This study will examine the mechanisms of action of probiotics and synbiotics for control of oral diseases, with a particular focus on exploring new strategies for caries prevention and treatment.

Subjects recruited in years 1, 2, and 4 will only be seen for one study visit and will follow the research visit protocol listed below:

Pre-Screening - If the subject chooses to be pre-screened for this study they will be asked to fill out a study registration form and an oral habits/medical history form. They will be asked to sign an Informed Consent. The subject will then have their teeth and gums examined. At this visit, the investigator will assess whether or not the subject is a good candidate for the study. During the phone interview each subject was asked not to brush or floss their teeth and not to eat or drink anything other than water for 8 hours prior to the pre-screening visit (Visit 0). If the subject was compliant with these requests, oral samples will be collected at this pre-screening visit and will now be considered Visit 1 (Baseline). If not, they will be asked to return to the clinic for another visit and asked not to brush or floss their teeth and not to eat or drink anything other than water 8 hours prior to that appointment. This visit will then be consider Visit 1 (Baseline).

Visit 1 (Baseline) - The subject will have their medical and dental history reviewed. They will have their teeth and gums examined. Saliva and plaque will be collected. This will be the end of the study for subjects recruited in years 1, 2, and 4.

Subjects will be grouped by the year they participate in the study. Subjects recruited in year 3 will follow the research visit protocol outlined below:

Pre-Screening - If the subject chooses to be pre-screened for this study they will be asked to fill out a study registration form and an oral habits/medical history form. They will be asked to sign an Informed Consent. The subject will then have their teeth and gums examined. At this visit, the investigator will assess whether or not the subject is a good candidate for the study. During the phone interview each subject was asked not to brush or floss their teeth and not to eat or drink anything other than water for 8 hours prior to the pre-screening visit (Visit 0). If the subject was compliant with these requests, oral samples will be collected at this pre-screening visit and will now be considered Visit 1 (Baseline). If not, they will be asked to return to the clinic for another visit and asked not to brush or floss their teeth and not to eat or drink anything other than water 8 hours prior to that appointment. This visit will then be considered Visit 1 (Baseline).

Visit 1 (Baseline) - The subject will have their medical and dental history reviewed. They will have their teeth and gums examined. Saliva and plaque will be collected. Each subject will be given a toothbrush and toothpaste and instructed to not use any other dental products. This will be considered the "washout" period.

Visit 2 - The subject will be asked to return the unused toothpaste. Their medical and dental history will be reviewed and they will have their teeth examined. Saliva and plaque will be collected at this visit. The subjects will then be randomly assigned (by chance, like the flip of a coin) to the group that will use a marketed fluoride-containing toothpaste or to the group that will use a marketed arginine containing toothpaste. The subject will also be instructed not to brush or floss their teeth or eat or drink anything other than water for 8 hours prior to the next appointment.

Visits 3, 4, and 5 - Subjects will not be allowed to brush or floss their teeth or eat or drink anything other than water 8 hours prior to these visits. Saliva and plaque will be collected. On the 5th visit subjects will be asked to return the unused toothpaste tube. At this time participation in this research study will end and they will be instructed to return to their regular oral hygiene regiments.

Inclusion Criteria:

• Twenty natural uncrowned teeth excluding third molars
• No contraindications to dental treatment
• Caries Free-(with no clinical evidence of past or present caries)
• Caries Active- (At least two active sites)

Exclusion Criteria:

• Less than 20 teeth
• Systemic disease that can cause xerostomia
• Taking medication known to cause xerostomia
• Have been treated with antibiotics within the past 3 months
• Advanced periodontal disease
• Removable or fixed dental appliances
• Bleeding disorders or taking anticoagulant medications
• Immune compromised individuals
• Uses tobacco products
• Participation in another clinical study one week prior to the start of the washout period or during the study period
• Use of any flavored products, such as mint flavored candies and chewing gum, one week prior to or during the study
• Unwilling or unable to provide informed consent and follow plaque/saliva collection instructions