The objective of this in situ clinical study is to determine whether a toothpaste containing hydroxyapatite microclusters is as effective as a fluoridated kid's toothpaste in promoting remineralization of early caries lesions and inhibiting the development of caries lesions.

The investigators hypothesize that (1) both the hydroxyapatite and the fluoridated toothpaste promote caries remineralization that is significantly greater than zero, and (2) the two toothpaste formulations are equally effective with respect to post-treatment remineralization and inhibition of demineralization.

• Non-inferiority will be considered established if there is no statistically significant difference in percentage of remineralization between the hydroxyapatite-containing toothpaste and the fluoridated kid's toothpaste for any one measurement method.
• Superiority/inferiority will be considered established if at least 20% statistically significant difference is observed between the hydroxyapatite-containing toothpaste and the fluoridated kid's toothpaste for any one measurement method

Inclusion Criteria:

1. Male and/or female subjects 18 to 50 years inclusive
2. Minimum of 20 natural uncrowned teeth (excluding third molars) must be present
3. Willing to wear retainer 24 hours per day
4. No active, unrestored cavities
5. Have normal salivary flow rate (stimulated and unstimulated flow of ≥0.7 ml/min and ≥0.2 ml/min respectively) ascertained from a preliminary sialometry test
6. Available throughout entire study
7. Willing to use only assigned products for oral hygiene throughout the duration of the study
8. Must give written informed consent
9. Must be in good general health
10. No known history of allergy to personal care/consumer products or their ingredients, relevant to any ingredient in the test products as determined by the dental/medical professional monitoring the study

Exclusion Criteria:

1. Advanced periodontal disease
2. Medical condition which requires premedication prior to dental visits/procedures
3. Not enough teeth to secure the oral retainer
4. Diseases of the soft or hard oral tissues
5. Wearing of an orthodontic retainer(s)
6. Impaired salivary function
7. Current use of drugs that can affect salivary flow
8. Use of antibiotics one (1) month prior to or during this study
9. Positive urine test for pregnancy or self-reported breastfeeding. A urine pregnancy test will be performed on female subjects of child-bearing potential.
10. Participation in another clinical study one (1) week prior to the start of the washout period or during this study period
11. Use of tobacco products
12. Allergic history to common toothpaste ingredients
13. Allergic history to amino acids
14. Immune compromised individuals (HIV, AIDS, immuno-suppressive drug therapy) as determined by review of medical history