Enamel Fluoride Uptake from a New Children’s Dentifrice

Objectives: Dental fluorosis has become more prevalent in the recent past.  The major cause of this is the ingestion of fluoride by very young children while tooth brushing.  If a more efficient fluoride delivery system could provide more fluoride uptake into enamel from the same fluoride concentration in the products, a smaller amount of delivered product could result in comparable anticaries benefits with reduced fluorosis risks.  The study was designed to determine if a more efficient delivery system (soluble phosphates) could provide increased enamel fluoride uptake.  Methods: The procedure used was the one identified as #40 in the FDA monograph.  Sound bovine enamel specimens were prepared as outlined previously resulting in 3mm enamel disks mounted in acrylic rods.  Baseline enamel samples were removed by a 15 second etch in 1M HClO4.  The specimens were repolished.  An artificial lesion was formed on each using a 0.1M lactic acid / Carbopol solution.  Treatments were performed for 30 minutes in 1:3 dentifrice slurries of placebo, USP NaF Ref, Aquafresh for Kids (AFK), Colgate Kids (COK), Crest Kids (CRK) and test dentifrices PD-5C and PD-5CX.  Following rinsing, a second layer of enamel was removed as outlined above.  Samples of both pre and post enamel layers were buffered with TISAB and the fluoride content determined by comparing to a standard curve.  Results: Significant differences were observed with Pl (13±6) < AFK (663±10) < COK (964±34) = USP 1037±38) = CRK 1079±25) < PD-5C 1660±43) = PD-5CX (1690±54).  The results indicate that the test dentifrices promote significantly more fluoride uptake into lesioned enamel at the same dentifrices quantities.  Conclusion: Increased delivery system efficacy of the test dentifrice could translate into comparable enamel fluoride uptake (to conventional dentifrices) with reduced dentifrice quantity resulting in less risk of fluorosis from ingested dentifrice.