METHODS: Bovine crowns were epoxy-mounted and ground/polished to expose the sound enamel layer. Surfaces were taped to leave only 5x5mm windows exposed. Artificial WSL were pre-formed on the enamel via 72-hour immersion in demineralization solution (pH=4.52, 37°C).
Samples were subjected to a 10-day pH cycling protocol that consisted of twice-daily 30-minute soaks in demineralization solution (pH=4.52, 37°C) followed by five-minute treatment periods (test product placed on WSL, 0.50mL DI water placed on product, undisturbed for 5 minutes, rinsed to remove visible product). Samples were soaked in artificial saliva (pH=7.00, 37°C) between the two demineralization/treatment periods.
Test groups/products were: A) WSL (72-hour lesion formation only), B) resorbable polymer strip (hydroxypropyl methylcellulose, HPMC), C) NovaMin®-containing polymer strip (HPMC+16% NovaMin®), D) SootheRx dentifrice (7.5% NovaMin®), and E) MI Paste (10% Recaldent™). Surface microhardness (Knoop, KHN) was measured on all samples using a load of 100 grams for 15 seconds.
RESULTS: Data were analyzed using one-way ANOVA and Student-Newman-Keuls statistical methods. All KHN data are mean±S.E.M. with n=15. Results were: A) 2.09±0.35, B) 2.41±0.17, C) 9.84±1.14, D) 7.71±0.56, and E) 2.32±0.16 with C = D > A = B = E (p<0.01). Enamel surfaces were drastically softened during WSL formation. Treatment with NovaMin®-containing resorbable strip significantly hardened artificial WSL compared to polymer-only resorbable strip.
CONCLUSIONS: The WSL formation used in this model was aggressive and needs to be adjusted in future studies. Within the limitations of this model, however, a novel NovaMin®-containing resorbable polymer strip shows potential for treatment and healing of enamel white spot lesions. Clinical confirmation of results and evaluation of product efficacy is planned.