The purpose of this clinical trial was to compare the desensitizing effect of 333% NaF paste (the equal parts of NaF/kaolui/glycerin) and two dentin bonding agents applied to dentine, and to observe the changes of dentinal tubules under scanning electron microscope. This study included 14 subjects and 45 vital teeth, of which 36 were experimentally treated group and 9 were non-treated group (5 of non-sensitive group, 4 of non-treated hypersensitive group). To evaluate dentin sensitivity, three clinical tests (tactile, compressed air, ?C water) and a subjective patient assessment were done using 100mm horizontal visual analogue scales before and 30 min., one week after treatment. The replicas prepared with epoxy resin at baseline and one week later were compared under SEM on the changes of dentinal tubules. The results were as follows :
1. NaF paste evoked the moderate discomfort due to´ burnishing forces on hypersensitive dentin.
2. There was significant difference between baseline and one week VAS scores in all treated groups (P(0.01).
3. There was significantly desensitizing effect in dentin bonding agent groups compared with NaF paste group at 31) min. after treatment (P<0.05), but one week later, there was no significant difference among the desensitizing effect of three groups.
4. Under SEM using the replica technique, there was few open dentinal tubules in non-sensitive group, and the number (_ the tubules was higher and the diameters larger in non-treated hypersensitive group than experimentally treated group.
5. The surface of NaF paste group exhibited partial occlusion of the tubular orifices with thin smear-like layer. The surfaces of dentin bonding agent groups were irregularly covered by films of dentin bonding agents.
These results suggest that VAS might to The useful method to assess the level of dentin hypersensitivity and the dentin bonding agents as desensitizing modalities could be positively employed ´ in clinical situation.
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