I was researching as you were posting 4 times.
Small white round pill imprinted ETH 433 is EtheDent Sodium Fluoride Chewable Tablet (grape flavor) containing Fluoride Ion .50 mg.
Per the prescribing info, EtheDent Chewable Tablets are indicated for:
Once daily self-applied systemic use as a dental caries preventive in pediatric patients....EtheDent Tablets were developed to provide systemic fluoride for use as a supplement in pediatric patients from 6 months to age 3 years and older living in areas where the drinking water fluoride content does not exceed 0.6 ppm F-.