Fluoride-Free Toothpastes Containing Calcium Trimetaphosphate Remineralize Dentin Subsurface Lesions

Objectives: The study evaluated the ability of toothpastes containing different concentrations of synthesized calcium trimetaphosphate in the in vitro remineralization of caries lesions in dentin.
Methods: Bovine root dentin blocks (4×4×2 mm, n = 60) were prepared, and caries-like lesions were induced in two-thirds of the surface (each block served as its control). Blocks were then randomly and divided into 5 groups of toothpaste (n = 12): Placebo (no-F-CaTMP); 1100 ppm F; 0.25% CaTMP; 0.5% CaTMP; and 1% CaTMP. One-third of each specimen was treated for one minute, twice a day, with the respective toothpastes, and subjected to a pH-cycling regime for 7 days, followed by computed X-ray microtomography analysis. Differential mineral concentration profiles were constructed by subtracting the profile of the caries-like lesion area from the sound area; and that of the treated area from the caries-like lesion. The integrated area of the differential profiles (g_HAp/cm³ × µm) was calculated and expressed in percentage. The thickness of the surface layer (µm) and depth of the lesion (µm) were determined. The data were submitted to two-way ANOVA and Student-Newman-Keuls’ test (p<0.05).
Results: The in vitro model led to the formation of an artificial subsurface carious lesion with depth of 225.2 µm (±44.3). The placebo led to mineral loss (-4.8% ±9.9; p<0.001), while toothpastes with 1100 ppm F (17.8% ±7.6) and 0.25% CaTMP (14.9% ±6.7) promoted a similar mineral gain (p=0.400). The toothpaste containing 1% CaTMP led to the greatest mineral gain (35.0% ±5.9) followed by 0.5% CaTMP (25.3% ±10.3) (p<0.001). Also, the toothpaste with 1100 ppm F produced the greatest surface layer thickness (31.0 µm ±7.6) and the 1% CaTMP dentifrice the smallest lesion depth (122.3 µm ±20.9) (p<0.001).
Conclusions: Toothpaste containing 1% CaTMP promoted superior dentin remineralization compared to the 1100 ppm F toothpaste, especially at deeper regions of the lesion.