This study aims to evaluate the effectiveness in reducing dentine permeability of three different toothpastes comparing with a sodium fluoride one. Dentine permeability was measured by a fluid filtration system. Dentin discs were randomized in four experimental groups and treated with different commercial toothpastes, as it follows. Group A: Sensodyne® Rapid, with strontium acetate; group B: Elmex Sensitive ProfessionalTM, with arginine and 450 ppm monofluoro-phosphate; group C: Colgate Total Advanced®, with 1450 ppm NaF; group D: AZ Pro-Expert®, with 1100 ppm SnF2. After brushing specimens of each groups were assigned to two subgroups and: 1) stored in artificial saliva (2 h) and treated with 6% citric acid for 1 min; 2) stored in artificial saliva for 24 h. SEM analysis was performed to investigate dentinal tubules occlusion of acid treated and stored in artificial saliva samples. Dentin permeability proved affected by dentifrice treatments. The toothpastes specifically formulated for hypersensitivity showed significant effects concerning decrease of dentine permeability. SEM observations demonstrated the presence of dentifrice particles on dentin surface and inside dentin tubules. Stannous fluoride treated samples exhibited the greater tubules occlusion.