The overwet phenomenon: An optical, micromorphological study of surface moisture in the acid-conditioned, resin-dentin interface

Purpose: To evaluate the morphological effect of different degrees of surface wetness on "wet bonding" upon the acid-conditioned, resin-dentin interface using an acetone-containing adhesive system (All-Bond 2). Materials and Methods: Dentin surfaces were conditioned with 10% phosphoric acid (20 seconds), washed and air dried (3 seconds) or blot dried. Results: The surfaces were characterized by the formation of an intact layer of resin impregnated dentin. Dentin tubules were sealed with solid cores of primers commonly below which were intratubular primer globules. Excess moisture on the dentin surface resulted in the creation of blister-like spaces at the primer-dentin interface. A layer of resin-impregnated intertubular dentin was present and below such spaces were incompletely sealed tubules. Primer globules were also observed on the dentin surface. The presence of microscopic voids at the primer-dentin interface may offer a morphological explanation for the published decrease in bond strength when this system was applied in the presence of excessive surface moisture.