In Situ Comparison of the Remineralization Potential of Optimized Fluoride Dentifrice With Control Fluoride Dentifrice

This will be a double blind, single center, 3-way crossover design study. Two to three days before the start of each treatment period the subjects will have their teeth cleaned to remove all accessible plaque and calculus and will be provided with a non-fluoride dentifrice to use until their next visit. At the beginning of each testing period, two gauze-covered 4 mm round partially demineralized bovine enamel specimens will be placed in the buccal surface of two posterior denture teeth (the specimen site may extend into the buccal flange area, if needed) of the same side of the partial denture. Once specimens are placed, subjects will wear their partial dentures twenty-four hours a day and use their assigned toothpaste twice daily, as instructed, until their next visit. Specimens will be removed after two weeks, and the subjects will undergo at least a four- to five-day washout period followed by another cleaning and two to three day lead in period. This process will be repeated until all subjects have used all three test products. Changes in the mineral content of the enamel specimens will be assessed using surface microhardness (SMH) and transverse microradiography (TMR). Enamel fluoride uptake (EFU) will be determined using the microdrill enamel biopsy technique. In addition, the net acid resistance (NAR) and the comparative acid resistance (CAR) of the demineralized enamel specimens will be determined.

Inclusion criteria

• provide voluntary, written informed consent;
• be between 18 and 85 years old;
• understand and be willing, able and likely to comply with all study procedures and restrictions;
• be wearing a removable mandibular partial denture with sufficient room to accommodate two 4 mm round specimens in the buccal surface of two posterior denture teeth on the same side;
• be willing and capable of wearing their removable partial denture 24 hours a day for three (3), two-week treatment periods;
• be willing to allow study personnel to drill specimen sites in two denture teeth in the posterior section of one side of their lower partial denture, which may extend into the buccal flange area below the teeth;
• 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; and
• 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 be pregnant, intending to become pregnant during the study period or breast feeding;
• currently have any medical condition that could be expected to interfere with the subject's safety during the study period;
• currently be taking antibiotics or have taken antibiotics in the two weeks prior to the beginning treatment 1;
• known or suspected intolerance or hypersensitivity to the study materials (or closely related compounds) or any of their stated ingredients;
• have participated in another clinical study or receipt of an investigational drug within 30 days of beginning treatment 1; or
• be taking fluoride supplements, required to use a fluoride mouthrinse or have received a professional fluoride treatment in the two weeks preceding specimen placement.