Purpose: The present study was carried out to assess and compare the efficacy of OliNano Seal (OS) and Curodont D'Senz (CS) in the treatment of dentin hypersensitivity (DH) and the reduction of dentin permeability. Materials and Methods: The current study was a single-blinded, clinical trial and in vitro study using OS and CS in the treatment of DH. A total of 72 hypersensitive teeth were selected from 18 patients and randomly divided into two groups. Prior to the desensitizing agent's application (the baseline), as well as immediately, 2 weeks, 4 weeks, and 3 months afterward, the evaluated materials were applied. Patients were instructed to use the visual analogue scale (VAS) to score their perception of tactile, air, and cold stimuli (VAS). In total, 90 samples were used for the evaluation, and they were randomly divided into two main groups: group A1, which had the smear layer fully removed, and group A2, which had the smear layer partially removed. According to the desensitizing agent used, each group was divided into three subgroups: OS, CS, and the control group that was left untreated. The results of the dentin permeability test were analyzed using the analysis of variance test, whereas the pain scores were analyzed using the Mann–Whitney test. Results: The study showed that there was a high statistically significant difference between pain scores prior to and after the application of both tested desensitizing agents. Permeability results revealed a high statistically significant difference between the study groups, with the lowest statistically significant mean depth of dye penetration found with OS-treated samples. Conclusion: OS and CS were both effective in the treatment of DH and the reduction of dentin permeability, with OS being more effective within 1 week and sustained up to 3 months. [ABSTRACT FROM AUTHOR]