CLOSING OF DENTINAL TUBULES BY GLUTARDIALDEHYDE TREATMENT, A SCANNINGELECTRON-MICROSCOPY STUDY

The properties of dentin are strongly influenced by the so-called smea r layer. This layer is always present on the dentin surface after cutt ing, drilling, sawing, etc. The smear layer can be removed by various chemical treatments, such as those of acid etching or ethylenediaminet etraacetic acid (EDTA). These treatments remove the smear layer and op en 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 investig ated by scanning electron microscope (SEM). The dentin samples were dr ied by air or critical-point drying before SEM photography was employe d. The number of open dentin tubules was quantified on micrographs of EDTA- and GDA + EDTA-treated dentin. The results show that the GDA tre atment fixed part of the smear layer and the superficial dentin surfac e 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.