Methods: The study design was experimental in vitro (n = 16), EEP was assessed against S. mutans and S. aureus. The antibacterial activity of 10% and 30% EEP were compared to 0.12% and 0.05% Chlorhexidine, Listerine ® and distilled water. All groups were evaluated by the method of Kirby - Bauer. To analyze the data we used Student's t test.
Results: The 30% EEP was the most effective against S. aureus (11.77 ± 0.19mm). Hence, 30% and 10% EEP showed antibacterial activity at 24 and 48 hours (p = 0.007). Furthermore, 30 and 10% EEP at 24 and 48 hours showed similar antimicrobial activity against S. mutans (P > 0.05). The antibacterial effect of 30% EEP was higher than Listerine® against S. mutans p <0.001 and 30% EEP showed similar antibacterial effect as 0.05% chlorhexidine against S. aureus because no significant difference were found between both.
Conclusions: The 30% and 10% EEP presented antibacterial activity against S. aureus at 24and 48 hours; however 30% EPP showed the highest antibacterial among substances tested in this study, so it had greater antibacterial effect than Listerine ® and equal antibacterial effect of 0.05% chlorhexidine.