Evaluation of the Fluoride Dose Response Using In Situ Caries Model

Inclusion Criteria: * Be between 18 and 85 years of age; * Provide written informed consent prior to participation and be given a signed copy of the informed consent form; * Be in general good health as determined by the Investigator based on a review of the health history/update for participation in the trial; * Be wearing a removable mandibular partial denture with sufficient room in one posterior buccal flange area to accommodate two 4 mm round enamel specimens and room on the same side to accommodate two 4 mm round specimens in the buccal surface of two posterior denture teeth; * Be willing and capable of wearing their removable partial denture 24 hours a day for four (4), three-week treatment periods; * Be willing to allow study personnel to drill specimen sites (as described in #iv) in their mandibular partial denture; * Be in good medical and dental health with no active caries or periodontal disease (NOTE: subjects presenting at screening with caries may continue in the study if their carious lesions are restored prior to beginning treatment 1); * Have a salivary flow rate in the range of normal values (unstimulated whole saliva flow rate ≥ 0.2 mL/min; gum base stimulated whole saliva flow rate ≥ 0.8 mL/min). Exclusion Criteria: * Currently being pregnant, intending to become pregnant during the study period, or breast feeding; * Currently having any medical condition that could be expected to interfere with the subject's safety during the study period; * Currently taking antibiotics or having taken antibiotics in the two weeks prior to beginning treatment 1; * Having participated in another clinical study or receipt of an investigational drug within 30 days of beginning treatment 1; or * Taking fluoride supplements, required to use a fluoride mouth rinse, or have received a professional fluoride treatment in the two weeks preceding specimen placement; * Currently taking or have ever taken bisphosphonate drugs (e.g., Fosamax, Actonel and Boniva) for the treatment of osteoporosis.