Inclusion Criteria:  The parent/guardian/caregiver understands and consents to procedures described in parental permission and consent form. Child is male or female, aged 2 months to 6 months at the screening visit. Child has no serious illnesses requiring frequent inpatient hospitalization, as reported by the parent/caregiver/guardian at the screening visit. Child does not use fluoride supplements, as reported by the parent/caregiver/guardian at the screening visit. Child either drinks water (either plain water, or water mixed with something) or is likely to drink water by their first birthday, as reported by the parent/ caregiver/guardian at the screening visit. The child's primary dwelling at the screening visit has tap water contains ≤0.60 mg/L F, based on measurement of a tap water sample made at Dr. Godebo's laboratory. (For children who live at more than dwelling, the primary dwelling is defined as the one at which they usually sleep at least four nights per week.)  Exclusion Criteria:  Parent/guardian/caregiver states at the screening visit the child will initiate fluoride supplementation before the child's 4th birthday The parent/caregiver/guardian anticipates that the child will move to an address more than 30 miles from Kinston, NC before the child's 4th birthday. The investigators determine that a child living at the same dwelling has already been enrolled in the study. (This means that if two or more children fulfilling the inclusion criteria live at the dwelling, the parent will be asked to select one such child to be the study participant.) Anything that, in the opinion of the principal investigator, would place the participant at increased risk or preclude the participant's full compliance with or completion of the study.