Hydraulic conductance of dentin after treatment with fluoride toothpaste containing sodium trimetaphosphate microparticles or nanoparticles

Objectives To evaluate the hydraulic conductance of dentin after treatment with fluoride toothpastes containing sodium trimetaphosphate microparticles (TMPmicro) or nanoparticles (TMPnano). Materials and methods The dentinal tubules of bovine dentin blocks (4 x 4 x 1 mm) were unobstructed for determination of the maximum hydraulic conductance of the dentin. The dentin blocks were randomized into four groups (n= 15/group) of toothpastes (placebo, 1100 ppm F, and 1100 with 3% TMPmicro or 3% TMPnano) which were applied for 7 days (2x/day) using a brushing machine. The dentin surface (5/group) was analyzed by scanning electron microscopy. The hydraulic conductance post-treatment was measured in the other ten blocks. Thereafter, the same blocks were immersed in citric acid (pH 3.2) for 1 min, and the conductance was determined again. The data were submitted to 2-way ANOVA repeated measures, followed by the Student-Newman-Keuls test (p< 0.05). Results The percentage conductance reduction post-treatment for the groups were placebo = 1100 ppm F < 1100 TMPnano < 1100 TMPmicro (p <0.001). After acid attack, the percentage reduction was placebo < 1100 ppm F < 1100 TMPnano < 1100 TMPmicro (p< 0.001). The toothpastes containing TMP showed the highest obliteration of dentinal tubules. Conclusions The addition of TMPmicro to fluoride toothpaste produced a greater reduction in hydraulic conductance when compared with 1100 ppm F toothpaste.