mutans_, _S. oralis_, and _S. sorbinus_ was analyzed by [PERSON] et al. [82]. Interestingly, OP2 showed the lowest MIC value for _S. sorbinus_, OP1 and OP3 showed the lowest MIC value for _S. oralis_, and OP1-OP4 showed the lowest MIC value for _S. mutans_. In case of MBC, the lowest values presented OP1 and OP7 for _S. mutans_, OP1, OP2, and OP7 for _S. oralis_. These values are shown in Table 3. It is worth observing that all variants of propolisis inhibited _S. mutans_ biofilm formation at the concentrations of 400 and 800 ug/mL for approximately 90%. OP5 significantly inhibited biofilm formation at 400 ug/mL, while OP5 and OP6 in the concentration of 200 ug/mL were not effective in biofilm inhibition. OP2 and OP3 showed the highest effectiveness for biofilm inhibition at about 50 and 60%, respectively, in the concentration of 100 ug/mL [82]. The antibacterial activity of NBF gel containing vitamin C, E, and propolisis against _S. mutans_ was examined by [PERSON] et al. [83]. The study showed a concentration-dependent rise in the inhibition zone from 2.3 \(\pm\) 1.7 to 16.5 \(\pm\) 3.1 mm and from 4.3 \(\pm\) 3.6 to 13.8 \(\pm\) 2.8 mm, respectively, for alcoholic and aqueous extracts. The authors used alcoholic and aqueous extracts in the concentration range from 10 to 50%. In the lowest concentration (10%), the inhibition zone was not detected, while in the concentration of 20%, the inhibition zone occurred only in the alcoholic extract. The study also demonstrated that the inhibition zone decreased with increasing the duration of use of the appliance. Moreover, the authors observed that the mean of the colony count increased with the increasing time of incubation [83]. The antimicrobial activity of Czech, German, and Irish ethanol propolisis extract and aqueous German propolisis extract against _S. oralis_ and _S. pyogenes_ were analyzed by [PERSON] et al. [84]. Interestingly, the Irish and Czech propolisis was most efficient against S. oralis_ and _S. pyogenes_, while German aqueous propolis extract was less efficient. The authors calculated MIC and MBC values (Table 3). Moreover, the authors analyzed also the impact of Irish ethanol propolisils extract and vancomycin in a checkerboard assay. In the checkerboard assay, synergistic interaction against _S. pyogenes_ of ethanol or aqueous extracts of propolis with antibiotics was shown [84]. The antibacterial action of 10% propolis ethanol tincture against _S. gordonii_, _S. sanguinis_, _S. mutans_, _S. sobrinus_, _L. acidophilus_, and _A. naslundii_ was evaluated by [PERSON] et al. [36]. The erosion study in which one hundred and twenty human enamel specimens were covered with a salivary pellicle and modified with propolis, then eroded with 1% citric acid (pH 3.6 for 2 min), showed that propolisis did not cause enamel erosion. In the microbiological assay, MIC values were calculated, and they are presented in Table 3. No antimicrobial activity was detected in case of ethanol (10%).