Influence of storage humidity on hardness of light-cured glass polyalkenoate cements

The influence of storage in various environments on the hardness of four commercial light-cured glass polyalkenoate cements and one conventional glass polyalkenoate cement was investigated. Specimens with or without light exposure were stored for 7 days in different humidity conditions. A hardness tester with a diamond indenter point was used and Vickers hardness numbers under minor load conditions were determined. Non-light-exposed specimens did not increase in hardness in either dry or wet conditions. Light-exposed specimens became harder with time in dry conditions. Light-exposed specimens stored in wet conditions hardened only slightly. To investigate the effects of humidity, some light-exposed specimens stored first in wet conditions were stored another 7 days in dry conditions. They became as hard as those first stored in dry conditions for 7 days. It is concluded that the hardness of these cements corresponds with the humidity of the storage environment.