Dental caries is a major cause of affliction in people living in the developing world. Oral hygiene is often maintained by the use of tree-based toothbrush sticks called Meswak. The aim of this study was to investigate the effect of Meswak along with probiotic bacteria on the growth of Streptococcus mutans, the organism most often associated with dental caries. The results indicated that Meswak has a marked inhibitory effect on the streptococci. Addition of Lactobacillus strains significantly reduced the viable counts of S. mutans. A prototype spray containing Meswak extract, lactobacilli, and mint was developed and shown to have potential as an anticaries mouthwash.