Dentinal hypersensitivity (DH) is characterized by temporary, sharp-shooting pain arising from exposed dentin in response to different types of stimuli, such as thermal, mechanical, osmotic or chemical elements This study looked the treatment of dentinal hypersensitivity (DH) by utilizing magnetic nanoparticles (MNPs). DH was simulated by creating a class V preparation on an extracted human tooth. 72 samples were divided into two groups. Three different MNPs (100nm, 300nm, 500nm) were applied to the class V preparation. A magnet was placed on the opposing side of the class V preparation for the experimental group. No magnet was used for the control group. All samples were decalcified, sectioned and mounted for visualization of MNPs through light and fluorescent microscopes. The percentage of dentinal tubule penetration of the three different MNP groups was calculated by measuring the total depth of the dentinal tubule from the inner surface of the preparation to the pulp. The second measurement was from the inner surface of the preparation to the depth that the MNPs travelled. Data were analyzed using ANOVA and Tukey's Honestly Significant Difference test. Overall, Smaller magnetic nanoparticles have a significantly higher percentage of dentinal tubule penetration than the larger magnetic nanoparticles with or without an external magnetic field (p≤.0005). There was no significant difference between the percentage of dentinal tubule penetration of 300nm and 500nm in control group. A significantly higher percentage of dentinal tubule penetration was found with application of the external magnetic field (p≤.0005). In conclusion, MNPs could potentially be utilized for DH treatment.