Fig. 3

SEM images of dentin specimen surfaces and longitudinal sections before and after treatments/post-treatment. Magnifications: × 750 (left), × 10,000 (middle) and × 5000 (right). a1–a3 SEM image obtained after acid etching in 35% phosphoric acid for 30 s, showing that the dentinal tubules are completely open and that the inside of the tubules is empty. b1–b3 SEM image obtained after GLU treatment in group 1, showing that the dentinal tubules are completely open and that the collagen mesh of the demineralized dentin presumably has a certain degree of crosslinking by glutaraldehyde, but has not collapsed. c1–c3 SEM image obtained after GLU treatment in group 2, showing that, under the effect of glutaraldehyde, nearly half of the tubule orifices are occluded due to the precipitation of the serum albumin remaining in tubules. Multiple reticular septa are observed in the lumen of the dentinal tubules. d1–d3 SEM image obtained after RD treatment in group 3, showing that most tubule orifices are occluded by deposits and that the diameter of the tubules is reduced. A small amount of granular deposit is observed on the wall of tubules. e1–e3 SEM image obtained after post-treatment by 24-h AS immersion in group 3, showing that most tubule orifices are exposed and that the amount of deposit inside the tubules has reduced. Some crystalline substances are observed inside the tubules. GLU, GLUMA Desensitizer; RD, Remineralizing and Desensitizing gel; SEM, scanning electron microscopy