https://www.selleckchem.com/products/ins018-055-ism001-055.html Objectives This study aimed to assess the dentin adaptability of a certain type of fluoride varnish, as a novel root canal sealer, in comparison with AH-Plus sealer. Materials and Methods Twenty-four extracted single-rooted, single-canal human permanent teeth with straight and fully formed roots and no internal calcification, resorption or cracks, were selected and decoronated such that the remaining root length was 14 mm in all teeth. Root canals were prepared using the Mtwo rotary file system according to the manufacturer's instructions and filled with gutta-percha and either AH-Plus (n=12) or fluoride varnish (n=12) via the lateral compaction technique. Each root was then sectioned at 4 and 8 mm distances from the apex for evaluation under a scanning electron microscope (SEM). The gap size between the sealer and dentin was measured. Statistical analysis was performed using the Kolmogorov-Smirnov test and t-test with the significance level set at 0.05. Results The mean gap size was 14.407±1.402 μm and 8.342±0.694 μm in the roots obturated with AH-Plus and fluoride varnish sealers, respectively. The t-test revealed a statistically significant difference (P less then 0.001) in this regard between the two groups. Conclusion Fluoride varnish, as a root canal sealer, has a superior adaptation to dentinal canal walls compared to the AH-Plus sealer. Copyright© Dental Research Center, Tehran University of Medical Sciences.Pain is a constant symptom of dentin hypersensitivity (DH), which is a common condition that affects daily life and negatively affects the quality of life (QoL). Diagnosis and outcome measurements following the treatment of the disease require accurate pain assessment. The definition of pain underlies the complexity of its measurement as different factors modulate daily experience. The reproducibility of the prescribed stimuli for inducing DH pain clinically is difficult to achieve. This pai