Dodonaea angustifolia a South African medicinal plant and oral pathogens

Objectives: Dental caries and periodontal diseases are the most common infections of oral cavity. Dental caries is the disease of the mineralized tissue such as tooth caused mainly by acid produced by Streptococcus mutans and Lactobacilli. Periodontal diseases are caused by many anaerobic gram negative bacteria. Medicinal plants are often used as antimicrobial agents in the prevention and control of both the diseases. An indigenous South African plant Dodonaea viscosa var. angustifolia is traditionally used for the treatment of oral thrush and the efficacy has been scientifically proven. No previous studies have been conducted to investigate the effect of this plant on the oral pathogens. Therefore, this study investigated the effect of D. viscosa var. angustifolia on the oral pathogens. Methods: D. viscosa var. angustifolia leaves were collected, dried, milled and extracted with acetone, methanol and ethanol. The minimal bactericidal concentration (MBC) of the extracts was determined by a microtitre serial dilution technique using S. mutans NCTC 10919, L. casei, P. gingivalis, Capnocytophaga sp., P. intermedia ATCC 25611, and 4 clinical isolates of each S. mutans and Lactobacilli. Each experiment was repeated three times. The effect of subinhibitory concentration of crude extract on acid production by S. mutans was also studied. Results: At concentrations 1.56 to 6.25 mg/ml D. viscosa var. angustifolia completely eliminated S. mutans whereas Lactobacilli were killed at 0.78 to 12.5 mg/ml. Capnocytophaga sp., P. gingivalis and P. intermedia were eliminated at 0.025, 0.0015 and 0.1 mg/ml respectively. At subinhibitory concentration crude extract inhibited acid production by S. mutans however it was related to the bacterial growth rather than effect of plant extract. Conclusion: These results therefore indicate that if it is used in a mouth rinse form, it has the potential to control and prevent dental caries as well as periodontal diseases.