The purpose of this study is to evaluate the efficacy of probiotic products on caries-associated salivary bacterial counts (Streptococcus mutans and Lactobacillus) and its effect on dental plaque accumulation in a group of preschool children in Saudi Arabia.

Among the dental conditions that are most common among the children is dental caries. This condition can afflict an individual in the course of their entire life. However, it is possible to develop prevention mechanisms especially during childhood (1). Dental caries can be defined as the damage of a specific susceptible part of the enamel through acids that are produced by bacteria as they ferment carbohydrates that have been trapped within the teeth (2). A number of endogenous bacteria are known of producing acidic by-products, which ends up destroying the tooth. Some of the notorious bacteria are Streptococci mutans, Lactobacillus spp. and Streptococcus sobrinus. Release of acids through fermentation cause a fall in pH causing decalcifying of the structure of enamel, thereby causing irreversible damage in form of caries (3, 4). Recent research studies have indicated that the use of probiotics provides a future prevention solution against caries. The use of probiotic therapy is based on the fact that the oral cavity has a specific ecosystem of bacteria comprising of normal flora and pathogenic bacteria, which live together. Probiotic therapy seeks to balance this oral ecosystem so as to ensure that harmful bacteria are eliminated. An imbalance in oral ecosystem can cause dental caries, for example, streptococcus mutans, which form part of the normal oral flora can result to decalcification of the enamel if their numbers rise beyond normal. Probiotic is a derivative of Greek work, which means "for life," it was first used in 1965 by Lilly and Stillwell and was found to be a contrast of the antibiotic (5). WHO/FAO (2002) defines probiotics as living organisms that have health benefits to the host when administered in the desirable amounts. In a number of studies on probiotics, the focus has been on reducing the number of mutans streptococci. The most widely used probiotic strains are Lactobacillus and Bifidobacterium. Irrespective of the strain or product used, various studies point to reduced number of mutans streptococci in saliva, an effect that is widely varied with the study groups being small (6,7,8,9) and conducted over a short period (6,7,8,9,10). Based on these findings, the efficacy of probiotic chewable tablets in prevention of caries require further analysis.

Inclusion Criteria:

• Healthy children having no history of any systemic conation, having full set of primary dentition, having high counts of salivary mutants streptococci ( ≥ 105 CFU ), dft score ≥ 3, with no history of recent antibiotics administration (At least one month prior to the intervention) .

Exclusion Criteria:

• Disapproved consent, medically compromised children, children using topical fluoride within the 4 weeks prior to baseline except the fluoride in the toothpaste, and children using xylitol chewing gums.