Closing of dentinal tubules by glutardialdehyde treatment, a scanning electron microscopy study

The properties of dentin are strongly influenced by the so-called smear layer. This layer is always present on the dentin surface after cutting, drilling, sawing, etc. The smear layer can be removed by various chemical treatments, such as those of acid etching or ethylenediaminetetraacetic acid (EDTA). These treatments remove the smear layer and open the tubules. In this paper, the effect on the smear layer of human dentin of treatment with a 2% glutardialdehyde (GDA) solution at pH 3.5 for 2 min and a 0.5-M EDTA solution at pH 7.4 for 4 min was investigated by scanning electron microscope (SEM). The dentin samples were dried by air or critical-point drying before SEM photography was employed. The number of open dentin tubules was quantified on micrographs of EDTA- and GDA+EDTA-treated dentin. The results show that the GDA treatment fixed part of the smear layer and the superficial dentin surface in such a way that at least 50% of the tubules remained closed after EDTA treatment. By closing the dentinal tubules, the GDA-fixed layer might have a positive effect on dentin hypersensitivity, root caries, and bonding of composite to dentin.