Enamel Protection: Deposition and Retention of SnF₂ on Enamel Surfaces

Deposition of an acid resistant barrier onto enamel represents a superior means for delivering protection against acid challenges. Objectives: The purpose of study was to demonstrate ability of Crest Pro-Health Enamel Shield toothpaste to: 1) deposit a SnF₂ barrier layer onto pellicle coated enamel surfaces; 2) increase intensity of barrier layer over time; and 3) demonstrate ability of barrier to retain on enamel surface for hours after product use. Methods: Squares of enamel (5x5x1mm) were exposed to pooled saliva for 1 hr (pellicle formation). One set of specimens was treated with 1:3 slurry supernatant of toothpaste:water for 2 minutes or Water control, rinsed with ddi H₂O. A second set of samples was treated similarly, and placed into saliva for 6 hours. A third set was cycled through repeated treatments (total=7 cycles) and a fourth set of samples was taken through this series of 7 treatment cycles and placed into saliva (6 hours). Surface analysis of specimens was done using laser ablation ICP-MS, with a field of view being 790mm x 590mm. The intensity of all isotopes was corrected pixel by pixel using ¹³C as the internal standard. Results: Deposition of a barrier layer was demonstrated, beginning with initial treatment, with Sn (using isotope ¹²⁰Sn) measured on the enamel surface as reference marker. Deposition of barrier layer was greater after 7 cycles, and retention of this layer was highly significant (p=0.05, ANOVA – 6 hrs), confirming the protective barrier layer remains for many hours after product use. Conclusions: This study confirms Crest Pro-Health Enamel Shield toothpaste: 1) deposits a barrier layer onto enamel surface beginning with the first use of product; 2) this barrier is enhanced following multiple treatments; and 3) barrier layer is retained on the enamel surface for hours after product use to help protect enamel against acid attack.