Psidium guajava, Phalaenopsis sp., Syzygium aromaticum and Cinnamomum verum as natural inhibitors of growth of Streptococcus mutans

Currently, an increase on research on plant extracts seeking therapeutic action in the control of diseases of the oral cavity are observed, especially dental caries. Several plant extracts are already incorporated into toothpastes and mouthwashes. The objective of this study was to evaluate in vitro the antibacterial action of Psidium guajava (guava), Phalaenopsis sp. (orchid), Syzygium aromaticum (clove) and Cinnamomum verum (Ceylon cinnamon) extracts. The tests were carried out with the oral cavity bacterium Streptococcus mutans. The antibacterial activity of plant extracts was evaluated by the disk diffusion method in agar and by minimal inhibitory concentration (MIC). The tests showed the effectiveness of the extracts through inhibition zones of bacterial growth (from 5 to 20 mm in diameter) and MIC of 100 mg. mL-1 Phalaenopsis sp. extract and 50 mg. mL-1 P. guajava extract. Complementary studies will be needed to evaluate other pharmacological actions in order to use these plant extracts in different dental specialties and mainly in the treatment and prophylaxis of dental caries.