SEM Observation of Human Enamel and Resin Tag Formation After Phosphoric Acid Etching : Influence of Saliva Contamination

Abstract

The objectives of this study were to observe the surface appearance as well as resin tag formation on acid-etched human enamel using field-emission scanning microscopy (FE-SEM) and to study the effects of saliva contamination and repeat etching. Phosphoric acid etching produced a finely roughened enamel surface with random arrangement of enamel crystals. Dissolution of both enamel prisms and peripheries was observed. FE-SEM observation reveals a large amount of remaining contaminated saliva on the etched enamel and subsequently no resin tag formation. Repeat etching after saliva contamination incompletely removed the contaminated saliva and produced less density of resin tags. The results of SEM observation may provide an explanation for the results of shear bond strengths ; that is, a large amount of contaminated saliva remaining on the etched enamel surface and incomplete removal of contaminated saliva after repeat etching result in the decrease of shear bond strength of 4-META/MMA-TBB resin to enamel.