An adequate and homogeneous cure of light-activated restorative material is very important for improvement of marginal adaptation and prevention of marginal lcakage, secondary caries and pulpal irritation ad well as expressing natural physical
property
of that material. The purpose of this study was to evaluate the change of surface hardness and cure uniformity of light-activated glass ionomer cements. Restorative(Fuji II LC. Virtremer) and lining (Baseline VIC, Vitrebond) light-activated glass
ionomer cements were investigated for this study. The surface hardness of the top and bottom surfaces and cure uniformity of each 1 mm, 1.5mm, 2mm, 2.5mm & 3mm in the thickness of specimen were measured immediately, at 1 hour, 24 hours and 1 week
after
light activation The surface hardness change and cure uniformity of all the specimens were measured by Knoop hardness tester.
@ES The results were as follows:
@EN 1. The surface hardness of top and bottom surfaces in all groups increased with time (p<0.01).
2. Both top and bottom surfaces hardness of Vitrebond group measured immediately after light-activation were significantly lower than those of the other groups(p<0.01).
3. The surface hardness of top and bottom surfaces of restorative light-activated glass ionomer cements was higher than those of lining materials at 1 week(p<0.01).
4. Surface hardness of Vitremer group decreased as the specimen thickness increased. except top and bottom surfaces hardness of the specimen at 1 week(p<0.01). There was no significant difference in the surface hardness of Fuji II LC with
changes
in
the thickness except bottom surface hardness of specimen at 24 hours and 1 week(p>0.05).
5. Surface hardness of Vitrebond group significantly decreased and the specimen thickness increased(p<0.01). there was no significant difference in the surface hardness of Baseline VLC group with changes in the thickness except bottom surface
hardness
of specimen measured immediately after light-activation(p>0.05).
6. The hardness ratio of top against botoom surface in all groups decreased with time (p<0.05).
7. There was no significant difference in the hardness ratio of top against surface with changes of the thickness except Vitrebond group, 24 hours and 1 week of viremer group and 1 week of Baselin VLC group (p<0.05).
These results suggest that surface hardnesses of restorative light-activated glass ionomer cements were higher than those of lining light-activated materials. In all group, the surface hardness and cure uniformity continuously increased with
time.
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