Evaluation of the Anticaries Efficacy of Various Dentifrice Formulations Using an In-situ Model

Twelve healthy adult participants will be recruited on a purely voluntary basis and will be free to exit the study at any time. Each participant will wear an upper custom-made removable denture-like appliance with pre- sterilized human enamel and dentine slabs containing artificially-created early decay attached. To allow dental plaque to form on the slabs participants will wear the appliances 24 hours a day except whenever eating or drinking and cleaning their teeth and appliance and participating in sporting activities. The dosage form of the treatment products is a dentifrice slurry. Each slurry of dentifrice will be prepared by diluting 1 g of the product in 4 mL of distilled de-ionized water in a 15mL tube. There will be six treatment periods each preceded by a one-week washout period during which participants will rest from the study. The investigational toothpaste products are: Experimental 1: MFP/CaCO3 Anticavity Toothpaste (1.16% ppm MFP, 1500 ppm F-); Experimental 2: SnF2/Silica Anticavity Toothpaste (0.454% stannous fluoride (SnF2), 1100 ppm F-). Participants will be randomly allocated to one of the six products consisting of 4 controls (see below) and 2 experimental treatments at the first treatment period. At each treatment period, participants will receive their assigned treatment product (in a slurry) and wear their palatal appliance all day for 14 consecutive days. Four times a day at 9:30 am, 11:00 am, 1:30 pm and 3:30 pm, participants will firstly rinse with 5 mL of a 10% sucrose solution (supplied) for 60 seconds and expectorate. Forty minutes after each sucrose rinse, participants will shake their product slurry and immediately rinse with all 5 mL of their allocated slurry for 60 seconds (i.e. four times a day at 10:10 am, 11:40 am, 2:10 pm and 4:10 pm). Participant will be required to record sugar solution rinse time, slurry rinse time and appliance wearing time each day on the diary provided. The duration of the intervention will be 15 weeks consisting of 5 x 14-day treatment phases with a 7-day wash-out/rest period between each treatment phase. Participants will clean their appliance twice a day during treatment periods, avoiding the slabs, with fluoride-free paste (supplied) and rinse their appliances, avoiding the slabs, with distilled filtered (DF) water (supplied). Participants will brush their teeth twice a day with fluoride toothpaste and toothbrush (supplied). They will be instructed not to use other mouthwashes or consume antibacterial lozenges or chewing gum during the study but will otherwise continue normal oral hygiene and dietary habits. At the start of each weekday, participants will be given enough solution and slurry to rinse with that day and, on Fridays, will be given enough solution and slurry to use over the following weekend. They will store their solutions and slurries in a refrigerator over the weekend and allow them to warm to room temperature before rinsing. The solutions and slurries will be prepared by the research team using DF water. There will be at least a week’s rest between each treatment period with a different slurry allocated for each treatment period. The order of slurries for each participant will be unknown to the participants or researchers. Participant will be paid $500 per 14-day treatment period and $3,000 for the 6 treatment study for their time and commitment.