Abstract
The authors previously reported that when nano-hydroxyapatite (nano-HA) was applied to artificial demineralized root canal dentin inside the root canal, the nano-HA particles naturally penetrated into the root canal dentin within approximately 24 hours, and the root canal dentin rehardened to largely the same degree of hardness as undecalcified dentin. However, the kinds of changes that take place in rehardened artificial demineralized root canal dentin over time remain unclear and no published reports have addressed this issue. Therefore, we investigated the time-dependent changes that take place in artificial demineralized root canal dentin that has been rehardened by applying nano-HA. The results indicated that over time, the hardness of the rehardened artificial demineralized root canal dentin tends to increase.The fact that there was no change in the hardness of the rehardened demineralized dentin over the long term when the dentin was rehardened to the hardness of undecalcified dentin using nano-HA suggests that it may be possible to conserve demineralized root canal dentin, which must normally be removed.
