Is the dentifrice containing calcium silicate, sodium phosphate, and fluoride able to protect enamel against chemical mechanical wear? An in situ/ex vivo study.

OBJECTIVES: The aim of this study was to investigate the effect of a dentifrice that contains calcium silicate, sodium phosphate, and fluoride on erosive-abrasive enamel wear. MATERIAL AND METHODS: This randomized, single-blind in situ/ex vivo study was conducted with four crossover phases of 5 days (one group tested per phase). Bovine enamel blocks (n = 256) were allocated to 16 volunteers and 8 groups. The groups under study were test dentifrice, with calcium silicate, sodium phosphate, and 1450 ppm sodium monofluorophosphate; tin dentifrice, with 3500 ppm stannous chloride, 700 ppm amine fluoride, and 700 ppm sodium fluoride; conventional dentifrice, with 1450 ppm sodium monofluorophosphate; and control (deionized water). Half of the enamel blocks were subjected to erosion and the other half to erosion plus abrasion. The daily extraoral protocol consisted in four citric acid exposures (2 min) and two applications of dentifrice slurry on all blocks for 30 s; after, half of the blocks were brushed for 15 s. The response variable was enamel loss. Data were analyzed by two-way ANOVA and Fisher's test (p < 0.05). RESULTS: For erosion, the test dentifrice promoted less enamel loss than water (4.7 +/- 3.1 and 5.8 +/- 2.5 mum, respectively, p < 0.05), and did not differ from tin (4.8 +/- 2.5 mum) and conventional (4.8 +/- 1.4 mum) dentifrices (p > 0.05). However, the test dentifrice (7.7 +/- 3.8 mum) promoted higher wear after erosive plus abrasive procedures than tin (5.4 +/- 1.5 mum) and conventional (6.2 +/- 1.7 mum, p < 0.05) dentifrices, and did not differ from water (6.9 +/- 2.0 mum). CONCLUSIONS: The investigated dentifrice reduced enamel loss against acid challenge but had no effect against acid and brushing challenge. CLINICAL RELEVANCE: Little is known regarding the preventive effect of dentifrices indicated for dental erosion. The tested anti-erosive dentifrice was unable to protect enamel when erosion was associated to toothbrushing abrasion.