This is a phase III clinical trial that aims to evaluate the enamel remineralization efficacy of three dentifrices on artificial caries lesions using an in situ model. The study involves 30 healthy volunteers, aged 18 to 70, who will participate in a randomized, triple-blind, three-period crossover design. Researchers will compare a 750 ppm MFP dentifrice against a 1450 ppm MFP positive control and a fluoride-free negative control to measure variations in mineral gain. Participants will wear a removable intraoral appliance containing human enamel blocks for three 14-day experimental phases. A 7-day washout period using will be implemented before and between each treatment phase.

This Phase III, randomized, single-center, triple-blind, crossover clinical study will evaluate the remineralization efficacy of three dentifrices on artificially induced initial enamel caries lesions. The research will involve 30 healthy participants aged 18 to 70 years who meet strict inclusion criteria. The experimental design will utilize an in situ model where participants will wear custom-made removable mandibular intraoral appliances containing four human enamel blocks with pre-formed artificial caries lesions. These lesions will be created laboratory-side using an acidified gel demineralization system before the blocks are mounted into the appliances.

The study will follow a nine-week timeline, divided into three 14-day experimental phases separated by 7-day washout periods to eliminate carryover effects, totaling 8 visits. During the treatment phases, subjects will be randomly assigned to a sequence of three test products: a test dentifrice with 750 ppm MFP, a positive control with 1450 ppm MFP, and a fluoride-free negative control. Each participant will receive a soft-bristle toothbrush and the assigned toothpastes.

The primary outcome will be the change in integrated mineral loss measured by transverse microradiography (TMR). Baseline mineral loss will be established from a slice of each block before intraoral exposure and compared to post-treatment analysis of the adjacent tissue. Secondary outcomes will include changes in lesion depth and fluorescence loss parameters assessed via Quantitative Light-induced Fluorescence (QLF).

Statistical analysis will be performed using a linear mixed-effects ANCOVA model to confirm the hypothesis that the 750 ppm MFP dentifrice promotes significantly greater remineralization than the negative control, with effects lower than or comparable to the high-fluoride positive control.

Inclusion Criteria:

• Males and females, between 18-70 years of age (inclusive);
• Informed Consent Form signed and availability for the duration of the study;
• Good general health (absence of any condition that, in the opinion of the Principal Investigator, might constitute a risk to the subject while participating in the study. Examples include heart problems, valve/hip replacements, etc);
• Willingness to provide information related to their medical history;
• Minimum of 20 uncrowned permanent natural teeth (excluding third molars);
• Normal salivary flow;
• Willingness to wear an intra-oral appliance all day as instructed except when eating and drinking.

Exclusion Criteria:

• Oral pathology, chronic disease, or a history of allergy to testing products;
• Subject using anticonvulsants, antihistamines, antidepressants, sedatives, tranquilizers, anti-inflammatory medication or daily analgesics within one month prior to the start of the study or scheduled to start such intake during the course of the study;
• Subject participating in any other clinical study;
• Subject pregnant or breastfeeding;
• Subject allergic to oral care products, personal care consumer products, or their ingredients;
• Extended use of antibiotics or therapeutic mouthwash any time during the three months prior to entry into the study;
• A medical history reporting that the subject has a current systemic or autoimmune disease, such as diabetes, lupus, etc.;
• Ongoing use of medications known to affect the gingival tissues (i.e. calcium channel blockers, phenytoin, cyclosporine);
• Advanced periodontal disease (purulent exudate, tooth mobility, and/or extensive loss of periodontal attachment or alveolar bone). Pocket depth equal or greater than 4 mm;
• Five or more decayed, untreated dental sites (cavities);
• Current smokers and subjects with a history of alcohol or drug abuse;
• Dental work prevents wearing of the appliance or a reported need to wear a night guard.