Abstract: Aim The preventive effect and mechanism of propolis on caries were studied. Methods Before and after chewing propolis gum, SM bacteria, plague index and salivary pH were determined in 3~4 years old children. Results Propolis gum significantly reduced the plaque index, the numbers of SM, and raised the salivary pH. Conclusion Propolis gum can depress the growth of SM and development of plaque, increase the pH value in saliva, and is usefull in preventing caries.

Key words: propolis gel, caries prevention