Purpose: Determining the dentinal tubules occlusion and permeability of desensitized dentin after its treatment with (MSN) slurry alone or combined with calcium phosphate (Ca2po4@MSN)versus (NHAp) suspension. Materials and Methods: eighty sound posterior teeth were extracted for orthodontic purpose. Dentin disks of 1 mm thickness were cut perpendicular to the long axis of the teeth at level of 1 mm above the cemento-enamel junction. All samples were treated with 6% citric acid solution for 2 minutes to stimulate sensitive teeth. The samples were divided into four main groups (30 each) according to the material used either Ca+2and PO4@ MSN slurry, slurry of MSN nanoparticles, NHAp suspension and no treatments a control group. These four groups were further subdivided into two groups according to time to after 1 day and after 4 weeks. In random samples from each group, the samples were evaluated for dentinal tubules occlusion using Environmental Scanning Electron Microscope and for dentin permeability. The samples were photographed using Stereomicroscope. Image analysis software was used for indicating degree of occlusion and the depth of dye penetration. The data were analyzed using two-way ANOVA and Turkey's HSD test. The significance level was set at p ≤ 0.05. Results: There was significant difference observed between Ca2Po4 @MSN nanoparticles and NHAp compared to (MSN alone) group but there was insignificant difference between groups (Ca2Po4@MSN) and (NHAp) in dentinal tubules occlusion and permeability. Conclusion: (Ca2Po4@MSN), MSN alone and NHAp are valuable tools to enhance dentinal tubules occlusion and permeability of desensitizing dentin.