Efficacy of smear layer removal by cavity cleaning solutions: an atomic force microscopy study

Purpose: To evaluate the efficacy of smear layer removal by cavity cleaning agents by the use of atomic force microscopy (AFM). Methods: Five intact human third molars were sectioned in the coronal portion to obtain dentin disks, which were ground with 600-grit abrasive paper for 10 s. Serial longitudinal sections were made perpendicular to each other to create four specimens, from each tooth. The specimens were divided into four treatment groups: GI, 2% chlorhexidine; GII, calcium hydroxide solution; GIII, 1.23% fluoride solution; and GIV, 37% phosphoric acid. The solutions were applied with a brush for 60 s, with the exception of the 37% phosphoric acid, which was applied for 15 s and rinsed with distilled water for 60 s. The specimens were examined by AFM. Results: All of the specimens in GI and GII showed 100% of the dentin tubules obliterated by the smear layer. However, all of the specimens in GIII and GIV showed 0% of the dentin tubules obliterated by the smear layer. Conclusion: The 1.23% fluoride solution was effective in removing the smear layer and can be used as a cavity cleanser.